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>

5 files changed, 28 insertions, 18 deletions

diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
index 7b0fb66bc04d..059434e0f36c 100644
--- a/fs/ext4/acl.c
+++ b/fs/ext4/acl.c
@@ -222,7 +222,8 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 }
 
 int
-ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+	     struct posix_acl *acl, int type)
 {
 	handle_t *handle;
 	int error, credits, retries = 0;
diff --git a/fs/ext4/acl.h b/fs/ext4/acl.h
index 9b63f5416a2f..84b8942a57f2 100644
--- a/fs/ext4/acl.h
+++ b/fs/ext4/acl.h
@@ -56,7 +56,8 @@ static inline int ext4_acl_count(size_t size)
 
 /* acl.c */
 struct posix_acl *ext4_get_acl(struct inode *inode, int type);
-int ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type);
+int ext4_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+		 struct posix_acl *acl, int type);
 extern int ext4_init_acl(handle_t *, struct inode *, struct inode *);
 
 #else  /* CONFIG_EXT4_FS_POSIX_ACL */
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2866d249f3d2..3c750f5e8ebd 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2877,11 +2877,14 @@ extern struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 	__ext4_iget((sb), (ino), (flags), __func__, __LINE__)
 
 extern int  ext4_write_inode(struct inode *, struct writeback_control *);
-extern int  ext4_setattr(struct dentry *, struct iattr *);
-extern int  ext4_getattr(const struct path *, struct kstat *, u32, unsigned int);
+extern int  ext4_setattr(struct user_namespace *, struct dentry *,
+			 struct iattr *);
+extern int  ext4_getattr(struct user_namespace *, const struct path *,
+			 struct kstat *, u32, unsigned int);
 extern void ext4_evict_inode(struct inode *);
 extern void ext4_clear_inode(struct inode *);
-extern int  ext4_file_getattr(const struct path *, struct kstat *, u32, unsigned int);
+extern int  ext4_file_getattr(struct user_namespace *, const struct path *,
+			      struct kstat *, u32, unsigned int);
 extern int  ext4_sync_inode(handle_t *, struct inode *);
 extern void ext4_dirty_inode(struct inode *, int);
 extern int ext4_change_inode_journal_flag(struct inode *, int);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3a303d3f8423..ce45535336fa 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5319,7 +5319,8 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
  *
  * Called with inode->i_mutex down.
  */
-int ext4_setattr(struct dentry *dentry, struct iattr *attr)
+int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		 struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error, rc = 0;
@@ -5535,8 +5536,8 @@ err_out:
 	return error;
 }
 
-int ext4_getattr(const struct path *path, struct kstat *stat,
-		 u32 request_mask, unsigned int query_flags)
+int ext4_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		 struct kstat *stat, u32 request_mask, unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
 	struct ext4_inode *raw_inode;
@@ -5575,13 +5576,14 @@ int ext4_getattr(const struct path *path, struct kstat *stat,
 	return 0;
 }
 
-int ext4_file_getattr(const struct path *path, struct kstat *stat,
+int ext4_file_getattr(struct user_namespace *mnt_userns,
+		      const struct path *path, struct kstat *stat,
 		      u32 request_mask, unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
 	u64 delalloc_blocks;
 
-	ext4_getattr(path, stat, request_mask, query_flags);
+	ext4_getattr(&init_user_ns, path, stat, request_mask, query_flags);
 
 	/*
 	 * If there is inline data in the inode, the inode will normally not
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index cf652ba3e74d..13dff80aedcb 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2596,8 +2596,8 @@ static int ext4_add_nondir(handle_t *handle,
  * If the create succeeds, we fill in the inode information
  * with d_instantiate().
  */
-static int ext4_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-		       bool excl)
+static int ext4_create(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, bool excl)
 {
 	handle_t *handle;
 	struct inode *inode;
@@ -2631,8 +2631,8 @@ retry:
 	return err;
 }
 
-static int ext4_mknod(struct inode *dir, struct dentry *dentry,
-		      umode_t mode, dev_t rdev)
+static int ext4_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	handle_t *handle;
 	struct inode *inode;
@@ -2665,7 +2665,8 @@ retry:
 	return err;
 }
 
-static int ext4_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int ext4_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode)
 {
 	handle_t *handle;
 	struct inode *inode;
@@ -2774,7 +2775,8 @@ out:
 	return err;
 }
 
-static int ext4_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int ext4_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode)
 {
 	handle_t *handle;
 	struct inode *inode;
@@ -3292,7 +3294,7 @@ out_trace:
 	return retval;
 }
 
-static int ext4_symlink(struct inode *dir,
+static int ext4_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 			struct dentry *dentry, const char *symname)
 {
 	handle_t *handle;
@@ -4085,7 +4087,8 @@ end_rename:
 	return retval;
 }
 
-static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry,
+static int ext4_rename2(struct user_namespace *mnt_userns,
+			struct inode *old_dir, struct dentry *old_dentry,
 			struct inode *new_dir, struct dentry *new_dentry,
 			unsigned int flags)
 {