[cifs-utils PATCH] cifs.upcall: trim even more capabilities

[Pavel Shilovsky]

2017-02-16 6:59 GMT-08:00 Jeff Layton <jlayton at samba.org>:
> We really only need CAP_DAC_READ_SEARCH, not CAP_DAC_OVERRIDE, and
> only when we are going to probe the environ file.
>
> Also, fix the non-libcap-ng trim_capabilities prototype.
>
> Signed-off-by: Jeff Layton <jlayton at samba.org>
> ---
>  cifs.upcall.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/cifs.upcall.c b/cifs.upcall.c
> index 6d9c427b7032..dae58b919408 100644
> --- a/cifs.upcall.c
> +++ b/cifs.upcall.c
> @@ -70,22 +70,21 @@ typedef enum _sectype {
>
>  #ifdef HAVE_LIBCAP_NG
>  static int
> -trim_capabilities(bool need_ptrace)
> +trim_capabilities(bool need_environ)
>  {
>         capng_clear(CAPNG_SELECT_BOTH);
>
> -       /*
> -        * Need PTRACE and DAC_OVERRIDE for environment scraping, SETGID to
> -        * change gid and grouplist, and SETUID to change uid.
> -        */
> +       /* SETUID and SETGID to change uid, gid, and grouplist */
>         if (capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,
> -                       CAP_SETUID, CAP_SETGID, CAP_DAC_OVERRIDE, -1)) {
> +                       CAP_SETUID, CAP_SETGID, -1)) {
>                 syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);
>                 return 1;
>         }
>
> -       if (need_ptrace &&
> -           capng_update(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE, CAP_SYS_PTRACE)) {
> +        /* Need PTRACE and DAC_OVERRIDE for environment scraping */

It seems that the comment above doesn't reflect the proposed change.
Should it be DAC_READ_SEARCH instead?

> +       if (need_environ &&
> +           capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,
> +                       CAP_SYS_PTRACE, CAP_DAC_READ_SEARCH, -1)) {
>                 syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);
>                 return 1;
>         }
> @@ -109,7 +108,7 @@ drop_all_capabilities(void)
>  }
>  #else /* HAVE_LIBCAP_NG */
>  static int
> -trim_capabilities(void)
> +trim_capabilities(bool unused)
>  {
>         return 0;
>  }
> --
> 2.9.3
>
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-- 
Best regards,
Pavel Shilovsky