diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2021-05-19 06:12:31 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-19 06:12:31 -1000
commitc3d0e3fd41b7f0f5d5d5b6022ab7e813f04ea727 (patch)
parent293837b9ac8d3021657f44c9d7a14948ec01c5d0 (diff)
parent2ca4dcc4909d787ee153272f7efc2bff3b498720 (diff)
Merge tag 'fs.idmapped.mount_setattr.v5.13-rc3' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux
Pull mount_setattr fix from Christian Brauner: "This makes an underlying idmapping assumption more explicit. We currently don't have any filesystems that support idmapped mounts which are mountable inside a user namespace, i.e. where s_user_ns != init_user_ns. That was a deliberate decision for now as userns root can just mount the filesystem themselves. Express this restriction explicitly and enforce it until there's a real use-case for this. This way we can notice it and will have a chance to adapt and audit our translation helpers and fstests appropriately if we need to support such filesystems" * tag 'fs.idmapped.mount_setattr.v5.13-rc3' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux: fs/mount_setattr: tighten permission checks
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index f63337828e1c..c3f1a78ba369 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3855,8 +3855,12 @@ static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)
if (!(m->mnt_sb->s_type->fs_flags & FS_ALLOW_IDMAP))
return -EINVAL;
+ /* Don't yet support filesystem mountable in user namespaces. */
+ if (m->mnt_sb->s_user_ns != &init_user_ns)
+ return -EINVAL;
/* We're not controlling the superblock. */
- if (!ns_capable(m->mnt_sb->s_user_ns, CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/* Mount has already been visible in the filesystem hierarchy. */

Privacy Policy