diff options
| author | Sowmini Varadhan <sowmini.varadhan@oracle.com> | 2017-01-12 05:10:11 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-01-12 10:23:26 -0500 |
| commit | 4d7b9dc1f36a99423a6171d393040165fb135530 (patch) | |
| tree | 9cf9841d98aa2b47e2b41ab5c6e2ed652d2cce80 | |
| parent | 79471b10d67a52f5b3744d2e14c06437a65746f2 (diff) | |
tools: psock_lib: harden socket filter used by psock tests
The filter added by sock_setfilter is intended to only permit
packets matching the pattern set up by create_payload(), but
we only check the ip_len, and a single test-character in
the IP packet to ensure this condition.
Harden the filter by adding additional constraints so that we only
permit UDP/IPv4 packets that meet the ip_len and test-character
requirements. Include the bpf_asm src as a comment, in case this
needs to be enhanced in the future
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | tools/testing/selftests/net/psock_lib.h | 39 |
1 files changed, 32 insertions, 7 deletions
diff --git a/tools/testing/selftests/net/psock_lib.h b/tools/testing/selftests/net/psock_lib.h index 24bc7ec1be7d..a77da88bf946 100644 --- a/tools/testing/selftests/net/psock_lib.h +++ b/tools/testing/selftests/net/psock_lib.h @@ -40,14 +40,39 @@ static __maybe_unused void sock_setfilter(int fd, int lvl, int optnum) { + /* the filter below checks for all of the following conditions that + * are based on the contents of create_payload() + * ether type 0x800 and + * ip proto udp and + * skb->len == DATA_LEN and + * udp[38] == 'a' or udp[38] == 'b' + * It can be generated from the following bpf_asm input: + * ldh [12] + * jne #0x800, drop ; ETH_P_IP + * ldb [23] + * jneq #17, drop ; IPPROTO_UDP + * ld len ; ld skb->len + * jlt #100, drop ; DATA_LEN + * ldb [80] + * jeq #97, pass ; DATA_CHAR + * jne #98, drop ; DATA_CHAR_1 + * pass: + * ret #-1 + * drop: + * ret #0 + */ struct sock_filter bpf_filter[] = { - { 0x80, 0, 0, 0x00000000 }, /* LD pktlen */ - { 0x35, 0, 4, DATA_LEN }, /* JGE DATA_LEN [f goto nomatch]*/ - { 0x30, 0, 0, 0x00000050 }, /* LD ip[80] */ - { 0x15, 1, 0, DATA_CHAR }, /* JEQ DATA_CHAR [t goto match]*/ - { 0x15, 0, 1, DATA_CHAR_1}, /* JEQ DATA_CHAR_1 [t goto match]*/ - { 0x06, 0, 0, 0x00000060 }, /* RET match */ - { 0x06, 0, 0, 0x00000000 }, /* RET no match */ + { 0x28, 0, 0, 0x0000000c }, + { 0x15, 0, 8, 0x00000800 }, + { 0x30, 0, 0, 0x00000017 }, + { 0x15, 0, 6, 0x00000011 }, + { 0x80, 0, 0, 0000000000 }, + { 0x35, 0, 4, 0x00000064 }, + { 0x30, 0, 0, 0x00000050 }, + { 0x15, 1, 0, 0x00000061 }, + { 0x15, 0, 1, 0x00000062 }, + { 0x06, 0, 0, 0xffffffff }, + { 0x06, 0, 0, 0000000000 }, }; struct sock_fprog bpf_prog; |