Re: commit b9ef5513c99b breaks ping to ipv6 linklocal addresses on debian buster

[Casey Schaufler <casey@schaufler-ca.com>]

On 1/6/2020 1:03 PM, Tetsuo Handa wrote:
> On 2020/01/07 1:41, David Ahern wrote:
>>>>  #ifdef SMACK_IPV6_SECMARK_LABELING
>>>>                 rsp = smack_ipv6host_label(sip);
>>>>
>>>>
>>>> ie., if the socket family is AF_INET6 the address length should be an
>>>> IPv6 address. The family in the sockaddr is not as important.
>>>>
>>> Commit b9ef5513c99b was wrong, but we need to also fix commit c673944347ed ?
>>>
>> not sure. I have not seen a problem related to it yet.
>>
> A sample program shown below is expected to return 0.
> Casey, what does smack wants to do for IPv4 address on IPv6 socket case?

I have to take a minute to look more closely at what's involved.


>
> ----------
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <sys/un.h>
> #include <arpa/inet.h>
> #include <unistd.h>
>
> int main(int argc, char *argv[])
> {
>         const int fd1 = socket(PF_INET6, SOCK_DGRAM, 0);
>         const int fd2 = socket(PF_INET, SOCK_DGRAM, 0);
>         struct sockaddr_in addr1 = {
>                 .sin_family = AF_INET,
>                 .sin_addr.s_addr = htonl(INADDR_LOOPBACK),
>                 .sin_port = htons(10000)
>         };
>         struct sockaddr_in addr2 = { };
>         char c = 0;
>         struct iovec iov1 = { "", 1 };
>         struct iovec iov2 = { &c, 1 };
>         const struct msghdr msg1 = {
>                 .msg_iov = &iov1,
>                 .msg_iovlen = 1,
>                 .msg_name = &addr1,
>                 .msg_namelen = sizeof(addr1)
>         };
>         struct msghdr msg2 = {
>                 .msg_iov = &iov2,
>                 .msg_iovlen = 1,
>                 .msg_name = &addr2,
>                 .msg_namelen = sizeof(addr2)
>         };
>         if (bind(fd2, (struct sockaddr *) &addr1, sizeof(addr1)))
>                 return 1;
>         if (sendmsg(fd1, &msg1, 0) != 1 || recvmsg(fd2, &msg2, 0) != 1)
>                 return 1;
>         if (connect(fd1, (struct sockaddr *) &addr1, sizeof(addr1)))
>                 return 1;
>         if (send(fd1, "", 1, 0) != 1 || recv(fd2, &c, 1, 0) != 1)
>                 return 1;
>         return 0;
> }
> ----------