[PATCH v2 17/28] inode: inode_owner_or_capable(): handle fsid mappings

Christian Brauner
2020-02-14T18:38:17Z

Switch inode_owner_or_capable() to lookup fsids in the fsid mappings. If no
fsid mappings are setup the behavior is unchanged, i.e. fsids are looked up in
the id mappings.

Filesystems that share a superblock in all user namespaces they are mounted in
will retain their old semantics even with the introduction of fsidmappings.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
unchanged
---
fs/inode.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/inode.c b/fs/inode.c
index 7d57068b6b7a..81d7a30b381d 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -21,6 +21,7 @@
#include <linux/ratelimit.h>
#include <linux/list_lru.h>
#include <linux/iversion.h>
+#include <linux/fsuidgid.h>
#include <trace/events/writeback.h>
#include "internal.h"

@@ -2087,8 +2088,12 @@ bool inode_owner_or_capable(const struct inode *inode)
return true;

ns = current_user_ns();
- if (kuid_has_mapping(ns, inode->i_uid) && ns_capable(ns, CAP_FOWNER))
+ if (is_userns_visible(inode->i_sb->s_iflags)) {
+ if (kuid_has_mapping(ns, inode->i_uid) && ns_capable(ns, CAP_FOWNER))
+ return true;
+ } else if (kfsuid_has_mapping(ns, inode->i_uid) && ns_capable(ns, CAP_FOWNER)) {
return true;
+ }
return false;
}
EXPORT_SYMBOL(inode_owner_or_capable);
--
2.25.0