On Tue, 2023-05-16 at 22:15 +0200, Nicolas Dichtel wrote:
> With a raw socket bound to IPPROTO_RAW (ie with hdrincl enabled), the
> protocol field of the flow structure, build by raw_sendmsg() /
> rawv6_sendmsg()), is set to IPPROTO_RAW. This breaks the ipsec policy
> lookup when some policies are defined with a protocol in the selector.
>
> For ipv6, the sin6_port field from 'struct sockaddr_in6' could be used to
> specify the protocol. Just accept all values for IPPROTO_RAW socket.
>
> For ipv4, the sin_port field of 'struct sockaddr_in' could not be used
> without breaking backward compatibility (the value of this field was never
> checked). Let's add a new kind of control message, so that the userland
> could specify which protocol is used.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
> ---
>
> The first version has been marked 'Awaiting Upstream'. Steffen confirmed
> that the 'net' tree should be the target, thus I resend this patch.
> I also CC stable@xxxxxxxxxxxxxxx.
>
> include/net/ip.h | 2 ++
> include/uapi/linux/in.h | 1 +
> net/ipv4/ip_sockglue.c | 15 ++++++++++++++-
> net/ipv4/raw.c | 5 ++++-
> net/ipv6/raw.c | 3 ++-
> 5 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/ip.h b/include/net/ip.h
> index c3fffaa92d6e..acec504c469a 100644
> --- a/include/net/ip.h
> +++ b/include/net/ip.h
> @@ -76,6 +76,7 @@ struct ipcm_cookie {
> __be32 addr;
> int oif;
> struct ip_options_rcu *opt;
> + __u8 protocol;
> __u8 ttl;
> __s16 tos;
> char priority;
> @@ -96,6 +97,7 @@ static inline void ipcm_init_sk(struct ipcm_cookie *ipcm,
> ipcm->sockc.tsflags = inet->sk.sk_tsflags;
> ipcm->oif = READ_ONCE(inet->sk.sk_bound_dev_if);
> ipcm->addr = inet->inet_saddr;
> + ipcm->protocol = inet->inet_num;
> }
>
> #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
> diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
> index 4b7f2df66b99..e682ab628dfa 100644
> --- a/include/uapi/linux/in.h
> +++ b/include/uapi/linux/in.h
> @@ -163,6 +163,7 @@ struct in_addr {
> #define IP_MULTICAST_ALL 49
> #define IP_UNICAST_IF 50
> #define IP_LOCAL_PORT_RANGE 51
> +#define IP_PROTOCOL 52
>
> #define MCAST_EXCLUDE 0
> #define MCAST_INCLUDE 1
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index b511ff0adc0a..ec0fbe874426 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -317,7 +317,17 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
> ipc->tos = val;
> ipc->priority = rt_tos2priority(ipc->tos);
> break;
> -
> + case IP_PROTOCOL:
> + if (cmsg->cmsg_len == CMSG_LEN(sizeof(int)))
> + val = *(int *)CMSG_DATA(cmsg);
> + else if (cmsg->cmsg_len == CMSG_LEN(sizeof(u8)))
> + val = *(u8 *)CMSG_DATA(cmsg);
AFAICS the 'dual' u8 support for IP_TOS has been introduce to cope with
asymmetry WRT recvmsg(). Here we don't have (yet) the recvmsg counter-
part, and if/when that will be added we can use the correct data type.
I think we are better off supporting only int, as e.g. IP_TTL does.
Side note, the above code could be factored out in an helper to be used
both for IP_PROTOCOL and IP_TTL (possibly in a net-next patch).
Thanks!
Paolo
