vfs: Distinguish between full xattr names and proper prefixes

Add an additional "name" field to struct xattr_handler.  When the name
is set, the handler matches attributes with exactly that name.  When the
prefix is set instead, the handler matches attributes with the given
prefix and with a non-empty suffix.

This patch should avoid bugs like the one fixed in commit c361016a in
the future.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

22 files changed, 47 insertions, 130 deletions

diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index 6ff30b14bc76..9da967f38387 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -220,15 +220,12 @@ static int v9fs_xattr_get_acl(const struct xattr_handler *handler,
         struct posix_acl *acl;
         int error;
 
-        if (strcmp(name, "") != 0)
-                return -EINVAL;
-
         v9ses = v9fs_dentry2v9ses(dentry);
         /*
          * We allow set/get/list of acl when access=client is not specified
          */
         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
-                return v9fs_xattr_get(dentry, handler->prefix, buffer, size);
+                return v9fs_xattr_get(dentry, handler->name, buffer, size);
 
         acl = v9fs_get_cached_acl(d_inode(dentry), handler->flags);
         if (IS_ERR(acl))
@@ -250,16 +247,13 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
         struct v9fs_session_info *v9ses;
         struct inode *inode = d_inode(dentry);
 
-        if (strcmp(name, "") != 0)
-                return -EINVAL;
-
         v9ses = v9fs_dentry2v9ses(dentry);
         /*
          * set the attribute on the remote. Without even looking at the
          * xattr value. We leave it to the server to validate
          */
         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
-                return v9fs_xattr_set(dentry, handler->prefix, value, size,
+                return v9fs_xattr_set(dentry, handler->name, value, size,
                                       flags);
 
         if (S_ISLNK(inode->i_mode))
@@ -319,7 +313,7 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
         default:
                 BUG();
         }
-        retval = v9fs_xattr_set(dentry, handler->prefix, value, size, flags);
+        retval = v9fs_xattr_set(dentry, handler->name, value, size, flags);
         if (!retval)
                 set_cached_acl(inode, handler->flags, acl);
 err_out:
@@ -328,14 +322,14 @@ err_out:
 }
 
 const struct xattr_handler v9fs_xattr_acl_access_handler = {
-        .prefix = XATTR_NAME_POSIX_ACL_ACCESS,
+        .name   = XATTR_NAME_POSIX_ACL_ACCESS,
         .flags  = ACL_TYPE_ACCESS,
         .get    = v9fs_xattr_get_acl,
         .set    = v9fs_xattr_set_acl,
 };
 
 const struct xattr_handler v9fs_xattr_acl_default_handler = {
-        .prefix = XATTR_NAME_POSIX_ACL_DEFAULT,
+        .name   = XATTR_NAME_POSIX_ACL_DEFAULT,
         .flags  = ACL_TYPE_DEFAULT,
         .get    = v9fs_xattr_get_acl,
         .set    = v9fs_xattr_set_acl,
diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c
index e3d026ac382e..9dd9b47a6c1a 100644
--- a/fs/9p/xattr.c
+++ b/fs/9p/xattr.c
@@ -143,8 +143,6 @@ static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
 {
         const char *full_name = xattr_full_name(handler, name);
 
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return v9fs_xattr_get(dentry, full_name, buffer, size);
 }
 
@@ -154,8 +152,6 @@ static int v9fs_xattr_handler_set(const struct xattr_handler *handler,
 {
         const char *full_name = xattr_full_name(handler, name);
 
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return v9fs_xattr_set(dentry, full_name, value, size, flags);
 }
 
diff --git a/fs/ext2/xattr_security.c b/fs/ext2/xattr_security.c
index dfb08750370d..118bf231bc7f 100644
--- a/fs/ext2/xattr_security.c
+++ b/fs/ext2/xattr_security.c
@@ -28,8 +28,6 @@ ext2_xattr_security_get(const struct xattr_handler *handler,
                         struct dentry *dentry, const char *name,
                         void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext2_xattr_get(d_inode(dentry), EXT2_XATTR_INDEX_SECURITY, name,
                               buffer, size);
 }
@@ -39,8 +37,6 @@ ext2_xattr_security_set(const struct xattr_handler *handler,
                         struct dentry *dentry, const char *name,
                         const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext2_xattr_set(d_inode(dentry), EXT2_XATTR_INDEX_SECURITY, name,
                               value, size, flags);
 }
diff --git a/fs/ext2/xattr_trusted.c b/fs/ext2/xattr_trusted.c
index 3150dd3a7859..3f8f2bc6539e 100644
--- a/fs/ext2/xattr_trusted.c
+++ b/fs/ext2/xattr_trusted.c
@@ -32,8 +32,6 @@ ext2_xattr_trusted_get(const struct xattr_handler *handler,
                        struct dentry *dentry, const char *name,
                        void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext2_xattr_get(d_inode(dentry), EXT2_XATTR_INDEX_TRUSTED, name,
                               buffer, size);
 }
@@ -43,8 +41,6 @@ ext2_xattr_trusted_set(const struct xattr_handler *handler,
                        struct dentry *dentry, const char *name,
                        const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext2_xattr_set(d_inode(dentry), EXT2_XATTR_INDEX_TRUSTED, name,
                               value, size, flags);
 }
diff --git a/fs/ext2/xattr_user.c b/fs/ext2/xattr_user.c
index 339a49bbb8ef..afd45ab1218c 100644
--- a/fs/ext2/xattr_user.c
+++ b/fs/ext2/xattr_user.c
@@ -34,8 +34,6 @@ ext2_xattr_user_get(const struct xattr_handler *handler,
                     struct dentry *dentry, const char *name,
                     void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         if (!test_opt(dentry->d_sb, XATTR_USER))
                 return -EOPNOTSUPP;
         return ext2_xattr_get(d_inode(dentry), EXT2_XATTR_INDEX_USER,
@@ -47,8 +45,6 @@ ext2_xattr_user_set(const struct xattr_handler *handler,
                     struct dentry *dentry, const char *name,
                     const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         if (!test_opt(dentry->d_sb, XATTR_USER))
                 return -EOPNOTSUPP;
 
diff --git a/fs/ext4/xattr_security.c b/fs/ext4/xattr_security.c
index 36f4c1a84c21..195abc4a88bb 100644
--- a/fs/ext4/xattr_security.c
+++ b/fs/ext4/xattr_security.c
@@ -33,8 +33,6 @@ ext4_xattr_security_get(const struct xattr_handler *handler,
                         struct dentry *dentry, const char *name,
                         void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext4_xattr_get(d_inode(dentry), EXT4_XATTR_INDEX_SECURITY,
                               name, buffer, size);
 }
@@ -44,8 +42,6 @@ ext4_xattr_security_set(const struct xattr_handler *handler,
                         struct dentry *dentry, const char *name,
                         const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext4_xattr_set(d_inode(dentry), EXT4_XATTR_INDEX_SECURITY,
                               name, value, size, flags);
 }
diff --git a/fs/ext4/xattr_trusted.c b/fs/ext4/xattr_trusted.c
index 488089053342..121fdf9fdc02 100644
--- a/fs/ext4/xattr_trusted.c
+++ b/fs/ext4/xattr_trusted.c
@@ -36,8 +36,6 @@ ext4_xattr_trusted_get(const struct xattr_handler *handler,
                        struct dentry *dentry, const char *name, void *buffer,
                        size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext4_xattr_get(d_inode(dentry), EXT4_XATTR_INDEX_TRUSTED,
                               name, buffer, size);
 }
@@ -47,8 +45,6 @@ ext4_xattr_trusted_set(const struct xattr_handler *handler,
                        struct dentry *dentry, const char *name,
                        const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ext4_xattr_set(d_inode(dentry), EXT4_XATTR_INDEX_TRUSTED,
                               name, value, size, flags);
 }
diff --git a/fs/ext4/xattr_user.c b/fs/ext4/xattr_user.c
index d2dec3364062..577fc122d884 100644
--- a/fs/ext4/xattr_user.c
+++ b/fs/ext4/xattr_user.c
@@ -35,8 +35,6 @@ ext4_xattr_user_get(const struct xattr_handler *handler,
                     struct dentry *dentry, const char *name,
                     void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         if (!test_opt(dentry->d_sb, XATTR_USER))
                 return -EOPNOTSUPP;
         return ext4_xattr_get(d_inode(dentry), EXT4_XATTR_INDEX_USER,
@@ -48,8 +46,6 @@ ext4_xattr_user_set(const struct xattr_handler *handler,
                     struct dentry *dentry, const char *name,
                     const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         if (!test_opt(dentry->d_sb, XATTR_USER))
                 return -EOPNOTSUPP;
         return ext4_xattr_set(d_inode(dentry), EXT4_XATTR_INDEX_USER,
diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index 862368a32e53..21cfe516034f 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -30,6 +30,7 @@ static size_t f2fs_xattr_generic_list(const struct xattr_handler *handler,
                 const char *name, size_t len)
 {
         struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb);
+        const char *prefix;
         int total_len, prefix_len;
 
         switch (handler->flags) {
@@ -47,10 +48,11 @@ static size_t f2fs_xattr_generic_list(const struct xattr_handler *handler,
                 return -EINVAL;
         }
 
-        prefix_len = strlen(handler->prefix);
+        prefix = xattr_prefix(handler);
+        prefix_len = strlen(prefix);
         total_len = prefix_len + len + 1;
         if (list && total_len <= list_size) {
-                memcpy(list, handler->prefix, prefix_len);
+                memcpy(list, prefix, prefix_len);
                 memcpy(list + prefix_len, name, len);
                 list[prefix_len + len] = '\0';
         }
@@ -77,8 +79,6 @@ static int f2fs_xattr_generic_get(const struct xattr_handler *handler,
         default:
                 return -EINVAL;
         }
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return f2fs_getxattr(d_inode(dentry), handler->flags, name,
                              buffer, size, NULL);
 }
@@ -103,9 +103,6 @@ static int f2fs_xattr_generic_set(const struct xattr_handler *handler,
         default:
                 return -EINVAL;
         }
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
-
         return f2fs_setxattr(d_inode(dentry), handler->flags, name,
                                         value, size, NULL, flags);
 }
@@ -114,7 +111,7 @@ static size_t f2fs_xattr_advise_list(const struct xattr_handler *handler,
                 struct dentry *dentry, char *list, size_t list_size,
                 const char *name, size_t len)
 {
-        const char *xname = F2FS_SYSTEM_ADVISE_PREFIX;
+        const char *xname = F2FS_SYSTEM_ADVISE_NAME;
         size_t size;
 
         size = strlen(xname) + 1;
@@ -129,9 +126,6 @@ static int f2fs_xattr_advise_get(const struct xattr_handler *handler,
 {
         struct inode *inode = d_inode(dentry);
 
-        if (strcmp(name, "") != 0)
-                return -EINVAL;
-
         if (buffer)
                 *((char *)buffer) = F2FS_I(inode)->i_advise;
         return sizeof(char);
@@ -143,8 +137,6 @@ static int f2fs_xattr_advise_set(const struct xattr_handler *handler,
 {
         struct inode *inode = d_inode(dentry);
 
-        if (strcmp(name, "") != 0)
-                return -EINVAL;
         if (!inode_owner_or_capable(inode))
                 return -EPERM;
         if (value == NULL)
@@ -197,7 +189,7 @@ const struct xattr_handler f2fs_xattr_trusted_handler = {
 };
 
 const struct xattr_handler f2fs_xattr_advise_handler = {
-        .prefix = F2FS_SYSTEM_ADVISE_PREFIX,
+        .name   = F2FS_SYSTEM_ADVISE_NAME,
         .flags  = F2FS_XATTR_INDEX_ADVISE,
         .list   = f2fs_xattr_advise_list,
         .get    = f2fs_xattr_advise_get,
diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h
index 71a7100d5492..79dccc8252dd 100644
--- a/fs/f2fs/xattr.h
+++ b/fs/f2fs/xattr.h
@@ -27,7 +27,7 @@
 #define F2FS_XATTR_REFCOUNT_MAX         1024
 
 /* Name indexes */
-#define F2FS_SYSTEM_ADVISE_PREFIX               "system.advise"
+#define F2FS_SYSTEM_ADVISE_NAME                 "system.advise"
 #define F2FS_XATTR_INDEX_USER                   1
 #define F2FS_XATTR_INDEX_POSIX_ACL_ACCESS       2
 #define F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT      3
diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index e41a010cd89c..ab01530b4930 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -431,9 +431,6 @@ int hfsplus_setxattr(struct dentry *dentry, const char *name,
         char *xattr_name;
         int res;
 
-        if (!strcmp(name, ""))
-                return -EINVAL;
-
         xattr_name = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN + 1,
                 GFP_KERNEL);
         if (!xattr_name)
@@ -589,9 +586,6 @@ ssize_t hfsplus_getxattr(struct dentry *dentry, const char *name,
         int res;
         char *xattr_name;
 
-        if (!strcmp(name, ""))
-                return -EINVAL;
-
         xattr_name = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN + 1,
                              GFP_KERNEL);
         if (!xattr_name)
@@ -853,9 +847,6 @@ static int hfsplus_osx_getxattr(const struct xattr_handler *handler,
                                 struct dentry *dentry, const char *name,
                                 void *buffer, size_t size)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
-
         /*
          * Don't allow retrieving properly prefixed attributes
          * by prepending them with "osx."
@@ -876,9 +867,6 @@ static int hfsplus_osx_setxattr(const struct xattr_handler *handler,
                                 struct dentry *dentry, const char *name,
                                 const void *buffer, size_t size, int flags)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
-
         /*
          * Don't allow setting properly prefixed attributes
          * by prepending them with "osx."
diff --git a/fs/jffs2/security.c b/fs/jffs2/security.c
index bf12fe5f83d7..ea79932cd665 100644
--- a/fs/jffs2/security.c
+++ b/fs/jffs2/security.c
@@ -52,9 +52,6 @@ static int jffs2_security_getxattr(const struct xattr_handler *handler,
                                    struct dentry *dentry, const char *name,
                                    void *buffer, size_t size)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
-
         return do_jffs2_getxattr(d_inode(dentry), JFFS2_XPREFIX_SECURITY,
                                  name, buffer, size);
 }
@@ -63,9 +60,6 @@ static int jffs2_security_setxattr(const struct xattr_handler *handler,
                                    struct dentry *dentry, const char *name,
                                    const void *buffer, size_t size, int flags)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
-
         return do_jffs2_setxattr(d_inode(dentry), JFFS2_XPREFIX_SECURITY,
                                  name, buffer, size, flags);
 }
diff --git a/fs/jffs2/xattr_trusted.c b/fs/jffs2/xattr_trusted.c
index a562da0d6a26..8b55fe44c777 100644
--- a/fs/jffs2/xattr_trusted.c
+++ b/fs/jffs2/xattr_trusted.c
@@ -20,8 +20,6 @@ static int jffs2_trusted_getxattr(const struct xattr_handler *handler,
                                   struct dentry *dentry, const char *name,
                                   void *buffer, size_t size)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
         return do_jffs2_getxattr(d_inode(dentry), JFFS2_XPREFIX_TRUSTED,
                                  name, buffer, size);
 }
@@ -30,8 +28,6 @@ static int jffs2_trusted_setxattr(const struct xattr_handler *handler,
                                   struct dentry *dentry, const char *name,
                                   const void *buffer, size_t size, int flags)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
         return do_jffs2_setxattr(d_inode(dentry), JFFS2_XPREFIX_TRUSTED,
                                  name, buffer, size, flags);
 }
diff --git a/fs/jffs2/xattr_user.c b/fs/jffs2/xattr_user.c
index cbc0472e59a8..b04335b84833 100644
--- a/fs/jffs2/xattr_user.c
+++ b/fs/jffs2/xattr_user.c
@@ -20,8 +20,6 @@ static int jffs2_user_getxattr(const struct xattr_handler *handler,
                                struct dentry *dentry, const char *name,
                                void *buffer, size_t size)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
         return do_jffs2_getxattr(d_inode(dentry), JFFS2_XPREFIX_USER,
                                  name, buffer, size);
 }
@@ -30,8 +28,6 @@ static int jffs2_user_setxattr(const struct xattr_handler *handler,
                                struct dentry *dentry, const char *name,
                                const void *buffer, size_t size, int flags)
 {
-        if (!strcmp(name, ""))
-                return -EINVAL;
         return do_jffs2_setxattr(d_inode(dentry), JFFS2_XPREFIX_USER,
                                  name, buffer, size, flags);
 }
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 89818036f035..f6f40aae92b1 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6253,9 +6253,6 @@ static int nfs4_xattr_set_nfs4_acl(const struct xattr_handler *handler,
                                    const void *buf, size_t buflen,
                                    int flags)
 {
-        if (strcmp(key, "") != 0)
-                return -EINVAL;
-
         return nfs4_proc_set_acl(d_inode(dentry), buf, buflen);
 }
 
@@ -6263,9 +6260,6 @@ static int nfs4_xattr_get_nfs4_acl(const struct xattr_handler *handler,
                                    struct dentry *dentry, const char *key,
                                    void *buf, size_t buflen)
 {
-        if (strcmp(key, "") != 0)
-                return -EINVAL;
-
         return nfs4_proc_get_acl(d_inode(dentry), buf, buflen);
 }
 
@@ -8834,7 +8828,7 @@ const struct nfs_rpc_ops nfs_v4_clientops = {
 };
 
 static const struct xattr_handler nfs4_xattr_nfs4_acl_handler = {
-        .prefix = XATTR_NAME_NFSV4_ACL,
+        .name   = XATTR_NAME_NFSV4_ACL,
         .list   = nfs4_xattr_list_nfs4_acl,
         .get    = nfs4_xattr_get_nfs4_acl,
         .set    = nfs4_xattr_set_nfs4_acl,
diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index e9164f09841b..5823f985a662 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -544,8 +544,7 @@ static inline const char *ocfs2_xattr_prefix(int name_index)
 
         if (name_index > 0 && name_index < OCFS2_XATTR_MAX)
                 handler = ocfs2_xattr_handler_map[name_index];
-
-        return handler ? handler->prefix : NULL;
+        return handler ? xattr_prefix(handler) : NULL;
 }
 
 static u32 ocfs2_xattr_name_hash(struct inode *inode,
@@ -7249,8 +7248,6 @@ static int ocfs2_xattr_security_get(const struct xattr_handler *handler,
                                     struct dentry *dentry, const char *name,
                                     void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ocfs2_xattr_get(d_inode(dentry), OCFS2_XATTR_INDEX_SECURITY,
                                name, buffer, size);
 }
@@ -7259,9 +7256,6 @@ static int ocfs2_xattr_security_set(const struct xattr_handler *handler,
                                     struct dentry *dentry, const char *name,
                                     const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
-
         return ocfs2_xattr_set(d_inode(dentry), OCFS2_XATTR_INDEX_SECURITY,
                                name, value, size, flags);
 }
@@ -7345,8 +7339,6 @@ static int ocfs2_xattr_trusted_get(const struct xattr_handler *handler,
                                    struct dentry *dentry, const char *name,
                                    void *buffer, size_t size)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         return ocfs2_xattr_get(d_inode(dentry), OCFS2_XATTR_INDEX_TRUSTED,
                                name, buffer, size);
 }
@@ -7355,9 +7347,6 @@ static int ocfs2_xattr_trusted_set(const struct xattr_handler *handler,
                                    struct dentry *dentry, const char *name,
                                    const void *value, size_t size, int flags)
 {
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
-
         return ocfs2_xattr_set(d_inode(dentry), OCFS2_XATTR_INDEX_TRUSTED,
                                name, value, size, flags);
 }
@@ -7398,8 +7387,6 @@ static int ocfs2_xattr_user_get(const struct xattr_handler *handler,
 {
         struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         if (osb->s_mount_opt & OCFS2_MOUNT_NOUSERXATTR)
                 return -EOPNOTSUPP;
         return ocfs2_xattr_get(d_inode(dentry), OCFS2_XATTR_INDEX_USER, name,
@@ -7412,8 +7399,6 @@ static int ocfs2_xattr_user_set(const struct xattr_handler *handler,
 {
         struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
         if (osb->s_mount_opt & OCFS2_MOUNT_NOUSERXATTR)
                 return -EOPNOTSUPP;
 
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 571465d6df58..17efd76978c8 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -769,8 +769,6 @@ posix_acl_xattr_get(const struct xattr_handler *handler,
         struct posix_acl *acl;
         int error;
 
-        if (strcmp(name, "") != 0)
-                return -EINVAL;
         if (!IS_POSIXACL(d_backing_inode(dentry)))
                 return -EOPNOTSUPP;
         if (d_is_symlink(dentry))
@@ -797,8 +795,6 @@ posix_acl_xattr_set(const struct xattr_handler *handler,
         struct posix_acl *acl = NULL;
         int ret;
 
-        if (strcmp(name, "") != 0)
-                return -EINVAL;
         if (!IS_POSIXACL(inode))
                 return -EOPNOTSUPP;
         if (!inode->i_op->set_acl)
@@ -832,7 +828,7 @@ posix_acl_xattr_list(const struct xattr_handler *handler,
                      struct dentry *dentry, char *list, size_t list_size,
                      const char *name, size_t name_len)
 {
-        const char *xname = handler->prefix;
+        const char *xname = handler->name;
         size_t size;
 
         if (!IS_POSIXACL(d_backing_inode(dentry)))
@@ -845,7 +841,7 @@ posix_acl_xattr_list(const struct xattr_handler *handler,
 }
 
 const struct xattr_handler posix_acl_access_xattr_handler = {
-        .prefix = XATTR_NAME_POSIX_ACL_ACCESS,
+        .name = XATTR_NAME_POSIX_ACL_ACCESS,
         .flags = ACL_TYPE_ACCESS,
         .list = posix_acl_xattr_list,
         .get = posix_acl_xattr_get,
@@ -854,7 +850,7 @@ const struct xattr_handler posix_acl_access_xattr_handler = {
 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
 
 const struct xattr_handler posix_acl_default_xattr_handler = {
-        .prefix = XATTR_NAME_POSIX_ACL_DEFAULT,
+        .name = XATTR_NAME_POSIX_ACL_DEFAULT,
         .flags = ACL_TYPE_DEFAULT,
         .list = posix_acl_xattr_list,
         .get = posix_acl_xattr_get,
diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 66b26fdfff8d..efe2ed3c13c5 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -756,7 +756,8 @@ find_xattr_handler_prefix(const struct xattr_handler **handlers,
                 return NULL;
 
         for_each_xattr_handler(handlers, xah) {
-                if (strncmp(xah->prefix, name, strlen(xah->prefix)) == 0)
+                const char *prefix = xattr_prefix(xah);
+                if (strncmp(prefix, name, strlen(prefix)) == 0)
                         break;
         }
 
diff --git a/fs/squashfs/xattr.c b/fs/squashfs/xattr.c
index 6a4cc344085c..2f0ccbaa2d92 100644
--- a/fs/squashfs/xattr.c
+++ b/fs/squashfs/xattr.c
@@ -228,9 +228,6 @@ static int squashfs_xattr_handler_get(const struct xattr_handler *handler,
                                       struct dentry *d, const char *name,
                                       void *buffer, size_t size)
 {
-        if (name[0] == '\0')
-                return  -EINVAL;
-
         return squashfs_xattr_get(d_inode(d), handler->flags, name,
                 buffer, size);
 }
diff --git a/fs/xattr.c b/fs/xattr.c
index 58bdabcc9d35..418ad691cf4e 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -681,13 +681,20 @@ xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
                 return NULL;
 
         for_each_xattr_handler(handlers, handler) {
-                const char *n = strcmp_prefix(*name, handler->prefix);
+                const char *n;
+
+                n = strcmp_prefix(*name, xattr_prefix(handler));
                 if (n) {
+                        if (!handler->prefix ^ !*n) {
+                                if (*n)
+                                        continue;
+                                return ERR_PTR(-EINVAL);
+                        }
                         *name = n;
-                        break;
+                        return handler;
                 }
         }
-        return handler;
+        return ERR_PTR(-EOPNOTSUPP);
 }
 
 /*
@@ -699,8 +706,8 @@ generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t s
         const struct xattr_handler *handler;
 
         handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
-        if (!handler)
-                return -EOPNOTSUPP;
+        if (IS_ERR(handler))
+                return PTR_ERR(handler);
         return handler->get(handler, dentry, name, buffer, size);
 }
 
@@ -746,8 +753,8 @@ generic_setxattr(struct dentry *dentry, const char *name, const void *value, siz
         if (size == 0)
                 value = "";  /* empty EA, do not remove */
         handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
-        if (!handler)
-                return -EOPNOTSUPP;
+        if (IS_ERR(handler))
+                return PTR_ERR(handler);
         return handler->set(handler, dentry, name, value, size, flags);
 }
 
@@ -761,8 +768,8 @@ generic_removexattr(struct dentry *dentry, const char *name)
         const struct xattr_handler *handler;
 
         handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
-        if (!handler)
-                return -EOPNOTSUPP;
+        if (IS_ERR(handler))
+                return PTR_ERR(handler);
         return handler->set(handler, dentry, name, NULL, 0, XATTR_REPLACE);
 }
 
@@ -789,7 +796,7 @@ EXPORT_SYMBOL(generic_removexattr);
 const char *xattr_full_name(const struct xattr_handler *handler,
                             const char *name)
 {
-        size_t prefix_len = strlen(handler->prefix);
+        size_t prefix_len = strlen(xattr_prefix(handler));
 
         return name - prefix_len;
 }
diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
index 7288795718c9..36a43851aac0 100644
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -39,9 +39,6 @@ xfs_xattr_get(const struct xattr_handler *handler, struct dentry *dentry,
         struct xfs_inode *ip = XFS_I(d_inode(dentry));
         int error, asize = size;
 
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
-
         /* Convert Linux syscall to XFS internal ATTR flags */
         if (!size) {
                 xflags |= ATTR_KERNOVAL;
@@ -84,9 +81,6 @@ xfs_xattr_set(const struct xattr_handler *handler, struct dentry *dentry,
         struct xfs_inode        *ip = XFS_I(d_inode(dentry));
         int                     error;
 
-        if (strcmp(name, "") == 0)
-                return -EINVAL;
-
         /* Convert Linux syscall to XFS internal ATTR flags */
         if (flags & XATTR_CREATE)
                 xflags |= ATTR_CREATE;
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index 45fa3456a0cc..03c847fb6cc1 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -19,7 +19,13 @@
 struct inode;
 struct dentry;
 
+/*
+ * struct xattr_handler: When @name is set, match attributes with exactly that
+ * name.  When @prefix is set instead, match attributes with that prefix and
+ * with a non-empty suffix.
+ */
 struct xattr_handler {
+        const char *name;
         const char *prefix;
         int flags;      /* fs private flags */
         size_t (*list)(const struct xattr_handler *, struct dentry *dentry,
@@ -54,6 +60,11 @@ int generic_removexattr(struct dentry *dentry, const char *name);
 ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
                            char **xattr_value, size_t size, gfp_t flags);
 
+static inline const char *xattr_prefix(const struct xattr_handler *handler)
+{
+        return handler->prefix ?: handler->name;
+}
+
 struct simple_xattrs {
         struct list_head head;
         spinlock_t lock;