Add the following tests:
1. A test with an (unimportant) ldimm64 (16 byte insn) and a Spectre-v4--induced nospec that clarifies and serves as a basic Spectre v4 test.
2. Make sure a Spectre v4 nospec_result does not prevent a Spectre v1 nospec from being added before the dangerous instruction (tests that [1] is fixed).
3. Combine the two, which is the combination that triggers the warning in [2]. This is because the unanalyzed stack write has nospec_result set, but the ldimm64 (which was just analyzed) had incremented insn_idx by 2. That violates the assertion that nospec_result is only used after insns that increment insn_idx by 1 (i.e., stack writes).
[1] https://lore.kernel.org/bpf/4266fd5de04092aa4971cbef14f1b4b96961f432.camel@g... [2] https://lore.kernel.org/bpf/685b3c1b.050a0220.2303ee.0010.GAE@google.com/
Signed-off-by: Luis Gerhorst luis.gerhorst@fau.de --- tools/testing/selftests/bpf/progs/bpf_misc.h | 4 + .../selftests/bpf/progs/verifier_unpriv.c | 149 ++++++++++++++++++ 2 files changed, 153 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h index 20dce508d8e0..530752ddde8e 100644 --- a/tools/testing/selftests/bpf/progs/bpf_misc.h +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h @@ -237,4 +237,8 @@ #define SPEC_V1 #endif
+#if defined(__TARGET_ARCH_x86) +#define SPEC_V4 +#endif + #endif diff --git a/tools/testing/selftests/bpf/progs/verifier_unpriv.c b/tools/testing/selftests/bpf/progs/verifier_unpriv.c index 4470541b5e71..28b4f7035ceb 100644 --- a/tools/testing/selftests/bpf/progs/verifier_unpriv.c +++ b/tools/testing/selftests/bpf/progs/verifier_unpriv.c @@ -801,4 +801,153 @@ l2_%=: \ : __clobber_all); }
+SEC("socket") +__description("unpriv: ldimm64 before Spectre v4 barrier") +__success __success_unpriv +__retval(0) +#ifdef SPEC_V4 +__xlated_unpriv("r1 = 0x2020200005642020") /* should not matter */ +__xlated_unpriv("*(u64 *)(r10 -8) = r1") +__xlated_unpriv("nospec") +#endif +__naked void unpriv_ldimm64_spectre_v4(void) +{ + asm volatile (" \ + r1 = 0x2020200005642020 ll; \ + *(u64 *)(r10 -8) = r1; \ + r0 = 0; \ + exit; \ +" ::: __clobber_all); +} + +SEC("socket") +__description("unpriv: Spectre v1 and v4 barrier") +__success __success_unpriv +__retval(0) +#ifdef SPEC_V1 +#ifdef SPEC_V4 +/* starts with r0 == r8 == r9 == 0 */ +__xlated_unpriv("if r8 != 0x0 goto pc+1") +__xlated_unpriv("goto pc+2") +__xlated_unpriv("if r9 == 0x0 goto pc+4") +__xlated_unpriv("r2 = r0") +/* Following nospec required to prevent following dangerous `*(u64 *)(NOT_FP -64) + * = r1` iff `if r9 == 0 goto pc+4` was mispredicted because of Spectre v1. The + * test therefore ensures the Spectre-v4--induced nospec does not prevent the + * Spectre-v1--induced speculative path from being fully analyzed. + */ +__xlated_unpriv("nospec") /* Spectre v1 */ +__xlated_unpriv("*(u64 *)(r2 -64) = r1") /* could be used to leak r2 */ +__xlated_unpriv("nospec") /* Spectre v4 */ +#endif +#endif +__naked void unpriv_spectre_v1_and_v4(void) +{ + asm volatile (" \ + r1 = 0; \ + *(u64*)(r10 - 8) = r1; \ + r2 = r10; \ + r2 += -8; \ + r1 = %[map_hash_8b] ll; \ + call %[bpf_map_lookup_elem]; \ + r8 = r0; \ + r2 = r10; \ + r2 += -8; \ + r1 = %[map_hash_8b] ll; \ + call %[bpf_map_lookup_elem]; \ + r9 = r0; \ + r0 = r10; \ + r1 = 0; \ + r2 = r10; \ + if r8 != 0 goto l0_%=; \ + if r9 != 0 goto l0_%=; \ + r0 = 0; \ +l0_%=: if r8 != 0 goto l1_%=; \ + goto l2_%=; \ +l1_%=: if r9 == 0 goto l3_%=; \ + r2 = r0; \ +l2_%=: *(u64 *)(r2 -64) = r1; \ +l3_%=: r0 = 0; \ + exit; \ +" : + : __imm(bpf_map_lookup_elem), + __imm_addr(map_hash_8b) + : __clobber_all); +} + +SEC("socket") +__description("unpriv: Spectre v1 and v4 barrier (simple)") +__success __success_unpriv +__retval(0) +#ifdef SPEC_V1 +#ifdef SPEC_V4 +__xlated_unpriv("if r8 != 0x0 goto pc+1") +__xlated_unpriv("goto pc+2") +__xlated_unpriv("goto pc-1") /* if r9 == 0 goto l3_%= */ +__xlated_unpriv("goto pc-1") /* r2 = r0 */ +__xlated_unpriv("nospec") +__xlated_unpriv("*(u64 *)(r2 -64) = r1") +__xlated_unpriv("nospec") +#endif +#endif +__naked void unpriv_spectre_v1_and_v4_simple(void) +{ + asm volatile (" \ + r8 = 0; \ + r9 = 0; \ + r0 = r10; \ + r1 = 0; \ + r2 = r10; \ + if r8 != 0 goto l0_%=; \ + if r9 != 0 goto l0_%=; \ + r0 = 0; \ +l0_%=: if r8 != 0 goto l1_%=; \ + goto l2_%=; \ +l1_%=: if r9 == 0 goto l3_%=; \ + r2 = r0; \ +l2_%=: *(u64 *)(r2 -64) = r1; \ +l3_%=: r0 = 0; \ + exit; \ +" ::: __clobber_all); +} + +SEC("socket") +__description("unpriv: ldimm64 before Spectre v1 and v4 barrier (simple)") +__success __success_unpriv +__retval(0) +#ifdef SPEC_V1 +#ifdef SPEC_V4 +__xlated_unpriv("if r8 != 0x0 goto pc+1") +__xlated_unpriv("goto pc+4") +__xlated_unpriv("goto pc-1") /* if r9 == 0 goto l3_%= */ +__xlated_unpriv("goto pc-1") /* r2 = r0 */ +__xlated_unpriv("goto pc-1") /* r1 = 0x2020200005642020 ll */ +__xlated_unpriv("goto pc-1") /* second part of ldimm64 */ +__xlated_unpriv("nospec") +__xlated_unpriv("*(u64 *)(r2 -64) = r1") +__xlated_unpriv("nospec") +#endif +#endif +__naked void unpriv_ldimm64_spectre_v1_and_v4_simple(void) +{ + asm volatile (" \ + r8 = 0; \ + r9 = 0; \ + r0 = r10; \ + r1 = 0; \ + r2 = r10; \ + if r8 != 0 goto l0_%=; \ + if r9 != 0 goto l0_%=; \ + r0 = 0; \ +l0_%=: if r8 != 0 goto l1_%=; \ + goto l2_%=; \ +l1_%=: if r9 == 0 goto l3_%=; \ + r2 = r0; \ + r1 = 0x2020200005642020 ll; \ +l2_%=: *(u64 *)(r2 -64) = r1; \ +l3_%=: r0 = 0; \ + exit; \ +" ::: __clobber_all); +} + char _license[] SEC("license") = "GPL";