selftests/bpf: Update EFAULT {g,s}etsockopt selftests

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>
Link: https://lore.kernel.org/r/20230511170456.1759459-3-sdf@google.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/testing/selftests/bpf/prog_tests/sockopt.c

@@ -5,10 +5,15 @@
 static char bpf_log_buf[4096];
 static bool verbose;
 
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
+
 enum sockopt_test_error {
 	OK = 0,
 	DENY_LOAD,
 	DENY_ATTACH,
+	EOPNOTSUPP_GETSOCKOPT,
 	EPERM_GETSOCKOPT,
 	EFAULT_GETSOCKOPT,
 	EPERM_SETSOCKOPT,
@@ -273,10 +278,31 @@ 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),
+			/* } */
+
+			/* retval changes are ignored */
+			/* ctx->retval = 5 */
+			BPF_MOV64_IMM(BPF_REG_0, 5),
 			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
 				    offsetof(struct bpf_sockopt, retval)),
 
@@ -287,9 +313,11 @@ 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 = PAGE_SIZE + 1,
+		.error = EOPNOTSUPP_GETSOCKOPT,
 	},
 	{
 		.descr = "getsockopt: support smaller ctx->optlen",
@@ -648,6 +676,45 @@ 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, 0xF0),
+			/* } */
+
+			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 = {},
+		.set_optlen = PAGE_SIZE + 1,
+
+		.get_level = SOL_IP,
+		.get_optname = IP_TOS,
+		.get_optval = {}, /* the changes are ignored */
+		.get_optlen = 4,
+	},
 	{
 		.descr = "setsockopt: allow changing ctx->optlen within bounds",
 		.insns = {
@@ -906,6 +973,13 @@ static int run_test(int cgroup_fd, struct sockopt_test *test)
 	}
 
 	if (test->set_optlen) {
+		if (test->set_optlen >= PAGE_SIZE) {
+			int num_pages = test->set_optlen / PAGE_SIZE;
+			int remainder = test->set_optlen % PAGE_SIZE;
+
+			test->set_optlen = num_pages * sysconf(_SC_PAGESIZE) + remainder;
+		}
+
 		err = setsockopt(sock_fd, test->set_level, test->set_optname,
 				 test->set_optval, test->set_optlen);
 		if (err) {
@@ -921,7 +995,15 @@ static int run_test(int cgroup_fd, struct sockopt_test *test)
 	}
 
 	if (test->get_optlen) {
+		if (test->get_optlen >= PAGE_SIZE) {
+			int num_pages = test->get_optlen / PAGE_SIZE;
+			int remainder = test->get_optlen % PAGE_SIZE;
+
+			test->get_optlen = num_pages * sysconf(_SC_PAGESIZE) + remainder;
+		}
+
 		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;
@@ -929,6 +1011,8 @@ static int run_test(int cgroup_fd, struct sockopt_test *test)
 		err = getsockopt(sock_fd, test->get_level, test->get_optname,
 				 optval, &optlen);
 		if (err) {
+			if (errno == EOPNOTSUPP && test->error == EOPNOTSUPP_GETSOCKOPT)
+				goto free_optval;
 			if (errno == EPERM && test->error == EPERM_GETSOCKOPT)
 				goto free_optval;
 			if (errno == EFAULT && test->error == EFAULT_GETSOCKOPT)