[PATCH] fs: move the posix_acl_fix_xattr_{to_from}_user out of xattr code

[Christoph Hellwig <hch@lst.de>]

There is no excuse to ever perform actions related to a specific handler
directly from the generic xattr code as we have handler that understand
the specific data in given attrs.  As a nice sideeffect this removes
tons of pointless boilerplate code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---

Changes since v1:
 - fix up file systems that have their own ACL xattr handlers

 fs/9p/acl.c                     |  4 +--
 fs/overlayfs/dir.c              |  2 +-
 fs/overlayfs/super.c            |  2 +-
 fs/posix_acl.c                  | 62 ++-------------------------------
 fs/xattr.c                      |  8 +----
 include/linux/posix_acl_xattr.h | 12 -------
 6 files changed, 7 insertions(+), 83 deletions(-)

diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index 6261719f6f2a..f3455ba2a84d 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -232,7 +232,7 @@ static int v9fs_xattr_get_acl(const struct xattr_handler *handler,
 		return PTR_ERR(acl);
 	if (acl == NULL)
 		return -ENODATA;
-	error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
+	error = posix_acl_to_xattr(current_user_ns(), acl, buffer, size);
 	posix_acl_release(acl);
 
 	return error;
@@ -262,7 +262,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 		return -EPERM;
 	if (value) {
 		/* update the cached acl value */
-		acl = posix_acl_from_xattr(&init_user_ns, value, size);
+		acl = posix_acl_from_xattr(current_user_ns(), value, size);
 		if (IS_ERR(acl))
 			return PTR_ERR(acl);
 		else if (acl) {
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 8e57d5372b8f..0b07e99475fd 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -416,7 +416,7 @@ static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
 	if (!buffer)
 		return -ENOMEM;
 
-	err = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
+	err = posix_acl_to_xattr(current_user_ns(), acl, buffer, size);
 	if (err < 0)
 		goto out_free;
 
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 319fe0d355b0..4c62636f295b 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -874,7 +874,7 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
 
 	/* Check that everything is OK before copy-up */
 	if (value) {
-		acl = posix_acl_from_xattr(&init_user_ns, value, size);
+		acl = posix_acl_from_xattr(current_user_ns(), value, size);
 		if (IS_ERR(acl))
 			return PTR_ERR(acl);
 	}
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 249672bf54fe..09f1b7d186f0 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -663,64 +663,6 @@ int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
 }
 EXPORT_SYMBOL(posix_acl_update_mode);
 
-/*
- * Fix up the uids and gids in posix acl extended attributes in place.
- */
-static void posix_acl_fix_xattr_userns(
-	struct user_namespace *to, struct user_namespace *from,
-	void *value, size_t size)
-{
-	struct posix_acl_xattr_header *header = value;
-	struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
-	int count;
-	kuid_t uid;
-	kgid_t gid;
-
-	if (!value)
-		return;
-	if (size < sizeof(struct posix_acl_xattr_header))
-		return;
-	if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
-		return;
-
-	count = posix_acl_xattr_count(size);
-	if (count < 0)
-		return;
-	if (count == 0)
-		return;
-
-	for (end = entry + count; entry != end; entry++) {
-		switch(le16_to_cpu(entry->e_tag)) {
-		case ACL_USER:
-			uid = make_kuid(from, le32_to_cpu(entry->e_id));
-			entry->e_id = cpu_to_le32(from_kuid(to, uid));
-			break;
-		case ACL_GROUP:
-			gid = make_kgid(from, le32_to_cpu(entry->e_id));
-			entry->e_id = cpu_to_le32(from_kgid(to, gid));
-			break;
-		default:
-			break;
-		}
-	}
-}
-
-void posix_acl_fix_xattr_from_user(void *value, size_t size)
-{
-	struct user_namespace *user_ns = current_user_ns();
-	if (user_ns == &init_user_ns)
-		return;
-	posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
-}
-
-void posix_acl_fix_xattr_to_user(void *value, size_t size)
-{
-	struct user_namespace *user_ns = current_user_ns();
-	if (user_ns == &init_user_ns)
-		return;
-	posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
-}
-
 /*
  * Convert from extended attribute to in-memory representation.
  */
@@ -851,7 +793,7 @@ posix_acl_xattr_get(const struct xattr_handler *handler,
 	if (acl == NULL)
 		return -ENODATA;
 
-	error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
+	error = posix_acl_to_xattr(current_user_ns(), acl, value, size);
 	posix_acl_release(acl);
 
 	return error;
@@ -889,7 +831,7 @@ posix_acl_xattr_set(const struct xattr_handler *handler,
 	int ret;
 
 	if (value) {
-		acl = posix_acl_from_xattr(&init_user_ns, value, size);
+		acl = posix_acl_from_xattr(current_user_ns(), value, size);
 		if (IS_ERR(acl))
 			return PTR_ERR(acl);
 	}
diff --git a/fs/xattr.c b/fs/xattr.c
index 90dd78f0eb27..c31e9a9ea172 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -437,10 +437,7 @@ setxattr(struct dentry *d, const char __user *name, const void __user *value,
 			error = -EFAULT;
 			goto out;
 		}
-		if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
-		    (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
-			posix_acl_fix_xattr_from_user(kvalue, size);
-		else if (strcmp(kname, XATTR_NAME_CAPS) == 0) {
+		if (strcmp(kname, XATTR_NAME_CAPS) == 0) {
 			error = cap_convert_nscap(d, &kvalue, size);
 			if (error < 0)
 				goto out;
@@ -537,9 +534,6 @@ getxattr(struct dentry *d, const char __user *name, void __user *value,
 
 	error = vfs_getxattr(d, kname, kvalue, size);
 	if (error > 0) {
-		if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
-		    (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
-			posix_acl_fix_xattr_to_user(kvalue, error);
 		if (size && copy_to_user(value, kvalue, error))
 			error = -EFAULT;
 	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
diff --git a/include/linux/posix_acl_xattr.h b/include/linux/posix_acl_xattr.h
index 2387709991b5..8f5e70a1bd05 100644
--- a/include/linux/posix_acl_xattr.h
+++ b/include/linux/posix_acl_xattr.h
@@ -32,18 +32,6 @@ posix_acl_xattr_count(size_t size)
 	return size / sizeof(struct posix_acl_xattr_entry);
 }
 
-#ifdef CONFIG_FS_POSIX_ACL
-void posix_acl_fix_xattr_from_user(void *value, size_t size);
-void posix_acl_fix_xattr_to_user(void *value, size_t size);
-#else
-static inline void posix_acl_fix_xattr_from_user(void *value, size_t size)
-{
-}
-static inline void posix_acl_fix_xattr_to_user(void *value, size_t size)
-{
-}
-#endif
-
 struct posix_acl *posix_acl_from_xattr(struct user_namespace *user_ns, 
 				       const void *value, size_t size);
 int posix_acl_to_xattr(struct user_namespace *user_ns,
-- 
2.25.1