linux-kernel - Re: [PATCH v4 12/15] smack: Remove redundant pdeath

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Date:   Tue, 1 Aug 2017 08:24:00 -0700
From:   Casey Schaufler <casey@...aufler-ca.com>
To:     Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     David Howells <dhowells@...hat.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        John Johansen <john.johansen@...onical.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        James Morris <james.l.morris@...cle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 12/15] smack: Remove redundant pdeath_signal clearing

On 7/31/2017 4:51 PM, Kees Cook wrote:
> This removes the redundant pdeath_signal clearing in Smack: the check in
> smack_bprm_committing_creds() matches the check in smack_bprm_set_creds()
> (which used to be in the now-removed smack_bprm_securexec() hook) and
> since secureexec is now being checked for clearing pdeath_signal, this
> is redundant to the common exec code.
>
> Cc: Casey Schaufler <casey@...aufler-ca.com>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> Acked-by: Serge Hallyn <serge@...lyn.com>

Reviewed-by: Casey Schaufler <casey@...aufler-ca.com>

> ---
>  security/smack/smack_lsm.c | 15 ---------------
>  1 file changed, 15 deletions(-)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 4f1967be3d20..4e33c650b224 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -957,20 +957,6 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
>  	return 0;
>  }
>  
> -/**
> - * smack_bprm_committing_creds - Prepare to install the new credentials
> - * from bprm.
> - *
> - * @bprm: binprm for exec
> - */
> -static void smack_bprm_committing_creds(struct linux_binprm *bprm)
> -{
> -	struct task_smack *bsp = bprm->cred->security;
> -
> -	if (bsp->smk_task != bsp->smk_forked)
> -		current->pdeath_signal = 0;
> -}
> -
>  /*
>   * Inode hooks
>   */
> @@ -4633,7 +4619,6 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
>  	LSM_HOOK_INIT(sb_parse_opts_str, smack_parse_opts_str),
>  
>  	LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),
> -	LSM_HOOK_INIT(bprm_committing_creds, smack_bprm_committing_creds),
>  
>  	LSM_HOOK_INIT(inode_alloc_security, smack_inode_alloc_security),
>  	LSM_HOOK_INIT(inode_free_security, smack_inode_free_security),