linux-kernel - Re: [PATCH 0/5] net: sysctl: share ipv4/ipv6 sysctl tables

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 4 Feb 2011 17:59:24 +0200
From:	Lucian Adrian Grijincu <lucian.grijincu@...il.com>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Octavian Purdila <opurdila@...acom.com>
Subject: Re: [PATCH 0/5] net: sysctl: share ipv4/ipv6 sysctl tables

On Fri, Feb 4, 2011 at 12:49 PM, Alexey Dobriyan <adobriyan@...il.com> wrote:
>> Finally share the leaf sysctl tables for ipv4/ipv6:
>>
>>  [PATCH 4/5] ipv4: share sysctl net/ipv4/conf/DEVNAME/ tables
>>  [PATCH 5/5] ipv6: share sysctl net/ipv6/conf/DEVNAME/ tables
>
> Meh.
>
> First you remove ->parent, then heroically pass "struct file *"
> to sysctl handlers which duplicates all information already passed
> and brings dcache into picture.
>
> Binary sysctl rewrite confused you into thinking that d_name.name
> is the way, but it isn't.
> For binary sysctl(2) you wouldn't get d_name.name.


Are you really sure?

I ran this code on a machine with and without these patches. It seems
to work fine.

It reads the value from /proc/sys/net/ipv4/conf/default/tag and writes 42 back.

I'm not sure what I have to do to pass the name of a device (e.g.
"eth0") instead of "default" but at least "default" and "all" work and
have valid dentries.


#define _GNU_SOURCE
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/sysctl.h>


int main(void)
{
	struct __sysctl_args args;
	int oldtag, newtag;
	size_t oldtaglen, newtaglen;

	int name[] = { CTL_NET, NET_IPV4, NET_IPV4_CONF,
NET_PROTO_CONF_DEFAULT, NET_IPV4_CONF_TAG };

	memset(&args, 0, sizeof(struct __sysctl_args));
	args.name = name;
	args.nlen = sizeof(name)/sizeof(name[0]);

	oldtag = -1;
	oldtaglen = sizeof(oldtag);
	args.oldval = &oldtag;
	args.oldlenp = &oldtaglen;

	newtag = 42;
	newtaglen = sizeof(newtag);
	args.newval = &newtag;
	args.newlen = newtaglen;

	if (syscall(SYS__sysctl, &args) == -1) {
		perror("_sysctl");
		exit(EXIT_FAILURE);
	}
	printf("Old tag was %d, new tag is %d\n", oldtag, newtag);
	exit(EXIT_SUCCESS);
}


-- 
 .
..: Lucian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/