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

PATCH In review Ilya Leoshkevich 2 participants 2 messages Aug 14, 2019

Subsystems (3)

Kselftest BPF BPF selftests

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Ilya Leoshkevich

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2019-08-14 10:41 UTC #0 lore raw

PATCH v2 1/1 selftests/bpf: fix "bind{4,6} deny specific IP & port" on s390

"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 <[email protected]>

---
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(-)

tools/testing/selftests/bpf/test_sock.c +5 -2

index fb679ac3d4b0..0e6652733462 100644
@@ -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),

Signature · 1 line

2.21.0

Daniel Borkmann

maintainer

2019-08-14 20:55 UTC #1 lore raw

Quoted 11 lines · 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 <[email protected]>

Looks good, applied, thanks.