From d07b846f6200454c50d791796edb82660192513d Mon Sep 17 00:00:00 2001 From: Seth Forshee Date: Wed, 23 Sep 2015 15:16:04 -0500 Subject: fs: Limit file caps to the user namespace of the super block Capability sets attached to files must be ignored except in the user namespaces where the mounter is privileged, i.e. s_user_ns and its descendants. Otherwise a vector exists for gaining privileges in namespaces where a user is not already privileged. Add a new helper function, current_in_user_ns(), to test whether a user namespace is the same as or a descendant of another namespace. Use this helper to determine whether a file's capability set should be applied to the caps constructed during exec. --EWB Replaced in_userns with the simpler current_in_userns. Acked-by: Serge Hallyn Signed-off-by: Seth Forshee Signed-off-by: Eric W. Biederman --- security/commoncap.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'security/commoncap.c') diff --git a/security/commoncap.c b/security/commoncap.c index e7fadde737f4..e109e6dac858 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -455,6 +455,8 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_c if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) return 0; + if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns)) + return 0; rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps); if (rc < 0) { -- cgit