[PATCH][IPv4/IPv6] Setting 0 for unused port field.

[PATCH][IPv4/IPv6] Setting 0 for unused port field.

[from-linux-kernel]

Hello.

The recvmsg() for raw socket seems to return random u16 value
from the kernel stack memory since port field is not initialized.
But I'm not sure this patch is correct.
Does raw socket return any information stored in port field?

---------- Start of patch ----------
diff -ur before/net/ipv4/raw.c after/net/ipv4/raw.c
--- before/net/ipv4/raw.c       2006-06-18 10:49:35.000000000 +0900
+++ after/net/ipv4/raw.c        2006-07-25 16:15:26.000000000 +0900
@@ -609,6 +609,7 @@
        if (sin) {
                sin->sin_family = AF_INET;
                sin->sin_addr.s_addr = skb->nh.iph->saddr;
+               sin->sin_port = 0;
                memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
        }
        if (inet->cmsg_flags)
diff -ur before/net/ipv6/raw.c after/net/ipv6/raw.c
--- before/net/ipv6/raw.c       2006-06-18 10:49:35.000000000 +0900
+++ after/net/ipv6/raw.c        2006-07-25 16:16:52.000000000 +0900
@@ -411,6 +411,7 @@
        /* Copy the address. */
        if (sin6) {
                sin6->sin6_family = AF_INET6;
+               sin6->sin6_port = 0;
                ipv6_addr_copy(&sin6->sin6_addr, &skb->nh.ipv6h->saddr);
                sin6->sin6_flowinfo = 0;
                sin6->sin6_scope_id = 0;
---------- End of patch ----------

Regards.

Re: [PATCH][IPv4/IPv6] Setting 0 for unused port field.

[David Miller]

Tetsuo-san can you please use a correct "From:" field in your patch
postings?  Thank you.

This will allow me to form a correct attribution when I apply your
patches in the future.

This time I had to perform a lengthy web search to find who is behind
these strange from-${LIST_NAME}@i-love.sakura.ne.jp email addresses
:-((  Using these per-listname email addresses really makes things
painful for other developers, even though it might simplify things
for you.

Thanks again.

Re: [PATCH][IPv4/IPv6] Setting 0 for unused port field.

[from-linux-kernel]

Hello.

I ran the following programs and I confirmed that
applying the patch attached to the previous message
suppresses returning random u16 values.

As with IPv4, I found that using
"sin->sin_port = sin->sin_port = htons(skb->nh.iph->protocol);"
instead of "sin->sin_port = 0;"
seems to set protocol number in port field,
but I couldn't find appropriate field for IPv6.

Regards.
--
  Tetsuo Handa

------- send.c -------
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/ip.h>

int main(int argc, char *argv[]) {
	static struct iphdr ip;
	struct sockaddr_in addr;
	const int fd = socket(PF_INET, SOCK_RAW, IPPROTO_RAW);
	memset(&addr, 0, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
	ip.version = 4;
	ip.ihl = sizeof(struct iphdr) / 4;
	ip.protocol = IPPROTO_RAW;
	ip.saddr = ip.daddr = addr.sin_addr.s_addr;
	while (1) {
		if (sendto(fd, &ip, sizeof(ip), 0, (struct sockaddr *) &addr, sizeof(addr)) == EOF) break;
		sleep(1);
	}
	return 0;
}

------- recv.c -------

#include <stdio.h>
#include <string.h> 
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(int argc, char *argv[]) {
	const int fd = socket(PF_INET, SOCK_RAW, IPPROTO_RAW);
	while (1) {
		static int counter = 0;
		static char buffer[16384];
		struct sockaddr_in addr;
		socklen_t len = sizeof(addr);
		if (counter++ % 5 == 0) {
			sendto(fd, NULL, 0, 0, (struct sockaddr *) &addr, 0);
		}
		memset(&addr, 0, sizeof(addr));
		if (recvfrom(fd, buffer, sizeof(buffer), 0, (struct sockaddr *) &addr, &len) >= 0) {
			printf("%d %08X %d\n", addr.sin_family, ntohl(addr.sin_addr.s_addr), ntohs(addr.sin_port));
		}
	}
	return 0;
}