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>

4 files changed, 20 insertions, 14 deletions

diff --git a/fs/minix/file.c b/fs/minix/file.c
index f07acd268577..6a7bd2d9eec0 100644
--- a/fs/minix/file.c
+++ b/fs/minix/file.c
@@ -22,7 +22,8 @@ const struct file_operations minix_file_operations = {
 	.splice_read	= generic_file_splice_read,
 };
 
-static int minix_setattr(struct dentry *dentry, struct iattr *attr)
+static int minix_setattr(struct user_namespace *mnt_userns,
+			 struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;
diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index 91c81d2fc90d..a532a99bbe81 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -652,8 +652,8 @@ static int minix_write_inode(struct inode *inode, struct writeback_control *wbc)
 	return err;
 }
 
-int minix_getattr(const struct path *path, struct kstat *stat,
-		  u32 request_mask, unsigned int flags)
+int minix_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		  struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct super_block *sb = path->dentry->d_sb;
 	struct inode *inode = d_inode(path->dentry);
diff --git a/fs/minix/minix.h b/fs/minix/minix.h
index 168d45d3de73..202173368025 100644
--- a/fs/minix/minix.h
+++ b/fs/minix/minix.h
@@ -51,7 +51,8 @@ extern unsigned long minix_count_free_inodes(struct super_block *sb);
 extern int minix_new_block(struct inode * inode);
 extern void minix_free_block(struct inode *inode, unsigned long block);
 extern unsigned long minix_count_free_blocks(struct super_block *sb);
-extern int minix_getattr(const struct path *, struct kstat *, u32, unsigned int);
+extern int minix_getattr(struct user_namespace *, const struct path *,
+			 struct kstat *, u32, unsigned int);
 extern int minix_prepare_chunk(struct page *page, loff_t pos, unsigned len);
 
 extern void V1_minix_truncate(struct inode *);
diff --git a/fs/minix/namei.c b/fs/minix/namei.c
index 1a6084d2b02e..937fa5fae2b8 100644
--- a/fs/minix/namei.c
+++ b/fs/minix/namei.c
@@ -33,7 +33,8 @@ static struct dentry *minix_lookup(struct inode * dir, struct dentry *dentry, un
 	return d_splice_alias(inode, dentry);
 }
 
-static int minix_mknod(struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
+static int minix_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	int error;
 	struct inode *inode;
@@ -51,7 +52,8 @@ static int minix_mknod(struct inode * dir, struct dentry *dentry, umode_t mode,
 	return error;
 }
 
-static int minix_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int minix_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
+			 struct dentry *dentry, umode_t mode)
 {
 	int error;
 	struct inode *inode = minix_new_inode(dir, mode, &error);
@@ -63,14 +65,14 @@ static int minix_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 	return error;
 }
 
-static int minix_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-		bool excl)
+static int minix_create(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, umode_t mode, bool excl)
 {
-	return minix_mknod(dir, dentry, mode, 0);
+	return minix_mknod(mnt_userns, dir, dentry, mode, 0);
 }
 
-static int minix_symlink(struct inode * dir, struct dentry *dentry,
-	  const char * symname)
+static int minix_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+			 struct dentry *dentry, const char *symname)
 {
 	int err = -ENAMETOOLONG;
 	int i = strlen(symname)+1;
@@ -109,7 +111,8 @@ static int minix_link(struct dentry * old_dentry, struct inode * dir,
 	return add_nondir(dentry, inode);
 }
 
-static int minix_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
+static int minix_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode)
 {
 	struct inode * inode;
 	int err;
@@ -181,8 +184,9 @@ static int minix_rmdir(struct inode * dir, struct dentry *dentry)
 	return err;
 }
 
-static int minix_rename(struct inode * old_dir, struct dentry *old_dentry,
-			struct inode * new_dir, struct dentry *new_dentry,
+static int minix_rename(struct user_namespace *mnt_userns,
+			struct inode *old_dir, struct dentry *old_dentry,
+			struct inode *new_dir, struct dentry *new_dentry,
 			unsigned int flags)
 {
 	struct inode * old_inode = d_inode(old_dentry);