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 <[email protected]> Link: https://lore.kernel.org/r/20240621-affekt-denkzettel-3c115f68355a@brauner Signed-off-by: Christian Brauner <[email protected]>
torvalds · Jun 27, 2024 · 9fb9ff7 · 9fb9ff7
1 parent 8e34478
commit 9fb9ff7
Showing 1 changed file with 35 additions and 16 deletions.
diff --git 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;
 }