[PATCH v6 11/40] stat: handle idmapped mounts

[Christian Brauner <christian.brauner@ubuntu.com>]

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/20210112220124.837960-19-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
- Christoph Hellwig <hch@lst.de>:
  - Don't pollute the vfs with additional helpers simply extend the existing
    helpers with an additional argument and switch all callers.

/* v3 */
unchanged

/* v4 */
unchanged

/* v5 */
unchanged
base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837

/* v6 */
base-commit: 19c329f6808995b142b3966301f217c831e7cf31

- Christoph Hellwig <hch@lst.de>:
  - Remove "extern" from headers.
---
 fs/9p/vfs_inode.c      |  4 ++--
 fs/9p/vfs_inode_dotl.c |  4 ++--
 fs/afs/inode.c         |  2 +-
 fs/btrfs/inode.c       |  2 +-
 fs/ceph/inode.c        |  2 +-
 fs/cifs/inode.c        |  2 +-
 fs/coda/inode.c        |  2 +-
 fs/ecryptfs/inode.c    |  4 ++--
 fs/erofs/inode.c       |  2 +-
 fs/exfat/file.c        |  2 +-
 fs/ext2/inode.c        |  2 +-
 fs/ext4/inode.c        |  2 +-
 fs/f2fs/file.c         |  2 +-
 fs/fat/file.c          |  2 +-
 fs/fuse/dir.c          |  2 +-
 fs/gfs2/inode.c        |  2 +-
 fs/hfsplus/inode.c     |  2 +-
 fs/kernfs/inode.c      |  2 +-
 fs/libfs.c             |  4 ++--
 fs/minix/inode.c       |  2 +-
 fs/nfs/inode.c         |  2 +-
 fs/nfs/namespace.c     |  2 +-
 fs/ocfs2/file.c        |  2 +-
 fs/orangefs/inode.c    |  2 +-
 fs/proc/base.c         |  4 ++--
 fs/proc/generic.c      |  2 +-
 fs/proc/proc_net.c     |  2 +-
 fs/proc/proc_sysctl.c  |  2 +-
 fs/proc/root.c         |  2 +-
 fs/stat.c              | 20 ++++++++++++++------
 fs/sysv/itree.c        |  2 +-
 fs/ubifs/dir.c         |  2 +-
 fs/udf/symlink.c       |  2 +-
 fs/vboxsf/utils.c      |  2 +-
 include/linux/fs.h     |  2 +-
 mm/shmem.c             |  2 +-
 36 files changed, 54 insertions(+), 46 deletions(-)

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 9c3ff6e9ab82..c21b146c8d91 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -1027,7 +1027,7 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
 	v9ses = v9fs_dentry2v9ses(dentry);
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
-		generic_fillattr(d_inode(dentry), stat);
+		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
 		return 0;
 	}
 	fid = v9fs_fid_lookup(dentry);
@@ -1040,7 +1040,7 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
 		return PTR_ERR(st);
 
 	v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
-	generic_fillattr(d_inode(dentry), stat);
+	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
 
 	p9stat_free(st);
 	kfree(st);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 302553101fcb..984f28315d2a 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -468,7 +468,7 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
 	v9ses = v9fs_dentry2v9ses(dentry);
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
-		generic_fillattr(d_inode(dentry), stat);
+		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
 		return 0;
 	}
 	fid = v9fs_fid_lookup(dentry);
@@ -485,7 +485,7 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
 		return PTR_ERR(st);
 
 	v9fs_stat2inode_dotl(st, d_inode(dentry), 0);
-	generic_fillattr(d_inode(dentry), stat);
+	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
 	/* Change block size to what the server returned */
 	stat->blksize = st->st_blksize;
 
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index b0d7b892090d..795ee5cb3817 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -745,7 +745,7 @@ int afs_getattr(const struct path *path, struct kstat *stat,
 
 	do {
 		read_seqbegin_or_lock(&vnode->cb_lock, &seq);
-		generic_fillattr(inode, stat);
+		generic_fillattr(&init_user_ns, inode, stat);
 		if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&
 		    stat->nlink > 0)
 			stat->nlink -= 1;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 6c18fb1a25af..a63faed171de 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8842,7 +8842,7 @@ static int btrfs_getattr(const struct path *path, struct kstat *stat,
 				  STATX_ATTR_IMMUTABLE |
 				  STATX_ATTR_NODUMP);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->dev = BTRFS_I(inode)->root->anon_dev;
 
 	spin_lock(&BTRFS_I(inode)->lock);
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 145e26a4ddbb..179a2bb88538 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -2385,7 +2385,7 @@ int ceph_getattr(const struct path *path, struct kstat *stat,
 			return err;
 	}
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->ino = ceph_present_inode(inode);
 
 	/*
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 27554f71f744..374abce7efaf 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -2408,7 +2408,7 @@ int cifs_getattr(const struct path *path, struct kstat *stat,
 			return rc;
 	}
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->blksize = cifs_sb->ctx->bsize;
 	stat->ino = CIFS_I(inode)->uniqueid;
 
diff --git a/fs/coda/inode.c b/fs/coda/inode.c
index b1c70e2b9b1e..4d113e191cb8 100644
--- a/fs/coda/inode.c
+++ b/fs/coda/inode.c
@@ -256,7 +256,7 @@ int coda_getattr(const struct path *path, struct kstat *stat,
 {
 	int err = coda_revalidate_inode(d_inode(path->dentry));
 	if (!err)
-		generic_fillattr(d_inode(path->dentry), stat);
+		generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
 	return err;
 }
 
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index b9ccc4085d46..385b5e8741c0 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -977,7 +977,7 @@ static int ecryptfs_getattr_link(const struct path *path, struct kstat *stat,
 
 	mount_crypt_stat = &ecryptfs_superblock_to_private(
 						dentry->d_sb)->mount_crypt_stat;
-	generic_fillattr(d_inode(dentry), stat);
+	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
 	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 		char *target;
 		size_t targetsiz;
@@ -1005,7 +1005,7 @@ static int ecryptfs_getattr(const struct path *path, struct kstat *stat,
 	if (!rc) {
 		fsstack_copy_attr_all(d_inode(dentry),
 				      ecryptfs_inode_to_lower(d_inode(dentry)));
-		generic_fillattr(d_inode(dentry), stat);
+		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
 		stat->blocks = lower_stat.blocks;
 	}
 	return rc;
diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index 3e21c0e8adae..083818063ac6 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -343,7 +343,7 @@ int erofs_getattr(const struct path *path, struct kstat *stat,
 	stat->attributes_mask |= (STATX_ATTR_COMPRESSED |
 				  STATX_ATTR_IMMUTABLE);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index ace35aa8e64b..e9705b3295d3 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -273,7 +273,7 @@ int exfat_getattr(const struct path *path, struct kstat *stat,
 	struct inode *inode = d_backing_inode(path->dentry);
 	struct exfat_inode_info *ei = EXFAT_I(inode);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	exfat_truncate_atime(&stat->atime);
 	stat->result_mask |= STATX_BTIME;
 	stat->btime.tv_sec = ei->i_crtime.tv_sec;
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 9de813635d8d..3d8acafca8ce 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1660,7 +1660,7 @@ int ext2_getattr(const struct path *path, struct kstat *stat,
 			STATX_ATTR_IMMUTABLE |
 			STATX_ATTR_NODUMP);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 24ea5851e90a..3a303d3f8423 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5571,7 +5571,7 @@ int ext4_getattr(const struct path *path, struct kstat *stat,
 				  STATX_ATTR_NODUMP |
 				  STATX_ATTR_VERITY);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 6ccdfe0606d9..44cd0dbdbb5d 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -820,7 +820,7 @@ int f2fs_getattr(const struct path *path, struct kstat *stat,
 				  STATX_ATTR_NODUMP |
 				  STATX_ATTR_VERITY);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 
 	/* we need to show initial sectors used for inline_data/dentries */
 	if ((S_ISREG(inode->i_mode) && f2fs_has_inline_data(inode)) ||
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 805b501467e9..f7e04f533d31 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -398,7 +398,7 @@ int fat_getattr(const struct path *path, struct kstat *stat,
 		u32 request_mask, unsigned int flags)
 {
 	struct inode *inode = d_inode(path->dentry);
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 
 	if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 74fdb6a7ebb3..d2e318ed9b26 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1087,7 +1087,7 @@ static int fuse_update_get_attr(struct inode *inode, struct file *file,
 		forget_all_cached_acls(inode);
 		err = fuse_do_getattr(inode, stat, file);
 	} else if (stat) {
-		generic_fillattr(inode, stat);
+		generic_fillattr(&init_user_ns, inode, stat);
 		stat->mode = fi->orig_i_mode;
 		stat->ino = fi->orig_ino;
 	}
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 728405d15a05..226b5b1dc1fa 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -2050,7 +2050,7 @@ static int gfs2_getattr(const struct path *path, struct kstat *stat,
 				  STATX_ATTR_IMMUTABLE |
 				  STATX_ATTR_NODUMP);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (gfs2_holder_initialized(&gh))
 		gfs2_glock_dq_uninit(&gh);
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index ffa137f8234e..642e067d8fe8 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -286,7 +286,7 @@ int hfsplus_getattr(const struct path *path, struct kstat *stat,
 	stat->attributes_mask |= STATX_ATTR_APPEND | STATX_ATTR_IMMUTABLE |
 				 STATX_ATTR_NODUMP;
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 7e44052b42e1..032d3d7546d8 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -193,7 +193,7 @@ int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
 	kernfs_refresh_inode(kn, inode);
 	mutex_unlock(&kernfs_mutex);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/libfs.c b/fs/libfs.c
index a73fe109403c..508e9ea8e6f3 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -31,7 +31,7 @@ int simple_getattr(const struct path *path, struct kstat *stat,
 		   u32 request_mask, unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
 	return 0;
 }
@@ -1304,7 +1304,7 @@ static int empty_dir_getattr(const struct path *path, struct kstat *stat,
 			     u32 request_mask, unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index 34f546404aa1..91c81d2fc90d 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -658,7 +658,7 @@ int minix_getattr(const struct path *path, struct kstat *stat,
 	struct super_block *sb = path->dentry->d_sb;
 	struct inode *inode = d_inode(path->dentry);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	if (INODE_VERSION(inode) == MINIX_V1)
 		stat->blocks = (BLOCK_SIZE / 512) * V1_minix_blocks(stat->size, sb);
 	else
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 522aa10a1a3e..cab123ec1664 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -857,7 +857,7 @@ int nfs_getattr(const struct path *path, struct kstat *stat,
 	/* Only return attributes that were revalidated. */
 	stat->result_mask &= request_mask;
 out_no_update:
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
 	if (S_ISDIR(inode->i_mode))
 		stat->blksize = NFS_SERVER(inode)->dtsize;
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 2bcbe38afe2e..55fc711e368b 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -213,7 +213,7 @@ nfs_namespace_getattr(const struct path *path, struct kstat *stat,
 {
 	if (NFS_FH(d_inode(path->dentry))->size != 0)
 		return nfs_getattr(path, stat, request_mask, query_flags);
-	generic_fillattr(d_inode(path->dentry), stat);
+	generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
 	return 0;
 }
 
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index cabf355b148f..a070d4c9b6ed 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1313,7 +1313,7 @@ int ocfs2_getattr(const struct path *path, struct kstat *stat,
 		goto bail;
 	}
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	/*
 	 * If there is inline data in the inode, the inode will normally not
 	 * have data blocks allocated (it may have an external xattr block).
diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c
index 563fe9ab8eb2..b94032f77e61 100644
--- a/fs/orangefs/inode.c
+++ b/fs/orangefs/inode.c
@@ -903,7 +903,7 @@ int orangefs_getattr(const struct path *path, struct kstat *stat,
 	ret = orangefs_inode_getattr(inode,
 	    request_mask & STATX_SIZE ? ORANGEFS_GETATTR_SIZE : 0);
 	if (ret == 0) {
-		generic_fillattr(inode, stat);
+		generic_fillattr(&init_user_ns, inode, stat);
 
 		/* override block size reported to stat */
 		if (!(request_mask & STATX_SIZE))
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);
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 6d4fabab8aa7..0db96a761149 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -145,7 +145,7 @@ static int proc_getattr(const struct path *path, struct kstat *stat,
 		}
 	}
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	return 0;
 }
 
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 18601042af99..4aef49ccf571 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -297,7 +297,7 @@ static int proc_tgid_net_getattr(const struct path *path, struct kstat *stat,
 
 	net = get_proc_task_net(inode);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (net != NULL) {
 		stat->nlink = net->proc_net->nlink;
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index ec67dbc1f705..87c828348140 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -840,7 +840,7 @@ static int proc_sys_getattr(const struct path *path, struct kstat *stat,
 	if (IS_ERR(head))
 		return PTR_ERR(head);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	if (table)
 		stat->mode = (stat->mode & S_IFMT) | table->mode;
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 5e444d4f9717..244e4b6f15ef 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -311,7 +311,7 @@ void __init proc_root_init(void)
 static int proc_root_getattr(const struct path *path, struct kstat *stat,
 			     u32 request_mask, unsigned int query_flags)
 {
-	generic_fillattr(d_inode(path->dentry), stat);
+	generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
 	stat->nlink = proc_root.nlink + nr_processes();
 	return 0;
 }
diff --git a/fs/stat.c b/fs/stat.c
index dacecdda2e79..2c471c2fd766 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -26,21 +26,29 @@
 
 /**
  * generic_fillattr - Fill in the basic attributes from the inode struct
- * @inode: Inode to use as the source
- * @stat: Where to fill in the attributes
+ * @mnt_userns:	user namespace of the mount the inode was found from
+ * @inode:	Inode to use as the source
+ * @stat:	Where to fill in the attributes
  *
  * Fill in the basic attributes in the kstat structure from data that's to be
  * found on the VFS inode structure.  This is the default if no getattr inode
  * operation is supplied.
+ *
+ * If the inode has been found through an idmapped mount the user namespace of
+ * the vfsmount must be passed through @mnt_userns. This function will then
+ * take care to map the inode according to @mnt_userns before filling in the
+ * uid and gid filds. On non-idmapped mounts or if permission checking is to be
+ * performed on the raw inode simply passs init_user_ns.
  */
-void generic_fillattr(struct inode *inode, struct kstat *stat)
+void generic_fillattr(struct user_namespace *mnt_userns, struct inode *inode,
+		      struct kstat *stat)
 {
 	stat->dev = inode->i_sb->s_dev;
 	stat->ino = inode->i_ino;
 	stat->mode = inode->i_mode;
 	stat->nlink = inode->i_nlink;
-	stat->uid = inode->i_uid;
-	stat->gid = inode->i_gid;
+	stat->uid = i_uid_into_mnt(mnt_userns, inode);
+	stat->gid = i_gid_into_mnt(mnt_userns, inode);
 	stat->rdev = inode->i_rdev;
 	stat->size = i_size_read(inode);
 	stat->atime = inode->i_atime;
@@ -87,7 +95,7 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
 		return inode->i_op->getattr(path, stat, request_mask,
 					    query_flags);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(mnt_user_ns(path->mnt), inode, stat);
 	return 0;
 }
 EXPORT_SYMBOL(vfs_getattr_nosec);
diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c
index bcb67b0cabe7..83cffab6955f 100644
--- a/fs/sysv/itree.c
+++ b/fs/sysv/itree.c
@@ -445,7 +445,7 @@ int sysv_getattr(const struct path *path, struct kstat *stat,
 		 u32 request_mask, unsigned int flags)
 {
 	struct super_block *s = path->dentry->d_sb;
-	generic_fillattr(d_inode(path->dentry), stat);
+	generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
 	stat->blocks = (s->s_blocksize / 512) * sysv_nblocks(s, stat->size);
 	stat->blksize = s->s_blocksize;
 	return 0;
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 694e7714545b..a8881ed61620 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1589,7 +1589,7 @@ int ubifs_getattr(const struct path *path, struct kstat *stat,
 				STATX_ATTR_ENCRYPTED |
 				STATX_ATTR_IMMUTABLE);
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	stat->blksize = UBIFS_BLOCK_SIZE;
 	stat->size = ui->ui_size;
 
diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c
index c973db239604..54a44d1f023c 100644
--- a/fs/udf/symlink.c
+++ b/fs/udf/symlink.c
@@ -159,7 +159,7 @@ static int udf_symlink_getattr(const struct path *path, struct kstat *stat,
 	struct inode *inode = d_backing_inode(dentry);
 	struct page *page;
 
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 	page = read_mapping_page(inode->i_mapping, 0, NULL);
 	if (IS_ERR(page))
 		return PTR_ERR(page);
diff --git a/fs/vboxsf/utils.c b/fs/vboxsf/utils.c
index 018057546067..d2cd1c99f48e 100644
--- a/fs/vboxsf/utils.c
+++ b/fs/vboxsf/utils.c
@@ -233,7 +233,7 @@ int vboxsf_getattr(const struct path *path, struct kstat *kstat,
 	if (err)
 		return err;
 
-	generic_fillattr(d_inode(dentry), kstat);
+	generic_fillattr(&init_user_ns, d_inode(dentry), kstat);
 	return 0;
 }
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e3ea1d7c3367..182641d8322f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3154,7 +3154,7 @@ extern int __page_symlink(struct inode *inode, const char *symname, int len,
 extern int page_symlink(struct inode *inode, const char *symname, int len);
 extern const struct inode_operations page_symlink_inode_operations;
 extern void kfree_link(void *);
-extern void generic_fillattr(struct inode *, struct kstat *);
+void generic_fillattr(struct user_namespace *, struct inode *, struct kstat *);
 extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
 extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
 void __inode_add_bytes(struct inode *inode, loff_t bytes);
diff --git a/mm/shmem.c b/mm/shmem.c
index 23b8e9c15a42..339d5530d3a9 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1072,7 +1072,7 @@ static int shmem_getattr(const struct path *path, struct kstat *stat,
 		shmem_recalc_inode(inode);
 		spin_unlock_irq(&info->lock);
 	}
-	generic_fillattr(inode, stat);
+	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (is_huge_enabled(sb_info))
 		stat->blksize = HPAGE_PMD_SIZE;
-- 
2.30.0

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