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Date:   Mon, 25 Mar 2019 17:43:39 -0700
From:   Andrey Ignatov <rdna@...com>
To:     <netdev@...r.kernel.org>
CC:     Andrey Ignatov <rdna@...com>, <ast@...nel.org>,
        <daniel@...earbox.net>, <guro@...com>, <kernel-team@...com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>
Subject: [PATCH v2 bpf-next 13/21] selftests/bpf: Test bpf_sysctl_{get,set}_new_value helpers

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@...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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