[PATCH xserver] xorg-wrapper: when starting the server as root, reset its environment

[Jeremy Huddleston Sequoia]

I would suggest maybe instead doing:

int main(int argc, char *argv[], char *envp[]) {
    ...
    if (getuid() != geteuid())
        envp = {NULL, };
    (void)execve(argv[0], argv, envp);
    ...
}

Or at least name the variable something like empty_envp to distinguish it more clearly from the process's environment since it's common to have a main signature of int main(int argc, char *argv[], char *envp[]).

--Jeremy

> On Oct 18, 2015, at 10:26, Julien Cristau <jcristau at debian.org> wrote:
> 
> When the server is privileged, we shouldn't be passing the user's
> environment directly.
> 
> Signed-off-by: Julien Cristau <jcristau at debian.org>
> ---
> hw/xfree86/xorg-wrapper.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
> 
> It's possible some variables should be passed, in which case we could
> use a whitelist; in my testing this patch seemed to work, though.
> 
> diff --git a/hw/xfree86/xorg-wrapper.c b/hw/xfree86/xorg-wrapper.c
> index 22e97ad..d6efb23 100644
> --- a/hw/xfree86/xorg-wrapper.c
> +++ b/hw/xfree86/xorg-wrapper.c
> @@ -190,6 +190,7 @@ int main(int argc, char *argv[])
>     int total_cards = 0;
>     int allowed = CONSOLE_ONLY;
>     int needs_root_rights = -1;
> +    char *const envp[1] = { NULL, };
> 
>     progname = argv[0];
> 
> @@ -265,7 +266,10 @@ int main(int argc, char *argv[])
>     }
> 
>     argv[0] = buf;
> -    (void) execv(argv[0], argv);
> +    if (getuid() == geteuid())
> +        (void) execv(argv[0], argv);
> +    else
> +        (void) execve(argv[0], argv, envp);
>     fprintf(stderr, "%s: Failed to execute %s: %s\n",
>         progname, buf, strerror(errno));
>     exit(1);
> -- 
> 2.6.1
> 
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