netdev - Re: inbound connection problems when "netlink: test for all flags of the NLM_F

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Date:	Tue, 18 Jan 2011 19:10:35 +0100
From:	Alessandro Suardi <alessandro.suardi@...il.com>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	jamal <hadi@...erus.ca>, David Miller <davem@...emloft.net>,
	pablo@...filter.org, arthur.marsh@...ernode.on.net,
	jengelh@...ozas.de, eric.dumazet@...il.com, netdev@...r.kernel.org
Subject: Re: inbound connection problems when "netlink: test for all flags of
 the NLM_F_DUMP composite" commit applied

On Tue, Jan 18, 2011 at 6:23 PM, Jarek Poplawski <jarkao2@...il.com> wrote:
> [PATCH] netlink: Fix possible NLM_F_DUMP misuse in genetlink
>
> NLM_F_DUMP flags should be applied to GET requests only, eg. rtnetlink
> tests message type to verify this. Since genetlink can't do the same
> use "practical" test for ops->dumpit (assuming NEW request won't be
> mixed with GET).
>
> Signed-off-by: Jarek Poplawski <jarkao2@...il.com>
> Cc: Jan Engelhardt <jengelh@...ozas.de>
> Cc: Pablo Neira Ayuso <pablo@...filter.org>
> Cc: Jamal Hadi Salim <hadi@...erus.ca>
> ---
> Not for stable before testing!
>
> diff -Nurp a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> --- a/net/netlink/genetlink.c   2011-01-18 16:58:16.000000000 +0100
> +++ b/net/netlink/genetlink.c   2011-01-18 17:08:43.000000000 +0100
> @@ -519,15 +519,16 @@ static int genl_rcv_msg(struct sk_buff *
>            security_netlink_recv(skb, CAP_NET_ADMIN))
>                return -EPERM;
>
> -       if (nlh->nlmsg_flags & NLM_F_DUMP) {
> -               if (ops->dumpit == NULL)
> +       if (ops->dumpit) {
> +               if (nlh->nlmsg_flags & NLM_F_DUMP) {
> +                       genl_unlock();
> +                       err = netlink_dump_start(net->genl_sock, skb, nlh,
> +                                                ops->dumpit, ops->done);
> +                       genl_lock();
> +                       return err;
> +               } else {
>                        return -EOPNOTSUPP;
> -
> -               genl_unlock();
> -               err = netlink_dump_start(net->genl_sock, skb, nlh,
> -                                        ops->dumpit, ops->done);
> -               genl_lock();
> -               return err;
> +               }
>        }
>
>        if (ops->doit == NULL)
>

2.6.37-git18 + netlink revert + this patch
 - fixes Avahi
 - breaks acpid

Upon startup I have:

Starting acpi daemon: RTNETLINK1 answers: Operation not supported
acpid: error talking to the kernel via netlink




>From strace output:

open("/dev/input/event6", O_RDONLY|O_NONBLOCK) = 8
fcntl(8, F_SETFD, FD_CLOEXEC)           = 0
ioctl(8, 0x80604520, 0x7fffb3418550)    = 8
ioctl(8, 0x80604521, 0x7fffb34185b0)    = 96
open("/dev/input/event8", O_RDONLY|O_NONBLOCK) = 9
fcntl(9, F_SETFD, FD_CLOEXEC)           = 0
ioctl(9, 0x80604520, 0x7fffb3418550)    = 8
ioctl(9, 0x80604532, 0x7fffb3418c10)    = 8
close(9)                                = 0
inotify_init()                          = 9
inotify_add_watch(9, "/dev/input", IN_CREATE) = 1
socket(PF_NETLINK, SOCK_RAW, 16)        = 10
setsockopt(10, SOL_SOCKET, SO_SNDBUF, [32768], 4) = 0
setsockopt(10, SOL_SOCKET, SO_RCVBUF, [32768], 4) = 0
bind(10, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
getsockname(10, {sa_family=AF_NETLINK, pid=4298, groups=00000000}, [12]) = 0
sendmsg(10, {msg_name(12)={sa_family=AF_NETLINK, pid=0,
groups=00000000},
msg_iov(1)=[{"$\0\0\0\20\0\5\0\346\3265M\0\0\0\0\3\0\0\0\17\0\2\0acpi_eve"...,
36}], msg_controllen=0, msg_flags=0}, 0) = 36
recvmsg(10, {msg_name(12)={sa_family=AF_NETLINK, pid=0,
groups=00000000},
msg_iov(1)=[{"8\0\0\0\2\0\0\0\346\3265M\312\20\0\0\241\377\377\377$\0\0\0\20\0\5\0\346\3265M"...,
16384}], msg_controllen=0, msg_flags=0}, 0) = 56
dup(2)                                  = 11
fcntl(11, F_GETFL)                      = 0x1 (flags O_WRONLY)
close(11)                               = 0
write(2, "RTNETLINK1 answers: Operation no"..., 44RTNETLINK1 answers:
Operation not supported
) = 44
write(2, "acpid: error talking to the kern"..., 47acpid: error talking
to the kernel via netlink
) = 47
close(10)                               = 0
socket(PF_NETLINK, SOCK_RAW, 16)        = 10
setsockopt(10, SOL_SOCKET, SO_SNDBUF, [32768], 4) = 0
setsockopt(10, SOL_SOCKET, SO_RCVBUF, [32768], 4) = 0
bind(10, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
getsockname(10, {sa_family=AF_NETLINK, pid=4298, groups=00000000}, [12]) = 0
unlink("/var/run/acpid.socket")         = 0
socket(PF_FILE, SOCK_STREAM, 0)         = 11
bind(11, {sa_family=AF_FILE, path="/var/run/acpid.socket"}, 110) = 0
listen(11, 10)                          = 0



If more debugging/testing is needed, do ping me. Thanks,

--alessandro

 "There's always a siren singing you to shipwreck"

   (Radiohead, "There There")
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