syslog: distinguish between /proc/kmsg and syscalls
This allows the LSM to distinguish between syslog functions originating
from /proc/kmsg access and direct syscalls. By default, the commoncaps
will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg
file descriptor. For example the kernel syslog reader can now drop
privileges after opening /proc/kmsg, instead of staying privileged with
CAP_SYS_ADMIN. MAC systems that implement security_syslog have unchanged
behavior.
Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/include/linux/security.h b/include/linux/security.h
index 26eca85..a4dc74d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -76,7 +76,7 @@
extern int cap_task_setscheduler(struct task_struct *p, int policy, struct sched_param *lp);
extern int cap_task_setioprio(struct task_struct *p, int ioprio);
extern int cap_task_setnice(struct task_struct *p, int nice);
-extern int cap_syslog(int type);
+extern int cap_syslog(int type, bool from_file);
extern int cap_vm_enough_memory(struct mm_struct *mm, long pages);
struct msghdr;
@@ -1349,6 +1349,7 @@
* logging to the console.
* See the syslog(2) manual page for an explanation of the @type values.
* @type contains the type of action.
+ * @from_file indicates the context of action (if it came from /proc).
* Return 0 if permission is granted.
* @settime:
* Check permission to change the system time.
@@ -1463,7 +1464,7 @@
int (*sysctl) (struct ctl_table *table, int op);
int (*quotactl) (int cmds, int type, int id, struct super_block *sb);
int (*quota_on) (struct dentry *dentry);
- int (*syslog) (int type);
+ int (*syslog) (int type, bool from_file);
int (*settime) (struct timespec *ts, struct timezone *tz);
int (*vm_enough_memory) (struct mm_struct *mm, long pages);
@@ -1762,7 +1763,7 @@
int security_sysctl(struct ctl_table *table, int op);
int security_quotactl(int cmds, int type, int id, struct super_block *sb);
int security_quota_on(struct dentry *dentry);
-int security_syslog(int type);
+int security_syslog(int type, bool from_file);
int security_settime(struct timespec *ts, struct timezone *tz);
int security_vm_enough_memory(long pages);
int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
@@ -2008,9 +2009,9 @@
return 0;
}
-static inline int security_syslog(int type)
+static inline int security_syslog(int type, bool from_file)
{
- return cap_syslog(type);
+ return cap_syslog(type, from_file);
}
static inline int security_settime(struct timespec *ts, struct timezone *tz)