ip: Add offset parameter to ip_cmsg_recv
Add ip_cmsg_recv_offset function which takes an offset argument
that indicates the starting offset in skb where data is being received
from. This will be useful in the case of UDP and provided checksum
to user space.
ip_cmsg_recv is an inline call to ip_cmsg_recv_offset with offset of
zero.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 513d506..a317797 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -37,6 +37,7 @@
#include <net/route.h>
#include <net/xfrm.h>
#include <net/compat.h>
+#include <net/checksum.h>
#if IS_ENABLED(CONFIG_IPV6)
#include <net/transp_v6.h>
#endif
@@ -96,6 +97,20 @@
put_cmsg(msg, SOL_IP, IP_RETOPTS, opt->optlen, opt->__data);
}
+static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
+ int offset)
+{
+ __wsum csum = skb->csum;
+
+ if (skb->ip_summed != CHECKSUM_COMPLETE)
+ return;
+
+ if (offset != 0)
+ csum = csum_sub(csum, csum_partial(skb->data, offset, 0));
+
+ put_cmsg(msg, SOL_IP, IP_CHECKSUM, sizeof(__wsum), &csum);
+}
+
static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
{
char *secdata;
@@ -191,9 +206,16 @@
return;
}
- if (flags & IP_CMSG_ORIGDSTADDR)
+ if (flags & IP_CMSG_ORIGDSTADDR) {
ip_cmsg_recv_dstaddr(msg, skb);
+ flags &= ~IP_CMSG_ORIGDSTADDR;
+ if (!flags)
+ return;
+ }
+
+ if (flags & IP_CMSG_CHECKSUM)
+ ip_cmsg_recv_checksum(msg, skb, offset);
}
EXPORT_SYMBOL(ip_cmsg_recv_offset);
@@ -533,6 +555,7 @@
case IP_MULTICAST_ALL:
case IP_MULTICAST_LOOP:
case IP_RECVORIGDSTADDR:
+ case IP_CHECKSUM:
if (optlen >= sizeof(int)) {
if (get_user(val, (int __user *) optval))
return -EFAULT;
@@ -630,6 +653,19 @@
else
inet->cmsg_flags &= ~IP_CMSG_ORIGDSTADDR;
break;
+ case IP_CHECKSUM:
+ if (val) {
+ if (!(inet->cmsg_flags & IP_CMSG_CHECKSUM)) {
+ inet_inc_convert_csum(sk);
+ inet->cmsg_flags |= IP_CMSG_CHECKSUM;
+ }
+ } else {
+ if (inet->cmsg_flags & IP_CMSG_CHECKSUM) {
+ inet_dec_convert_csum(sk);
+ inet->cmsg_flags &= ~IP_CMSG_CHECKSUM;
+ }
+ }
+ break;
case IP_TOS: /* This sets both TOS and Precedence */
if (sk->sk_type == SOCK_STREAM) {
val &= ~INET_ECN_MASK;
@@ -1233,6 +1269,9 @@
case IP_RECVORIGDSTADDR:
val = (inet->cmsg_flags & IP_CMSG_ORIGDSTADDR) != 0;
break;
+ case IP_CHECKSUM:
+ val = (inet->cmsg_flags & IP_CMSG_CHECKSUM) != 0;
+ break;
case IP_TOS:
val = inet->tos;
break;