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Subject[PATCH v3 bpf-next 11/21] selftests/bpf: Test bpf_sysctl_get_name helper
Date
Test w/ and w/o BPF_F_SYSCTL_BASE_NAME, buffers with enough space and
too small buffers to get E2BIG and truncated result, etc.

# ./test_sysctl
...
Test case: sysctl_get_name sysctl_value:base ok .. [PASS]
Test case: sysctl_get_name sysctl_value:base E2BIG truncated .. [PASS]
Test case: sysctl_get_name sysctl:full ok .. [PASS]
Test case: sysctl_get_name sysctl:full E2BIG truncated .. [PASS]
Test case: sysctl_get_name sysctl:full E2BIG truncated small .. [PASS]
Summary: 11 PASSED, 0 FAILED

Signed-off-by: Andrey Ignatov <rdna@fb.com>
---
tools/testing/selftests/bpf/test_sysctl.c | 222 ++++++++++++++++++++++
1 file changed, 222 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_sysctl.c b/tools/testing/selftests/bpf/test_sysctl.c
index 6d0ab09789ad..2e7ef04503a8 100644
--- a/tools/testing/selftests/bpf/test_sysctl.c
+++ b/tools/testing/selftests/bpf/test_sysctl.c
@@ -128,6 +128,228 @@ static struct sysctl_test tests[] = {
.open_flags = O_RDONLY,
.result = LOAD_REJECT,
},
+ {
+ .descr = "sysctl_get_name sysctl_value:base ok",
+ .insns = {
+ /* sysctl_get_name arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_name arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 8),
+
+ /* sysctl_get_name arg4 (flags) */
+ BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME),
+
+ /* sysctl_get_name(ctx, buf, buf_len, flags) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, sizeof("tcp_mem") - 1, 6),
+ /* buf == "tcp_mem\0") */
+ BPF_LD_IMM64(BPF_REG_8, 0x006d656d5f706374ULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
+
+ /* return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_JMP_A(1),
+
+ /* else return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/tcp_mem",
+ .open_flags = O_RDONLY,
+ .result = SUCCESS,
+ },
+ {
+ .descr = "sysctl_get_name sysctl_value:base E2BIG truncated",
+ .insns = {
+ /* sysctl_get_name arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_name arg3 (buf_len) too small */
+ BPF_MOV64_IMM(BPF_REG_3, 7),
+
+ /* sysctl_get_name arg4 (flags) */
+ BPF_MOV64_IMM(BPF_REG_4, BPF_F_SYSCTL_BASE_NAME),
+
+ /* sysctl_get_name(ctx, buf, buf_len, flags) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6),
+
+ /* buf[0:7] == "tcp_me\0") */
+ BPF_LD_IMM64(BPF_REG_8, 0x00656d5f706374ULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
+
+ /* return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_JMP_A(1),
+
+ /* else return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/tcp_mem",
+ .open_flags = O_RDONLY,
+ .result = SUCCESS,
+ },
+ {
+ .descr = "sysctl_get_name sysctl:full ok",
+ .insns = {
+ /* sysctl_get_name arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 16),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_name arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 17),
+
+ /* sysctl_get_name arg4 (flags) */
+ BPF_MOV64_IMM(BPF_REG_4, 0),
+
+ /* sysctl_get_name(ctx, buf, buf_len, flags) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 16, 14),
+
+ /* buf[0:8] == "net/ipv4" && */
+ BPF_LD_IMM64(BPF_REG_8, 0x347670692f74656eULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 10),
+
+ /* buf[8:16] == "/tcp_mem" && */
+ BPF_LD_IMM64(BPF_REG_8, 0x6d656d5f7063742fULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6),
+
+ /* buf[16:24] == "\0") */
+ BPF_LD_IMM64(BPF_REG_8, 0x0ULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 16),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
+
+ /* return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_JMP_A(1),
+
+ /* else return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/tcp_mem",
+ .open_flags = O_RDONLY,
+ .result = SUCCESS,
+ },
+ {
+ .descr = "sysctl_get_name sysctl:full E2BIG truncated",
+ .insns = {
+ /* sysctl_get_name arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -16),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 8),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_name arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 16),
+
+ /* sysctl_get_name arg4 (flags) */
+ BPF_MOV64_IMM(BPF_REG_4, 0),
+
+ /* sysctl_get_name(ctx, buf, buf_len, flags) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 10),
+
+ /* buf[0:8] == "net/ipv4" && */
+ BPF_LD_IMM64(BPF_REG_8, 0x347670692f74656eULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 6),
+
+ /* buf[8:16] == "/tcp_me\0") */
+ BPF_LD_IMM64(BPF_REG_8, 0x00656d5f7063742fULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 8),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
+
+ /* return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_JMP_A(1),
+
+ /* else return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/tcp_mem",
+ .open_flags = O_RDONLY,
+ .result = SUCCESS,
+ },
+ {
+ .descr = "sysctl_get_name sysctl:full E2BIG truncated small",
+ .insns = {
+ /* sysctl_get_name arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_name arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 7),
+
+ /* sysctl_get_name arg4 (flags) */
+ BPF_MOV64_IMM(BPF_REG_4, 0),
+
+ /* sysctl_get_name(ctx, buf, buf_len, flags) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_name),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6),
+
+ /* buf[0:8] == "net/ip\0") */
+ BPF_LD_IMM64(BPF_REG_8, 0x000070692f74656eULL),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2),
+
+ /* return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_JMP_A(1),
+
+ /* else return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/tcp_mem",
+ .open_flags = O_RDONLY,
+ .result = SUCCESS,
+ },
};

static size_t probe_prog_length(const struct bpf_insn *fp)
--
2.17.1
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