Hello,
aoa...@google.com, le mer. 25 juil. 2018 21:08:12 -0400, a ecrit:
> From: Andrew Oates <aoa...@google.com>
>
> On Linux, SOCK_DGRAM+IPPROTO_ICMP sockets give only the ICMP packet when
> read from. On macOS, however, the socket acts like a SOCK_RAW socket
> and includes the IP header as well.
>
> This change strips the extra IP header from the received packet on macOS
> before sending it to the guest.
>
> Signed-off-by: Andrew Oates <aoa...@google.com>
> ---
> slirp/ip_icmp.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/slirp/ip_icmp.c b/slirp/ip_icmp.c
> index 0b667a429a..5fa67814f4 100644
> --- a/slirp/ip_icmp.c
> +++ b/slirp/ip_icmp.c
> @@ -420,7 +420,15 @@ void icmp_receive(struct socket *so)
> icp = mtod(m, struct icmp *);
>
> id = icp->icmp_id;
> - len = qemu_recv(so->s, icp, m->m_len, 0);
> + len = qemu_recv(so->s, icp, M_ROOM(m), 0);
> +#ifdef CONFIG_DARWIN
> + if (len > 0) {
> + /* Skip the IP header that OS X (unlike Linux) includes. */
> + struct ip *inner_ip = mtod(m, struct ip *);
> + int inner_hlen = inner_ip->ip_hl << 2;
> + memmove(icp, (unsigned char *)icp + inner_hlen, len - inner_hlen);
Please also check that the provided inner_hlen is not bigger than len.
(otherwise it'd be a security issue). Also, substract inner_len from len
for coherency. In case inner_len is bigger than len, you'd set len to -1
and set errno to EINVAL, handled below.
Thanks,
Samuel
