selinux: restrict kernel module loading
Utilize existing kernel_read_file hook on kernel module load.
Add module_load permission to the system class.
Enforces restrictions on kernel module origin when calling the
finit_module syscall. The hook checks that source type has
permission module_load for the target type.
Example for finit_module:
allow foo bar_file:system module_load;
Similarly restrictions are enforced on kernel module loading when
calling the init_module syscall. The hook checks that source
type has permission module_load with itself as the target object
because the kernel module is sourced from the calling process.
Example for init_module:
allow foo foo:system module_load;
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
[PM: fixed return value of selinux_kernel_read_file()]
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 5003b5a..fce7dc8 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3722,6 +3722,52 @@
SYSTEM__MODULE_REQUEST, &ad);
}
+static int selinux_kernel_module_from_file(struct file *file)
+{
+ struct common_audit_data ad;
+ struct inode_security_struct *isec;
+ struct file_security_struct *fsec;
+ u32 sid = current_sid();
+ int rc;
+
+ /* init_module */
+ if (file == NULL)
+ return avc_has_perm(sid, sid, SECCLASS_SYSTEM,
+ SYSTEM__MODULE_LOAD, NULL);
+
+ /* finit_module */
+ ad.type = LSM_AUDIT_DATA_PATH;
+ ad.u.path = file->f_path;
+
+ isec = inode_security(file_inode(file));
+ fsec = file->f_security;
+
+ if (sid != fsec->sid) {
+ rc = avc_has_perm(sid, fsec->sid, SECCLASS_FD, FD__USE, &ad);
+ if (rc)
+ return rc;
+ }
+
+ return avc_has_perm(sid, isec->sid, SECCLASS_SYSTEM,
+ SYSTEM__MODULE_LOAD, &ad);
+}
+
+static int selinux_kernel_read_file(struct file *file,
+ enum kernel_read_file_id id)
+{
+ int rc = 0;
+
+ switch (id) {
+ case READING_MODULE:
+ rc = selinux_kernel_module_from_file(file);
+ break;
+ default:
+ break;
+ }
+
+ return rc;
+}
+
static int selinux_task_setpgid(struct task_struct *p, pid_t pgid)
{
return current_has_perm(p, PROCESS__SETPGID);
@@ -6018,6 +6064,7 @@
LSM_HOOK_INIT(kernel_act_as, selinux_kernel_act_as),
LSM_HOOK_INIT(kernel_create_files_as, selinux_kernel_create_files_as),
LSM_HOOK_INIT(kernel_module_request, selinux_kernel_module_request),
+ LSM_HOOK_INIT(kernel_read_file, selinux_kernel_read_file),
LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
LSM_HOOK_INIT(task_getsid, selinux_task_getsid),