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, 38 insertions, 29 deletions

diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index 1c14f18a6ec9..bb1b286c49ae 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -280,7 +280,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 			struct iattr iattr = { 0 };
 			struct posix_acl *old_acl = acl;
 
-			retval = posix_acl_update_mode(mnt_userns, inode,
+			retval = posix_acl_update_mode(&init_user_ns, inode,
 						       &iattr.ia_mode, &acl);
 			if (retval)
 				goto err_out;
@@ -299,7 +299,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 			 * What is the following setxattr update the
 			 * mode ?
 			 */
-			v9fs_vfs_setattr_dotl(dentry, &iattr);
+			v9fs_vfs_setattr_dotl(&init_user_ns, dentry, &iattr);
 		}
 		break;
 	case ACL_TYPE_DEFAULT:
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 7b763776306e..4ca56c5dd637 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -135,7 +135,8 @@ extern struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
 			unsigned int flags);
 extern int v9fs_vfs_unlink(struct inode *i, struct dentry *d);
 extern int v9fs_vfs_rmdir(struct inode *i, struct dentry *d);
-extern int v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+extern int v9fs_vfs_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);
 extern struct inode *v9fs_inode_from_fid(struct v9fs_session_info *v9ses,
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index fd2a2b040250..d44ade76966a 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -59,7 +59,8 @@ void v9fs_inode2stat(struct inode *inode, struct p9_wstat *stat);
 int v9fs_uflags2omode(int uflags, int extended);
 
 void v9fs_blank_wstat(struct p9_wstat *wstat);
-int v9fs_vfs_setattr_dotl(struct dentry *, struct iattr *);
+int v9fs_vfs_setattr_dotl(struct user_namespace *, struct dentry *,
+			  struct iattr *);
 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
 			 int datasync);
 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode);
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index c21b146c8d91..648eb4c4cf7f 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -676,8 +676,8 @@ error:
  */
 
 static int
-v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-		bool excl)
+v9fs_vfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+		struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
 	u32 perm = unixmode2p9mode(v9ses, mode);
@@ -702,7 +702,8 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
  *
  */
 
-static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+static int v9fs_vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+			  struct dentry *dentry, umode_t mode)
 {
 	int err;
 	u32 perm;
@@ -907,9 +908,9 @@ int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
  */
 
 int
-v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-		struct inode *new_dir, struct dentry *new_dentry,
-		unsigned int flags)
+v9fs_vfs_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)
 {
 	int retval;
 	struct inode *old_inode;
@@ -1016,8 +1017,8 @@ done:
  */
 
 static int
-v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
-		 u32 request_mask, unsigned int flags)
+v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct dentry *dentry = path->dentry;
 	struct v9fs_session_info *v9ses;
@@ -1054,7 +1055,8 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
  *
  */
 
-static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
+static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
+			    struct dentry *dentry, struct iattr *iattr)
 {
 	int retval, use_dentry = 0;
 	struct v9fs_session_info *v9ses;
@@ -1295,7 +1297,8 @@ static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
  */
 
 static int
-v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+v9fs_vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+		 struct dentry *dentry, const char *symname)
 {
 	p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
 		 dir->i_ino, dentry, symname);
@@ -1348,7 +1351,8 @@ v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
  */
 
 static int
-v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
+v9fs_vfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+	       struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
 	int retval;
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 984f28315d2a..1dc7af046615 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -33,8 +33,8 @@
 #include "acl.h"
 
 static int
-v9fs_vfs_mknod_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
-		    dev_t rdev);
+v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
+		    struct dentry *dentry, umode_t omode, dev_t rdev);
 
 /**
  * v9fs_get_fsgid_for_create - Helper function to get the gid for creating a
@@ -218,10 +218,10 @@ int v9fs_open_to_dotl_flags(int flags)
  */
 
 static int
-v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
-		bool excl)
+v9fs_vfs_create_dotl(struct user_namespace *mnt_userns, struct inode *dir,
+		     struct dentry *dentry, umode_t omode, bool excl)
 {
-	return v9fs_vfs_mknod_dotl(dir, dentry, omode, 0);
+	return v9fs_vfs_mknod_dotl(mnt_userns, dir, dentry, omode, 0);
 }
 
 static int
@@ -367,8 +367,9 @@ err_clunk_old_fid:
  *
  */
 
-static int v9fs_vfs_mkdir_dotl(struct inode *dir,
-			       struct dentry *dentry, umode_t omode)
+static int v9fs_vfs_mkdir_dotl(struct user_namespace *mnt_userns,
+			       struct inode *dir, struct dentry *dentry,
+			       umode_t omode)
 {
 	int err;
 	struct v9fs_session_info *v9ses;
@@ -457,8 +458,9 @@ error:
 }
 
 static int
-v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
-		 u32 request_mask, unsigned int flags)
+v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
+		      const struct path *path, struct kstat *stat,
+		      u32 request_mask, unsigned int flags)
 {
 	struct dentry *dentry = path->dentry;
 	struct v9fs_session_info *v9ses;
@@ -540,7 +542,8 @@ static int v9fs_mapped_iattr_valid(int iattr_valid)
  *
  */
 
-int v9fs_vfs_setattr_dotl(struct dentry *dentry, struct iattr *iattr)
+int v9fs_vfs_setattr_dotl(struct user_namespace *mnt_userns,
+			  struct dentry *dentry, struct iattr *iattr)
 {
 	int retval, use_dentry = 0;
 	struct p9_fid *fid = NULL;
@@ -684,8 +687,8 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode,
 }
 
 static int
-v9fs_vfs_symlink_dotl(struct inode *dir, struct dentry *dentry,
-		const char *symname)
+v9fs_vfs_symlink_dotl(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *dentry, const char *symname)
 {
 	int err;
 	kgid_t gid;
@@ -824,8 +827,8 @@ v9fs_vfs_link_dotl(struct dentry *old_dentry, struct inode *dir,
  *
  */
 static int
-v9fs_vfs_mknod_dotl(struct inode *dir, struct dentry *dentry, umode_t omode,
-		dev_t rdev)
+v9fs_vfs_mknod_dotl(struct user_namespace *mnt_userns, struct inode *dir,
+		    struct dentry *dentry, umode_t omode, dev_t rdev)
 {
 	int err;
 	kgid_t gid;