[PATCH net 0/2] ioam6: fix write to cloned skb's

[PATCH net 0/2] ioam6: fix write to cloned skb's

[Justin Iurman]

Make sure the IOAM data insertion is not applied on cloned skb's. As a
consequence, ioam selftests needed a refactoring.

Justin Iurman (2):
  ioam6: fix write to cloned skb in ipv6_hop_ioam()
  selftests: ioam6: refactoring to align with the fix

 net/ipv6/exthdrs.c                         |   8 ++
 tools/testing/selftests/net/ioam6.sh       |  38 ++++----
 tools/testing/selftests/net/ioam6_parser.c | 101 +++++++++++----------
 3 files changed, 81 insertions(+), 66 deletions(-)


base-commit: 166c2c8a6a4dc2e4ceba9e10cfe81c3e469e3210
-- 
2.34.1

[PATCH net 1/2] ioam6: fix write to cloned skb in ipv6_hop_ioam()

[Justin Iurman]

ioam6_fill_trace_data() writes inside the skb payload without ensuring
it's writeable (e.g., not cloned). This function is called both from the
input and output path. The output path (ioam6_iptunnel) already does the
check. This commit provides a fix for the input path, inside
ipv6_hop_ioam().

Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ")
Reported-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
---
 net/ipv6/exthdrs.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 4952ae792450..f68e5faab3aa 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
 		if (!skb_valid_dst(skb))
 			ip6_route_input(skb);
 
+		if (skb_cloned(skb)) {
+			if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+				goto drop;
+
+			hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
+			trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));
+		}
+
 		ioam6_fill_trace_data(skb, ns, trace, true);
 		break;
 	default:
-- 
2.34.1

Re: [PATCH net 1/2] ioam6: fix write to cloned skb in ipv6_hop_ioam()

[Paolo Abeni]

On Sat, 2024-02-17 at 00:43 +0100, Justin Iurman wrote:
> ioam6_fill_trace_data() writes inside the skb payload without ensuring
> it's writeable (e.g., not cloned). This function is called both from the
> input and output path. The output path (ioam6_iptunnel) already does the
> check. This commit provides a fix for the input path, inside
> ipv6_hop_ioam().
> 
> Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ")
> Reported-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
> ---
>  net/ipv6/exthdrs.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
> index 4952ae792450..f68e5faab3aa 100644
> --- a/net/ipv6/exthdrs.c
> +++ b/net/ipv6/exthdrs.c
> @@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
>  		if (!skb_valid_dst(skb))
>  			ip6_route_input(skb);
>  
> +		if (skb_cloned(skb)) {
> +			if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
> +				goto drop;

My personal preference would be for using skb_ensure_writable() here,
with write_len == optoff + hdr->opt_len.

> +
> +			hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
> +			trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));

Note that this can potentially change the network header ptr and the
caller - ip6_parse_tlv() - has cached such value in 'nh'. You also need
to update ip6_parse_tlv() to reload such pointer.

Side note: a bunch of self-tests are apparently stuck after this
series. I think it's an unrelated problem. I'll try to have a better
look.

Cheers,

Paolo

Re: [PATCH net 1/2] ioam6: fix write to cloned skb in ipv6_hop_ioam()

[Justin Iurman]

On 2/19/24 10:05, Paolo Abeni wrote:
> On Sat, 2024-02-17 at 00:43 +0100, Justin Iurman wrote:
>> ioam6_fill_trace_data() writes inside the skb payload without ensuring
>> it's writeable (e.g., not cloned). This function is called both from the
>> input and output path. The output path (ioam6_iptunnel) already does the
>> check. This commit provides a fix for the input path, inside
>> ipv6_hop_ioam().
>>
>> Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ")
>> Reported-by: Paolo Abeni <pabeni@redhat.com>
>> Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
>> ---
>>   net/ipv6/exthdrs.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
>> index 4952ae792450..f68e5faab3aa 100644
>> --- a/net/ipv6/exthdrs.c
>> +++ b/net/ipv6/exthdrs.c
>> @@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
>>   		if (!skb_valid_dst(skb))
>>   			ip6_route_input(skb);
>>   
>> +		if (skb_cloned(skb)) {
>> +			if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
>> +				goto drop;
> 
> My personal preference would be for using skb_ensure_writable() here,
> with write_len == optoff + hdr->opt_len.

OK, will do!

>> +
>> +			hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff);
>> +			trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr));
> 
> Note that this can potentially change the network header ptr and the
> caller - ip6_parse_tlv() - has cached such value in 'nh'. You also need
> to update ip6_parse_tlv() to reload such pointer.

+1, I completely missed it, thanks!

> Side note: a bunch of self-tests are apparently stuck after this
> series. I think it's an unrelated problem. I'll try to have a better
> look.

Can you share the config to observe such behavior? I'll try to 
investigate too.

> Cheers,
> 
> Paolo
> 

[PATCH net 2/2] selftests: ioam6: refactoring to align with the fix

[Justin Iurman]

ioam6_parser uses a packet socket. After the fix to prevent writing to
cloned skb's, the receiver does not see its IOAM data anymore, which
makes input/forward ioam-selftests to fail. As a workaround,
ioam6_parser now uses an IPv6 raw socket and leverages ancillary data to
get hop-by-hop options. As a consequence, the hook is "after" the IOAM
data insertion by the receiver and all tests are working again.

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
---
 tools/testing/selftests/net/ioam6.sh       |  38 ++++----
 tools/testing/selftests/net/ioam6_parser.c | 101 +++++++++++----------
 2 files changed, 73 insertions(+), 66 deletions(-)

diff --git a/tools/testing/selftests/net/ioam6.sh b/tools/testing/selftests/net/ioam6.sh
index fe59ca3e5596..12491850ae98 100755
--- a/tools/testing/selftests/net/ioam6.sh
+++ b/tools/testing/selftests/net/ioam6.sh
@@ -367,14 +367,12 @@ run_test()
   local desc=$2
   local node_src=$3
   local node_dst=$4
-  local ip6_src=$5
-  local ip6_dst=$6
-  local if_dst=$7
-  local trace_type=$8
-  local ioam_ns=$9
-
-  ip netns exec $node_dst ./ioam6_parser $if_dst $name $ip6_src $ip6_dst \
-         $trace_type $ioam_ns &
+  local ip6_dst=$5
+  local trace_type=$6
+  local ioam_ns=$7
+  local type=$8
+
+  ip netns exec $node_dst ./ioam6_parser $name $trace_type $ioam_ns $type &
   local spid=$!
   sleep 0.1
 
@@ -489,7 +487,7 @@ out_undef_ns()
          trace prealloc type 0x800000 ns 0 size 4 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0x800000 0
+         db01::1 0x800000 0 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 }
@@ -509,7 +507,7 @@ out_no_room()
          trace prealloc type 0xc00000 ns 123 size 4 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0xc00000 123
+         db01::1 0xc00000 123 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 }
@@ -543,14 +541,14 @@ out_bits()
       if [ $cmd_res != 0 ]
       then
         npassed=$((npassed+1))
-        log_test_passed "$descr"
+        log_test_passed "$descr ($1 mode)"
       else
         nfailed=$((nfailed+1))
-        log_test_failed "$descr"
+        log_test_failed "$descr ($1 mode)"
       fi
     else
 	run_test "out_bit$i" "$descr ($1 mode)" $ioam_node_alpha \
-           $ioam_node_beta db01::2 db01::1 veth0 ${bit2type[$i]} 123
+           $ioam_node_beta db01::1 ${bit2type[$i]} 123 $1
     fi
   done
 
@@ -574,7 +572,7 @@ out_full_supp_trace()
          trace prealloc type 0xfff002 ns 123 size 100 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0xfff002 123
+         db01::1 0xfff002 123 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 }
@@ -604,7 +602,7 @@ in_undef_ns()
          trace prealloc type 0x800000 ns 0 size 4 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0x800000 0
+         db01::1 0x800000 0 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 }
@@ -624,7 +622,7 @@ in_no_room()
          trace prealloc type 0xc00000 ns 123 size 4 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0xc00000 123
+         db01::1 0xc00000 123 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 }
@@ -651,7 +649,7 @@ in_bits()
            dev veth0
 
     run_test "in_bit$i" "${desc/<n>/$i} ($1 mode)" $ioam_node_alpha \
-           $ioam_node_beta db01::2 db01::1 veth0 ${bit2type[$i]} 123
+           $ioam_node_beta db01::1 ${bit2type[$i]} 123 $1
   done
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
@@ -679,7 +677,7 @@ in_oflag()
          trace prealloc type 0xc00000 ns 123 size 4 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0xc00000 123
+         db01::1 0xc00000 123 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 
@@ -703,7 +701,7 @@ in_full_supp_trace()
          trace prealloc type 0xfff002 ns 123 size 80 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_beta \
-         db01::2 db01::1 veth0 0xfff002 123
+         db01::1 0xfff002 123 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_beta link set ip6tnl0 down
 }
@@ -731,7 +729,7 @@ fwd_full_supp_trace()
          trace prealloc type 0xfff002 ns 123 size 244 via db01::1 dev veth0
 
   run_test ${FUNCNAME[0]} "${desc} ($1 mode)" $ioam_node_alpha $ioam_node_gamma \
-         db01::2 db02::2 veth0 0xfff002 123
+         db02::2 0xfff002 123 $1
 
   [ "$1" = "encap" ] && ip -netns $ioam_node_gamma link set ip6tnl0 down
 }
diff --git a/tools/testing/selftests/net/ioam6_parser.c b/tools/testing/selftests/net/ioam6_parser.c
index d9d1d4190126..14b354e14d25 100644
--- a/tools/testing/selftests/net/ioam6_parser.c
+++ b/tools/testing/selftests/net/ioam6_parser.c
@@ -8,7 +8,6 @@
 #include <errno.h>
 #include <limits.h>
 #include <linux/const.h>
-#include <linux/if_ether.h>
 #include <linux/ioam6.h>
 #include <linux/ipv6.h>
 #include <stdlib.h>
@@ -512,14 +511,6 @@ static int str2id(const char *tname)
 	return -1;
 }
 
-static int ipv6_addr_equal(const struct in6_addr *a1, const struct in6_addr *a2)
-{
-	return ((a1->s6_addr32[0] ^ a2->s6_addr32[0]) |
-		(a1->s6_addr32[1] ^ a2->s6_addr32[1]) |
-		(a1->s6_addr32[2] ^ a2->s6_addr32[2]) |
-		(a1->s6_addr32[3] ^ a2->s6_addr32[3])) == 0;
-}
-
 static int get_u32(__u32 *val, const char *arg, int base)
 {
 	unsigned long res;
@@ -603,70 +594,88 @@ static int (*func[__TEST_MAX])(int, struct ioam6_trace_hdr *, __u32, __u16) = {
 
 int main(int argc, char **argv)
 {
-	int fd, size, hoplen, tid, ret = 1;
-	struct in6_addr src, dst;
+	int fd, size, hoplen, tid, ret = 1, on = 1;
+	__u8 buffer[512], is_encap;
 	struct ioam6_hdr *opt;
-	struct ipv6hdr *ip6h;
-	__u8 buffer[400], *p;
-	__u16 ioam_ns;
+	struct cmsghdr *cmsg;
+	struct msghdr msg;
+	struct iovec iov;
 	__u32 tr_type;
+	__u16 ioam_ns;
+	__u8 *ptr;
 
-	if (argc != 7)
+	if (argc != 5)
 		goto out;
 
-	tid = str2id(argv[2]);
+	tid = str2id(argv[1]);
 	if (tid < 0 || !func[tid])
 		goto out;
 
-	if (inet_pton(AF_INET6, argv[3], &src) != 1 ||
-	    inet_pton(AF_INET6, argv[4], &dst) != 1)
+	if (get_u32(&tr_type, argv[2], 16) ||
+	    get_u16(&ioam_ns, argv[3], 0))
 		goto out;
 
-	if (get_u32(&tr_type, argv[5], 16) ||
-	    get_u16(&ioam_ns, argv[6], 0))
+	if (!strcmp(argv[4], "inline"))
+		is_encap = 0;
+	else if (!strcmp(argv[4], "encap"))
+		is_encap = 1;
+	else
 		goto out;
 
-	fd = socket(AF_PACKET, SOCK_DGRAM, __cpu_to_be16(ETH_P_IPV6));
-	if (!fd)
+	fd = socket(PF_INET6, SOCK_RAW,
+		    is_encap ? IPPROTO_IPV6 : IPPROTO_ICMPV6);
+	if (fd < 0)
 		goto out;
 
-	if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE,
-		       argv[1], strlen(argv[1])))
-		goto close;
+	setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPOPTS,  &on, sizeof(on));
 
+	iov.iov_len = 1;
+	iov.iov_base = malloc(CMSG_SPACE(sizeof(buffer)));
+	if (!iov.iov_base)
+		goto close;
 recv:
-	size = recv(fd, buffer, sizeof(buffer), 0);
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	msg.msg_control = buffer;
+	msg.msg_controllen = CMSG_SPACE(sizeof(buffer));
+
+	size = recvmsg(fd, &msg, 0);
 	if (size <= 0)
 		goto close;
 
-	ip6h = (struct ipv6hdr *)buffer;
+	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
+	     cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+		if (cmsg->cmsg_level != IPPROTO_IPV6 ||
+		    cmsg->cmsg_type != IPV6_HOPOPTS ||
+		    cmsg->cmsg_len < sizeof(struct ipv6_hopopt_hdr))
+			continue;
 
-	if (!ipv6_addr_equal(&ip6h->saddr, &src) ||
-	    !ipv6_addr_equal(&ip6h->daddr, &dst))
-		goto recv;
+		ptr = (__u8 *)CMSG_DATA(cmsg);
 
-	if (ip6h->nexthdr != IPPROTO_HOPOPTS)
-		goto close;
+		hoplen = (ptr[1] + 1) << 3;
+		ptr += sizeof(struct ipv6_hopopt_hdr);
 
-	p = buffer + sizeof(*ip6h);
-	hoplen = (p[1] + 1) << 3;
-	p += sizeof(struct ipv6_hopopt_hdr);
+		while (hoplen > 0) {
+			opt = (struct ioam6_hdr *)ptr;
 
-	while (hoplen > 0) {
-		opt = (struct ioam6_hdr *)p;
+			if (opt->opt_type == IPV6_TLV_IOAM &&
+			    opt->type == IOAM6_TYPE_PREALLOC) {
+				ptr += sizeof(*opt);
+				ret = func[tid](tid,
+						(struct ioam6_trace_hdr *)ptr,
+						tr_type, ioam_ns);
+				goto close;
+			}
 
-		if (opt->opt_type == IPV6_TLV_IOAM &&
-		    opt->type == IOAM6_TYPE_PREALLOC) {
-			p += sizeof(*opt);
-			ret = func[tid](tid, (struct ioam6_trace_hdr *)p,
-					   tr_type, ioam_ns);
-			break;
+			ptr += opt->opt_len + 2;
+			hoplen -= opt->opt_len + 2;
 		}
-
-		p += opt->opt_len + 2;
-		hoplen -= opt->opt_len + 2;
 	}
+
+	goto recv;
 close:
+	free(iov.iov_base);
 	close(fd);
 out:
 	return ret;
-- 
2.34.1