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| author | Miklos Szeredi <mszeredi@redhat.com> | 2023-01-24 16:41:18 +0100 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2023-01-27 16:17:19 +0100 |
| commit | 4f11ada10d0ad3fd53e2bd67806351de63a4f9c3 (patch) | |
| tree | 421cb460c1012536a5e712dab16aba1b1c9cb954 | |
| parent | baabaa505563362b71f2637aedd7b807d270656c (diff) | |
| download | linux-4f11ada10d0ad3fd53e2bd67806351de63a4f9c3.tar.bz2 | |
ovl: fail on invalid uid/gid mapping at copy up
If st_uid/st_gid doesn't have a mapping in the mounter's user_ns, then
copy-up should fail, just like it would fail if the mounter task was doing
the copy using "cp -a".
There's a corner case where the "cp -a" would succeed but copy up fail: if
there's a mapping of the invalid uid/gid (65534 by default) in the user
namespace. This is because stat(2) will return this value if the mapping
doesn't exist in the current user_ns and "cp -a" will in turn be able to
create a file with this uid/gid.
This behavior would be inconsistent with POSIX ACL's, which return -1 for
invalid uid/gid which result in a failed copy.
For consistency and simplicity fail the copy of the st_uid/st_gid are
invalid.
Fixes: 459c7c565ac3 ("ovl: unprivieged mounts")
Cc: <stable@vger.kernel.org> # v5.11
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Seth Forshee <sforshee@kernel.org>
| -rw-r--r-- | fs/overlayfs/copy_up.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 140f2742074d..c14e90764e35 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -1011,6 +1011,10 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, if (err) return err; + if (!kuid_has_mapping(current_user_ns(), ctx.stat.uid) || + !kgid_has_mapping(current_user_ns(), ctx.stat.gid)) + return -EOVERFLOW; + ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags); if (parent) { |