On 5/1/23 12:48 PM, Stanislav Fomichev wrote:
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@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/sockopt.c | 98 +++++++++++++++++--
1 file changed, 92 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..a7bc9dc93ce0 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt.c
@@ -5,6 +5,10 @@
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,
@@ -273,10 +277,30 @@ 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),
This is an interesting test case. One more question just came to my mind,
does it make sense to also ignore the bpf-prog's 'ctx->retval = 0' in getsockopt
considering its optval change has already been ignored. Something like:
if (optval && (ctx.optlen > max_optlen || ctx.optlen < 0)) {
if (orig_optlen > PAGE_SIZE && ctx.optlen >= 0) {
pr_info_once("bpf getsockopt: ignoring program buffer with optlen=%d
(max_optlen=%d)\n",
ctx.optlen, max_optlen);
ret = retval;
goto out;
}
ret = -EFAULT;
goto out;
}
BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
offsetof(struct bpf_sockopt, retval)),
@@ -287,9 +311,10 @@ 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 = PAGE_SIZE + 1,
}
+ 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");
