Re: [PATCH] proc: Report no_new_privs state

[Jann Horn <jann@thejh.net>]

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On Thu, Nov 03, 2016 at 02:40:41PM -0700, Kees Cook wrote:
> Similar to being able to examine if a process has been correctly confined
> with seccomp, the state of no_new_privs is equally interesting, so this
> adds it to /proc/$pid/status.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>

(Note: The proc.5 manpage also lists all the entries of the "status" file,
so it should also be updated.)

Reviewed-by: Jann Horn <jann@thejh.net>

> ---
>  Documentation/filesystems/proc.txt | 2 ++
>  fs/proc/array.c                    | 5 +++--
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
> index 74329fd0add2..c03f2f91c6ab 100644
> --- a/Documentation/filesystems/proc.txt
> +++ b/Documentation/filesystems/proc.txt
> @@ -191,6 +191,7 @@ read the file /proc/PID/status:
>    CapPrm: 0000000000000000
>    CapEff: 0000000000000000
>    CapBnd: ffffffffffffffff
> +  NoNewPrivs:     0
>    Seccomp:        0
>    voluntary_ctxt_switches:        0
>    nonvoluntary_ctxt_switches:     1
> @@ -262,6 +263,7 @@ Table 1-2: Contents of the status files (as of 4.1)
>   CapPrm                      bitmap of permitted capabilities
>   CapEff                      bitmap of effective capabilities
>   CapBnd                      bitmap of capabilities bounding set
> + NoNewPrivs                  no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...)
>   Seccomp                     seccomp mode, like prctl(PR_GET_SECCOMP, ...)
>   Cpus_allowed                mask of CPUs on which this process may run
>   Cpus_allowed_list           Same as previous, but in "list format"
> diff --git a/fs/proc/array.c b/fs/proc/array.c
> index 81818adb8e9e..082676ab4878 100644
> --- a/fs/proc/array.c
> +++ b/fs/proc/array.c
> @@ -342,10 +342,11 @@ static inline void task_cap(struct seq_file *m, struct task_struct *p)
>  
>  static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
>  {
> +	seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p));
>  #ifdef CONFIG_SECCOMP
> -	seq_put_decimal_ull(m, "Seccomp:\t", p->seccomp.mode);
> -	seq_putc(m, '\n');
> +	seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
>  #endif
> +	seq_putc(m, '\n');
>  }
>  
>  static inline void task_context_switch_counts(struct seq_file *m,
> -- 
> 2.7.4
> 
> 
> -- 
> Kees Cook
> Nexus Security

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