Vulnerability in Linux

[ Description ]Official description

In the Linux kernel, the following vulnerability has been resolved: selinux: preserve NATIVE_LABELS on already-initialized sb in set_mnt_opts When an NFSv4 filesystem exported with security_label is mounted a second time, sget_fc() returns the existing superblock and nfs_get_root() calls security_sb_set_mnt_opts() again on it. Since the superblock is already SB_INITIALIZED, selinux_set_mnt_opts() takes an early exit without setting SECURITY_LSM_NATIVE_LABELS in *set_kern_flags. nfs_get_root() then sees kflags without SECURITY_LSM_NATIVE_LABELS set and clears NFS_CAP_SECURITY_LABEL on the shared nfs_server, silently disabling per-file labeling for both the new and the original mount. Commit 3815a245b501 ("security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock") fixed the same problem in selinux_sb_clone_mnt_opts(). The reused-superblock path for a plain second mount now goes through sb_set_mnt_opts rather than sb_clone_mnt_opts, so it needs the same treatment: on both SE_SBINITIALIZED early exits, set SECURITY_LSM_NATIVE_LABELS in *set_kern_flags when the superblock was already using SECURITY_FS_USE_NATVE.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• git.kernel.org/stable/c/28b7260548af3d35773477993ad4e4de41578dd7
• git.kernel.org/stable/c/5509d498e1b9edafebd5a60ba3cb9ecfda23dc2b
• git.kernel.org/stable/c/a545def625860d4ccedc14fe45e884a62a041cef
• git.kernel.org/stable/c/a6da93c625b3557dd23ff6db45d2d1bafeae1565
• git.kernel.org/stable/c/c997832414f1d846de0a1fa38d7d4f62ba2ea917