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Subject[PATCH v3 bpf-next 13/21] selftests/bpf: Test bpf_sysctl_{get,set}_new_value helpers
Date
Test that new value provided by user space on sysctl write can be read
by bpf_sysctl_get_new_value and overridden by bpf_sysctl_set_new_value.

# ./test_sysctl
...
Test case: sysctl_get_new_value sysctl:read EINVAL .. [PASS]
Test case: sysctl_get_new_value sysctl:write ok .. [PASS]
Test case: sysctl_get_new_value sysctl:write ok long .. [PASS]
Test case: sysctl_get_new_value sysctl:write E2BIG .. [PASS]
Test case: sysctl_set_new_value sysctl:read EINVAL .. [PASS]
Test case: sysctl_set_new_value sysctl:write ok .. [PASS]
Summary: 22 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 9fb6560fa775..95437b72404f 100644
--- a/tools/testing/selftests/bpf/test_sysctl.c
+++ b/tools/testing/selftests/bpf/test_sysctl.c
@@ -536,6 +536,228 @@ static struct sysctl_test tests[] = {
.newval = "600", /* same as default, should fail anyway */
.result = OP_EPERM,
},
+ {
+ .descr = "sysctl_get_new_value sysctl:read EINVAL",
+ .insns = {
+ /* sysctl_get_new_value 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_new_value arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 8),
+
+ /* sysctl_get_new_value(ctx, buf, buf_len) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
+
+ /* if (ret == expected) */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 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_new_value sysctl:write ok",
+ .insns = {
+ /* sysctl_get_new_value arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_new_value arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 4),
+
+ /* sysctl_get_new_value(ctx, buf, buf_len) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 3, 4),
+
+ /* buf[0:4] == "606\0") */
+ BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0x00363036, 2),
+
+ /* return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_JMP_A(1),
+
+ /* else return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/route/mtu_expires",
+ .open_flags = O_WRONLY,
+ .newval = "606",
+ .result = OP_EPERM,
+ },
+ {
+ .descr = "sysctl_get_new_value sysctl:write ok long",
+ .insns = {
+ /* sysctl_get_new_value arg2 (buf) */
+ BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -24),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_new_value arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 24),
+
+ /* sysctl_get_new_value(ctx, buf, buf_len) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 23, 14),
+
+ /* buf[0:8] == "3000000 " && */
+ BPF_LD_IMM64(BPF_REG_8, 0x2030303030303033ULL),
+ 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] == "4000000 " && */
+ BPF_LD_IMM64(BPF_REG_8, 0x2030303030303034ULL),
+ 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] == "6000000\0") */
+ BPF_LD_IMM64(BPF_REG_8, 0x0030303030303036ULL),
+ 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 DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_JMP_A(1),
+
+ /* else return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/tcp_mem",
+ .open_flags = O_WRONLY,
+ .newval = "3000000 4000000 6000000",
+ .result = OP_EPERM,
+ },
+ {
+ .descr = "sysctl_get_new_value sysctl:write E2BIG",
+ .insns = {
+ /* sysctl_get_new_value 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_B, BPF_REG_7, BPF_REG_0, 3),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_get_new_value arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 3),
+
+ /* sysctl_get_new_value(ctx, buf, buf_len) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_get_new_value),
+
+ /* if (ret == expected && */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 4),
+
+ /* buf[0:3] == "60\0") */
+ BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_7, 0),
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0x003036, 2),
+
+ /* return DENY; */
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_JMP_A(1),
+
+ /* else return ALLOW; */
+ BPF_MOV64_IMM(BPF_REG_0, 1),
+ BPF_EXIT_INSN(),
+ },
+ .attach_type = BPF_CGROUP_SYSCTL,
+ .sysctl = "net/ipv4/route/mtu_expires",
+ .open_flags = O_WRONLY,
+ .newval = "606",
+ .result = OP_EPERM,
+ },
+ {
+ .descr = "sysctl_set_new_value sysctl:read EINVAL",
+ .insns = {
+ /* sysctl_set_new_value 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, 0x00303036),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_set_new_value arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 3),
+
+ /* sysctl_set_new_value(ctx, buf, buf_len) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_set_new_value),
+
+ /* if (ret == expected) */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 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/route/mtu_expires",
+ .open_flags = O_RDONLY,
+ .result = SUCCESS,
+ },
+ {
+ .descr = "sysctl_set_new_value sysctl:write ok",
+ .fixup_value_insn = 2,
+ .insns = {
+ /* sysctl_set_new_value 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, FIXUP_SYSCTL_VALUE),
+ BPF_STX_MEM(BPF_DW, BPF_REG_7, BPF_REG_0, 0),
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
+
+ /* sysctl_set_new_value arg3 (buf_len) */
+ BPF_MOV64_IMM(BPF_REG_3, 3),
+
+ /* sysctl_set_new_value(ctx, buf, buf_len) */
+ BPF_EMIT_CALL(BPF_FUNC_sysctl_set_new_value),
+
+ /* if (ret == expected) */
+ BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 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/route/mtu_expires",
+ .open_flags = O_WRONLY,
+ .newval = "606",
+ .result = SUCCESS,
+ },
};

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