* Re: [PATCH] netlink: fix append of whole original message on negative ack. [not found] <4900BFCF.2030707@gmail.com> @ 2008-10-23 20:45 ` David Miller 2008-10-23 20:55 ` Evgeniy Polyakov 2008-10-23 21:02 ` Patrick McHardy 0 siblings, 2 replies; 3+ messages in thread From: David Miller @ 2008-10-23 20:45 UTC (permalink / raw) To: michellammertink; +Cc: linux-kernel, netdev From: M Lammertink <michellammertink@gmail.com> Date: Thu, 23 Oct 2008 20:17:51 +0200 You'll get a much better review of this if you send it to the netdev mailing list, which is where all the networking developers are subscribed. They don't read linux-kernel Added to CC: > From: Michel Lammertink <mlammertink <at> ti-wmc.nl> > Signed-off-by: Michel Lammertink <mlammertink <at> ti-wmc.nl> > > Netlink can return an negative acknowledgement, which AFAICT should include an error code and the whole original message. This patch fixes the size argument given to the __nlmsg_put call. Without this patch only the original header was attached. > --- > > Can anyone explain to me why struct nlmsgerr contains an int error and the nlmsghdr struct. The comment in netlink_ack states that the whole message should be appended. Why not only include an int error in struct nlmsgerr and just append the original message? > > Comments appreciated. > > diff -uprN linux-2.6.27.3.orig/net/netlink/af_netlink.c linux-2.6.27.3/net/netlink/af_netlink.c > --- linux-2.6.27.3.orig/net/netlink/af_netlink.c 2008-10-23 18:01:54.000000000 +0200 > +++ linux-2.6.27.3/net/netlink/af_netlink.c 2008-10-23 18:04:22.000000000 +0200 > @@ -1656,7 +1656,7 @@ void netlink_ack(struct sk_buff *in_skb, > } > > rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq, > - NLMSG_ERROR, sizeof(struct nlmsgerr), 0); > + NLMSG_ERROR, payload, 0); > errmsg = nlmsg_data(rep); > errmsg->error = err; > memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh)); > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] netlink: fix append of whole original message on negative ack. 2008-10-23 20:45 ` [PATCH] netlink: fix append of whole original message on negative ack David Miller @ 2008-10-23 20:55 ` Evgeniy Polyakov 2008-10-23 21:02 ` Patrick McHardy 1 sibling, 0 replies; 3+ messages in thread From: Evgeniy Polyakov @ 2008-10-23 20:55 UTC (permalink / raw) To: David Miller; +Cc: michellammertink, linux-kernel, netdev Hi. On Thu, Oct 23, 2008 at 01:45:13PM -0700, David Miller (davem@davemloft.net) wrote: > > Netlink can return an negative acknowledgement, which AFAICT should include an error code and the whole original message. This patch fixes the size argument given to the __nlmsg_put call. Without this patch only the original header was attached. > > --- > > > > Can anyone explain to me why struct nlmsgerr contains an int error and the nlmsghdr struct. The comment in netlink_ack states that the whole message should be appended. Why not only include an int error in struct nlmsgerr and just append the original message? Having header (even seq/pid only) is enough to find a message for that userspace which cares. Looks like your patch can break existing applications which are used to work with header only, even if that was a mistake? Although application is supposed to check the length, it still can expect only a header. I have to note, that I do not know any such application though. -- Evgeniy Polyakov ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] netlink: fix append of whole original message on negative ack. 2008-10-23 20:45 ` [PATCH] netlink: fix append of whole original message on negative ack David Miller 2008-10-23 20:55 ` Evgeniy Polyakov @ 2008-10-23 21:02 ` Patrick McHardy 1 sibling, 0 replies; 3+ messages in thread From: Patrick McHardy @ 2008-10-23 21:02 UTC (permalink / raw) To: David Miller; +Cc: michellammertink, linux-kernel, netdev David Miller wrote: > From: M Lammertink <michellammertink@gmail.com> > Date: Thu, 23 Oct 2008 20:17:51 +0200 > >> Can anyone explain to me why struct nlmsgerr contains an int error and the nlmsghdr struct. The comment in netlink_ack states that the whole message should be appended. Why not only include an int error in struct nlmsgerr and just append the original message? >> >> Comments appreciated. >> >> diff -uprN linux-2.6.27.3.orig/net/netlink/af_netlink.c linux-2.6.27.3/net/netlink/af_netlink.c >> --- linux-2.6.27.3.orig/net/netlink/af_netlink.c 2008-10-23 18:01:54.000000000 +0200 >> +++ linux-2.6.27.3/net/netlink/af_netlink.c 2008-10-23 18:04:22.000000000 +0200 >> @@ -1656,7 +1656,7 @@ void netlink_ack(struct sk_buff *in_skb, >> } >> >> rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq, >> - NLMSG_ERROR, sizeof(struct nlmsgerr), 0); >> + NLMSG_ERROR, payload, 0) You can't include the full message since the resulting message might exceed the 64k netlink limit. ^ permalink raw reply [flat|nested] 3+ messages in thread
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2008-10-23 20:45 ` [PATCH] netlink: fix append of whole original message on negative ack David Miller
2008-10-23 20:55 ` Evgeniy Polyakov
2008-10-23 21:02 ` Patrick McHardy
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