Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: tracefs: Reset permissions on remount if permissions are options There's an inconsistency with the way permissions are handled in tracefs. Because the permissions are generated when accessed, they default to the root inode's permission if they were never set by the user. If the user sets the permissions, then a flag is set and the permissions are saved via the inode (for tracefs files) or an internal attribute field (for eventfs). But if a remount happens that specify the permissions, all the files that were not changed by the user gets updated, but the ones that were are not. If the user were to remount the file system with a given permission, then all files and directories within that file system should be updated. This can cause security issues if a file's permission was updated but the admin forgot about it. They could incorrectly think that remounting with permissions set would update all files, but miss some. For example: # cd /sys/kernel/tracing # chgrp 1002 current_tracer # ls -l [..] -rw-r----- 1 root root 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root root 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root root 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root root 0 May 1 21:25 dynamic_events -r--r----- 1 root root 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root root 0 May 1 21:25 enabled_functions Where current_tracer now has group "lkp". # mount -o remount,gid=1001 . # ls -l -rw-r----- 1 root tracing 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root tracing 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root tracing 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root tracing 0 May 1 21:25 dynamic_events -r--r----- 1 root tracing 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root tracing 0 May 1 21:25 enabled_functions Everything changed but the "current_tracer". Add a new link list that keeps track of all the tracefs_inodes which has the permission flags that tell if the file/dir should use the root inode's permission or not. Then on remount, clear all the flags so that the default behavior of using the root inode's permission is done for all files and directories.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 628adb842bd5e1c2c598534a7a022b8235289de6 before 5f91fc82794d4a6e41cdcd02d00baa377d94ca78; affected 8186fff7ab649085e2c60d032d9a20a85af1d87c before 414fb08628143203d29ccd0264b5a83fb9523c03; affected 8186fff7ab649085e2c60d032d9a20a85af1d87c before baa23a8d4360d981a49913841a726edede5cdd54; affected 9c2ac5e0ea7899411fd900d4681890722a020735; affected 6.6.18 before 6.6.31; affected 6.7.4 before 6.8 |
| Linux / Linux | affected 6.8; unaffected 0 before 6.8; unaffected 6.6.31 through 6.6.*; unaffected 6.8.10 through 6.8.*; unaffected 6.9 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/5f91fc82794d4a6e41cdcd02d00baa377d94ca78
- https://git.kernel.org/stable/c/414fb08628143203d29ccd0264b5a83fb9523c03
- https://git.kernel.org/stable/c/baa23a8d4360d981a49913841a726edede5cdd54
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.