Re: [PATCH 30/43] userns: Fail exec for suid and sgid binaries with ids outside our user namespace.

Serge E. Hallyn
2012-04-18T19:04:18Z

Quoting Eric W. Beiderman (ebiederm@xmission.com):
> From: Eric W. Biederman <ebiederm@xmission.com>
>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>

> ---
> fs/exec.c | 5 +++++
> 1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 00ae2ef..e001bdf 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1291,8 +1291,11 @@ int prepare_binprm(struct linux_binprm *bprm)
> if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
> /* Set-uid? */
> if (mode & S_ISUID) {
> + if (!kuid_has_mapping(bprm->cred->user_ns, inode->i_uid))
> + return -EPERM;
> bprm->per_clear |= PER_CLEAR_ON_SETID;
> bprm->cred->euid = inode->i_uid;
> +
> }
>
> /* Set-gid? */
> @@ -1302,6 +1305,8 @@ int prepare_binprm(struct linux_binprm *bprm)
> * executable.
> */
> if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
> + if (!kgid_has_mapping(bprm->cred->user_ns, inode->i_gid))
> + return -EPERM;
> bprm->per_clear |= PER_CLEAR_ON_SETID;
> bprm->cred->egid = inode->i_gid;
> }
> --
> 1.7.2.5
>
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