stat: handle idmapped mounts

The generic_fillattr() helper fills in the basic attributes associated
with an inode. Enable it to handle idmapped mounts. If the inode is
accessed through an idmapped mount map it into the mount's user
namespace before we store the uid and gid. If the initial user namespace
is passed nothing changes so non-idmapped mounts will see identical
behavior as before.

Link: https://lore.kernel.org/r/[email protected]
Cc: Christoph Hellwig <[email protected]>
Cc: David Howells <[email protected]>
Cc: Al Viro <[email protected]>
Cc: [email protected]
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: James Morris <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index bb4e63a3684f..d45aa68c1f17 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1934,7 +1934,7 @@ int pid_getattr(const struct path *path, struct kstat *stat,
 	struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb);
 	struct task_struct *task;
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 
 	stat->uid = GLOBAL_ROOT_UID;
 	stat->gid = GLOBAL_ROOT_GID;
@@ -3803,7 +3803,7 @@ static int proc_task_getattr(const struct path *path, struct kstat *stat,
 {
 	struct inode *inode = d_inode(path->dentry);
 	struct task_struct *p = get_proc_task(inode);
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (p) {
 		stat->nlink += get_nr_threads(p);