xfs: Change how listxattr generates synthetic attributes

Instead of adding the synthesized POSIX ACL attribute names after listing all
non-synthesized attributes, generate them immediately when listing the
non-synthesized attributes.

In addition, merge xfs_xattr_put_listent and xfs_xattr_put_listent_sizes to
ensure that the list size is computed correctly; the split version was
overestimating the list size for non-root users.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 59 insertions, 78 deletions

diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
index 36a43851aac0..110f1d7d86b0 100644
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -129,47 +129,19 @@ const struct xattr_handler *xfs_xattr_handlers[] = {
         NULL
 };
 
-static unsigned int xfs_xattr_prefix_len(int flags)
-{
-        if (flags & XFS_ATTR_SECURE)
-                return sizeof("security");
-        else if (flags & XFS_ATTR_ROOT)
-                return sizeof("trusted");
-        else
-                return sizeof("user");
-}
-
-static const char *xfs_xattr_prefix(int flags)
-{
-        if (flags & XFS_ATTR_SECURE)
-                return xfs_xattr_security_handler.prefix;
-        else if (flags & XFS_ATTR_ROOT)
-                return xfs_xattr_trusted_handler.prefix;
-        else
-                return xfs_xattr_user_handler.prefix;
-}
-
 static int
-xfs_xattr_put_listent(
+__xfs_xattr_put_listent(
         struct xfs_attr_list_context *context,
-        int             flags,
-        unsigned char   *name,
-        int             namelen,
-        int             valuelen,
-        unsigned char   *value)
+        char *prefix,
+        int prefix_len,
+        unsigned char *name,
+        int namelen)
 {
-        unsigned int prefix_len = xfs_xattr_prefix_len(flags);
         char *offset;
         int arraytop;
 
-        ASSERT(context->count >= 0);
-
-        /*
-         * Only show root namespace entries if we are actually allowed to
-         * see them.
-         */
-        if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
-                return 0;
+        if (!context->alist)
+                goto compute_size;
 
         arraytop = context->count + prefix_len + namelen + 1;
         if (arraytop > context->firstu) {
@@ -177,17 +149,19 @@ xfs_xattr_put_listent(
                 return 1;
         }
         offset = (char *)context->alist + context->count;
-        strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
+        strncpy(offset, prefix, prefix_len);
         offset += prefix_len;
         strncpy(offset, (char *)name, namelen);                 /* real name */
         offset += namelen;
         *offset = '\0';
+
+compute_size:
         context->count += prefix_len + namelen + 1;
         return 0;
 }
 
 static int
-xfs_xattr_put_listent_sizes(
+xfs_xattr_put_listent(
         struct xfs_attr_list_context *context,
         int             flags,
         unsigned char   *name,
@@ -195,24 +169,55 @@ xfs_xattr_put_listent_sizes(
         int             valuelen,
         unsigned char   *value)
 {
-        context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
-        return 0;
-}
+        char *prefix;
+        int prefix_len;
 
-static int
-list_one_attr(const char *name, const size_t len, void *data,
-                size_t size, ssize_t *result)
-{
-        char *p = data + *result;
+        ASSERT(context->count >= 0);
 
-        *result += len;
-        if (!size)
-                return 0;
-        if (*result > size)
-                return -ERANGE;
+        if (flags & XFS_ATTR_ROOT) {
+#ifdef CONFIG_XFS_POSIX_ACL
+                if (namelen == SGI_ACL_FILE_SIZE &&
+                    strncmp(name, SGI_ACL_FILE,
+                            SGI_ACL_FILE_SIZE) == 0) {
+                        int ret = __xfs_xattr_put_listent(
+                                        context, XATTR_SYSTEM_PREFIX,
+                                        XATTR_SYSTEM_PREFIX_LEN,
+                                        XATTR_POSIX_ACL_ACCESS,
+                                        strlen(XATTR_POSIX_ACL_ACCESS));
+                        if (ret)
+                                return ret;
+                } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
+                         strncmp(name, SGI_ACL_DEFAULT,
+                                 SGI_ACL_DEFAULT_SIZE) == 0) {
+                        int ret = __xfs_xattr_put_listent(
+                                        context, XATTR_SYSTEM_PREFIX,
+                                        XATTR_SYSTEM_PREFIX_LEN,
+                                        XATTR_POSIX_ACL_DEFAULT,
+                                        strlen(XATTR_POSIX_ACL_DEFAULT));
+                        if (ret)
+                                return ret;
+                }
+#endif
 
-        strcpy(p, name);
-        return 0;
+                /*
+                 * Only show root namespace entries if we are actually allowed to
+                 * see them.
+                 */
+                if (!capable(CAP_SYS_ADMIN))
+                        return 0;
+
+                prefix = XATTR_TRUSTED_PREFIX;
+                prefix_len = XATTR_TRUSTED_PREFIX_LEN;
+        } else if (flags & XFS_ATTR_SECURE) {
+                prefix = XATTR_SECURITY_PREFIX;
+                prefix_len = XATTR_SECURITY_PREFIX_LEN;
+        } else {
+                prefix = XATTR_USER_PREFIX;
+                prefix_len = XATTR_USER_PREFIX_LEN;
+        }
+
+        return __xfs_xattr_put_listent(context, prefix, prefix_len, name,
+                                       namelen);
 }
 
 ssize_t
@@ -221,7 +226,6 @@ xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
         struct xfs_attr_list_context context;
         struct attrlist_cursor_kern cursor = { 0 };
         struct inode            *inode = d_inode(dentry);
-        int                     error;
 
         /*
          * First read the regular on-disk attributes.
@@ -230,37 +234,14 @@ xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
         context.dp = XFS_I(inode);
         context.cursor = &cursor;
         context.resynch = 1;
-        context.alist = data;
+        context.alist = size ? data : NULL;
         context.bufsize = size;
         context.firstu = context.bufsize;
-
-        if (size)
-                context.put_listent = xfs_xattr_put_listent;
-        else
-                context.put_listent = xfs_xattr_put_listent_sizes;
+        context.put_listent = xfs_xattr_put_listent;
 
         xfs_attr_list_int(&context);
         if (context.count < 0)
                 return -ERANGE;
 
-        /*
-         * Then add the two synthetic ACL attributes.
-         */
-        if (posix_acl_access_exists(inode)) {
-                error = list_one_attr(XATTR_NAME_POSIX_ACL_ACCESS,
-                                strlen(XATTR_NAME_POSIX_ACL_ACCESS) + 1,
-                                data, size, &context.count);
-                if (error)
-                        return error;
-        }
-
-        if (posix_acl_default_exists(inode)) {
-                error = list_one_attr(XATTR_NAME_POSIX_ACL_DEFAULT,
-                                strlen(XATTR_NAME_POSIX_ACL_DEFAULT) + 1,
-                                data, size, &context.count);
-                if (error)
-                        return error;
-        }
-
         return context.count;
 }