[PATCH bpf v2] selftests/bpf: fix "bind{4,6} deny specific IP & port" on s390

[PATCH bpf v2] selftests/bpf: fix "bind{4,6} deny specific IP & port" on s390

[Ilya Leoshkevich]

"bind4 allow specific IP & port" and "bind6 deny specific IP & port"
fail on s390 because of endianness issue: the 4 IP address bytes are
loaded as a word and compared with a constant, but the value of this
constant should be different on big- and little- endian machines, which
is not the case right now.

Use __bpf_constant_ntohl to generate proper value based on machine
endianness.

Fixes: 1d436885b23b ("selftests/bpf: Selftest for sys_bind post-hooks.")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
v1->v2: Use bpf_endian.h and __bpf_constant_ntohl.

 tools/testing/selftests/bpf/test_sock.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_sock.c b/tools/testing/selftests/bpf/test_sock.c
index fb679ac3d4b0..0e6652733462 100644
--- a/tools/testing/selftests/bpf/test_sock.c
+++ b/tools/testing/selftests/bpf/test_sock.c
@@ -13,6 +13,7 @@
 #include <bpf/bpf.h>
 
 #include "cgroup_helpers.h"
+#include "bpf_endian.h"
 #include "bpf_rlimit.h"
 #include "bpf_util.h"
 
@@ -232,7 +233,8 @@ static struct sock_test tests[] = {
 			/* if (ip == expected && port == expected) */
 			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
 				    offsetof(struct bpf_sock, src_ip6[3])),
-			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x01000000, 4),
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
+				    __bpf_constant_ntohl(0x00000001), 4),
 			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
 				    offsetof(struct bpf_sock, src_port)),
 			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x2001, 2),
@@ -261,7 +263,8 @@ static struct sock_test tests[] = {
 			/* if (ip == expected && port == expected) */
 			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
 				    offsetof(struct bpf_sock, src_ip4)),
-			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x0100007F, 4),
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
+				    __bpf_constant_ntohl(0x7F000001), 4),
 			BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
 				    offsetof(struct bpf_sock, src_port)),
 			BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x1002, 2),
-- 
2.21.0

Re: [PATCH bpf v2] selftests/bpf: fix "bind{4,6} deny specific IP & port" on s390

[Daniel Borkmann]

On 8/14/19 12:41 PM, Ilya Leoshkevich wrote:
> "bind4 allow specific IP & port" and "bind6 deny specific IP & port"
> fail on s390 because of endianness issue: the 4 IP address bytes are
> loaded as a word and compared with a constant, but the value of this
> constant should be different on big- and little- endian machines, which
> is not the case right now.
> 
> Use __bpf_constant_ntohl to generate proper value based on machine
> endianness.
> 
> Fixes: 1d436885b23b ("selftests/bpf: Selftest for sys_bind post-hooks.")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

Looks good, applied, thanks.