fs: reflow may_create_in_sticky()

This function is so messy and hard to read, let's reflow it to make it
more readable.

Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240621-affekt-denkzettel-3c115f68355a@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/namei.c b/fs/namei.c
index 8b40991cb59e0441676df0c662e4e315e3e6c1aa..f10b6dde7daba73ce5cf7969cd705638c3cfa71d 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1240,29 +1240,48 @@ int may_linkat(struct mnt_idmap *idmap, const struct path *link)
  *
  * Returns 0 if the open is allowed, -ve on error.
  */
-static int may_create_in_sticky(struct mnt_idmap *idmap,
-                               struct nameidata *nd, struct inode *const inode)
+static int may_create_in_sticky(struct mnt_idmap *idmap, struct nameidata *nd,
+                               struct inode *const inode)
 {
        umode_t dir_mode = nd->dir_mode;
-       vfsuid_t dir_vfsuid = nd->dir_vfsuid;
+       vfsuid_t dir_vfsuid = nd->dir_vfsuid, i_vfsuid;
 
-       if (likely(!(dir_mode & S_ISVTX)) ||
-           (S_ISREG(inode->i_mode) && !sysctl_protected_regular) ||
-           (S_ISFIFO(inode->i_mode) && !sysctl_protected_fifos) ||
-           vfsuid_eq(i_uid_into_vfsuid(idmap, inode), dir_vfsuid) ||
-           vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid()))
+       if (likely(!(dir_mode & S_ISVTX)))
                return 0;
 
-       if (likely(dir_mode & 0002) ||
-           (dir_mode & 0020 &&
-            ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) ||
-             (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) {
-               const char *operation = S_ISFIFO(inode->i_mode) ?
-                                       "sticky_create_fifo" :
-                                       "sticky_create_regular";
-               audit_log_path_denied(AUDIT_ANOM_CREAT, operation);
+       if (S_ISREG(inode->i_mode) && !sysctl_protected_regular)
+               return 0;
+
+       if (S_ISFIFO(inode->i_mode) && !sysctl_protected_fifos)
+               return 0;
+
+       i_vfsuid = i_uid_into_vfsuid(idmap, inode);
+
+       if (vfsuid_eq(i_vfsuid, dir_vfsuid))
+               return 0;
+
+       if (vfsuid_eq_kuid(i_vfsuid, current_fsuid()))
+               return 0;
+
+       if (likely(dir_mode & 0002)) {
+               audit_log_path_denied(AUDIT_ANOM_CREAT, "sticky_create");
                return -EACCES;
        }
+
+       if (dir_mode & 0020) {
+               if (sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) {
+                       audit_log_path_denied(AUDIT_ANOM_CREAT,
+                                             "sticky_create_fifo");
+                       return -EACCES;
+               }
+
+               if (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode)) {
+                       audit_log_path_denied(AUDIT_ANOM_CREAT,
+                                             "sticky_create_regular");
+                       return -EACCES;
+               }
+       }
+
        return 0;
 }