From e4f8b5d4edc1edb0709531bd1a342655d5e8b98e Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 11 Feb 2008 17:50:30 -0800 Subject: [PATCH] [IPV4]: Remove IP_TOS setting privilege checks. Various RFCs have all sorts of things to say about the CS field of the DSCP value. In particular they try to make the distinction between values that should be used by "user applications" and things like routing daemons. This seems to have influenced the CAP_NET_ADMIN check which exists for IP_TOS socket option settings, but in fact it has an off-by-one error so it wasn't allowing CS5 which is meant for "user applications" as well. Further adding to the inconsistency and brokenness here, IPV6 does not validate the DSCP values specified for the IPV6_TCLASS socket option. The real actual uses of these TOS values are system specific in the final analysis, and these RFC recommendations are just that, "a recommendation". In fact the standards very purposefully use "SHOULD" and "SHOULD NOT" when describing how these values can be used. In the final analysis the only clean way to provide consistency here is to remove the CAP_NET_ADMIN check. The alternatives just don't work out: 1) If we add the CAP_NET_ADMIN check to ipv6, this can break existing setups. 2) If we just fix the off-by-one error in the class comparison in IPV4, certain DSCP values can be used in IPV6 but not IPV4 by default. So people will just ask for a sysctl asking to override that. I checked several other freely available kernel trees and they do not make any privilege checks in this area like we do. For the BSD stacks, this goes back all the way to Stevens Volume 2 and beyond. Signed-off-by: David S. Miller --- net/ipv4/ip_sockglue.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 754b0a5bbf..de0572c888 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -514,11 +514,6 @@ static int do_ip_setsockopt(struct sock *sk, int level, val &= ~3; val |= inet->tos & 3; } - if (IPTOS_PREC(val) >= IPTOS_PREC_CRITIC_ECP && - !capable(CAP_NET_ADMIN)) { - err = -EPERM; - break; - } if (inet->tos != val) { inet->tos = val; sk->sk_priority = rt_tos2priority(val); -- 2.39.5