[PATCH bpf-next v2 2/4] selftests/bpf: Update EFAULT {g,s}etsockopt selftests

[Stanislav Fomichev <sdf@google.com>]

Instead of assuming EFAULT, let's assume the BPF program's
output is ignored.

Remove "getsockopt: deny arbitrary ctx->retval" because it
was actually testing optlen. We have separate set of tests
for retval.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 .../selftests/bpf/prog_tests/sockopt.c        | 80 +++++++++++++++++--
 1 file changed, 74 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt.c b/tools/testing/selftests/bpf/prog_tests/sockopt.c
index aa4debf62fc6..8dad30ce910e 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt.c
@@ -273,10 +273,30 @@ static struct sockopt_test {
 		.error = EFAULT_GETSOCKOPT,
 	},
 	{
-		.descr = "getsockopt: deny arbitrary ctx->retval",
+		.descr = "getsockopt: ignore >PAGE_SIZE optlen",
 		.insns = {
-			/* ctx->retval = 123 */
-			BPF_MOV64_IMM(BPF_REG_0, 123),
+			/* write 0xFF to the first optval byte */
+
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+			/* r2 = ctx->optval */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_6),
+			/* r6 = ctx->optval + 1 */
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 1),
+
+			/* r7 = ctx->optval_end */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval_end)),
+
+			/* if (ctx->optval + 1 <= ctx->optval_end) { */
+			BPF_JMP_REG(BPF_JGT, BPF_REG_6, BPF_REG_7, 1),
+			/* ctx->optval[0] = 0xF0 */
+			BPF_ST_MEM(BPF_B, BPF_REG_2, 0, 0xFF),
+			/* } */
+
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
 				    offsetof(struct bpf_sockopt, retval)),
 
@@ -287,9 +307,10 @@ static struct sockopt_test {
 		.attach_type = BPF_CGROUP_GETSOCKOPT,
 		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
 
-		.get_optlen = 64,
-
-		.error = EFAULT_GETSOCKOPT,
+		.get_level = 1234,
+		.get_optname = 5678,
+		.get_optval = {}, /* the changes are ignored */
+		.get_optlen = 4096 + 1,
 	},
 	{
 		.descr = "getsockopt: support smaller ctx->optlen",
@@ -648,6 +669,49 @@ static struct sockopt_test {
 
 		.error = EFAULT_SETSOCKOPT,
 	},
+	{
+		.descr = "setsockopt: ignore >PAGE_SIZE optlen",
+		.insns = {
+			/* write 0xFF to the first optval byte */
+
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+			/* r2 = ctx->optval */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_6),
+			/* r6 = ctx->optval + 1 */
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 1),
+
+			/* r7 = ctx->optval_end */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval_end)),
+
+			/* if (ctx->optval + 1 <= ctx->optval_end) { */
+			BPF_JMP_REG(BPF_JGT, BPF_REG_6, BPF_REG_7, 1),
+			/* ctx->optval[0] = 0xF0 */
+			BPF_ST_MEM(BPF_B, BPF_REG_2, 0, 0xFF),
+			/* } */
+
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.set_level = SOL_IP,
+		.set_optname = IP_TOS,
+		.set_optval = { 1 << 3 },
+		.set_optlen = 4096 + 1,
+
+		.get_level = SOL_IP,
+		.get_optname = IP_TOS,
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+		.get_optval = { 1 << 3, 0, 0, 0 }, /* the changes are ignored */
+#else
+		.get_optval = { 0, 0, 0, 1 << 3 }, /* the changes are ignored */
+#endif
+		.get_optlen = 4,
+	},
 	{
 		.descr = "setsockopt: allow changing ctx->optlen within bounds",
 		.insns = {
@@ -922,6 +986,7 @@ static int run_test(int cgroup_fd, struct sockopt_test *test)
 
 	if (test->get_optlen) {
 		optval = malloc(test->get_optlen);
+		memset(optval, 0, test->get_optlen);
 		socklen_t optlen = test->get_optlen;
 		socklen_t expected_get_optlen = test->get_optlen_ret ?:
 			test->get_optlen;
@@ -946,6 +1011,9 @@ static int run_test(int cgroup_fd, struct sockopt_test *test)
 			goto free_optval;
 		}
 
+		if (optlen > sizeof(test->get_optval))
+			optlen = sizeof(test->get_optval);
+
 		if (memcmp(optval, test->get_optval, optlen) != 0) {
 			errno = 0;
 			log_err("getsockopt returned unexpected optval");
-- 
2.40.1.495.gc816e09b53d-goog