xfs: fix capability check in xfs
Impact
In the Linux kernel, the following vulnerability has been resolved:
Source excerpt · LinuxAffected packages
Affected products
Vendor version evidence. Product records are separate from automatic dependency matching.
Linux · Linux
Other versions: unaffected
| Version / range | Source status |
|---|---|
| eba0549bc7d100691c13384b774346b8aa9cf9a9 to before 19a1a22029ad3ae3604c763af6bd1195cb73648f | affected |
| eba0549bc7d100691c13384b774346b8aa9cf9a9 to before 7809ac0161c7c5f52ed348fb1ec683b2b454a83e | affected |
| eba0549bc7d100691c13384b774346b8aa9cf9a9 to before e2f62a9744ebad3bcb6347a648e615026e9efeff | affected |
Linux · Linux
Other versions: affected
| Version / range | Source status |
|---|---|
| 5.18 | affected |
| 0 to before 5.18 | unaffected |
| 6.18.59 through 6.18.* (inclusive) | unaffected |
| 7.2.13 through 7.2.* (inclusive) | unaffected |
| 7.3 through * (inclusive) | unaffected |
Original source description
In the Linux kernel, the following vulnerability has been resolved:
xfs: fix capability check in xfs
An user reported a bug where he managed to evade group's quota by changing a file's gid to a different group id the same user belonged to, even though quotas were enforced on both gids and the file's size was big enough to exceed the quota's hardlimit.
Commit eba0549bc7d1 replaced a capable() call by a has_capability_noaudit() to prevent unnecessary selinux audit messages. Turns out that both calls have slightly different semantics even though their documentation seems similar. Where in a nutshell:
capable() - Tests the task's effective credentials has_ns_capability_noaudit() - Tests the task's real credentials
This most of the time has no practical difference but in some cases like changing attrs (specifically group id in this case) through a NFS client this will allow the quota code to use XFS_QMOPT_FORCE_RES, effectively bypassing quota accounting checks.
Using instead ns_capable_noaudit() should fix this issue and prevent selinux audit messages.
This also fix the remaining calls to has_capability_noaudit()