Andrew Oates, le mar. 14 août 2018 22:35:21 -0400, a ecrit:
> 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. SOCK_DGRAM ICMP sockets aren't
> supported on other BSDs, but we enable this behavior for them as well to
> treat the sockets the same as raw sockets.
Applied to my tree, thanks!
> Signed-off-by: Andrew Oates <aoa...@google.com>
> ---
> v2: check validity of inner_hlen and update len appropriately
> v3: CONFIG_DARWIN -> CONFIG_BSD; add comment explaining #ifdef
>
> slirp/ip_icmp.c | 24 +++++++++++++++++++++++-
> 1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/slirp/ip_icmp.c b/slirp/ip_icmp.c
> index 0b667a429a..0e289fd9d9 100644
> --- a/slirp/ip_icmp.c
> +++ b/slirp/ip_icmp.c
> @@ -420,7 +420,29 @@ 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);
> + /*
> + * The behavior of reading SOCK_DGRAM+IPPROTO_ICMP sockets is
> inconsistent
> + * between host OSes. On Linux, only the ICMP header and payload is
> + * included. On macOS/Darwin, the socket acts like a raw socket and
> + * includes the IP header as well. On other BSDs,
> SOCK_DGRAM+IPPROTO_ICMP
> + * sockets aren't supported at all, so we treat them like raw sockets.
> It
> + * isn't possible to detect this difference at runtime, so we must use an
> + * #ifdef to determine if we need to remove the IP header.
> + */
> +#ifdef CONFIG_BSD
> + if (len > 0) {
> + struct ip *inner_ip = mtod(m, struct ip *);
> + int inner_hlen = inner_ip->ip_hl << 2;
> + if (inner_hlen > len) {
> + len = -1;
> + errno = -EINVAL;
> + } else {
> + len -= inner_hlen;
> + memmove(icp, (unsigned char *)icp + inner_hlen, len);
> + }
> + }
> +#endif
> icp->icmp_id = id;
>
> m->m_data -= hlen;
> --
> 2.18.0.865.gffc8e1a3cd6-goog
>
--
Samuel
As usual, this being a 1.3.x release, I haven't even compiled this
kernel yet. So if it works, you should be doubly impressed.
(Linus Torvalds, announcing kernel 1.3.3 on the linux-kernel mailing list.)
