From: Kuniyuki Iwashima kuniyu@amazon.com Date: Fri, 10 Mar 2023 13:25:47 -0800

From: Paul Holzinger pholzing@redhat.com Date: Fri, 10 Mar 2023 17:01:31 +0100

...

Hi all,

there seems to be a regression which allows you to bind the same port twice when the first bind call bound to all ip addresses (i. e. dual stack).

A second bind call for the same port will succeed if you try to bind to a specific ipv4 (e. g. 127.0.0.1), binding to 0.0.0.0 or an ipv6 address fails correctly with EADDRINUSE.

I included a small c program below to show the issue. Normally the second bind call should fail, this was the case before v6.1.

I bisected the regression to commit 5456262d2baa ("net: Fix incorrect address comparison when searching for a bind2 bucket").

I also checked that the issue is still present in v6.3-rc1.

Thanks for the detailed report.

It seems we should take care of the special case in inet_bind2_bucket_match_addr_any().

I confimed this change fixes the regression. I'll check other paths that 5456262d2baa touched.

---8<--- diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index e41fdc38ce19..62c5f7501571 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -828,8 +828,15 @@ bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const #if IS_ENABLED(CONFIG_IPV6) struct in6_addr addr_any = {};

- if (sk->sk_family != tb->family) - return false; + if (sk->sk_family != tb->family) { + if (sk->sk_family == AF_INET6) + return net_eq(ib2_net(tb), net) && tb->port == port && + tb->l3mdev == l3mdev && tb->rcv_saddr == 0; + else + return net_eq(ib2_net(tb), net) && tb->port == port && + tb->l3mdev == l3mdev && + ipv6_addr_equal(&tb->v6_rcv_saddr, &in6addr_any); + }

if (sk->sk_family == AF_INET6) return net_eq(ib2_net(tb), net) && tb->port == port && ---8<---

Tested:

---8<---

...

...

from socket import *

s = socket(AF_INET6, SOCK_STREAM, 0) s2 = socket(AF_INET, SOCK_STREAM, 0)

s.bind(('::', 0)) s

<socket.socket fd=3, family=AddressFamily.AF_INET6, type=SocketKind.SOCK_STREAM, proto=0, laddr=('::', 53147, 0, 0)>

...

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s2.bind(('0.0.0.0', s.getsockname()[1]))

Traceback (most recent call last): File "<stdin>", line 1, in <module> OSError: [Errno 98] Address already in use

...

...

s2.bind(('127.0.0.1', s.getsockname()[1]))

Traceback (most recent call last): File "<stdin>", line 1, in <module> OSError: [Errno 98] Address already in use

...

...

s3 = socket(AF_INET, SOCK_STREAM, 0) s4 = socket(AF_INET6, SOCK_STREAM, 0)

s3.bind(('0.0.0.0', 0)) s3

<socket.socket fd=5, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('0.0.0.0', 58359)>

...

...

s4.bind(('::0', s3.getsockname()[1]))

Traceback (most recent call last): File "<stdin>", line 1, in <module> OSError: [Errno 98] Address already in use

...

...

s4.bind(('::1', s3.getsockname()[1]))

Traceback (most recent call last): File "<stdin>", line 1, in <module> OSError: [Errno 98] Address already in use ---8<---

Thanks, Kuniyuki

I'll fix it.

Thanks, Kuniyuki

...

Original report: https://github.com/containers/podman/issues/17719

#regzbot introduced: 5456262d2baa

#include <sys/socket.h>
#include <sys/un.h>
#include <stdlib.h>
#include <stdio.h>
#include <netinet/in.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
     int ret, sock1, sock2;
     struct sockaddr_in6 addr;
     struct sockaddr_in addr2;

     sock1 = socket(AF_INET6, SOCK_STREAM, 0);
     if (sock1 == -1)
     {
         perror("socket1");
         exit(1);
     }
     sock2 = socket(AF_INET, SOCK_STREAM, 0);
     if (sock2 == -1)
     {
         perror("socket2");
         exit(1);
     }

     memset(&addr, 0, sizeof(addr));
     addr.sin6_family = AF_INET6;
     addr.sin6_addr = in6addr_any;
     addr.sin6_port = htons(8080);

     memset(&addr2, 0, sizeof(addr2));
     addr2.sin_family = AF_INET;
     addr2.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
     addr2.sin_port = htons(8080);

     ret = bind(sock1, (struct sockaddr *)&addr, sizeof(addr));
     if (ret == -1)
     {
         perror("bind1");
         exit(1);
     }
     printf("bind1 ret: %d\n", ret);

     if ((listen(sock1, 5)) != 0)
     {
         perror("listen1");
         exit(1);
     }

     ret = bind(sock2, (struct sockaddr *)&addr2, sizeof(addr2));
     if (ret == -1)
     {
         perror("bind2");
         exit(1);
     }
     printf("bind2 ret: %d\n", ret);

     if ((listen(sock2, 5)) != 0)
     {
         perror("listen2");
         exit(1);
     }

     // uncomment pause() to see with ss -tlpn the bound ports
     // pause();

     return 0;
}

Best regards,

Paul