Re: [PATCH bpf-next v3 2/4] selftests/bpf: Update EFAULT {g,s}etsockopt selftests

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 5/2/23 5:29 PM, Martin KaFai Lau wrote:
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;
         }

Previous one has indentation off. Meaning to be:

	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");





[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux