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, 18 insertions, 13 deletions

diff --git a/fs/sysv/file.c b/fs/sysv/file.c
index ca7e216b7b9e..90e00124ea07 100644
--- a/fs/sysv/file.c
+++ b/fs/sysv/file.c
@@ -29,7 +29,8 @@ const struct file_operations sysv_file_operations = {
 	.splice_read	= generic_file_splice_read,
 };
 
-static int sysv_setattr(struct dentry *dentry, struct iattr *attr)
+static int sysv_setattr(struct user_namespace *mnt_userns,
+			struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;
diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c
index 83cffab6955f..8b2e99b7bc9f 100644
--- a/fs/sysv/itree.c
+++ b/fs/sysv/itree.c
@@ -441,8 +441,8 @@ static unsigned sysv_nblocks(struct super_block *s, loff_t size)
 	return blocks;
 }
 
-int sysv_getattr(const struct path *path, struct kstat *stat,
-		 u32 request_mask, unsigned int flags)
+int sysv_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct super_block *s = path->dentry->d_sb;
 	generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
diff --git a/fs/sysv/namei.c b/fs/sysv/namei.c
index ea2414b385ec..b2e6abc06a2d 100644
--- a/fs/sysv/namei.c
+++ b/fs/sysv/namei.c
@@ -41,7 +41,8 @@ static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, un
 	return d_splice_alias(inode, dentry);
 }
 
-static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode, dev_t rdev)
+static int sysv_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct inode * inode;
 	int err;
@@ -60,13 +61,14 @@ static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode,
 	return err;
 }
 
-static int sysv_create(struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
+static int sysv_create(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *dentry, umode_t mode, bool excl)
 {
-	return sysv_mknod(dir, dentry, mode, 0);
+	return sysv_mknod(&init_user_ns, dir, dentry, mode, 0);
 }
 
-static int sysv_symlink(struct inode * dir, struct dentry * dentry, 
-	const char * symname)
+static int sysv_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+			struct dentry *dentry, const char *symname)
 {
 	int err = -ENAMETOOLONG;
 	int l = strlen(symname)+1;
@@ -108,7 +110,8 @@ static int sysv_link(struct dentry * old_dentry, struct inode * dir,
 	return add_nondir(dentry, inode);
 }
 
-static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
+static int sysv_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, umode_t mode)
 {
 	struct inode * inode;
 	int err;
@@ -186,9 +189,9 @@ static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
  * Anybody can rename anything with this: the permission checks are left to the
  * higher-level routines.
  */
-static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
-		       struct inode * new_dir, struct dentry * new_dentry,
-		       unsigned int flags)
+static int sysv_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);
 	struct inode * new_inode = d_inode(new_dentry);
diff --git a/fs/sysv/sysv.h b/fs/sysv/sysv.h
index 1cff585526b1..99ddf033da4f 100644
--- a/fs/sysv/sysv.h
+++ b/fs/sysv/sysv.h
@@ -141,7 +141,8 @@ extern struct inode *sysv_iget(struct super_block *, unsigned int);
 extern int sysv_write_inode(struct inode *, struct writeback_control *wbc);
 extern int sysv_sync_inode(struct inode *);
 extern void sysv_set_inode(struct inode *, dev_t);
-extern int sysv_getattr(const struct path *, struct kstat *, u32, unsigned int);
+extern int sysv_getattr(struct user_namespace *, const struct path *,
+			struct kstat *, u32, unsigned int);
 extern int sysv_init_icache(void);
 extern void sysv_destroy_icache(void);