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Message-ID: <20240325175117.45750-1-kuniyu@amazon.com>
Date: Mon, 25 Mar 2024 10:51:17 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <wujianguo106@....com>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuniyu@...zon.com>,
<netdev@...r.kernel.org>
Subject: Re: [PATCH] tcp: Fix inet_bind2_bucket_match_addr_any() regression
From: Jianguo Wu <wujianguo106@....com>
Date: Fri, 22 Mar 2024 11:16:09 +0800
> Hi Kuniyuki,
> Thanks for your reply!
>
> On 2024/3/21 12:55, Kuniyuki Iwashima wrote:
> > Hi,
> >
> > Thanks for the patch.
> >
> > From: Jianguo Wu <wujianguo106@....com>
> > Date: Thu, 21 Mar 2024 11:02:36 +0800
> >> From: Jianguo Wu <wujianguo@...natelecom.cn>
> >>
> >> If we bind() a TCPv4 socket to 0.0.0.0:8090, then bind() a TCPv6(ipv6only) socket
> >
> > Please wrap each line at <75 characters except for logs/output like below.
> >
> OK.
> >
> >> to :::8090, both without SO_REUSEPORT, then bind() 127.0.0.1:8090, it should fail
> >
> > [::]:8090 is easier to read and the recommended way.
> > https://datatracker.ietf.org/doc/html/rfc5952#section-6
> >
> > But please keep the netstat output as is.
> >
> >> but now succeeds. like this:
> >> tcp 0 0 127.0.0.1:8090 0.0.0.0:* LISTEN
> >> tcp 0 0 0.0.0.0:8090 0.0.0.0:* LISTEN
> >> tcp6 0 0 :::8090 :::* LISTEN
> >>
> >> bind() 0.0.0.0:8090, :::8090 and ::1:8090 are all fail.
> >
> > What do you mean by all fail ?
> > At least, [::1]:8090 would fail with the current code in this case.
> In my test, 127.0.0.1:8090 succeeds, 0.0.0.0:8090, [::]:8090 and [::1]:8090 are all fail
>
> >
> >
> >> But if we bind() a TCPv6(ipv6only) socket to :::8090 first, then bind() a TCPv4
> >> socket to 0.0.0.0:8090, then bind() 127.0.0.1:8090, 0.0.0.0:8090, :::8090 and ::1:8090 are all fail.
> >>
> >> When bind() 127.0.0.1:8090, inet_bind2_bucket_match_addr_any() will return true as tb->addr_type == IPV6_ADDR_ANY,
> >
> > Let's use tb2 here for inet_bind2_bucket.. yes it's not consistent
> > in some functions like inet_bind2_bucket_match_addr_any() though.
> yes, inet_bind2_bucket_match_addr_any() use tb, so I use tb here.
>
> >
> >
> >> and tb is refer to the TCPv6 socket(:::8090), then inet_bhash2_conflict() return false, That is, there is no conflict,
> >
> > Also make it clear that the TCPv6 socket is ipv6only one.
> >
> >
> >> so bind() succeeds.
> >>
> >> inet_bhash2_addr_any_conflict()
> >> {
> >> inet_bind_bucket_for_each(tb2, &head2->chain)
> >> // tb2 is IPv6
> >> if (inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
> >> break;
> >>
> >> // inet_bhash2_conflict() return false
> >> if (tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
> >> reuseport_ok)) {
> >> spin_unlock(&head2->lock);
> >> return true;
> >> }
> >>
> >> }
> >>
> >> Fixes: 5a22bba13d01 ("tcp: Save address type in inet_bind2_bucket.")
> >
> > This is not the commit that introduced the regression.
> I will remove this.
> >
> > Also, you need Signed-off-by tag here.
> OK.
> >
> >
> >> ---
> >> net/ipv4/inet_hashtables.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> >> index 7498af320164..3eeaca8a113f 100644
> >> --- a/net/ipv4/inet_hashtables.c
> >> +++ b/net/ipv4/inet_hashtables.c
> >> @@ -830,8 +830,8 @@ bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const
> >> return false;
> >>
> >> #if IS_ENABLED(CONFIG_IPV6)
> >> - if (tb->addr_type == IPV6_ADDR_ANY)
> >> - return true;
> >> + if (sk->sk_family == AF_INET6)
> >> + return tb->addr_type == IPV6_ADDR_ANY;
> >
> > This fix is not correct and will break v4-mapped-v6 address cases.
> > You can run bind_wildcard under the selftest directory.
> >> Probably we need v6_only bit in tb2 and should add some test cases
> > in the selftest.
> How about this?
> I add a new field ipv6_only to struct inet_bind2_bucket{}
>
> diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
> index 7f1b38458743..fb7c250a663b 100644
> --- a/include/net/inet_hashtables.h
> +++ b/include/net/inet_hashtables.h
> @@ -96,6 +96,7 @@ struct inet_bind2_bucket {
> int l3mdev;
> unsigned short port;
> #if IS_ENABLED(CONFIG_IPV6)
> + bool ipv6_only;
> unsigned short addr_type;
> struct in6_addr v6_rcv_saddr;
> #define rcv_saddr v6_rcv_saddr.s6_addr32[3]
> diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
> index cf88eca5f1b4..5fc749f8f2b1 100644
> --- a/net/ipv4/inet_hashtables.c
> +++ b/net/ipv4/inet_hashtables.c
> @@ -110,6 +110,7 @@ static void inet_bind2_bucket_init(struct inet_bind2_bucket *tb2,
> tb2->port = tb->port;
> #if IS_ENABLED(CONFIG_IPV6)
> BUILD_BUG_ON(USHRT_MAX < (IPV6_ADDR_ANY | IPV6_ADDR_MAPPED));
> + tb2->ipv6_only = ipv6_only_sock(sk);
> if (sk->sk_family == AF_INET6) {
> tb2->addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
> tb2->v6_rcv_saddr = sk->sk_v6_rcv_saddr;
> @@ -831,7 +832,8 @@ bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const
>
> #if IS_ENABLED(CONFIG_IPV6)
> if (tb->addr_type == IPV6_ADDR_ANY)
> - return true;
> + if (sk->sk_family == AF_INET6 || !tb->ipv6_only)
> + return true;
>
> if (tb->addr_type != IPV6_ADDR_MAPPED)
> return false;
>
I found a corner case that does not work with this change.
The 3rd bind() should fail but succeeds with the v6only flag approach.
---8<---
from socket import *
s1 = socket(AF_INET6)
s1.setsockopt(41, IPV6_V6ONLY, 1)
s1.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
s1.bind(('::', 8000))
s2 = socket(AF_INET6)
s2.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
s2.bind(('::', 8000))
s3 = socket(AF_INET)
s3.bind(('127.0.0.1', 8000))
---8<---
To cover this case, the only solution is to iterate over the buckets
in the same hash. Also, this change can be backported to 6.1.
---8<---
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 612aa1d2eff7..63e8f2df0681 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -288,6 +288,7 @@ static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l
struct sock_reuseport *reuseport_cb;
struct inet_bind_hashbucket *head2;
struct inet_bind2_bucket *tb2;
+ bool conflict = false;
bool reuseport_cb_ok;
rcu_read_lock();
@@ -300,18 +301,20 @@ static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l
spin_lock(&head2->lock);
- inet_bind_bucket_for_each(tb2, &head2->chain)
- if (inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
- break;
+ inet_bind_bucket_for_each(tb2, &head2->chain) {
+ if (!inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
+ continue;
- if (tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
- reuseport_ok)) {
- spin_unlock(&head2->lock);
- return true;
+ if (!inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok, reuseport_ok))
+ continue;
+
+ conflict = true;
+ break;
}
spin_unlock(&head2->lock);
- return false;
+
+ return conflict;
}
/*
---8<---
Also, I found another regression that my recent patch introduced.
The second bind() should succeed but now fails.
---8<---
from socket import *
s1 = socket(AF_INET6)
s1.setsockopt(41, IPV6_V6ONLY, 1)
s1.bind(('::', 8000))
s2 = socket(AF_INET6)
s2.bind(('::ffff:127.0.0.1', 8000))
---8<---
and we need this change.
---8<---
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 7d8090f109ef..612aa1d2eff7 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -203,7 +203,8 @@ static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
kuid_t sk_uid, bool relax,
bool reuseport_cb_ok, bool reuseport_ok)
{
- if (sk->sk_family == AF_INET && ipv6_only_sock(sk2))
+ if (ipv6_only_sock(sk2) &&
+ (sk->sk_family == AF_INET || ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)))
return false;
return inet_bind_conflict(sk, sk2, sk_uid, relax,
---8<---
I'll post a series including necessary tests.
Thanks!
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