> -----邮件原件----- > 发件人: David Ahern [mailto:dsah...@gmail.com] > 发送时间: Monday, August 24, 2020 10:34 > 收件人: Guodeqing (A) <geffrey....@huawei.com>; da...@davemloft.net > 抄送: k...@kernel.org; netdev@vger.kernel.org > 主题: Re: [PATCH] ipv4: fix the problem of ping failure in some cases > > On 8/23/20 8:27 PM, David Ahern wrote: > > On 8/22/20 1:46 AM, guodeqing wrote: > >> ie., > >> $ ifconfig eth0 9.9.9.9 netmask 255.255.255.0 > >> > >> $ ping -I lo 9.9.9.9 > > If that ever worked it was wrong; the address is scoped to eth0, not lo. > > >> ping: Warning: source address might be selected on device other than lo. > >> PING 9.9.9.9 (9.9.9.9) from 9.9.9.9 lo: 56(84) bytes of data. > >> > >> 4 packets transmitted, 0 received, 100% packet loss, time 3068ms > >> > >> This is because the return value of __raw_v4_lookup in raw_v4_input > >> is null, the packets cannot be sent to the ping application. > >> The reason of the __raw_v4_lookup failure is that sk_bound_dev_if and > >> dif/sdif are not equal in raw_sk_bound_dev_eq. > >> > >> Here I add a check of whether the sk_bound_dev_if is LOOPBACK_IFINDEX > >> to solve this problem. > >> > >> Fixes: 19e4e768064a8 ("ipv4: Fix raw socket lookup for local > >> traffic") > >> Signed-off-by: guodeqing <geffrey....@huawei.com> > >> --- > >> include/net/inet_sock.h | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index > >> a3702d1..7707b1d 100644 > >> --- a/include/net/inet_sock.h > >> +++ b/include/net/inet_sock.h > >> @@ -144,7 +144,7 @@ static inline bool inet_bound_dev_eq(bool > >> l3mdev_accept, int bound_dev_if, { > >> if (!bound_dev_if) > >> return !sdif || l3mdev_accept; > >> - return bound_dev_if == dif || bound_dev_if == sdif; > >> + return bound_dev_if == dif || bound_dev_if == sdif || bound_dev_if > >> +== LOOPBACK_IFINDEX; > >> } > >> > >> struct inet_cork { > >> > > > > this is used by more than just raw socket lookups. > > > > And assuming it should work, this is definitely the wrong fix.
ok, I see now. I misunderstood the function of the loopback interface, thanks.
