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

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Message-ID: <20120418190514.GH5186@mail.hallyn.com>
Date:	Wed, 18 Apr 2012 19:05:14 +0000
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	"Eric W. Beiderman" <ebiederm@...ssion.com>
Cc:	linux-kernel@...r.kernel.org,
	Linux Containers <containers@...ts.linux-foundation.org>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	linux-security-module@...r.kernel.org,
	Al Viro <viro@...IV.linux.org.uk>,
	linux-fsdevel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 30/43] userns: Fail exec for suid and sgid binaries
 with ids outside our user namespace.

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

Acked-by: Serge Hallyn <serge.hallyn@...onical.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
> 
> _______________________________________________
> Containers mailing list
> Containers@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/containers
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