fs: make helpers idmap mount aware

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-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>

1 files changed, 32 insertions, 21 deletions

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 226b5b1dc1fa..cfac2c1e67fa 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -325,7 +325,7 @@ struct inode *gfs2_lookupi(struct inode *dir, const struct qstr *name,
 	}
 
 	if (!is_root) {
-		error = gfs2_permission(dir, MAY_EXEC);
+		error = gfs2_permission(&init_user_ns, dir, MAY_EXEC);
 		if (error)
 			goto out;
 	}
@@ -355,7 +355,8 @@ static int create_ok(struct gfs2_inode *dip, const struct qstr *name,
 {
 	int error;
 
-	error = gfs2_permission(&dip->i_inode, MAY_WRITE | MAY_EXEC);
+	error = gfs2_permission(&init_user_ns, &dip->i_inode,
+				MAY_WRITE | MAY_EXEC);
 	if (error)
 		return error;
 
@@ -843,8 +844,8 @@ fail:
  * Returns: errno
  */
 
-static int gfs2_create(struct inode *dir, struct dentry *dentry,
-		       umode_t mode, bool excl)
+static int gfs2_create(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, bool excl)
 {
 	return gfs2_create_inode(dir, dentry, NULL, S_IFREG | mode, 0, NULL, 0, excl);
 }
@@ -951,7 +952,7 @@ static int gfs2_link(struct dentry *old_dentry, struct inode *dir,
 	if (inode->i_nlink == 0)
 		goto out_gunlock;
 
-	error = gfs2_permission(dir, MAY_WRITE | MAY_EXEC);
+	error = gfs2_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC);
 	if (error)
 		goto out_gunlock;
 
@@ -1068,7 +1069,8 @@ static int gfs2_unlink_ok(struct gfs2_inode *dip, const struct qstr *name,
 	if (IS_APPEND(&dip->i_inode))
 		return -EPERM;
 
-	error = gfs2_permission(&dip->i_inode, MAY_WRITE | MAY_EXEC);
+	error = gfs2_permission(&init_user_ns, &dip->i_inode,
+				MAY_WRITE | MAY_EXEC);
 	if (error)
 		return error;
 
@@ -1204,8 +1206,8 @@ out_inodes:
  * Returns: errno
  */
 
-static int gfs2_symlink(struct inode *dir, struct dentry *dentry,
-			const char *symname)
+static int gfs2_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, const char *symname)
 {
 	unsigned int size;
 
@@ -1225,7 +1227,8 @@ static int gfs2_symlink(struct inode *dir, struct dentry *dentry,
  * Returns: errno
  */
 
-static int gfs2_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int gfs2_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode)
 {
 	unsigned dsize = gfs2_max_stuffed_size(GFS2_I(dir));
 	return gfs2_create_inode(dir, dentry, NULL, S_IFDIR | mode, 0, NULL, dsize, 0);
@@ -1240,8 +1243,8 @@ static int gfs2_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
  *
  */
 
-static int gfs2_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
-		      dev_t dev)
+static int gfs2_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode, dev_t dev)
 {
 	return gfs2_create_inode(dir, dentry, NULL, mode, dev, NULL, 0, 0);
 }
@@ -1490,7 +1493,8 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 			}
 		}
 	} else {
-		error = gfs2_permission(ndir, MAY_WRITE | MAY_EXEC);
+		error = gfs2_permission(&init_user_ns, ndir,
+					MAY_WRITE | MAY_EXEC);
 		if (error)
 			goto out_gunlock;
 
@@ -1525,7 +1529,8 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 	/* Check out the dir to be renamed */
 
 	if (dir_rename) {
-		error = gfs2_permission(d_inode(odentry), MAY_WRITE);
+		error = gfs2_permission(&init_user_ns, d_inode(odentry),
+					MAY_WRITE);
 		if (error)
 			goto out_gunlock;
 	}
@@ -1688,12 +1693,14 @@ static int gfs2_exchange(struct inode *odir, struct dentry *odentry,
 		goto out_gunlock;
 
 	if (S_ISDIR(old_mode)) {
-		error = gfs2_permission(odentry->d_inode, MAY_WRITE);
+		error = gfs2_permission(&init_user_ns, odentry->d_inode,
+					MAY_WRITE);
 		if (error)
 			goto out_gunlock;
 	}
 	if (S_ISDIR(new_mode)) {
-		error = gfs2_permission(ndentry->d_inode, MAY_WRITE);
+		error = gfs2_permission(&init_user_ns, ndentry->d_inode,
+					MAY_WRITE);
 		if (error)
 			goto out_gunlock;
 	}
@@ -1747,9 +1754,9 @@ out:
 	return error;
 }
 
-static int gfs2_rename2(struct inode *odir, struct dentry *odentry,
-			struct inode *ndir, struct dentry *ndentry,
-			unsigned int flags)
+static int gfs2_rename2(struct user_namespace *mnt_userns, struct inode *odir,
+			struct dentry *odentry, struct inode *ndir,
+			struct dentry *ndentry, unsigned int flags)
 {
 	flags &= ~RENAME_NOREPLACE;
 
@@ -1833,7 +1840,8 @@ out:
  * Returns: errno
  */
 
-int gfs2_permission(struct inode *inode, int mask)
+int gfs2_permission(struct user_namespace *mnt_userns, struct inode *inode,
+		    int mask)
 {
 	struct gfs2_inode *ip;
 	struct gfs2_holder i_gh;
@@ -1963,7 +1971,8 @@ out:
  * Returns: errno
  */
 
-static int gfs2_setattr(struct dentry *dentry, struct iattr *attr)
+static int gfs2_setattr(struct user_namespace *mnt_userns,
+			struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct gfs2_inode *ip = GFS2_I(inode);
@@ -2008,6 +2017,7 @@ out:
 
 /**
  * gfs2_getattr - Read out an inode's attributes
+ * @mnt_userns:	user namespace of the mount the inode was found from
  * @path: Object to query
  * @stat: The inode's stats
  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
@@ -2022,7 +2032,8 @@ out:
  * Returns: errno
  */
 
-static int gfs2_getattr(const struct path *path, struct kstat *stat,
+static int gfs2_getattr(struct user_namespace *mnt_userns,
+			const struct path *path, struct kstat *stat,
 			u32 request_mask, unsigned int flags)
 {
 	struct inode *inode = d_inode(path->dentry);