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authorChristian Brauner <brauner@kernel.org>2022-04-19 15:14:23 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2022-04-19 10:19:02 -0700
commit705191b03d507744c7e097f78d583621c14988ac (patch)
treec8016d1a47fbb3ccba5d8dfd20324ab021a8c576 /fs/posix_acl.c
parentb2d229d4ddb17db541098b83524d901257e93845 (diff)
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fs: fix acl translation
Last cycle we extended the idmapped mounts infrastructure to support idmapped mounts of idmapped filesystems (No such filesystem yet exist.). Since then, the meaning of an idmapped mount is a mount whose idmapping is different from the filesystems idmapping. While doing that work we missed to adapt the acl translation helpers. They still assume that checking for the identity mapping is enough. But they need to use the no_idmapping() helper instead. Note, POSIX ACLs are always translated right at the userspace-kernel boundary using the caller's current idmapping and the initial idmapping. The order depends on whether we're coming from or going to userspace. The filesystem's idmapping doesn't matter at the border. Consequently, if a non-idmapped mount is passed we need to make sure to always pass the initial idmapping as the mount's idmapping and not the filesystem idmapping. Since it's irrelevant here it would yield invalid ids and prevent setting acls for filesystems that are mountable in a userns and support posix acls (tmpfs and fuse). I verified the regression reported in [1] and verified that this patch fixes it. A regression test will be added to xfstests in parallel. Link: https://bugzilla.kernel.org/show_bug.cgi?id=215849 [1] Fixes: bd303368b776 ("fs: support mapped mounts of mapped filesystems") Cc: Seth Forshee <sforshee@digitalocean.com> Cc: Christoph Hellwig <hch@lst.de> Cc: <stable@vger.kernel.org> # 5.17 Cc: <regressions@lists.linux.dev> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/posix_acl.c')
-rw-r--r--fs/posix_acl.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 80acb6885cf9..962d32468eb4 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -759,9 +759,14 @@ static void posix_acl_fix_xattr_userns(
}
void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
+ struct inode *inode,
void *value, size_t size)
{
struct user_namespace *user_ns = current_user_ns();
+
+ /* Leave ids untouched on non-idmapped mounts. */
+ if (no_idmapping(mnt_userns, i_user_ns(inode)))
+ mnt_userns = &init_user_ns;
if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
return;
posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
@@ -769,9 +774,14 @@ void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
}
void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
+ struct inode *inode,
void *value, size_t size)
{
struct user_namespace *user_ns = current_user_ns();
+
+ /* Leave ids untouched on non-idmapped mounts. */
+ if (no_idmapping(mnt_userns, i_user_ns(inode)))
+ mnt_userns = &init_user_ns;
if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
return;
posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,