bpf: fix selftests/bpf test_kmod.sh failure when CONFIG_BPF_JIT_ALWAYS_ON=y

With CONFIG_BPF_JIT_ALWAYS_ON is defined in the config file,
tools/testing/selftests/bpf/test_kmod.sh failed like below:
  [root@localhost bpf]# ./test_kmod.sh
  sysctl: setting key "net.core.bpf_jit_enable": Invalid argument
  [ JIT enabled:0 hardened:0 ]
  [  132.175681] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096
  [  132.458834] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed]
  [ JIT enabled:1 hardened:0 ]
  [  133.456025] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096
  [  133.730935] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed]
  [ JIT enabled:1 hardened:1 ]
  [  134.769730] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096
  [  135.050864] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed]
  [ JIT enabled:1 hardened:2 ]
  [  136.442882] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096
  [  136.821810] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed]
  [root@localhost bpf]#

The test_kmod.sh load/remove test_bpf.ko multiple times with different
settings for sysctl net.core.bpf_jit_{enable,harden}. The failed test #297
of test_bpf.ko is designed such that JIT always fails.

Commit 290af86629b2 (bpf: introduce BPF_JIT_ALWAYS_ON config)
introduced the following tightening logic:
    ...
        if (!bpf_prog_is_dev_bound(fp->aux)) {
                fp = bpf_int_jit_compile(fp);
    #ifdef CONFIG_BPF_JIT_ALWAYS_ON
                if (!fp->jited) {
                        *err = -ENOTSUPP;
                        return fp;
                }
    #endif
    ...
With this logic, Test #297 always gets return value -ENOTSUPP
when CONFIG_BPF_JIT_ALWAYS_ON is defined, causing the test failure.

This patch fixed the failure by marking Test #297 as expected failure
when CONFIG_BPF_JIT_ALWAYS_ON is defined.

Fixes: 290af86629b2 (bpf: introduce BPF_JIT_ALWAYS_ON config)
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 26 insertions, 5 deletions

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 4cd9ea9b3449..b4e22345963f 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -83,6 +83,7 @@ struct bpf_test {
                 __u32 result;
         } test[MAX_SUBTESTS];
         int (*fill_helper)(struct bpf_test *self);
+        int expected_errcode; /* used when FLAG_EXPECTED_FAIL is set in the aux */
         __u8 frag_data[MAX_DATA];
         int stack_depth; /* for eBPF only, since tests don't call verifier */
 };
@@ -2026,7 +2027,9 @@ static struct bpf_test tests[] = {
                 },
                 CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
                 { },
-                { }
+                { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {
                 "check: div_k_0",
@@ -2036,7 +2039,9 @@ static struct bpf_test tests[] = {
                 },
                 CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
                 { },
-                { }
+                { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {
                 "check: unknown insn",
@@ -2047,7 +2052,9 @@ static struct bpf_test tests[] = {
                 },
                 CLASSIC | FLAG_EXPECTED_FAIL,
                 { },
-                { }
+                { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {
                 "check: out of range spill/fill",
@@ -2057,7 +2064,9 @@ static struct bpf_test tests[] = {
                 },
                 CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
                 { },
-                { }
+                { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {
                 "JUMPS + HOLES",
@@ -2149,6 +2158,8 @@ static struct bpf_test tests[] = {
                 CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
                 { },
                 { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {
                 "check: LDX + RET X",
@@ -2159,6 +2170,8 @@ static struct bpf_test tests[] = {
                 CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
                 { },
                 { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {       /* Mainly checking JIT here. */
                 "M[]: alt STX + LDX",
@@ -2333,6 +2346,8 @@ static struct bpf_test tests[] = {
                 CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
                 { },
                 { },
+                .fill_helper = NULL,
+                .expected_errcode = -EINVAL,
         },
         {       /* Passes checker but fails during runtime. */
                 "LD [SKF_AD_OFF-1]",
@@ -5395,6 +5410,7 @@ static struct bpf_test tests[] = {
                 { },
                 { },
                 .fill_helper = bpf_fill_maxinsns4,
+                .expected_errcode = -EINVAL,
         },
         {       /* Mainly checking JIT here. */
                 "BPF_MAXINSNS: Very long jump",
@@ -5450,10 +5466,15 @@ static struct bpf_test tests[] = {
         {
                 "BPF_MAXINSNS: Jump, gap, jump, ...",
                 { },
+#ifdef CONFIG_BPF_JIT_ALWAYS_ON
+                CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
+#else
                 CLASSIC | FLAG_NO_DATA,
+#endif
                 { },
                 { { 0, 0xababcbac } },
                 .fill_helper = bpf_fill_maxinsns11,
+                .expected_errcode = -ENOTSUPP,
         },
         {
                 "BPF_MAXINSNS: ld_abs+get_processor_id",
@@ -6344,7 +6365,7 @@ static struct bpf_prog *generate_filter(int which, int *err)
 
                 *err = bpf_prog_create(&fp, &fprog);
                 if (tests[which].aux & FLAG_EXPECTED_FAIL) {
-                        if (*err == -EINVAL) {
+                        if (*err == tests[which].expected_errcode) {
                                 pr_cont("PASS\n");
                                 /* Verifier rejected filter as expected. */
                                 *err = 0;