[RFC bpf-next v1 8/8] selftests/bpf: test no_caller_saved_registers spill/fill removal

Eduard Zingerman
2024-06-29T09:48:14Z

Tests for no_caller_saved_registers processing logic
(see verifier.c:match_and_mark_nocsr_pattern()):
- a canary positive test case;
- various tests with broken patterns;
- tests with read/write fixed/varying stack access that violate nocsr
stack access contract;
- tests with multiple subprograms.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
.../selftests/bpf/prog_tests/verifier.c | 7 +
.../selftests/bpf/progs/verifier_nocsr.c | 437 ++++++++++++++++++
2 files changed, 444 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/verifier_nocsr.c

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index 6816ff064516..8e056c36c549 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -53,6 +53,7 @@
#include "verifier_movsx.skel.h"
#include "verifier_netfilter_ctx.skel.h"
#include "verifier_netfilter_retcode.skel.h"
+#include "verifier_nocsr.skel.h"
#include "verifier_precision.skel.h"
#include "verifier_prevent_map_lookup.skel.h"
#include "verifier_raw_stack.skel.h"
@@ -171,6 +172,12 @@ void test_verifier_meta_access(void) { RUN(verifier_meta_access); }
void test_verifier_movsx(void) { RUN(verifier_movsx); }
void test_verifier_netfilter_ctx(void) { RUN(verifier_netfilter_ctx); }
void test_verifier_netfilter_retcode(void) { RUN(verifier_netfilter_retcode); }
+void test_verifier_nocsr(void)
+{
+#if defined(__x86_64__)
+ RUN(verifier_nocsr);
+#endif /* __x86_64__ */
+}
void test_verifier_precision(void) { RUN(verifier_precision); }
void test_verifier_prevent_map_lookup(void) { RUN(verifier_prevent_map_lookup); }
void test_verifier_raw_stack(void) { RUN(verifier_raw_stack); }
diff --git a/tools/testing/selftests/bpf/progs/verifier_nocsr.c b/tools/testing/selftests/bpf/progs/verifier_nocsr.c
new file mode 100644
index 000000000000..5ddc2c97ada6
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_nocsr.c
@@ -0,0 +1,437 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+#define __xlated_bpf_get_smp_processor_id \
+ __xlated(": w0 = ") \
+ __xlated(": r0 = &(void __percpu *)(r0)") \
+ __xlated(": r0 = *(u32 *)(r0 +0)")
+
+SEC("raw_tp")
+__xlated("4: r5 = 5")
+__xlated_bpf_get_smp_processor_id
+__xlated("8: exit")
+__success
+__naked void simple(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "r2 = 2;"
+ "r3 = 3;"
+ "r4 = 4;"
+ "r5 = 5;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "*(u64 *)(r10 - 24) = r2;"
+ "*(u64 *)(r10 - 32) = r3;"
+ "*(u64 *)(r10 - 40) = r4;"
+ "*(u64 *)(r10 - 48) = r5;"
+ "call %[bpf_get_smp_processor_id];"
+ "r5 = *(u64 *)(r10 - 48);"
+ "r4 = *(u64 *)(r10 - 40);"
+ "r3 = *(u64 *)(r10 - 32);"
+ "r2 = *(u64 *)(r10 - 24);"
+ "r1 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r2 = *(u64 *)(r10 -16)")
+__success
+__naked void wrong_reg_in_pattern1(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r2 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -16) = r6")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r6 = *(u64 *)(r10 -16)")
+__success
+__naked void wrong_reg_in_pattern2(void)
+{
+ asm volatile (
+ "r6 = 1;"
+ "*(u64 *)(r10 - 16) = r6;"
+ "call %[bpf_get_smp_processor_id];"
+ "r6 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -16) = r0")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r0 = *(u64 *)(r10 -16)")
+__success
+__naked void wrong_reg_in_pattern3(void)
+{
+ asm volatile (
+ "r0 = 1;"
+ "*(u64 *)(r10 - 16) = r0;"
+ "call %[bpf_get_smp_processor_id];"
+ "r0 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("2: *(u64 *)(r2 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("6: r1 = *(u64 *)(r10 -16)")
+__success
+__naked void wrong_base_in_pattern(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "r2 = r10;"
+ "*(u64 *)(r2 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r2 = 1")
+__success
+__naked void wrong_insn_in_pattern(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r2 = 1;"
+ "r1 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("2: *(u64 *)(r10 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("6: r1 = *(u64 *)(r10 -8)")
+__success
+__naked void wrong_off_in_pattern(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 8) = r1;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 8);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u32 *)(r10 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r1 = *(u32 *)(r10 -16)")
+__success
+__naked void wrong_size_in_pattern(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u32 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u32 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("2: *(u32 *)(r10 -8) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("6: r1 = *(u32 *)(r10 -8)")
+__success
+__naked void partial_pattern(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "r2 = 2;"
+ "*(u32 *)(r10 - 8) = r1;"
+ "*(u64 *)(r10 - 16) = r2;"
+ "call %[bpf_get_smp_processor_id];"
+ "r2 = *(u64 *)(r10 - 16);"
+ "r1 = *(u32 *)(r10 - 8);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("0: r1 = 1")
+__xlated("1: r2 = 2")
+/* not patched, spills for -8, -16 not removed */
+__xlated("2: *(u64 *)(r10 -8) = r1")
+__xlated("3: *(u64 *)(r10 -16) = r2")
+__xlated_bpf_get_smp_processor_id
+__xlated("7: r2 = *(u64 *)(r10 -16)")
+__xlated("8: r1 = *(u64 *)(r10 -8)")
+/* patched, spills for -16, -24 removed */
+__xlated_bpf_get_smp_processor_id
+__xlated("12: exit")
+__success
+__naked void min_stack_offset(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "r2 = 2;"
+ /* this call won't be patched */
+ "*(u64 *)(r10 - 8) = r1;"
+ "*(u64 *)(r10 - 16) = r2;"
+ "call %[bpf_get_smp_processor_id];"
+ "r2 = *(u64 *)(r10 - 16);"
+ "r1 = *(u64 *)(r10 - 8);"
+ /* this call would be patched */
+ "*(u64 *)(r10 - 16) = r1;"
+ "*(u64 *)(r10 - 24) = r2;"
+ "call %[bpf_get_smp_processor_id];"
+ "r2 = *(u64 *)(r10 - 24);"
+ "r1 = *(u64 *)(r10 - 16);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -8) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r1 = *(u64 *)(r10 -8)")
+__success
+__naked void bad_fixed_read(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 8) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 8);"
+ "r1 = r10;"
+ "r1 += -8;"
+ "r1 = *(u64 *)(r1 - 0);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -8) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r1 = *(u64 *)(r10 -8)")
+__success
+__naked void bad_fixed_write(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 8) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 8);"
+ "r1 = r10;"
+ "r1 += -8;"
+ "*(u64 *)(r1 - 0) = r1;"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("6: *(u64 *)(r10 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("10: r1 = *(u64 *)(r10 -16)")
+__success
+__naked void bad_varying_read(void)
+{
+ asm volatile (
+ "r6 = *(u64 *)(r1 + 0);" /* random scalar value */
+ "r6 &= 0x7;" /* r6 range [0..7] */
+ "r6 += 0x2;" /* r6 range [2..9] */
+ "r7 = 0;"
+ "r7 -= r6;" /* r7 range [-9..-2] */
+ "r1 = 1;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 16);"
+ "r1 = r10;"
+ "r1 += r7;"
+ "r1 = *(u8 *)(r1 - 0);" /* touches slot [-16..-9] where spills are stored */
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("6: *(u64 *)(r10 -16) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("10: r1 = *(u64 *)(r10 -16)")
+__success
+__naked void bad_varying_write(void)
+{
+ asm volatile (
+ "r6 = *(u64 *)(r1 + 0);" /* random scalar value */
+ "r6 &= 0x7;" /* r6 range [0..7] */
+ "r6 += 0x2;" /* r6 range [2..9] */
+ "r7 = 0;"
+ "r7 -= r6;" /* r7 range [-9..-2] */
+ "r1 = 1;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 16);"
+ "r1 = r10;"
+ "r1 += r7;"
+ "*(u8 *)(r1 - 0) = r7;" /* touches slot [-16..-9] where spills are stored */
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+__xlated("1: *(u64 *)(r10 -8) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r1 = *(u64 *)(r10 -8)")
+__success
+__naked void bad_write_in_subprog(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 8) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 8);"
+ "r1 = r10;"
+ "r1 += -8;"
+ "call bad_write_in_subprog_aux;"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+__used
+__naked static void bad_write_in_subprog_aux(void)
+{
+ asm volatile (
+ "r0 = 1;"
+ "*(u64 *)(r1 - 0) = r0;" /* invalidates nocsr contract for caller: */
+ "exit;" /* caller stack at -8 used outside of the pattern */
+ ::: __clobber_all);
+}
+
+SEC("raw_tp")
+/* main, not patched */
+__xlated("1: *(u64 *)(r10 -8) = r1")
+__xlated_bpf_get_smp_processor_id
+__xlated("5: r1 = *(u64 *)(r10 -8)")
+__xlated("9: call pc+1")
+__xlated("10: exit")
+/* subprogram, patched */
+__xlated("11: r1 = 1")
+__xlated_bpf_get_smp_processor_id
+__xlated("15: exit")
+__success
+__naked void invalidate_one_subprog(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 8) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 8);"
+ "r1 = r10;"
+ "r1 += -8;"
+ "r1 = *(u64 *)(r1 - 0);"
+ "call invalidate_one_subprog_aux;"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+__used
+__naked static void invalidate_one_subprog_aux(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 8) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 8);"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+SEC("raw_tp")
+/* main */
+__xlated("0: r1 = 1")
+__xlated_bpf_get_smp_processor_id
+__xlated("4: call pc+1")
+__xlated("5: exit")
+/* subprogram */
+__xlated("6: r1 = 1")
+__xlated_bpf_get_smp_processor_id
+__xlated("10: *(u64 *)(r10 -16) = r1")
+__xlated("11: exit")
+__success
+__naked void subprogs_use_independent_offsets(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 16) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 16);"
+ "call subprogs_use_independent_offsets_aux;"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+__used
+__naked static void subprogs_use_independent_offsets_aux(void)
+{
+ asm volatile (
+ "r1 = 1;"
+ "*(u64 *)(r10 - 24) = r1;"
+ "call %[bpf_get_smp_processor_id];"
+ "r1 = *(u64 *)(r10 - 24);"
+ "*(u64 *)(r10 - 16) = r1;"
+ "exit;"
+ :
+ : __imm(bpf_get_smp_processor_id)
+ : __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";
--
2.45.2