[PATCH net-next 2/2] tools: psock_tpacket: verify that packet was received on lo before counting it

[Sowmini Varadhan]

Packets from any/all interfaces may be queued up on the PF_PACKET socket
before it is bound to the loopback interface by psock_tpacket, and
when these are passed up by the kernel, they should not be counted
toward the conditions needed to pass/fail the Rx tests.

psock_tpacket discards these packets by examining the sll_ifindex sent
up in each frame and ensuring that this is the same as the ifindex
that was used in bind_ring()

Signed-off-by: Sowmini Varadhan <sowmini.varad...@oracle.com>
---
 tools/testing/selftests/net/psock_tpacket.c |   25 ++++++++++++++++++++-----
 1 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/net/psock_tpacket.c 
b/tools/testing/selftests/net/psock_tpacket.c
index 4a1bc64..3c3f1aa 100644
--- a/tools/testing/selftests/net/psock_tpacket.c
+++ b/tools/testing/selftests/net/psock_tpacket.c
@@ -235,6 +235,7 @@ static void walk_v1_v2_rx(int sock, struct ring *ring)
        int udp_sock[2];
        union frame_map ppd;
        unsigned int frame_num = 0;
+       int ifindex = ring->ll.sll_ifindex;
 
        bug_on(ring->type != PACKET_RX_RING);
 
@@ -255,12 +256,18 @@ static void walk_v1_v2_rx(int sock, struct ring *ring)
 
                        switch (ring->version) {
                        case TPACKET_V1:
+                               if (ppd.v1->s_ll.sll_ifindex != ifindex)
+                                       goto skip;
+
                                test_payload((uint8_t *) ppd.raw + 
ppd.v1->tp_h.tp_mac,
                                             ppd.v1->tp_h.tp_snaplen);
                                total_bytes += ppd.v1->tp_h.tp_snaplen;
                                break;
 
                        case TPACKET_V2:
+                               if (ppd.v2->s_ll.sll_ifindex != ifindex)
+                                       goto skip;
+
                                test_payload((uint8_t *) ppd.raw + 
ppd.v2->tp_h.tp_mac,
                                             ppd.v2->tp_h.tp_snaplen);
                                total_bytes += ppd.v2->tp_h.tp_snaplen;
@@ -270,6 +277,7 @@ static void walk_v1_v2_rx(int sock, struct ring *ring)
                        status_bar_update();
                        total_packets++;
 
+skip:
                        __v1_v2_rx_user_ready(ppd.raw, ring->version);
 
                        frame_num = (frame_num + 1) % ring->rd_num;
@@ -553,11 +561,13 @@ static void __v3_test_block_header(struct block_desc 
*pbd, const int block_num)
        __v3_test_block_seq_num(pbd);
 }
 
-static void __v3_walk_block(struct block_desc *pbd, const int block_num)
+static void __v3_walk_block(struct block_desc *pbd, const int block_num,
+                           int ifindex)
 {
        int num_pkts = pbd->h1.num_pkts, i;
        unsigned long bytes = 0, bytes_with_padding = ALIGN_8(sizeof(*pbd));
        struct tpacket3_hdr *ppd;
+       struct sockaddr_ll *s_ll;
 
        __v3_test_block_header(pbd, block_num);
 
@@ -572,10 +582,15 @@ static void __v3_walk_block(struct block_desc *pbd, const 
int block_num)
                else
                        bytes_with_padding += ALIGN_8(ppd->tp_snaplen + 
ppd->tp_mac);
 
-               test_payload((uint8_t *) ppd + ppd->tp_mac, ppd->tp_snaplen);
+               s_ll = (struct sockaddr_ll *)&ppd[1];
 
-               status_bar_update();
-               total_packets++;
+               if (ifindex == s_ll->sll_ifindex) {
+                       test_payload((uint8_t *) ppd + ppd->tp_mac,
+                                    ppd->tp_snaplen);
+
+                       status_bar_update();
+                       total_packets++;
+               }
 
                ppd = (struct tpacket3_hdr *) ((uint8_t *) ppd + 
ppd->tp_next_offset);
                __sync_synchronize();
@@ -616,7 +631,7 @@ static void walk_v3_rx(int sock, struct ring *ring)
                while ((pbd->h1.block_status & TP_STATUS_USER) == 0)
                        poll(&pfd, 1, 1);
 
-               __v3_walk_block(pbd, block_num);
+               __v3_walk_block(pbd, block_num, ring->ll.sll_ifindex);
                __v3_flush_block(pbd);
 
                block_num = (block_num + 1) % ring->rd_num;
-- 
1.7.1