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>

6 files changed, 39 insertions, 24 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 727e01a84503..19a9f434442f 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2095,8 +2095,8 @@ EXPORT_SYMBOL_GPL(nfs_instantiate);
  * that the operation succeeded on the server, but an error in the
  * reply path made it appear to have failed.
  */
-int nfs_create(struct inode *dir, struct dentry *dentry,
-		umode_t mode, bool excl)
+int nfs_create(struct user_namespace *mnt_userns, struct inode *dir,
+	       struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct iattr attr;
 	int open_flags = excl ? O_CREAT | O_EXCL : O_CREAT;
@@ -2124,7 +2124,8 @@ EXPORT_SYMBOL_GPL(nfs_create);
  * See comments for nfs_proc_create regarding failed operations.
  */
 int
-nfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
+nfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+	  struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct iattr attr;
 	int status;
@@ -2150,7 +2151,8 @@ EXPORT_SYMBOL_GPL(nfs_mknod);
 /*
  * See comments for nfs_proc_create regarding failed operations.
  */
-int nfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+int nfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+	      struct dentry *dentry, umode_t mode)
 {
 	struct iattr attr;
 	int error;
@@ -2295,7 +2297,8 @@ EXPORT_SYMBOL_GPL(nfs_unlink);
  * now have a new file handle and can instantiate an in-core NFS inode
  * and move the raw page into its mapping.
  */
-int nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+int nfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+		struct dentry *dentry, const char *symname)
 {
 	struct page *page;
 	char *kaddr;
@@ -2398,9 +2401,9 @@ EXPORT_SYMBOL_GPL(nfs_link);
  * If these conditions are met, we can drop the dentries before doing
  * the rename.
  */
-int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-	       struct inode *new_dir, struct dentry *new_dentry,
-	       unsigned int flags)
+int nfs_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);
@@ -2939,7 +2942,9 @@ static int nfs_execute_ok(struct inode *inode, int mask)
 	return ret;
 }
 
-int nfs_permission(struct inode *inode, int mask)
+int nfs_permission(struct user_namespace *mnt_userns,
+		   struct inode *inode,
+		   int mask)
 {
 	const struct cred *cred = current_cred();
 	int res = 0;
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index cab123ec1664..447e95974386 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -594,7 +594,8 @@ EXPORT_SYMBOL_GPL(nfs_fhget);
 #define NFS_VALID_ATTRS (ATTR_MODE|ATTR_UID|ATTR_GID|ATTR_SIZE|ATTR_ATIME|ATTR_ATIME_SET|ATTR_MTIME|ATTR_MTIME_SET|ATTR_FILE|ATTR_OPEN)
 
 int
-nfs_setattr(struct dentry *dentry, struct iattr *attr)
+nfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+	    struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct nfs_fattr *fattr;
@@ -787,8 +788,8 @@ static bool nfs_need_revalidate_inode(struct inode *inode)
 	return false;
 }
 
-int nfs_getattr(const struct path *path, struct kstat *stat,
-		u32 request_mask, unsigned int query_flags)
+int nfs_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 nfs_server *server = NFS_SERVER(inode);
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 62d3189745cd..25fb43b69e5a 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -378,14 +378,18 @@ extern unsigned long nfs_access_cache_count(struct shrinker *shrink,
 extern unsigned long nfs_access_cache_scan(struct shrinker *shrink,
 					   struct shrink_control *sc);
 struct dentry *nfs_lookup(struct inode *, struct dentry *, unsigned int);
-int nfs_create(struct inode *, struct dentry *, umode_t, bool);
-int nfs_mkdir(struct inode *, struct dentry *, umode_t);
+int nfs_create(struct user_namespace *, struct inode *, struct dentry *,
+	       umode_t, bool);
+int nfs_mkdir(struct user_namespace *, struct inode *, struct dentry *,
+	      umode_t);
 int nfs_rmdir(struct inode *, struct dentry *);
 int nfs_unlink(struct inode *, struct dentry *);
-int nfs_symlink(struct inode *, struct dentry *, const char *);
+int nfs_symlink(struct user_namespace *, struct inode *, struct dentry *,
+		const char *);
 int nfs_link(struct dentry *, struct inode *, struct dentry *);
-int nfs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
-int nfs_rename(struct inode *, struct dentry *,
+int nfs_mknod(struct user_namespace *, struct inode *, struct dentry *, umode_t,
+	      dev_t);
+int nfs_rename(struct user_namespace *, struct inode *, struct dentry *,
 	       struct inode *, struct dentry *, unsigned int);
 
 /* file.c */
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 55fc711e368b..93e60e921f92 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -208,20 +208,23 @@ out_fc:
 }
 
 static int
-nfs_namespace_getattr(const struct path *path, struct kstat *stat,
-			u32 request_mask, unsigned int query_flags)
+nfs_namespace_getattr(struct user_namespace *mnt_userns,
+		      const struct path *path, struct kstat *stat,
+		      u32 request_mask, unsigned int query_flags)
 {
 	if (NFS_FH(d_inode(path->dentry))->size != 0)
-		return nfs_getattr(path, stat, request_mask, query_flags);
+		return nfs_getattr(mnt_userns, path, stat, request_mask,
+				   query_flags);
 	generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
 	return 0;
 }
 
 static int
-nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
+nfs_namespace_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+		      struct iattr *attr)
 {
 	if (NFS_FH(d_inode(dentry))->size != 0)
-		return nfs_setattr(dentry, attr);
+		return nfs_setattr(mnt_userns, dentry, attr);
 	return -EACCES;
 }
 
diff --git a/fs/nfs/nfs3_fs.h b/fs/nfs/nfs3_fs.h
index 1b950b66b3bb..c8a192802dda 100644
--- a/fs/nfs/nfs3_fs.h
+++ b/fs/nfs/nfs3_fs.h
@@ -12,7 +12,8 @@
  */
 #ifdef CONFIG_NFS_V3_ACL
 extern struct posix_acl *nfs3_get_acl(struct inode *inode, int type);
-extern int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int type);
+extern int nfs3_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+			struct posix_acl *acl, int type);
 extern int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 		struct posix_acl *dfacl);
 extern ssize_t nfs3_listxattr(struct dentry *, char *, size_t);
diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index c6c863382f37..5604e807fc01 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -251,7 +251,8 @@ int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 
 }
 
-int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+int nfs3_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
+		 struct posix_acl *acl, int type)
 {
 	struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
 	int status;