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| author |   Al Viro <viro@zeniv.linux.org.uk> | 2025-06-01 20:11:06 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-06-07 01:37:24 -0400 |
| commit | c28f922c9dcee0e4876a2c095939d77fe7e15116 (patch) | |
| tree | 97840ebb01c456fa8edef1485461d5e5ece96444 | |
| parent | selftests/mount_setattr: adapt detached mount propagation test (diff) | |
| download | linux-rng-c28f922c9dcee0e4876a2c095939d77fe7e15116.tar.xz linux-rng-c28f922c9dcee0e4876a2c095939d77fe7e15116.zip | |
clone_private_mnt(): make sure that caller has CAP_SYS_ADMIN in the right userns
What we want is to verify there is that clone won't expose something
hidden by a mount we wouldn't be able to undo. "Wouldn't be able to undo"
may be a result of MNT_LOCKED on a child, but it may also come from
lacking admin rights in the userns of the namespace mount belongs to.
clone_private_mnt() checks the former, but not the latter.
There's a number of rather confusing CAP_SYS_ADMIN checks in various
userns during the mount, especially with the new mount API; they serve
different purposes and in case of clone_private_mnt() they usually,
but not always end up covering the missing check mentioned above.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reported-by: "Orlando, Noah" <Noah.Orlando@deshaw.com>
Fixes: 427215d85e8d ("ovl: prevent private clone if bind mount is not allowed")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/namespace.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 2e939b783618..1c54c16c7bab 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2510,6 +2510,9 @@ struct vfsmount *clone_private_mount(const struct path *path) return ERR_PTR(-EINVAL); } + if (!ns_capable(old_mnt->mnt_ns->user_ns, CAP_SYS_ADMIN)) + return ERR_PTR(-EPERM); + if (__has_locked_children(old_mnt, path->dentry)) return ERR_PTR(-EINVAL); |