Thomas Gleixner | 2874c5f | 2019-05-27 08:55:01 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
James Morris | 3e1c251 | 2009-10-20 13:48:33 +0900 | [diff] [blame] | 2 | /* Common capabilities, needed by capability.o. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | */ |
| 4 | |
Randy.Dunlap | c59ede7 | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 5 | #include <linux/capability.h> |
Eric Paris | 3fc689e | 2008-11-11 21:48:18 +1100 | [diff] [blame] | 6 | #include <linux/audit.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | #include <linux/init.h> |
| 8 | #include <linux/kernel.h> |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 9 | #include <linux/lsm_hooks.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | #include <linux/file.h> |
| 11 | #include <linux/mm.h> |
| 12 | #include <linux/mman.h> |
| 13 | #include <linux/pagemap.h> |
| 14 | #include <linux/swap.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <linux/skbuff.h> |
| 16 | #include <linux/netlink.h> |
| 17 | #include <linux/ptrace.h> |
| 18 | #include <linux/xattr.h> |
| 19 | #include <linux/hugetlb.h> |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 20 | #include <linux/mount.h> |
Serge E. Hallyn | b460cbc | 2007-10-18 23:39:52 -0700 | [diff] [blame] | 21 | #include <linux/sched.h> |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 22 | #include <linux/prctl.h> |
| 23 | #include <linux/securebits.h> |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 24 | #include <linux/user_namespace.h> |
Al Viro | 4040153 | 2012-02-13 03:58:52 +0000 | [diff] [blame] | 25 | #include <linux/binfmts.h> |
Jonghwan Choi | 51b79be | 2012-04-18 17:23:04 -0400 | [diff] [blame] | 26 | #include <linux/personality.h> |
Andrew Morgan | 72c2d58 | 2007-10-18 03:05:59 -0700 | [diff] [blame] | 27 | |
Serge E. Hallyn | b5f22a5 | 2009-04-02 18:47:14 -0500 | [diff] [blame] | 28 | /* |
| 29 | * If a non-root user executes a setuid-root binary in |
| 30 | * !secure(SECURE_NOROOT) mode, then we raise capabilities. |
| 31 | * However if fE is also set, then the intent is for only |
| 32 | * the file capabilities to be applied, and the setuid-root |
| 33 | * bit is left on either to change the uid (plausible) or |
| 34 | * to get full privilege on a kernel without file capabilities |
| 35 | * support. So in that case we do not raise capabilities. |
| 36 | * |
| 37 | * Warn if that happens, once per boot. |
| 38 | */ |
David Howells | d762746 | 2010-08-17 23:52:56 +0100 | [diff] [blame] | 39 | static void warn_setuid_and_fcaps_mixed(const char *fname) |
Serge E. Hallyn | b5f22a5 | 2009-04-02 18:47:14 -0500 | [diff] [blame] | 40 | { |
| 41 | static int warned; |
| 42 | if (!warned) { |
| 43 | printk(KERN_INFO "warning: `%s' has both setuid-root and" |
| 44 | " effective capabilities. Therefore not raising all" |
| 45 | " capabilities.\n", fname); |
| 46 | warned = 1; |
| 47 | } |
| 48 | } |
| 49 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 50 | /** |
| 51 | * cap_capable - Determine whether a task has a particular effective capability |
David Howells | 3699c53 | 2009-01-06 22:27:01 +0000 | [diff] [blame] | 52 | * @cred: The credentials to use |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 53 | * @targ_ns: The user namespace in which we need the capability |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 54 | * @cap: The capability to check for |
Micah Morton | e88ed48 | 2019-02-25 14:17:10 -0800 | [diff] [blame] | 55 | * @opts: Bitmask of options defined in include/linux/security.h |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 56 | * |
| 57 | * Determine whether the nominated task has the specified capability amongst |
| 58 | * its effective set, returning 0 if it does, -ve if it does not. |
| 59 | * |
David Howells | 3699c53 | 2009-01-06 22:27:01 +0000 | [diff] [blame] | 60 | * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable() |
| 61 | * and has_capability() functions. That is, it has the reverse semantics: |
| 62 | * cap_has_capability() returns 0 when a task has a capability, but the |
| 63 | * kernel's capable() and has_capability() returns 1 for this case. |
Andrew G. Morgan | a6dbb1e | 2008-01-21 17:18:30 -0800 | [diff] [blame] | 64 | */ |
Eric Paris | 6a9de49 | 2012-01-03 12:25:14 -0500 | [diff] [blame] | 65 | int cap_capable(const struct cred *cred, struct user_namespace *targ_ns, |
Micah Morton | c1a85a0 | 2019-01-07 16:10:53 -0800 | [diff] [blame] | 66 | int cap, unsigned int opts) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | { |
Eric W. Biederman | 520d9ea | 2012-12-13 18:06:40 -0800 | [diff] [blame] | 68 | struct user_namespace *ns = targ_ns; |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 69 | |
Eric W. Biederman | 520d9ea | 2012-12-13 18:06:40 -0800 | [diff] [blame] | 70 | /* See if cred has the capability in the target user namespace |
| 71 | * by examining the target user namespace and all of the target |
| 72 | * user namespace's parents. |
| 73 | */ |
| 74 | for (;;) { |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 75 | /* Do we have the necessary capabilities? */ |
Eric W. Biederman | 520d9ea | 2012-12-13 18:06:40 -0800 | [diff] [blame] | 76 | if (ns == cred->user_ns) |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 77 | return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; |
| 78 | |
Kirill Tkhai | 64db4c7 | 2017-05-02 20:11:52 +0300 | [diff] [blame] | 79 | /* |
| 80 | * If we're already at a lower level than we're looking for, |
| 81 | * we're done searching. |
| 82 | */ |
| 83 | if (ns->level <= cred->user_ns->level) |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 84 | return -EPERM; |
| 85 | |
Eric W. Biederman | 520d9ea | 2012-12-13 18:06:40 -0800 | [diff] [blame] | 86 | /* |
| 87 | * The owner of the user namespace in the parent of the |
| 88 | * user namespace has all caps. |
| 89 | */ |
| 90 | if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) |
| 91 | return 0; |
| 92 | |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 93 | /* |
Eric W. Biederman | 520d9ea | 2012-12-13 18:06:40 -0800 | [diff] [blame] | 94 | * If you have a capability in a parent user ns, then you have |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 95 | * it over all children user namespaces as well. |
| 96 | */ |
Eric W. Biederman | 520d9ea | 2012-12-13 18:06:40 -0800 | [diff] [blame] | 97 | ns = ns->parent; |
Serge E. Hallyn | 3486740 | 2011-03-23 16:43:17 -0700 | [diff] [blame] | 98 | } |
| 99 | |
| 100 | /* We never get here */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | } |
| 102 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 103 | /** |
| 104 | * cap_settime - Determine whether the current process may set the system clock |
| 105 | * @ts: The time to set |
| 106 | * @tz: The timezone to set |
| 107 | * |
| 108 | * Determine whether the current process may set the system clock and timezone |
| 109 | * information, returning 0 if permission granted, -ve if denied. |
| 110 | */ |
Baolin Wang | 457db29 | 2016-04-08 14:02:11 +0800 | [diff] [blame] | 111 | int cap_settime(const struct timespec64 *ts, const struct timezone *tz) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | { |
| 113 | if (!capable(CAP_SYS_TIME)) |
| 114 | return -EPERM; |
| 115 | return 0; |
| 116 | } |
| 117 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 118 | /** |
Ingo Molnar | 9e48858 | 2009-05-07 19:26:19 +1000 | [diff] [blame] | 119 | * cap_ptrace_access_check - Determine whether the current process may access |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 120 | * another |
| 121 | * @child: The process to be accessed |
| 122 | * @mode: The mode of attachment. |
| 123 | * |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 124 | * If we are in the same or an ancestor user_ns and have all the target |
| 125 | * task's capabilities, then ptrace access is allowed. |
| 126 | * If we have the ptrace capability to the target user_ns, then ptrace |
| 127 | * access is allowed. |
| 128 | * Else denied. |
| 129 | * |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 130 | * Determine whether a process may access another, returning 0 if permission |
| 131 | * granted, -ve if denied. |
| 132 | */ |
Ingo Molnar | 9e48858 | 2009-05-07 19:26:19 +1000 | [diff] [blame] | 133 | int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | { |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 135 | int ret = 0; |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 136 | const struct cred *cred, *child_cred; |
Jann Horn | caaee62 | 2016-01-20 15:00:04 -0800 | [diff] [blame] | 137 | const kernel_cap_t *caller_caps; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 138 | |
| 139 | rcu_read_lock(); |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 140 | cred = current_cred(); |
| 141 | child_cred = __task_cred(child); |
Jann Horn | caaee62 | 2016-01-20 15:00:04 -0800 | [diff] [blame] | 142 | if (mode & PTRACE_MODE_FSCREDS) |
| 143 | caller_caps = &cred->cap_effective; |
| 144 | else |
| 145 | caller_caps = &cred->cap_permitted; |
Eric W. Biederman | c4a4d60 | 2011-11-16 23:15:31 -0800 | [diff] [blame] | 146 | if (cred->user_ns == child_cred->user_ns && |
Jann Horn | caaee62 | 2016-01-20 15:00:04 -0800 | [diff] [blame] | 147 | cap_issubset(child_cred->cap_permitted, *caller_caps)) |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 148 | goto out; |
Eric W. Biederman | c4a4d60 | 2011-11-16 23:15:31 -0800 | [diff] [blame] | 149 | if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 150 | goto out; |
| 151 | ret = -EPERM; |
| 152 | out: |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 153 | rcu_read_unlock(); |
| 154 | return ret; |
David Howells | 5cd9c58 | 2008-08-14 11:37:28 +0100 | [diff] [blame] | 155 | } |
| 156 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 157 | /** |
| 158 | * cap_ptrace_traceme - Determine whether another process may trace the current |
| 159 | * @parent: The task proposed to be the tracer |
| 160 | * |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 161 | * If parent is in the same or an ancestor user_ns and has all current's |
| 162 | * capabilities, then ptrace access is allowed. |
| 163 | * If parent has the ptrace capability to current's user_ns, then ptrace |
| 164 | * access is allowed. |
| 165 | * Else denied. |
| 166 | * |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 167 | * Determine whether the nominated task is permitted to trace the current |
| 168 | * process, returning 0 if permission is granted, -ve if denied. |
| 169 | */ |
David Howells | 5cd9c58 | 2008-08-14 11:37:28 +0100 | [diff] [blame] | 170 | int cap_ptrace_traceme(struct task_struct *parent) |
| 171 | { |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 172 | int ret = 0; |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 173 | const struct cred *cred, *child_cred; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 174 | |
| 175 | rcu_read_lock(); |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 176 | cred = __task_cred(parent); |
| 177 | child_cred = current_cred(); |
Eric W. Biederman | c4a4d60 | 2011-11-16 23:15:31 -0800 | [diff] [blame] | 178 | if (cred->user_ns == child_cred->user_ns && |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 179 | cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) |
| 180 | goto out; |
Eric W. Biederman | c4a4d60 | 2011-11-16 23:15:31 -0800 | [diff] [blame] | 181 | if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) |
Serge E. Hallyn | 8409cca | 2011-03-23 16:43:20 -0700 | [diff] [blame] | 182 | goto out; |
| 183 | ret = -EPERM; |
| 184 | out: |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 185 | rcu_read_unlock(); |
| 186 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 187 | } |
| 188 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 189 | /** |
| 190 | * cap_capget - Retrieve a task's capability sets |
| 191 | * @target: The task from which to retrieve the capability sets |
| 192 | * @effective: The place to record the effective set |
| 193 | * @inheritable: The place to record the inheritable set |
| 194 | * @permitted: The place to record the permitted set |
| 195 | * |
| 196 | * This function retrieves the capabilities of the nominated task and returns |
| 197 | * them to the caller. |
| 198 | */ |
| 199 | int cap_capget(struct task_struct *target, kernel_cap_t *effective, |
| 200 | kernel_cap_t *inheritable, kernel_cap_t *permitted) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 201 | { |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 202 | const struct cred *cred; |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 203 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | /* Derived from kernel/capability.c:sys_capget. */ |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 205 | rcu_read_lock(); |
| 206 | cred = __task_cred(target); |
David Howells | b6dff3e | 2008-11-14 10:39:16 +1100 | [diff] [blame] | 207 | *effective = cred->cap_effective; |
| 208 | *inheritable = cred->cap_inheritable; |
| 209 | *permitted = cred->cap_permitted; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 210 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | return 0; |
| 212 | } |
| 213 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 214 | /* |
| 215 | * Determine whether the inheritable capabilities are limited to the old |
| 216 | * permitted set. Returns 1 if they are limited, 0 if they are not. |
| 217 | */ |
Andrew Morgan | 72c2d58 | 2007-10-18 03:05:59 -0700 | [diff] [blame] | 218 | static inline int cap_inh_is_capped(void) |
| 219 | { |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 220 | /* they are so limited unless the current task has the CAP_SETPCAP |
| 221 | * capability |
Andrew Morgan | 72c2d58 | 2007-10-18 03:05:59 -0700 | [diff] [blame] | 222 | */ |
Eric W. Biederman | c4a4d60 | 2011-11-16 23:15:31 -0800 | [diff] [blame] | 223 | if (cap_capable(current_cred(), current_cred()->user_ns, |
Micah Morton | c1a85a0 | 2019-01-07 16:10:53 -0800 | [diff] [blame] | 224 | CAP_SETPCAP, CAP_OPT_NONE) == 0) |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 225 | return 0; |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 226 | return 1; |
Andrew Morgan | 72c2d58 | 2007-10-18 03:05:59 -0700 | [diff] [blame] | 227 | } |
| 228 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 229 | /** |
| 230 | * cap_capset - Validate and apply proposed changes to current's capabilities |
| 231 | * @new: The proposed new credentials; alterations should be made here |
| 232 | * @old: The current task's current credentials |
| 233 | * @effective: A pointer to the proposed new effective capabilities set |
| 234 | * @inheritable: A pointer to the proposed new inheritable capabilities set |
| 235 | * @permitted: A pointer to the proposed new permitted capabilities set |
| 236 | * |
| 237 | * This function validates and applies a proposed mass change to the current |
| 238 | * process's capability sets. The changes are made to the proposed new |
| 239 | * credentials, and assuming no error, will be committed by the caller of LSM. |
| 240 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 241 | int cap_capset(struct cred *new, |
| 242 | const struct cred *old, |
| 243 | const kernel_cap_t *effective, |
| 244 | const kernel_cap_t *inheritable, |
| 245 | const kernel_cap_t *permitted) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | { |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 247 | if (cap_inh_is_capped() && |
| 248 | !cap_issubset(*inheritable, |
| 249 | cap_combine(old->cap_inheritable, |
| 250 | old->cap_permitted))) |
Andrew Morgan | 72c2d58 | 2007-10-18 03:05:59 -0700 | [diff] [blame] | 251 | /* incapable of using this inheritable set */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | return -EPERM; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 253 | |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 254 | if (!cap_issubset(*inheritable, |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 255 | cap_combine(old->cap_inheritable, |
| 256 | old->cap_bset))) |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 257 | /* no new pI capabilities outside bounding set */ |
| 258 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 259 | |
| 260 | /* verify restrictions on target's new Permitted set */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 261 | if (!cap_issubset(*permitted, old->cap_permitted)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 262 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 263 | |
| 264 | /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 265 | if (!cap_issubset(*effective, *permitted)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 266 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 268 | new->cap_effective = *effective; |
| 269 | new->cap_inheritable = *inheritable; |
| 270 | new->cap_permitted = *permitted; |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 271 | |
| 272 | /* |
| 273 | * Mask off ambient bits that are no longer both permitted and |
| 274 | * inheritable. |
| 275 | */ |
| 276 | new->cap_ambient = cap_intersect(new->cap_ambient, |
| 277 | cap_intersect(*permitted, |
| 278 | *inheritable)); |
| 279 | if (WARN_ON(!cap_ambient_invariant_ok(new))) |
| 280 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 281 | return 0; |
| 282 | } |
| 283 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 284 | /** |
| 285 | * cap_inode_need_killpriv - Determine if inode change affects privileges |
| 286 | * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV |
| 287 | * |
| 288 | * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV |
| 289 | * affects the security markings on that inode, and if it is, should |
Stefan Berger | ab5348c | 2017-07-26 22:27:05 -0400 | [diff] [blame] | 290 | * inode_killpriv() be invoked or the change rejected. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 291 | * |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 292 | * Return: 1 if security.capability has a value, meaning inode_killpriv() |
Stefan Berger | ab5348c | 2017-07-26 22:27:05 -0400 | [diff] [blame] | 293 | * is required, 0 otherwise, meaning inode_killpriv() is not required. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 294 | */ |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 295 | int cap_inode_need_killpriv(struct dentry *dentry) |
| 296 | { |
David Howells | c6f493d | 2015-03-17 22:26:22 +0000 | [diff] [blame] | 297 | struct inode *inode = d_backing_inode(dentry); |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 298 | int error; |
| 299 | |
Andreas Gruenbacher | 5d6c319 | 2016-09-29 17:48:42 +0200 | [diff] [blame] | 300 | error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); |
| 301 | return error > 0; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 302 | } |
| 303 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 304 | /** |
| 305 | * cap_inode_killpriv - Erase the security markings on an inode |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 306 | * |
| 307 | * @mnt_userns: user namespace of the mount the inode was found from |
| 308 | * @dentry: The inode/dentry to alter |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 309 | * |
| 310 | * Erase the privilege-enhancing security markings on an inode. |
| 311 | * |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 312 | * If the inode has been found through an idmapped mount the user namespace of |
| 313 | * the vfsmount must be passed through @mnt_userns. This function will then |
| 314 | * take care to map the inode according to @mnt_userns before checking |
| 315 | * permissions. On non-idmapped mounts or if permission checking is to be |
| 316 | * performed on the raw inode simply passs init_user_ns. |
| 317 | * |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 318 | * Return: 0 if successful, -ve on error. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 319 | */ |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 320 | int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 321 | { |
Andreas Gruenbacher | 5d6c319 | 2016-09-29 17:48:42 +0200 | [diff] [blame] | 322 | int error; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 323 | |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 324 | error = __vfs_removexattr(mnt_userns, dentry, XATTR_NAME_CAPS); |
Andreas Gruenbacher | 5d6c319 | 2016-09-29 17:48:42 +0200 | [diff] [blame] | 325 | if (error == -EOPNOTSUPP) |
| 326 | error = 0; |
| 327 | return error; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 328 | } |
| 329 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 330 | static bool rootid_owns_currentns(kuid_t kroot) |
| 331 | { |
| 332 | struct user_namespace *ns; |
| 333 | |
| 334 | if (!uid_valid(kroot)) |
| 335 | return false; |
| 336 | |
| 337 | for (ns = current_user_ns(); ; ns = ns->parent) { |
| 338 | if (from_kuid(ns, kroot) == 0) |
| 339 | return true; |
| 340 | if (ns == &init_user_ns) |
| 341 | break; |
| 342 | } |
| 343 | |
| 344 | return false; |
| 345 | } |
| 346 | |
| 347 | static __u32 sansflags(__u32 m) |
| 348 | { |
| 349 | return m & ~VFS_CAP_FLAGS_EFFECTIVE; |
| 350 | } |
| 351 | |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 352 | static bool is_v2header(size_t size, const struct vfs_cap_data *cap) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 353 | { |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 354 | if (size != XATTR_CAPS_SZ_2) |
| 355 | return false; |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 356 | return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_2; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 357 | } |
| 358 | |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 359 | static bool is_v3header(size_t size, const struct vfs_cap_data *cap) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 360 | { |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 361 | if (size != XATTR_CAPS_SZ_3) |
| 362 | return false; |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 363 | return sansflags(le32_to_cpu(cap->magic_etc)) == VFS_CAP_REVISION_3; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 364 | } |
| 365 | |
| 366 | /* |
| 367 | * getsecurity: We are called for security.* before any attempt to read the |
| 368 | * xattr from the inode itself. |
| 369 | * |
| 370 | * This gives us a chance to read the on-disk value and convert it. If we |
| 371 | * return -EOPNOTSUPP, then vfs_getxattr() will call the i_op handler. |
| 372 | * |
| 373 | * Note we are not called by vfs_getxattr_alloc(), but that is only called |
| 374 | * by the integrity subsystem, which really wants the unconverted values - |
| 375 | * so that's good. |
| 376 | */ |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 377 | int cap_inode_getsecurity(struct user_namespace *mnt_userns, |
| 378 | struct inode *inode, const char *name, void **buffer, |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 379 | bool alloc) |
| 380 | { |
| 381 | int size, ret; |
| 382 | kuid_t kroot; |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 383 | u32 nsmagic, magic; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 384 | uid_t root, mappedroot; |
| 385 | char *tmpbuf = NULL; |
| 386 | struct vfs_cap_data *cap; |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 387 | struct vfs_ns_cap_data *nscap = NULL; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 388 | struct dentry *dentry; |
| 389 | struct user_namespace *fs_ns; |
| 390 | |
| 391 | if (strcmp(name, "capability") != 0) |
| 392 | return -EOPNOTSUPP; |
| 393 | |
Eddie.Horng | 355139a | 2018-07-20 15:30:00 +0800 | [diff] [blame] | 394 | dentry = d_find_any_alias(inode); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 395 | if (!dentry) |
| 396 | return -EINVAL; |
| 397 | |
| 398 | size = sizeof(struct vfs_ns_cap_data); |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 399 | ret = (int)vfs_getxattr_alloc(mnt_userns, dentry, XATTR_NAME_CAPS, |
Tycho Andersen | c7c7a1a1 | 2021-01-21 14:19:28 +0100 | [diff] [blame] | 400 | &tmpbuf, size, GFP_NOFS); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 401 | dput(dentry); |
| 402 | |
Arnd Bergmann | 82e5d8c | 2021-03-22 17:02:41 +0100 | [diff] [blame] | 403 | if (ret < 0 || !tmpbuf) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 404 | return ret; |
| 405 | |
| 406 | fs_ns = inode->i_sb->s_user_ns; |
| 407 | cap = (struct vfs_cap_data *) tmpbuf; |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 408 | if (is_v2header((size_t) ret, cap)) { |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 409 | root = 0; |
| 410 | } else if (is_v3header((size_t) ret, cap)) { |
| 411 | nscap = (struct vfs_ns_cap_data *) tmpbuf; |
| 412 | root = le32_to_cpu(nscap->rootid); |
| 413 | } else { |
| 414 | size = -EINVAL; |
| 415 | goto out_free; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 416 | } |
| 417 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 418 | kroot = make_kuid(fs_ns, root); |
| 419 | |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 420 | /* If this is an idmapped mount shift the kuid. */ |
| 421 | kroot = kuid_into_mnt(mnt_userns, kroot); |
| 422 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 423 | /* If the root kuid maps to a valid uid in current ns, then return |
| 424 | * this as a nscap. */ |
| 425 | mappedroot = from_kuid(current_user_ns(), kroot); |
| 426 | if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) { |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 427 | size = sizeof(struct vfs_ns_cap_data); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 428 | if (alloc) { |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 429 | if (!nscap) { |
| 430 | /* v2 -> v3 conversion */ |
| 431 | nscap = kzalloc(size, GFP_ATOMIC); |
| 432 | if (!nscap) { |
| 433 | size = -ENOMEM; |
| 434 | goto out_free; |
| 435 | } |
| 436 | nsmagic = VFS_CAP_REVISION_3; |
| 437 | magic = le32_to_cpu(cap->magic_etc); |
| 438 | if (magic & VFS_CAP_FLAGS_EFFECTIVE) |
| 439 | nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; |
| 440 | memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); |
| 441 | nscap->magic_etc = cpu_to_le32(nsmagic); |
| 442 | } else { |
| 443 | /* use allocated v3 buffer */ |
| 444 | tmpbuf = NULL; |
| 445 | } |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 446 | nscap->rootid = cpu_to_le32(mappedroot); |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 447 | *buffer = nscap; |
| 448 | } |
| 449 | goto out_free; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 450 | } |
| 451 | |
| 452 | if (!rootid_owns_currentns(kroot)) { |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 453 | size = -EOVERFLOW; |
| 454 | goto out_free; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 455 | } |
| 456 | |
| 457 | /* This comes from a parent namespace. Return as a v2 capability */ |
| 458 | size = sizeof(struct vfs_cap_data); |
| 459 | if (alloc) { |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 460 | if (nscap) { |
| 461 | /* v3 -> v2 conversion */ |
| 462 | cap = kzalloc(size, GFP_ATOMIC); |
| 463 | if (!cap) { |
| 464 | size = -ENOMEM; |
| 465 | goto out_free; |
| 466 | } |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 467 | magic = VFS_CAP_REVISION_2; |
| 468 | nsmagic = le32_to_cpu(nscap->magic_etc); |
| 469 | if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE) |
| 470 | magic |= VFS_CAP_FLAGS_EFFECTIVE; |
| 471 | memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); |
| 472 | cap->magic_etc = cpu_to_le32(magic); |
Tetsuo Handa | 1f57817 | 2018-04-10 15:15:16 +0900 | [diff] [blame] | 473 | } else { |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 474 | /* use unconverted v2 */ |
| 475 | tmpbuf = NULL; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 476 | } |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 477 | *buffer = cap; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 478 | } |
Miklos Szeredi | f2b00be | 2021-01-28 10:22:48 +0100 | [diff] [blame] | 479 | out_free: |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 480 | kfree(tmpbuf); |
| 481 | return size; |
| 482 | } |
| 483 | |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 484 | /** |
| 485 | * rootid_from_xattr - translate root uid of vfs caps |
| 486 | * |
| 487 | * @value: vfs caps value which may be modified by this function |
| 488 | * @size: size of @ivalue |
| 489 | * @task_ns: user namespace of the caller |
| 490 | * @mnt_userns: user namespace of the mount the inode was found from |
| 491 | * |
| 492 | * If the inode has been found through an idmapped mount the user namespace of |
| 493 | * the vfsmount must be passed through @mnt_userns. This function will then |
| 494 | * take care to map the inode according to @mnt_userns before checking |
| 495 | * permissions. On non-idmapped mounts or if permission checking is to be |
| 496 | * performed on the raw inode simply passs init_user_ns. |
| 497 | */ |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 498 | static kuid_t rootid_from_xattr(const void *value, size_t size, |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 499 | struct user_namespace *task_ns, |
| 500 | struct user_namespace *mnt_userns) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 501 | { |
| 502 | const struct vfs_ns_cap_data *nscap = value; |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 503 | kuid_t rootkid; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 504 | uid_t rootid = 0; |
| 505 | |
| 506 | if (size == XATTR_CAPS_SZ_3) |
| 507 | rootid = le32_to_cpu(nscap->rootid); |
| 508 | |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 509 | rootkid = make_kuid(task_ns, rootid); |
| 510 | return kuid_from_mnt(mnt_userns, rootkid); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 511 | } |
| 512 | |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 513 | static bool validheader(size_t size, const struct vfs_cap_data *cap) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 514 | { |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 515 | return is_v2header(size, cap) || is_v3header(size, cap); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 516 | } |
| 517 | |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 518 | /** |
| 519 | * cap_convert_nscap - check vfs caps |
| 520 | * |
| 521 | * @mnt_userns: user namespace of the mount the inode was found from |
| 522 | * @dentry: used to retrieve inode to check permissions on |
| 523 | * @ivalue: vfs caps value which may be modified by this function |
| 524 | * @size: size of @ivalue |
| 525 | * |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 526 | * User requested a write of security.capability. If needed, update the |
| 527 | * xattr to change from v2 to v3, or to fixup the v3 rootid. |
| 528 | * |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 529 | * If the inode has been found through an idmapped mount the user namespace of |
| 530 | * the vfsmount must be passed through @mnt_userns. This function will then |
| 531 | * take care to map the inode according to @mnt_userns before checking |
| 532 | * permissions. On non-idmapped mounts or if permission checking is to be |
| 533 | * performed on the raw inode simply passs init_user_ns. |
| 534 | * |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 535 | * Return: On success, return the new size; on error, return < 0. |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 536 | */ |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 537 | int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry, |
| 538 | const void **ivalue, size_t size) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 539 | { |
| 540 | struct vfs_ns_cap_data *nscap; |
| 541 | uid_t nsrootid; |
| 542 | const struct vfs_cap_data *cap = *ivalue; |
| 543 | __u32 magic, nsmagic; |
| 544 | struct inode *inode = d_backing_inode(dentry); |
| 545 | struct user_namespace *task_ns = current_user_ns(), |
Eric W. Biederman | 3b0c2d3 | 2021-03-12 15:07:09 -0600 | [diff] [blame] | 546 | *fs_ns = inode->i_sb->s_user_ns; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 547 | kuid_t rootid; |
| 548 | size_t newsize; |
| 549 | |
| 550 | if (!*ivalue) |
| 551 | return -EINVAL; |
Eric Biggers | dc32b5c | 2018-01-01 09:28:31 -0600 | [diff] [blame] | 552 | if (!validheader(size, cap)) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 553 | return -EINVAL; |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 554 | if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 555 | return -EPERM; |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 556 | if (size == XATTR_CAPS_SZ_2 && (mnt_userns == &init_user_ns)) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 557 | if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP)) |
| 558 | /* user is privileged, just write the v2 */ |
| 559 | return size; |
| 560 | |
Christian Brauner | e65ce2a | 2021-01-21 14:19:27 +0100 | [diff] [blame] | 561 | rootid = rootid_from_xattr(*ivalue, size, task_ns, mnt_userns); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 562 | if (!uid_valid(rootid)) |
| 563 | return -EINVAL; |
| 564 | |
| 565 | nsrootid = from_kuid(fs_ns, rootid); |
| 566 | if (nsrootid == -1) |
| 567 | return -EINVAL; |
| 568 | |
| 569 | newsize = sizeof(struct vfs_ns_cap_data); |
| 570 | nscap = kmalloc(newsize, GFP_ATOMIC); |
| 571 | if (!nscap) |
| 572 | return -ENOMEM; |
| 573 | nscap->rootid = cpu_to_le32(nsrootid); |
| 574 | nsmagic = VFS_CAP_REVISION_3; |
| 575 | magic = le32_to_cpu(cap->magic_etc); |
| 576 | if (magic & VFS_CAP_FLAGS_EFFECTIVE) |
| 577 | nsmagic |= VFS_CAP_FLAGS_EFFECTIVE; |
| 578 | nscap->magic_etc = cpu_to_le32(nsmagic); |
| 579 | memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32); |
| 580 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 581 | *ivalue = nscap; |
| 582 | return newsize; |
| 583 | } |
| 584 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 585 | /* |
| 586 | * Calculate the new process capability sets from the capability sets attached |
| 587 | * to a file. |
| 588 | */ |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 589 | static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps, |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 590 | struct linux_binprm *bprm, |
Zhi Li | 4d49f67 | 2011-08-11 13:27:50 +0800 | [diff] [blame] | 591 | bool *effective, |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 592 | bool *has_fcap) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 593 | { |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 594 | struct cred *new = bprm->cred; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 595 | unsigned i; |
| 596 | int ret = 0; |
| 597 | |
| 598 | if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 599 | *effective = true; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 600 | |
Zhi Li | 4d49f67 | 2011-08-11 13:27:50 +0800 | [diff] [blame] | 601 | if (caps->magic_etc & VFS_CAP_REVISION_MASK) |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 602 | *has_fcap = true; |
Zhi Li | 4d49f67 | 2011-08-11 13:27:50 +0800 | [diff] [blame] | 603 | |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 604 | CAP_FOR_EACH_U32(i) { |
| 605 | __u32 permitted = caps->permitted.cap[i]; |
| 606 | __u32 inheritable = caps->inheritable.cap[i]; |
| 607 | |
| 608 | /* |
| 609 | * pP' = (X & fP) | (pI & fI) |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 610 | * The addition of pA' is handled later. |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 611 | */ |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 612 | new->cap_permitted.cap[i] = |
| 613 | (new->cap_bset.cap[i] & permitted) | |
| 614 | (new->cap_inheritable.cap[i] & inheritable); |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 615 | |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 616 | if (permitted & ~new->cap_permitted.cap[i]) |
| 617 | /* insufficient to execute correctly */ |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 618 | ret = -EPERM; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 619 | } |
| 620 | |
| 621 | /* |
| 622 | * For legacy apps, with no internal support for recognizing they |
| 623 | * do not have enough capabilities, we return an error if they are |
| 624 | * missing some "forced" (aka file-permitted) capabilities. |
| 625 | */ |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 626 | return *effective ? ret : 0; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 627 | } |
| 628 | |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 629 | /** |
| 630 | * get_vfs_caps_from_disk - retrieve vfs caps from disk |
| 631 | * |
| 632 | * @mnt_userns: user namespace of the mount the inode was found from |
| 633 | * @dentry: dentry from which @inode is retrieved |
| 634 | * @cpu_caps: vfs capabilities |
| 635 | * |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 636 | * Extract the on-exec-apply capability sets for an executable file. |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 637 | * |
| 638 | * If the inode has been found through an idmapped mount the user namespace of |
| 639 | * the vfsmount must be passed through @mnt_userns. This function will then |
| 640 | * take care to map the inode according to @mnt_userns before checking |
| 641 | * permissions. On non-idmapped mounts or if permission checking is to be |
| 642 | * performed on the raw inode simply passs init_user_ns. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 643 | */ |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 644 | int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, |
| 645 | const struct dentry *dentry, |
| 646 | struct cpu_vfs_cap_data *cpu_caps) |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 647 | { |
David Howells | c6f493d | 2015-03-17 22:26:22 +0000 | [diff] [blame] | 648 | struct inode *inode = d_backing_inode(dentry); |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 649 | __u32 magic_etc; |
Andrew Morgan | e338d26 | 2008-02-04 22:29:42 -0800 | [diff] [blame] | 650 | unsigned tocopy, i; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 651 | int size; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 652 | struct vfs_ns_cap_data data, *nscaps = &data; |
| 653 | struct vfs_cap_data *caps = (struct vfs_cap_data *) &data; |
| 654 | kuid_t rootkuid; |
Colin Ian King | 76ba89c7 | 2017-09-04 18:50:05 +0100 | [diff] [blame] | 655 | struct user_namespace *fs_ns; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 656 | |
| 657 | memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); |
| 658 | |
Andreas Gruenbacher | 5d6c319 | 2016-09-29 17:48:42 +0200 | [diff] [blame] | 659 | if (!inode) |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 660 | return -ENODATA; |
| 661 | |
Colin Ian King | 76ba89c7 | 2017-09-04 18:50:05 +0100 | [diff] [blame] | 662 | fs_ns = inode->i_sb->s_user_ns; |
Andreas Gruenbacher | 5d6c319 | 2016-09-29 17:48:42 +0200 | [diff] [blame] | 663 | size = __vfs_getxattr((struct dentry *)dentry, inode, |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 664 | XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 665 | if (size == -ENODATA || size == -EOPNOTSUPP) |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 666 | /* no data, that's ok */ |
| 667 | return -ENODATA; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 668 | |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 669 | if (size < 0) |
| 670 | return size; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 671 | |
Andrew Morgan | e338d26 | 2008-02-04 22:29:42 -0800 | [diff] [blame] | 672 | if (size < sizeof(magic_etc)) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 673 | return -EINVAL; |
| 674 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 675 | cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps->magic_etc); |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 676 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 677 | rootkuid = make_kuid(fs_ns, 0); |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 678 | switch (magic_etc & VFS_CAP_REVISION_MASK) { |
Andrew Morgan | e338d26 | 2008-02-04 22:29:42 -0800 | [diff] [blame] | 679 | case VFS_CAP_REVISION_1: |
| 680 | if (size != XATTR_CAPS_SZ_1) |
| 681 | return -EINVAL; |
| 682 | tocopy = VFS_CAP_U32_1; |
| 683 | break; |
| 684 | case VFS_CAP_REVISION_2: |
| 685 | if (size != XATTR_CAPS_SZ_2) |
| 686 | return -EINVAL; |
| 687 | tocopy = VFS_CAP_U32_2; |
| 688 | break; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 689 | case VFS_CAP_REVISION_3: |
| 690 | if (size != XATTR_CAPS_SZ_3) |
| 691 | return -EINVAL; |
| 692 | tocopy = VFS_CAP_U32_3; |
| 693 | rootkuid = make_kuid(fs_ns, le32_to_cpu(nscaps->rootid)); |
| 694 | break; |
| 695 | |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 696 | default: |
| 697 | return -EINVAL; |
| 698 | } |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 699 | /* Limit the caps to the mounter of the filesystem |
| 700 | * or the more limited uid specified in the xattr. |
| 701 | */ |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 702 | rootkuid = kuid_into_mnt(mnt_userns, rootkuid); |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 703 | if (!rootid_owns_currentns(rootkuid)) |
| 704 | return -ENODATA; |
Andrew Morgan | e338d26 | 2008-02-04 22:29:42 -0800 | [diff] [blame] | 705 | |
Andrew G. Morgan | 5459c16 | 2008-07-23 21:28:24 -0700 | [diff] [blame] | 706 | CAP_FOR_EACH_U32(i) { |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 707 | if (i >= tocopy) |
| 708 | break; |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 709 | cpu_caps->permitted.cap[i] = le32_to_cpu(caps->data[i].permitted); |
| 710 | cpu_caps->inheritable.cap[i] = le32_to_cpu(caps->data[i].inheritable); |
Andrew Morgan | e338d26 | 2008-02-04 22:29:42 -0800 | [diff] [blame] | 711 | } |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 712 | |
Eric Paris | 7d8b6c6 | 2014-07-23 15:36:26 -0400 | [diff] [blame] | 713 | cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; |
| 714 | cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; |
| 715 | |
Richard Guy Briggs | 2fec30e | 2019-01-23 21:36:25 -0500 | [diff] [blame] | 716 | cpu_caps->rootid = rootkuid; |
| 717 | |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 718 | return 0; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 719 | } |
| 720 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 721 | /* |
| 722 | * Attempt to get the on-exec apply capability sets for an executable file from |
| 723 | * its xattrs and, if present, apply them to the proposed credentials being |
| 724 | * constructed by execve(). |
| 725 | */ |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 726 | static int get_file_caps(struct linux_binprm *bprm, struct file *file, |
| 727 | bool *effective, bool *has_fcap) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 728 | { |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 729 | int rc = 0; |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 730 | struct cpu_vfs_cap_data vcaps; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 731 | |
Kees Cook | ee67ae7 | 2017-07-18 15:25:28 -0700 | [diff] [blame] | 732 | cap_clear(bprm->cred->cap_permitted); |
Serge Hallyn | 3318a38 | 2008-10-30 11:52:23 -0500 | [diff] [blame] | 733 | |
Serge E. Hallyn | 1f29fae | 2008-11-05 16:08:52 -0600 | [diff] [blame] | 734 | if (!file_caps_enabled) |
| 735 | return 0; |
| 736 | |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 737 | if (!mnt_may_suid(file->f_path.mnt)) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 738 | return 0; |
Andy Lutomirski | 380cf5b | 2016-06-23 16:41:05 -0500 | [diff] [blame] | 739 | |
| 740 | /* |
| 741 | * This check is redundant with mnt_may_suid() but is kept to make |
| 742 | * explicit that capability bits are limited to s_user_ns and its |
| 743 | * descendants. |
| 744 | */ |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 745 | if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns)) |
Seth Forshee | d07b846 | 2015-09-23 15:16:04 -0500 | [diff] [blame] | 746 | return 0; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 747 | |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 748 | rc = get_vfs_caps_from_disk(file_mnt_user_ns(file), |
| 749 | file->f_path.dentry, &vcaps); |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 750 | if (rc < 0) { |
| 751 | if (rc == -EINVAL) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 752 | printk(KERN_NOTICE "Invalid argument reading file caps for %s\n", |
| 753 | bprm->filename); |
Eric Paris | c0b0044 | 2008-11-11 21:48:10 +1100 | [diff] [blame] | 754 | else if (rc == -ENODATA) |
| 755 | rc = 0; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 756 | goto out; |
| 757 | } |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 758 | |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 759 | rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_fcap); |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 760 | |
| 761 | out: |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 762 | if (rc) |
Kees Cook | ee67ae7 | 2017-07-18 15:25:28 -0700 | [diff] [blame] | 763 | cap_clear(bprm->cred->cap_permitted); |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 764 | |
| 765 | return rc; |
| 766 | } |
| 767 | |
Richard Guy Briggs | 9304b46 | 2017-10-11 20:57:08 -0400 | [diff] [blame] | 768 | static inline bool root_privileged(void) { return !issecure(SECURE_NOROOT); } |
| 769 | |
Richard Guy Briggs | 81a6a01 | 2017-10-11 20:57:09 -0400 | [diff] [blame] | 770 | static inline bool __is_real(kuid_t uid, struct cred *cred) |
| 771 | { return uid_eq(cred->uid, uid); } |
| 772 | |
| 773 | static inline bool __is_eff(kuid_t uid, struct cred *cred) |
| 774 | { return uid_eq(cred->euid, uid); } |
| 775 | |
| 776 | static inline bool __is_suid(kuid_t uid, struct cred *cred) |
| 777 | { return !__is_real(uid, cred) && __is_eff(uid, cred); } |
| 778 | |
Richard Guy Briggs | db1a892 | 2017-10-11 20:57:05 -0400 | [diff] [blame] | 779 | /* |
| 780 | * handle_privileged_root - Handle case of privileged root |
| 781 | * @bprm: The execution parameters, including the proposed creds |
| 782 | * @has_fcap: Are any file capabilities set? |
| 783 | * @effective: Do we have effective root privilege? |
| 784 | * @root_uid: This namespace' root UID WRT initial USER namespace |
| 785 | * |
| 786 | * Handle the case where root is privileged and hasn't been neutered by |
| 787 | * SECURE_NOROOT. If file capabilities are set, they won't be combined with |
| 788 | * set UID root and nothing is changed. If we are root, cap_permitted is |
| 789 | * updated. If we have become set UID root, the effective bit is set. |
| 790 | */ |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 791 | static void handle_privileged_root(struct linux_binprm *bprm, bool has_fcap, |
Richard Guy Briggs | db1a892 | 2017-10-11 20:57:05 -0400 | [diff] [blame] | 792 | bool *effective, kuid_t root_uid) |
| 793 | { |
| 794 | const struct cred *old = current_cred(); |
| 795 | struct cred *new = bprm->cred; |
| 796 | |
Richard Guy Briggs | 9304b46 | 2017-10-11 20:57:08 -0400 | [diff] [blame] | 797 | if (!root_privileged()) |
Richard Guy Briggs | db1a892 | 2017-10-11 20:57:05 -0400 | [diff] [blame] | 798 | return; |
| 799 | /* |
| 800 | * If the legacy file capability is set, then don't set privs |
| 801 | * for a setuid root binary run by a non-root user. Do set it |
| 802 | * for a root user just to cause least surprise to an admin. |
| 803 | */ |
Richard Guy Briggs | 81a6a01 | 2017-10-11 20:57:09 -0400 | [diff] [blame] | 804 | if (has_fcap && __is_suid(root_uid, new)) { |
Richard Guy Briggs | db1a892 | 2017-10-11 20:57:05 -0400 | [diff] [blame] | 805 | warn_setuid_and_fcaps_mixed(bprm->filename); |
| 806 | return; |
| 807 | } |
| 808 | /* |
| 809 | * To support inheritance of root-permissions and suid-root |
| 810 | * executables under compatibility mode, we override the |
| 811 | * capability sets for the file. |
| 812 | */ |
Richard Guy Briggs | 81a6a01 | 2017-10-11 20:57:09 -0400 | [diff] [blame] | 813 | if (__is_eff(root_uid, new) || __is_real(root_uid, new)) { |
Richard Guy Briggs | db1a892 | 2017-10-11 20:57:05 -0400 | [diff] [blame] | 814 | /* pP' = (cap_bset & ~0) | (pI & ~0) */ |
| 815 | new->cap_permitted = cap_combine(old->cap_bset, |
| 816 | old->cap_inheritable); |
| 817 | } |
| 818 | /* |
| 819 | * If only the real uid is 0, we do not set the effective bit. |
| 820 | */ |
Richard Guy Briggs | 81a6a01 | 2017-10-11 20:57:09 -0400 | [diff] [blame] | 821 | if (__is_eff(root_uid, new)) |
Richard Guy Briggs | db1a892 | 2017-10-11 20:57:05 -0400 | [diff] [blame] | 822 | *effective = true; |
| 823 | } |
| 824 | |
Richard Guy Briggs | 4c7e715 | 2017-10-11 20:57:06 -0400 | [diff] [blame] | 825 | #define __cap_gained(field, target, source) \ |
| 826 | !cap_issubset(target->cap_##field, source->cap_##field) |
| 827 | #define __cap_grew(target, source, cred) \ |
| 828 | !cap_issubset(cred->cap_##target, cred->cap_##source) |
| 829 | #define __cap_full(field, cred) \ |
| 830 | cap_issubset(CAP_FULL_SET, cred->cap_##field) |
Richard Guy Briggs | 81a6a01 | 2017-10-11 20:57:09 -0400 | [diff] [blame] | 831 | |
| 832 | static inline bool __is_setuid(struct cred *new, const struct cred *old) |
| 833 | { return !uid_eq(new->euid, old->uid); } |
| 834 | |
| 835 | static inline bool __is_setgid(struct cred *new, const struct cred *old) |
| 836 | { return !gid_eq(new->egid, old->gid); } |
| 837 | |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 838 | /* |
Richard Guy Briggs | dbbbe11 | 2017-10-11 20:57:14 -0400 | [diff] [blame] | 839 | * 1) Audit candidate if current->cap_effective is set |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 840 | * |
| 841 | * We do not bother to audit if 3 things are true: |
| 842 | * 1) cap_effective has all caps |
Richard Guy Briggs | 588fb2c | 2017-10-11 20:57:13 -0400 | [diff] [blame] | 843 | * 2) we became root *OR* are were already root |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 844 | * 3) root is supposed to have all caps (SECURE_NOROOT) |
| 845 | * Since this is just a normal root execing a process. |
| 846 | * |
| 847 | * Number 1 above might fail if you don't have a full bset, but I think |
| 848 | * that is interesting information to audit. |
Richard Guy Briggs | dbbbe11 | 2017-10-11 20:57:14 -0400 | [diff] [blame] | 849 | * |
| 850 | * A number of other conditions require logging: |
| 851 | * 2) something prevented setuid root getting all caps |
| 852 | * 3) non-setuid root gets fcaps |
| 853 | * 4) non-setuid root gets ambient |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 854 | */ |
Richard Guy Briggs | dbbbe11 | 2017-10-11 20:57:14 -0400 | [diff] [blame] | 855 | static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old, |
| 856 | kuid_t root, bool has_fcap) |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 857 | { |
| 858 | bool ret = false; |
| 859 | |
Richard Guy Briggs | dbbbe11 | 2017-10-11 20:57:14 -0400 | [diff] [blame] | 860 | if ((__cap_grew(effective, ambient, new) && |
| 861 | !(__cap_full(effective, new) && |
| 862 | (__is_eff(root, new) || __is_real(root, new)) && |
| 863 | root_privileged())) || |
| 864 | (root_privileged() && |
| 865 | __is_suid(root, new) && |
| 866 | !__cap_full(effective, new)) || |
| 867 | (!__is_setuid(new, old) && |
| 868 | ((has_fcap && |
| 869 | __cap_gained(permitted, new, old)) || |
| 870 | __cap_gained(ambient, new, old)))) |
| 871 | |
Richard Guy Briggs | 02ebbaf | 2017-10-11 20:57:11 -0400 | [diff] [blame] | 872 | ret = true; |
Richard Guy Briggs | dbbbe11 | 2017-10-11 20:57:14 -0400 | [diff] [blame] | 873 | |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 874 | return ret; |
| 875 | } |
| 876 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 877 | /** |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 878 | * cap_bprm_creds_from_file - Set up the proposed credentials for execve(). |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 879 | * @bprm: The execution parameters, including the proposed creds |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 880 | * @file: The file to pull the credentials from |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 881 | * |
| 882 | * Set up the proposed credentials for a new execution context being |
| 883 | * constructed by execve(). The proposed creds in @bprm->cred is altered, |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 884 | * which won't take effect immediately. |
| 885 | * |
| 886 | * Return: 0 if successful, -ve on error. |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 887 | */ |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 888 | int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 889 | { |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 890 | /* Process setpcap binaries and capabilities for uid 0 */ |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 891 | const struct cred *old = current_cred(); |
| 892 | struct cred *new = bprm->cred; |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 893 | bool effective = false, has_fcap = false, is_setid; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 894 | int ret; |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 895 | kuid_t root_uid; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 896 | |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 897 | if (WARN_ON(!cap_ambient_invariant_ok(old))) |
| 898 | return -EPERM; |
| 899 | |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 900 | ret = get_file_caps(bprm, file, &effective, &has_fcap); |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 901 | if (ret < 0) |
| 902 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 903 | |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 904 | root_uid = make_kuid(new->user_ns, 0); |
| 905 | |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 906 | handle_privileged_root(bprm, has_fcap, &effective, root_uid); |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 907 | |
Eric Paris | d52fc5d | 2012-04-17 16:26:54 -0400 | [diff] [blame] | 908 | /* if we have fs caps, clear dangerous personality flags */ |
Richard Guy Briggs | 4c7e715 | 2017-10-11 20:57:06 -0400 | [diff] [blame] | 909 | if (__cap_gained(permitted, new, old)) |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 910 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
Eric Paris | d52fc5d | 2012-04-17 16:26:54 -0400 | [diff] [blame] | 911 | |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 912 | /* Don't let someone trace a set[ug]id/setpcap binary with the revised |
Andy Lutomirski | 259e5e6 | 2012-04-12 16:47:50 -0500 | [diff] [blame] | 913 | * credentials unless they have the appropriate permit. |
| 914 | * |
| 915 | * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 916 | */ |
Richard Guy Briggs | 81a6a01 | 2017-10-11 20:57:09 -0400 | [diff] [blame] | 917 | is_setid = __is_setuid(new, old) || __is_setgid(new, old); |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 918 | |
Richard Guy Briggs | 4c7e715 | 2017-10-11 20:57:06 -0400 | [diff] [blame] | 919 | if ((is_setid || __cap_gained(permitted, new, old)) && |
Eric W. Biederman | 9227dd2 | 2017-01-23 17:26:31 +1300 | [diff] [blame] | 920 | ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || |
Eric W. Biederman | 2052313 | 2017-01-23 17:17:26 +1300 | [diff] [blame] | 921 | !ptracer_capable(current, new->user_ns))) { |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 922 | /* downgrade; they get no more than they had, and maybe less */ |
Eric W. Biederman | 7016942 | 2016-11-17 01:38:35 -0600 | [diff] [blame] | 923 | if (!ns_capable(new->user_ns, CAP_SETUID) || |
Andy Lutomirski | 259e5e6 | 2012-04-12 16:47:50 -0500 | [diff] [blame] | 924 | (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 925 | new->euid = new->uid; |
| 926 | new->egid = new->gid; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 927 | } |
Serge E. Hallyn | b3a222e | 2009-11-23 16:21:30 -0600 | [diff] [blame] | 928 | new->cap_permitted = cap_intersect(new->cap_permitted, |
| 929 | old->cap_permitted); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 930 | } |
| 931 | |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 932 | new->suid = new->fsuid = new->euid; |
| 933 | new->sgid = new->fsgid = new->egid; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 934 | |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 935 | /* File caps or setid cancels ambient. */ |
Richard Guy Briggs | fc7eadf | 2017-10-11 20:57:07 -0400 | [diff] [blame] | 936 | if (has_fcap || is_setid) |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 937 | cap_clear(new->cap_ambient); |
| 938 | |
| 939 | /* |
| 940 | * Now that we've computed pA', update pP' to give: |
| 941 | * pP' = (X & fP) | (pI & fI) | pA' |
| 942 | */ |
| 943 | new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); |
| 944 | |
| 945 | /* |
| 946 | * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, |
| 947 | * this is the same as pE' = (fE ? pP' : 0) | pA'. |
| 948 | */ |
Eric Paris | 4bf2ea7 | 2011-04-01 17:08:28 -0400 | [diff] [blame] | 949 | if (effective) |
| 950 | new->cap_effective = new->cap_permitted; |
| 951 | else |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 952 | new->cap_effective = new->cap_ambient; |
| 953 | |
| 954 | if (WARN_ON(!cap_ambient_invariant_ok(new))) |
| 955 | return -EPERM; |
| 956 | |
Richard Guy Briggs | dbbbe11 | 2017-10-11 20:57:14 -0400 | [diff] [blame] | 957 | if (nonroot_raised_pE(new, old, root_uid, has_fcap)) { |
Richard Guy Briggs | 9fbc2c7 | 2017-10-11 20:57:10 -0400 | [diff] [blame] | 958 | ret = audit_log_bprm_fcaps(bprm, new, old); |
| 959 | if (ret < 0) |
| 960 | return ret; |
Eric Paris | 3fc689e | 2008-11-11 21:48:18 +1100 | [diff] [blame] | 961 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 962 | |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 963 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 964 | |
| 965 | if (WARN_ON(!cap_ambient_invariant_ok(new))) |
| 966 | return -EPERM; |
| 967 | |
Kees Cook | 46d98eb | 2017-07-18 15:25:27 -0700 | [diff] [blame] | 968 | /* Check for privilege-elevated exec. */ |
Richard Guy Briggs | 02ebbaf | 2017-10-11 20:57:11 -0400 | [diff] [blame] | 969 | if (is_setid || |
| 970 | (!__is_real(root_uid, new) && |
| 971 | (effective || |
| 972 | __cap_grew(permitted, ambient, new)))) |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 973 | bprm->secureexec = 1; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 974 | |
Kees Cook | ee67ae7 | 2017-07-18 15:25:28 -0700 | [diff] [blame] | 975 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 976 | } |
| 977 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 978 | /** |
| 979 | * cap_inode_setxattr - Determine whether an xattr may be altered |
| 980 | * @dentry: The inode/dentry being altered |
| 981 | * @name: The name of the xattr to be changed |
| 982 | * @value: The value that the xattr will be changed to |
| 983 | * @size: The size of value |
| 984 | * @flags: The replacement flag |
| 985 | * |
| 986 | * Determine whether an xattr may be altered or set on an inode, returning 0 if |
| 987 | * permission is granted, -ve if denied. |
| 988 | * |
| 989 | * This is used to make sure security xattrs don't get updated or set by those |
| 990 | * who aren't privileged to do so. |
| 991 | */ |
David Howells | 8f0cfa5 | 2008-04-29 00:59:41 -0700 | [diff] [blame] | 992 | int cap_inode_setxattr(struct dentry *dentry, const char *name, |
| 993 | const void *value, size_t size, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 994 | { |
Eric W. Biederman | b1d749c5 | 2017-04-21 19:14:32 -0500 | [diff] [blame] | 995 | struct user_namespace *user_ns = dentry->d_sb->s_user_ns; |
| 996 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 997 | /* Ignore non-security xattrs */ |
| 998 | if (strncmp(name, XATTR_SECURITY_PREFIX, |
Carmeli Tamir | c5eaab1 | 2019-07-06 11:07:38 -0400 | [diff] [blame] | 999 | XATTR_SECURITY_PREFIX_LEN) != 0) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1000 | return 0; |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1001 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 1002 | /* |
| 1003 | * For XATTR_NAME_CAPS the check will be done in |
| 1004 | * cap_convert_nscap(), called by setxattr() |
| 1005 | */ |
| 1006 | if (strcmp(name, XATTR_NAME_CAPS) == 0) |
| 1007 | return 0; |
| 1008 | |
Eric W. Biederman | b1d749c5 | 2017-04-21 19:14:32 -0500 | [diff] [blame] | 1009 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1010 | return -EPERM; |
| 1011 | return 0; |
| 1012 | } |
| 1013 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1014 | /** |
| 1015 | * cap_inode_removexattr - Determine whether an xattr may be removed |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 1016 | * |
| 1017 | * @mnt_userns: User namespace of the mount the inode was found from |
| 1018 | * @dentry: The inode/dentry being altered |
| 1019 | * @name: The name of the xattr to be changed |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1020 | * |
| 1021 | * Determine whether an xattr may be removed from an inode, returning 0 if |
| 1022 | * permission is granted, -ve if denied. |
| 1023 | * |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 1024 | * If the inode has been found through an idmapped mount the user namespace of |
| 1025 | * the vfsmount must be passed through @mnt_userns. This function will then |
| 1026 | * take care to map the inode according to @mnt_userns before checking |
| 1027 | * permissions. On non-idmapped mounts or if permission checking is to be |
| 1028 | * performed on the raw inode simply passs init_user_ns. |
| 1029 | * |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1030 | * This is used to make sure security xattrs don't get removed by those who |
| 1031 | * aren't privileged to remove them. |
| 1032 | */ |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 1033 | int cap_inode_removexattr(struct user_namespace *mnt_userns, |
| 1034 | struct dentry *dentry, const char *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1035 | { |
Eric W. Biederman | b1d749c5 | 2017-04-21 19:14:32 -0500 | [diff] [blame] | 1036 | struct user_namespace *user_ns = dentry->d_sb->s_user_ns; |
| 1037 | |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 1038 | /* Ignore non-security xattrs */ |
| 1039 | if (strncmp(name, XATTR_SECURITY_PREFIX, |
Carmeli Tamir | c5eaab1 | 2019-07-06 11:07:38 -0400 | [diff] [blame] | 1040 | XATTR_SECURITY_PREFIX_LEN) != 0) |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 1041 | return 0; |
| 1042 | |
| 1043 | if (strcmp(name, XATTR_NAME_CAPS) == 0) { |
| 1044 | /* security.capability gets namespaced */ |
| 1045 | struct inode *inode = d_backing_inode(dentry); |
| 1046 | if (!inode) |
| 1047 | return -EINVAL; |
Christian Brauner | 71bc356 | 2021-01-21 14:19:29 +0100 | [diff] [blame] | 1048 | if (!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_SETFCAP)) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1049 | return -EPERM; |
| 1050 | return 0; |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1051 | } |
| 1052 | |
Eric W. Biederman | b1d749c5 | 2017-04-21 19:14:32 -0500 | [diff] [blame] | 1053 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1054 | return -EPERM; |
| 1055 | return 0; |
| 1056 | } |
| 1057 | |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1058 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1059 | * cap_emulate_setxuid() fixes the effective / permitted capabilities of |
| 1060 | * a process after a call to setuid, setreuid, or setresuid. |
| 1061 | * |
| 1062 | * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of |
| 1063 | * {r,e,s}uid != 0, the permitted and effective capabilities are |
| 1064 | * cleared. |
| 1065 | * |
| 1066 | * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective |
| 1067 | * capabilities of the process are cleared. |
| 1068 | * |
| 1069 | * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective |
| 1070 | * capabilities are set to the permitted capabilities. |
| 1071 | * |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1072 | * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1073 | * never happen. |
| 1074 | * |
David Howells | a6f76f2 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1075 | * -astor |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1076 | * |
| 1077 | * cevans - New behaviour, Oct '99 |
| 1078 | * A process may, via prctl(), elect to keep its capabilities when it |
| 1079 | * calls setuid() and switches away from uid==0. Both permitted and |
| 1080 | * effective sets will be retained. |
| 1081 | * Without this change, it was impossible for a daemon to drop only some |
| 1082 | * of its privilege. The call to setuid(!=0) would drop all privileges! |
| 1083 | * Keeping uid 0 is not an option because uid 0 owns too many vital |
| 1084 | * files.. |
| 1085 | * Thanks to Olaf Kirch and Peter Benie for spotting this. |
| 1086 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1087 | static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1088 | { |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 1089 | kuid_t root_uid = make_kuid(old->user_ns, 0); |
| 1090 | |
| 1091 | if ((uid_eq(old->uid, root_uid) || |
| 1092 | uid_eq(old->euid, root_uid) || |
| 1093 | uid_eq(old->suid, root_uid)) && |
| 1094 | (!uid_eq(new->uid, root_uid) && |
| 1095 | !uid_eq(new->euid, root_uid) && |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 1096 | !uid_eq(new->suid, root_uid))) { |
| 1097 | if (!issecure(SECURE_KEEP_CAPS)) { |
| 1098 | cap_clear(new->cap_permitted); |
| 1099 | cap_clear(new->cap_effective); |
| 1100 | } |
| 1101 | |
| 1102 | /* |
| 1103 | * Pre-ambient programs expect setresuid to nonroot followed |
| 1104 | * by exec to drop capabilities. We should make sure that |
| 1105 | * this remains the case. |
| 1106 | */ |
| 1107 | cap_clear(new->cap_ambient); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1108 | } |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 1109 | if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1110 | cap_clear(new->cap_effective); |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 1111 | if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1112 | new->cap_effective = new->cap_permitted; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1113 | } |
| 1114 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1115 | /** |
| 1116 | * cap_task_fix_setuid - Fix up the results of setuid() call |
| 1117 | * @new: The proposed credentials |
| 1118 | * @old: The current task's current credentials |
| 1119 | * @flags: Indications of what has changed |
| 1120 | * |
| 1121 | * Fix up the results of setuid() call before the credential changes are |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1122 | * actually applied. |
| 1123 | * |
| 1124 | * Return: 0 to grant the changes, -ve to deny them. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1125 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1126 | int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1127 | { |
| 1128 | switch (flags) { |
| 1129 | case LSM_SETID_RE: |
| 1130 | case LSM_SETID_ID: |
| 1131 | case LSM_SETID_RES: |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1132 | /* juggle the capabilities to follow [RES]UID changes unless |
| 1133 | * otherwise suppressed */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1134 | if (!issecure(SECURE_NO_SETUID_FIXUP)) |
| 1135 | cap_emulate_setxuid(new, old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1136 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1137 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1138 | case LSM_SETID_FS: |
| 1139 | /* juggle the capabilties to follow FSUID changes, unless |
| 1140 | * otherwise suppressed |
| 1141 | * |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1142 | * FIXME - is fsuser used for all CAP_FS_MASK capabilities? |
| 1143 | * if not, we might be a bit too harsh here. |
| 1144 | */ |
| 1145 | if (!issecure(SECURE_NO_SETUID_FIXUP)) { |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 1146 | kuid_t root_uid = make_kuid(old->user_ns, 0); |
| 1147 | if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1148 | new->cap_effective = |
| 1149 | cap_drop_fs_set(new->cap_effective); |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1150 | |
Eric W. Biederman | 18815a1 | 2012-02-07 16:45:47 -0800 | [diff] [blame] | 1151 | if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1152 | new->cap_effective = |
| 1153 | cap_raise_fs_set(new->cap_effective, |
| 1154 | new->cap_permitted); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1155 | } |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1156 | break; |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1157 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1158 | default: |
| 1159 | return -EINVAL; |
| 1160 | } |
| 1161 | |
| 1162 | return 0; |
| 1163 | } |
| 1164 | |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1165 | /* |
| 1166 | * Rationale: code calling task_setscheduler, task_setioprio, and |
| 1167 | * task_setnice, assumes that |
| 1168 | * . if capable(cap_sys_nice), then those actions should be allowed |
| 1169 | * . if not capable(cap_sys_nice), but acting on your own processes, |
| 1170 | * then those actions should be allowed |
| 1171 | * This is insufficient now since you can call code without suid, but |
| 1172 | * yet with increased caps. |
| 1173 | * So we check for increased caps on the target process. |
| 1174 | */ |
Serge E. Hallyn | de45e80 | 2008-09-26 22:27:47 -0400 | [diff] [blame] | 1175 | static int cap_safe_nice(struct task_struct *p) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1176 | { |
Serge Hallyn | f54fb86 | 2013-07-23 13:18:53 -0500 | [diff] [blame] | 1177 | int is_subset, ret = 0; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 1178 | |
| 1179 | rcu_read_lock(); |
| 1180 | is_subset = cap_issubset(__task_cred(p)->cap_permitted, |
| 1181 | current_cred()->cap_permitted); |
Serge Hallyn | f54fb86 | 2013-07-23 13:18:53 -0500 | [diff] [blame] | 1182 | if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) |
| 1183 | ret = -EPERM; |
David Howells | c69e8d9 | 2008-11-14 10:39:19 +1100 | [diff] [blame] | 1184 | rcu_read_unlock(); |
| 1185 | |
Serge Hallyn | f54fb86 | 2013-07-23 13:18:53 -0500 | [diff] [blame] | 1186 | return ret; |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1187 | } |
| 1188 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1189 | /** |
| 1190 | * cap_task_setscheduler - Detemine if scheduler policy change is permitted |
| 1191 | * @p: The task to affect |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1192 | * |
| 1193 | * Detemine if the requested scheduler policy change is permitted for the |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1194 | * specified task. |
| 1195 | * |
| 1196 | * Return: 0 if permission is granted, -ve if denied. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1197 | */ |
KOSAKI Motohiro | b0ae198 | 2010-10-15 04:21:18 +0900 | [diff] [blame] | 1198 | int cap_task_setscheduler(struct task_struct *p) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1199 | { |
| 1200 | return cap_safe_nice(p); |
| 1201 | } |
| 1202 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1203 | /** |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1204 | * cap_task_setioprio - Detemine if I/O priority change is permitted |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1205 | * @p: The task to affect |
| 1206 | * @ioprio: The I/O priority to set |
| 1207 | * |
| 1208 | * Detemine if the requested I/O priority change is permitted for the specified |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1209 | * task. |
| 1210 | * |
| 1211 | * Return: 0 if permission is granted, -ve if denied. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1212 | */ |
| 1213 | int cap_task_setioprio(struct task_struct *p, int ioprio) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1214 | { |
| 1215 | return cap_safe_nice(p); |
| 1216 | } |
| 1217 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1218 | /** |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1219 | * cap_task_setnice - Detemine if task priority change is permitted |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1220 | * @p: The task to affect |
| 1221 | * @nice: The nice value to set |
| 1222 | * |
| 1223 | * Detemine if the requested task priority change is permitted for the |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1224 | * specified task. |
| 1225 | * |
| 1226 | * Return: 0 if permission is granted, -ve if denied. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1227 | */ |
| 1228 | int cap_task_setnice(struct task_struct *p, int nice) |
Serge E. Hallyn | b537677 | 2007-10-16 23:31:36 -0700 | [diff] [blame] | 1229 | { |
| 1230 | return cap_safe_nice(p); |
| 1231 | } |
| 1232 | |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 1233 | /* |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1234 | * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from |
| 1235 | * the current task's bounding set. Returns 0 on success, -ve on error. |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 1236 | */ |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1237 | static int cap_prctl_drop(unsigned long cap) |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 1238 | { |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1239 | struct cred *new; |
| 1240 | |
Eric W. Biederman | 160da84 | 2013-07-02 10:04:54 -0700 | [diff] [blame] | 1241 | if (!ns_capable(current_user_ns(), CAP_SETPCAP)) |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 1242 | return -EPERM; |
| 1243 | if (!cap_valid(cap)) |
| 1244 | return -EINVAL; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1245 | |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1246 | new = prepare_creds(); |
| 1247 | if (!new) |
| 1248 | return -ENOMEM; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1249 | cap_lower(new->cap_bset, cap); |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1250 | return commit_creds(new); |
Serge E. Hallyn | 3b7391d | 2008-02-04 22:29:45 -0800 | [diff] [blame] | 1251 | } |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1252 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1253 | /** |
| 1254 | * cap_task_prctl - Implement process control functions for this security module |
| 1255 | * @option: The process control function requested |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1256 | * @arg2: The argument data for this function |
| 1257 | * @arg3: The argument data for this function |
| 1258 | * @arg4: The argument data for this function |
| 1259 | * @arg5: The argument data for this function |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1260 | * |
| 1261 | * Allow process control functions (sys_prctl()) to alter capabilities; may |
| 1262 | * also deny access to other functions not otherwise implemented here. |
| 1263 | * |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1264 | * Return: 0 or +ve on success, -ENOSYS if this function is not implemented |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1265 | * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM |
| 1266 | * modules will consider performing the function. |
| 1267 | */ |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1268 | int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1269 | unsigned long arg4, unsigned long arg5) |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1270 | { |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1271 | const struct cred *old = current_cred(); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1272 | struct cred *new; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1273 | |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1274 | switch (option) { |
| 1275 | case PR_CAPBSET_READ: |
| 1276 | if (!cap_valid(arg2)) |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1277 | return -EINVAL; |
| 1278 | return !!cap_raised(old->cap_bset, arg2); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1279 | |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1280 | case PR_CAPBSET_DROP: |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1281 | return cap_prctl_drop(arg2); |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1282 | |
| 1283 | /* |
| 1284 | * The next four prctl's remain to assist with transitioning a |
| 1285 | * system from legacy UID=0 based privilege (when filesystem |
| 1286 | * capabilities are not in use) to a system using filesystem |
| 1287 | * capabilities only - as the POSIX.1e draft intended. |
| 1288 | * |
| 1289 | * Note: |
| 1290 | * |
| 1291 | * PR_SET_SECUREBITS = |
| 1292 | * issecure_mask(SECURE_KEEP_CAPS_LOCKED) |
| 1293 | * | issecure_mask(SECURE_NOROOT) |
| 1294 | * | issecure_mask(SECURE_NOROOT_LOCKED) |
| 1295 | * | issecure_mask(SECURE_NO_SETUID_FIXUP) |
| 1296 | * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED) |
| 1297 | * |
| 1298 | * will ensure that the current process and all of its |
| 1299 | * children will be locked into a pure |
| 1300 | * capability-based-privilege environment. |
| 1301 | */ |
| 1302 | case PR_SET_SECUREBITS: |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1303 | if ((((old->securebits & SECURE_ALL_LOCKS) >> 1) |
| 1304 | & (old->securebits ^ arg2)) /*[1]*/ |
| 1305 | || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1306 | || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ |
Eric Paris | 6a9de49 | 2012-01-03 12:25:14 -0500 | [diff] [blame] | 1307 | || (cap_capable(current_cred(), |
Micah Morton | c1a85a0 | 2019-01-07 16:10:53 -0800 | [diff] [blame] | 1308 | current_cred()->user_ns, |
| 1309 | CAP_SETPCAP, |
| 1310 | CAP_OPT_NONE) != 0) /*[4]*/ |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1311 | /* |
| 1312 | * [1] no changing of bits that are locked |
| 1313 | * [2] no unlocking of locks |
| 1314 | * [3] no setting of unsupported bits |
| 1315 | * [4] doing anything requires privilege (go read about |
| 1316 | * the "sendmail capabilities bug") |
| 1317 | */ |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1318 | ) |
| 1319 | /* cannot change a locked bit */ |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1320 | return -EPERM; |
| 1321 | |
| 1322 | new = prepare_creds(); |
| 1323 | if (!new) |
| 1324 | return -ENOMEM; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1325 | new->securebits = arg2; |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1326 | return commit_creds(new); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1327 | |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1328 | case PR_GET_SECUREBITS: |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1329 | return old->securebits; |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1330 | |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1331 | case PR_GET_KEEPCAPS: |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1332 | return !!issecure(SECURE_KEEP_CAPS); |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1333 | |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1334 | case PR_SET_KEEPCAPS: |
| 1335 | if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */ |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1336 | return -EINVAL; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1337 | if (issecure(SECURE_KEEP_CAPS_LOCKED)) |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1338 | return -EPERM; |
| 1339 | |
| 1340 | new = prepare_creds(); |
| 1341 | if (!new) |
| 1342 | return -ENOMEM; |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1343 | if (arg2) |
| 1344 | new->securebits |= issecure_mask(SECURE_KEEP_CAPS); |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1345 | else |
David Howells | d84f4f9 | 2008-11-14 10:39:23 +1100 | [diff] [blame] | 1346 | new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1347 | return commit_creds(new); |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1348 | |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 1349 | case PR_CAP_AMBIENT: |
| 1350 | if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) { |
| 1351 | if (arg3 | arg4 | arg5) |
| 1352 | return -EINVAL; |
| 1353 | |
| 1354 | new = prepare_creds(); |
| 1355 | if (!new) |
| 1356 | return -ENOMEM; |
| 1357 | cap_clear(new->cap_ambient); |
| 1358 | return commit_creds(new); |
| 1359 | } |
| 1360 | |
| 1361 | if (((!cap_valid(arg3)) | arg4 | arg5)) |
| 1362 | return -EINVAL; |
| 1363 | |
| 1364 | if (arg2 == PR_CAP_AMBIENT_IS_SET) { |
| 1365 | return !!cap_raised(current_cred()->cap_ambient, arg3); |
| 1366 | } else if (arg2 != PR_CAP_AMBIENT_RAISE && |
| 1367 | arg2 != PR_CAP_AMBIENT_LOWER) { |
| 1368 | return -EINVAL; |
| 1369 | } else { |
| 1370 | if (arg2 == PR_CAP_AMBIENT_RAISE && |
| 1371 | (!cap_raised(current_cred()->cap_permitted, arg3) || |
| 1372 | !cap_raised(current_cred()->cap_inheritable, |
Andy Lutomirski | 746bf6d | 2015-09-04 15:42:51 -0700 | [diff] [blame] | 1373 | arg3) || |
| 1374 | issecure(SECURE_NO_CAP_AMBIENT_RAISE))) |
Andy Lutomirski | 5831905 | 2015-09-04 15:42:45 -0700 | [diff] [blame] | 1375 | return -EPERM; |
| 1376 | |
| 1377 | new = prepare_creds(); |
| 1378 | if (!new) |
| 1379 | return -ENOMEM; |
| 1380 | if (arg2 == PR_CAP_AMBIENT_RAISE) |
| 1381 | cap_raise(new->cap_ambient, arg3); |
| 1382 | else |
| 1383 | cap_lower(new->cap_ambient, arg3); |
| 1384 | return commit_creds(new); |
| 1385 | } |
| 1386 | |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1387 | default: |
| 1388 | /* No functionality available - continue with default */ |
Tetsuo Handa | 6d6f332 | 2014-07-22 21:20:01 +0900 | [diff] [blame] | 1389 | return -ENOSYS; |
Andrew G. Morgan | 3898b1b | 2008-04-28 02:13:40 -0700 | [diff] [blame] | 1390 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1391 | } |
| 1392 | |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1393 | /** |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1394 | * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted |
| 1395 | * @mm: The VM space in which the new mapping is to be made |
| 1396 | * @pages: The size of the mapping |
| 1397 | * |
| 1398 | * Determine whether the allocation of a new virtual mapping by the current |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1399 | * task is permitted. |
| 1400 | * |
| 1401 | * Return: 1 if permission is granted, 0 if not. |
David Howells | 1d04598 | 2008-11-14 10:39:24 +1100 | [diff] [blame] | 1402 | */ |
Alan Cox | 34b4e4a | 2007-08-22 14:01:28 -0700 | [diff] [blame] | 1403 | int cap_vm_enough_memory(struct mm_struct *mm, long pages) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1404 | { |
| 1405 | int cap_sys_admin = 0; |
| 1406 | |
Micah Morton | c1a85a0 | 2019-01-07 16:10:53 -0800 | [diff] [blame] | 1407 | if (cap_capable(current_cred(), &init_user_ns, |
| 1408 | CAP_SYS_ADMIN, CAP_OPT_NOAUDIT) == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1409 | cap_sys_admin = 1; |
Micah Morton | c1a85a0 | 2019-01-07 16:10:53 -0800 | [diff] [blame] | 1410 | |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1411 | return cap_sys_admin; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1412 | } |
Eric Paris | 7c73875 | 2009-07-31 12:53:58 -0400 | [diff] [blame] | 1413 | |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1414 | /** |
Al Viro | d007794 | 2012-05-30 13:11:37 -0400 | [diff] [blame] | 1415 | * cap_mmap_addr - check if able to map given addr |
| 1416 | * @addr: address attempting to be mapped |
| 1417 | * |
| 1418 | * If the process is attempting to map memory below dac_mmap_min_addr they need |
| 1419 | * CAP_SYS_RAWIO. The other parameters to this function are unused by the |
Randy Dunlap | 049ae60 | 2021-04-11 17:55:28 -0700 | [diff] [blame] | 1420 | * capability security module. |
| 1421 | * |
| 1422 | * Return: 0 if this mapping should be allowed or -EPERM if not. |
Al Viro | d007794 | 2012-05-30 13:11:37 -0400 | [diff] [blame] | 1423 | */ |
| 1424 | int cap_mmap_addr(unsigned long addr) |
| 1425 | { |
| 1426 | int ret = 0; |
| 1427 | |
| 1428 | if (addr < dac_mmap_min_addr) { |
| 1429 | ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO, |
Micah Morton | c1a85a0 | 2019-01-07 16:10:53 -0800 | [diff] [blame] | 1430 | CAP_OPT_NONE); |
Al Viro | d007794 | 2012-05-30 13:11:37 -0400 | [diff] [blame] | 1431 | /* set PF_SUPERPRIV if it turns out we allow the low mmap */ |
| 1432 | if (ret == 0) |
| 1433 | current->flags |= PF_SUPERPRIV; |
| 1434 | } |
| 1435 | return ret; |
| 1436 | } |
| 1437 | |
Al Viro | e546785 | 2012-05-30 13:30:51 -0400 | [diff] [blame] | 1438 | int cap_mmap_file(struct file *file, unsigned long reqprot, |
| 1439 | unsigned long prot, unsigned long flags) |
Eric Paris | 7c73875 | 2009-07-31 12:53:58 -0400 | [diff] [blame] | 1440 | { |
Al Viro | e546785 | 2012-05-30 13:30:51 -0400 | [diff] [blame] | 1441 | return 0; |
Eric Paris | 7c73875 | 2009-07-31 12:53:58 -0400 | [diff] [blame] | 1442 | } |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1443 | |
| 1444 | #ifdef CONFIG_SECURITY |
| 1445 | |
YueHaibing | d1c5947 | 2019-06-11 21:48:15 +0800 | [diff] [blame] | 1446 | static struct security_hook_list capability_hooks[] __lsm_ro_after_init = { |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1447 | LSM_HOOK_INIT(capable, cap_capable), |
| 1448 | LSM_HOOK_INIT(settime, cap_settime), |
| 1449 | LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check), |
| 1450 | LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme), |
| 1451 | LSM_HOOK_INIT(capget, cap_capget), |
| 1452 | LSM_HOOK_INIT(capset, cap_capset), |
Eric W. Biederman | 56305aa | 2020-05-29 22:00:54 -0500 | [diff] [blame] | 1453 | LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file), |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1454 | LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv), |
| 1455 | LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv), |
Serge E. Hallyn | 8db6c34 | 2017-05-08 13:11:56 -0500 | [diff] [blame] | 1456 | LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity), |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1457 | LSM_HOOK_INIT(mmap_addr, cap_mmap_addr), |
| 1458 | LSM_HOOK_INIT(mmap_file, cap_mmap_file), |
| 1459 | LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid), |
| 1460 | LSM_HOOK_INIT(task_prctl, cap_task_prctl), |
| 1461 | LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler), |
| 1462 | LSM_HOOK_INIT(task_setioprio, cap_task_setioprio), |
| 1463 | LSM_HOOK_INIT(task_setnice, cap_task_setnice), |
| 1464 | LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory), |
| 1465 | }; |
| 1466 | |
Kees Cook | d117a15 | 2018-09-14 15:40:45 -0700 | [diff] [blame] | 1467 | static int __init capability_init(void) |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1468 | { |
Casey Schaufler | d69dece5 | 2017-01-18 17:09:05 -0800 | [diff] [blame] | 1469 | security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), |
| 1470 | "capability"); |
Kees Cook | d117a15 | 2018-09-14 15:40:45 -0700 | [diff] [blame] | 1471 | return 0; |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1472 | } |
| 1473 | |
Kees Cook | d117a15 | 2018-09-14 15:40:45 -0700 | [diff] [blame] | 1474 | DEFINE_LSM(capability) = { |
| 1475 | .name = "capability", |
| 1476 | .order = LSM_ORDER_FIRST, |
| 1477 | .init = capability_init, |
| 1478 | }; |
| 1479 | |
Casey Schaufler | b1d9e6b | 2015-05-02 15:11:42 -0700 | [diff] [blame] | 1480 | #endif /* CONFIG_SECURITY */ |