[v3,04/11] fs/fuse: support idmapped getattr inode op

Commit Message

Aleksandr Mikhalitsyn Aug. 15, 2024, 9:24 a.m. UTC

We have to:
- pass an idmapping to the generic_fillattr()
to properly handle UIG/GID mapping for the userspace.
- pass -/- to fuse_fillattr() (analog of generic_fillattr() in fuse).

Difference between these two is that generic_fillattr() takes all
the stat() data from the inode directly, while fuse_fillattr() codepath
takes a fresh data just from the userspace reply on the FUSE_GETATTR request.

In some cases we can just pass &nop_mnt_idmap, because idmapping won't
be used in these codepaths. For example, when 3rd argument of fuse_do_getattr()
is NULL then idmap argument is not used.

Cc: Christian Brauner <[e-mail]>
Cc: Seth Forshee <[e-mail]>
Cc: Miklos Szeredi <[e-mail]>
Cc: Amir Goldstein <[e-mail]>
Cc: Bernd Schubert <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Alexander Mikhalitsyn <[e-mail]>
---
v2:
	- pass idmap in more cases to make code easier to understand
---
 fs/fuse/dir.c | 44 ++++++++++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 20 deletions(-)

Patch

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 1e45c6157af4..a5bf8c18a0ae 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1157,18 +1157,22 @@  static int fuse_link(struct dentry *entry, struct inode *newdir,
 	return err;
 }
 
-static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr,
-			  struct kstat *stat)
+static void fuse_fillattr(struct mnt_idmap *idmap, struct inode *inode,
+			  struct fuse_attr *attr, struct kstat *stat)
 {
 	unsigned int blkbits;
 	struct fuse_conn *fc = get_fuse_conn(inode);
+	vfsuid_t vfsuid = make_vfsuid(idmap, fc->user_ns,
+				      make_kuid(fc->user_ns, attr->uid));
+	vfsgid_t vfsgid = make_vfsgid(idmap, fc->user_ns,
+				      make_kgid(fc->user_ns, attr->gid));
 
 	stat->dev = inode->i_sb->s_dev;
 	stat->ino = attr->ino;
 	stat->mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 	stat->nlink = attr->nlink;
-	stat->uid = make_kuid(fc->user_ns, attr->uid);
-	stat->gid = make_kgid(fc->user_ns, attr->gid);
+	stat->uid = vfsuid_into_kuid(vfsuid);
+	stat->gid = vfsgid_into_kgid(vfsgid);
 	stat->rdev = inode->i_rdev;
 	stat->atime.tv_sec = attr->atime;
 	stat->atime.tv_nsec = attr->atimensec;
@@ -1207,8 +1211,8 @@  static void fuse_statx_to_attr(struct fuse_statx *sx, struct fuse_attr *attr)
 	attr->blksize = sx->blksize;
 }
 
-static int fuse_do_statx(struct inode *inode, struct file *file,
-			 struct kstat *stat)
+static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
+			 struct file *file, struct kstat *stat)
 {
 	int err;
 	struct fuse_attr attr;
@@ -1261,15 +1265,15 @@  static int fuse_do_statx(struct inode *inode, struct file *file,
 		stat->result_mask = sx->mask & (STATX_BASIC_STATS | STATX_BTIME);
 		stat->btime.tv_sec = sx->btime.tv_sec;
 		stat->btime.tv_nsec = min_t(u32, sx->btime.tv_nsec, NSEC_PER_SEC - 1);
-		fuse_fillattr(inode, &attr, stat);
+		fuse_fillattr(idmap, inode, &attr, stat);
 		stat->result_mask |= STATX_TYPE;
 	}
 
 	return 0;
 }
 
-static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
-			   struct file *file)
+static int fuse_do_getattr(struct mnt_idmap *idmap, struct inode *inode,
+			   struct kstat *stat, struct file *file)
 {
 	int err;
 	struct fuse_getattr_in inarg;
@@ -1308,15 +1312,15 @@  static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
 					       ATTR_TIMEOUT(&outarg),
 					       attr_version);
 			if (stat)
-				fuse_fillattr(inode, &outarg.attr, stat);
+				fuse_fillattr(idmap, inode, &outarg.attr, stat);
 		}
 	}
 	return err;
 }
 
-static int fuse_update_get_attr(struct inode *inode, struct file *file,
-				struct kstat *stat, u32 request_mask,
-				unsigned int flags)
+static int fuse_update_get_attr(struct mnt_idmap *idmap, struct inode *inode,
+				struct file *file, struct kstat *stat,
+				u32 request_mask, unsigned int flags)
 {
 	struct fuse_inode *fi = get_fuse_inode(inode);
 	struct fuse_conn *fc = get_fuse_conn(inode);
@@ -1347,17 +1351,17 @@  static int fuse_update_get_attr(struct inode *inode, struct file *file,
 		forget_all_cached_acls(inode);
 		/* Try statx if BTIME is requested */
 		if (!fc->no_statx && (request_mask & ~STATX_BASIC_STATS)) {
-			err = fuse_do_statx(inode, file, stat);
+			err = fuse_do_statx(idmap, inode, file, stat);
 			if (err == -ENOSYS) {
 				fc->no_statx = 1;
 				err = 0;
 				goto retry;
 			}
 		} else {
-			err = fuse_do_getattr(inode, stat, file);
+			err = fuse_do_getattr(idmap, inode, stat, file);
 		}
 	} else if (stat) {
-		generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
+		generic_fillattr(idmap, request_mask, inode, stat);
 		stat->mode = fi->orig_i_mode;
 		stat->ino = fi->orig_ino;
 		if (test_bit(FUSE_I_BTIME, &fi->state)) {
@@ -1371,7 +1375,7 @@  static int fuse_update_get_attr(struct inode *inode, struct file *file,
 
 int fuse_update_attributes(struct inode *inode, struct file *file, u32 mask)
 {
-	return fuse_update_get_attr(inode, file, NULL, mask, 0);
+	return fuse_update_get_attr(&nop_mnt_idmap, inode, file, NULL, mask, 0);
 }
 
 int fuse_reverse_inval_entry(struct fuse_conn *fc, u64 parent_nodeid,
@@ -1515,7 +1519,7 @@  static int fuse_perm_getattr(struct inode *inode, int mask)
 		return -ECHILD;
 
 	forget_all_cached_acls(inode);
-	return fuse_do_getattr(inode, NULL, NULL);
+	return fuse_do_getattr(&nop_mnt_idmap, inode, NULL, NULL);
 }
 
 /*
@@ -2094,7 +2098,7 @@  static int fuse_setattr(struct mnt_idmap *idmap, struct dentry *entry,
 			 * ia_mode calculation may have used stale i_mode.
 			 * Refresh and recalculate.
 			 */
-			ret = fuse_do_getattr(inode, NULL, file);
+			ret = fuse_do_getattr(idmap, inode, NULL, file);
 			if (ret)
 				return ret;
 
@@ -2151,7 +2155,7 @@  static int fuse_getattr(struct mnt_idmap *idmap,
 		return -EACCES;
 	}
 
-	return fuse_update_get_attr(inode, NULL, stat, request_mask, flags);
+	return fuse_update_get_attr(idmap, inode, NULL, stat, request_mask, flags);
 }
 
 static const struct inode_operations fuse_dir_inode_operations = {