diff options
Diffstat (limited to 'fs/attr.c')
| -rw-r--r-- | fs/attr.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/fs/attr.c b/fs/attr.c index 9b9a70e0cc54..3172f57f71f8 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -394,9 +394,25 @@ int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry, return error; if ((ia_valid & ATTR_MODE)) { - umode_t amode = attr->ia_mode; + /* + * Don't allow changing the mode of symlinks: + * + * (1) The vfs doesn't take the mode of symlinks into account + * during permission checking. + * (2) This has never worked correctly. Most major filesystems + * did return EOPNOTSUPP due to interactions with POSIX ACLs + * but did still updated the mode of the symlink. + * This inconsistency led system call wrapper providers such + * as libc to block changing the mode of symlinks with + * EOPNOTSUPP already. + * (3) To even do this in the first place one would have to use + * specific file descriptors and quite some effort. + */ + if (S_ISLNK(inode->i_mode)) + return -EOPNOTSUPP; + /* Flag setting protected by i_mutex */ - if (is_sxid(amode)) + if (is_sxid(attr->ia_mode)) inode->i_flags &= ~S_NOSEC; } |