Commit dec02028 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Andrii Nakryiko
Browse files

selftests/bpf: Check if mark_chain_precision() follows scalar ids 



Check __mark_chain_precision() log to verify that scalars with same
IDs are marked as precise. Use several scenarios to test that
precision marks are propagated through:
- registers of scalar type with the same ID within one state;
- registers of scalar type with the same ID cross several states;
- registers of scalar type  with the same ID cross several stack frames;
- stack slot of scalar type with the same ID;
- multiple scalar IDs are tracked independently.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230613153824.3324830-3-eddyz87@gmail.com
parent 904e6ddf

tools/testing/selftests/bpf/prog_tests/verifier.c

+2 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ 
#include "verifier_regalloc.skel.h"

#include "verifier_ringbuf.skel.h"

#include "verifier_runtime_jit.skel.h"

#include "verifier_scalar_ids.skel.h"

#include "verifier_search_pruning.skel.h"

#include "verifier_sock.skel.h"

#include "verifier_spill_fill.skel.h"
@@ -150,6 +151,7 @@ void test_verifier_ref_tracking(void) { RUN(verifier_ref_tracking); } 
void test_verifier_regalloc(void)             { RUN(verifier_regalloc); }

void test_verifier_ringbuf(void)              { RUN(verifier_ringbuf); }

void test_verifier_runtime_jit(void)          { RUN(verifier_runtime_jit); }

void test_verifier_scalar_ids(void)           { RUN(verifier_scalar_ids); }

void test_verifier_search_pruning(void)       { RUN(verifier_search_pruning); }

void test_verifier_sock(void)                 { RUN(verifier_sock); }

void test_verifier_spill_fill(void)           { RUN(verifier_spill_fill); }

tools/testing/selftests/bpf/progs/verifier_scalar_ids.c

0 → 100644
+344 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"



/* Check that precision marks propagate through scalar IDs.

 * Registers r{0,1,2} have the same scalar ID at the moment when r0 is

 * marked to be precise, this mark is immediately propagated to r{1,2}.

 */

SEC("socket")

__success __log_level(2)

__msg("frame0: regs=r0,r1,r2 stack= before 4: (bf) r3 = r10")

__msg("frame0: regs=r0,r1,r2 stack= before 3: (bf) r2 = r0")

__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")

__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")

__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_same_state(void)

{

	asm volatile (

	/* r0 = random number up to 0xff */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	/* tie r0.id == r1.id == r2.id */

	"r1 = r0;"

	"r2 = r0;"

	/* force r0 to be precise, this immediately marks r1 and r2 as

	 * precise as well because of shared IDs

	 */

	"r3 = r10;"

	"r3 += r0;"

	"r0 = 0;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



/* Same as precision_same_state, but mark propagates through state /

 * parent state boundary.

 */

SEC("socket")

__success __log_level(2)

__msg("frame0: last_idx 6 first_idx 5 subseq_idx -1")

__msg("frame0: regs=r0,r1,r2 stack= before 5: (bf) r3 = r10")

__msg("frame0: parent state regs=r0,r1,r2 stack=:")

__msg("frame0: regs=r0,r1,r2 stack= before 4: (05) goto pc+0")

__msg("frame0: regs=r0,r1,r2 stack= before 3: (bf) r2 = r0")

__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")

__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")

__msg("frame0: parent state regs=r0 stack=:")

__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_cross_state(void)

{

	asm volatile (

	/* r0 = random number up to 0xff */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	/* tie r0.id == r1.id == r2.id */

	"r1 = r0;"

	"r2 = r0;"

	/* force checkpoint */

	"goto +0;"

	/* force r0 to be precise, this immediately marks r1 and r2 as

	 * precise as well because of shared IDs

	 */

	"r3 = r10;"

	"r3 += r0;"

	"r0 = 0;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



/* Same as precision_same_state, but break one of the

 * links, note that r1 is absent from regs=... in __msg below.

 */

SEC("socket")

__success __log_level(2)

__msg("frame0: regs=r0,r2 stack= before 5: (bf) r3 = r10")

__msg("frame0: regs=r0,r2 stack= before 4: (b7) r1 = 0")

__msg("frame0: regs=r0,r2 stack= before 3: (bf) r2 = r0")

__msg("frame0: regs=r0 stack= before 2: (bf) r1 = r0")

__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")

__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_same_state_broken_link(void)

{

	asm volatile (

	/* r0 = random number up to 0xff */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	/* tie r0.id == r1.id == r2.id */

	"r1 = r0;"

	"r2 = r0;"

	/* break link for r1, this is the only line that differs

	 * compared to the previous test

	 */

	"r1 = 0;"

	/* force r0 to be precise, this immediately marks r1 and r2 as

	 * precise as well because of shared IDs

	 */

	"r3 = r10;"

	"r3 += r0;"

	"r0 = 0;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



/* Same as precision_same_state_broken_link, but with state /

 * parent state boundary.

 */

SEC("socket")

__success __log_level(2)

__msg("frame0: regs=r0,r2 stack= before 6: (bf) r3 = r10")

__msg("frame0: regs=r0,r2 stack= before 5: (b7) r1 = 0")

__msg("frame0: parent state regs=r0,r2 stack=:")

__msg("frame0: regs=r0,r1,r2 stack= before 4: (05) goto pc+0")

__msg("frame0: regs=r0,r1,r2 stack= before 3: (bf) r2 = r0")

__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")

__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")

__msg("frame0: parent state regs=r0 stack=:")

__msg("frame0: regs=r0 stack= before 0: (85) call bpf_ktime_get_ns")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_cross_state_broken_link(void)

{

	asm volatile (

	/* r0 = random number up to 0xff */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	/* tie r0.id == r1.id == r2.id */

	"r1 = r0;"

	"r2 = r0;"

	/* force checkpoint, although link between r1 and r{0,2} is

	 * broken by the next statement current precision tracking

	 * algorithm can't react to it and propagates mark for r1 to

	 * the parent state.

	 */

	"goto +0;"

	/* break link for r1, this is the only line that differs

	 * compared to precision_cross_state()

	 */

	"r1 = 0;"

	/* force r0 to be precise, this immediately marks r1 and r2 as

	 * precise as well because of shared IDs

	 */

	"r3 = r10;"

	"r3 += r0;"

	"r0 = 0;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



/* Check that precision marks propagate through scalar IDs.

 * Use the same scalar ID in multiple stack frames, check that

 * precision information is propagated up the call stack.

 */

SEC("socket")

__success __log_level(2)

__msg("11: (0f) r2 += r1")

/* Current state */

__msg("frame2: last_idx 11 first_idx 10 subseq_idx -1")

__msg("frame2: regs=r1 stack= before 10: (bf) r2 = r10")

__msg("frame2: parent state regs=r1 stack=")

/* frame1.r{6,7} are marked because mark_precise_scalar_ids()

 * looks for all registers with frame2.r1.id in the current state

 */

__msg("frame1: parent state regs=r6,r7 stack=")

__msg("frame0: parent state regs=r6 stack=")

/* Parent state */

__msg("frame2: last_idx 8 first_idx 8 subseq_idx 10")

__msg("frame2: regs=r1 stack= before 8: (85) call pc+1")

/* frame1.r1 is marked because of backtracking of call instruction */

__msg("frame1: parent state regs=r1,r6,r7 stack=")

__msg("frame0: parent state regs=r6 stack=")

/* Parent state */

__msg("frame1: last_idx 7 first_idx 6 subseq_idx 8")

__msg("frame1: regs=r1,r6,r7 stack= before 7: (bf) r7 = r1")

__msg("frame1: regs=r1,r6 stack= before 6: (bf) r6 = r1")

__msg("frame1: parent state regs=r1 stack=")

__msg("frame0: parent state regs=r6 stack=")

/* Parent state */

__msg("frame1: last_idx 4 first_idx 4 subseq_idx 6")

__msg("frame1: regs=r1 stack= before 4: (85) call pc+1")

__msg("frame0: parent state regs=r1,r6 stack=")

/* Parent state */

__msg("frame0: last_idx 3 first_idx 1 subseq_idx 4")

__msg("frame0: regs=r0,r1,r6 stack= before 3: (bf) r6 = r0")

__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")

__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_many_frames(void)

{

	asm volatile (

	/* r0 = random number up to 0xff */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	/* tie r0.id == r1.id == r6.id */

	"r1 = r0;"

	"r6 = r0;"

	"call precision_many_frames__foo;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



static __naked __noinline __used

void precision_many_frames__foo(void)

{

	asm volatile (

	/* conflate one of the register numbers (r6) with outer frame,

	 * to verify that those are tracked independently

	 */

	"r6 = r1;"

	"r7 = r1;"

	"call precision_many_frames__bar;"

	"exit"

	::: __clobber_all);

}



static __naked __noinline __used

void precision_many_frames__bar(void)

{

	asm volatile (

	/* force r1 to be precise, this immediately marks:

	 * - bar frame r1

	 * - foo frame r{1,6,7}

	 * - main frame r{1,6}

	 */

	"r2 = r10;"

	"r2 += r1;"

	"r0 = 0;"

	"exit;"

	::: __clobber_all);

}



/* Check that scalars with the same IDs are marked precise on stack as

 * well as in registers.

 */

SEC("socket")

__success __log_level(2)

/* foo frame */

__msg("frame1: regs=r1 stack=-8,-16 before 9: (bf) r2 = r10")

__msg("frame1: regs=r1 stack=-8,-16 before 8: (7b) *(u64 *)(r10 -16) = r1")

__msg("frame1: regs=r1 stack=-8 before 7: (7b) *(u64 *)(r10 -8) = r1")

__msg("frame1: regs=r1 stack= before 4: (85) call pc+2")

/* main frame */

__msg("frame0: regs=r0,r1 stack=-8 before 3: (7b) *(u64 *)(r10 -8) = r1")

__msg("frame0: regs=r0,r1 stack= before 2: (bf) r1 = r0")

__msg("frame0: regs=r0 stack= before 1: (57) r0 &= 255")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_stack(void)

{

	asm volatile (

	/* r0 = random number up to 0xff */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	/* tie r0.id == r1.id == fp[-8].id */

	"r1 = r0;"

	"*(u64*)(r10 - 8) = r1;"

	"call precision_stack__foo;"

	"r0 = 0;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



static __naked __noinline __used

void precision_stack__foo(void)

{

	asm volatile (

	/* conflate one of the register numbers (r6) with outer frame,

	 * to verify that those are tracked independently

	 */

	"*(u64*)(r10 - 8) = r1;"

	"*(u64*)(r10 - 16) = r1;"

	/* force r1 to be precise, this immediately marks:

	 * - foo frame r1,fp{-8,-16}

	 * - main frame r1,fp{-8}

	 */

	"r2 = r10;"

	"r2 += r1;"

	"exit"

	::: __clobber_all);

}



/* Use two separate scalar IDs to check that these are propagated

 * independently.

 */

SEC("socket")

__success __log_level(2)

/* r{6,7} */

__msg("11: (0f) r3 += r7")

__msg("frame0: regs=r6,r7 stack= before 10: (bf) r3 = r10")

/* ... skip some insns ... */

__msg("frame0: regs=r6,r7 stack= before 3: (bf) r7 = r0")

__msg("frame0: regs=r0,r6 stack= before 2: (bf) r6 = r0")

/* r{8,9} */

__msg("12: (0f) r3 += r9")

__msg("frame0: regs=r8,r9 stack= before 11: (0f) r3 += r7")

/* ... skip some insns ... */

__msg("frame0: regs=r8,r9 stack= before 7: (bf) r9 = r0")

__msg("frame0: regs=r0,r8 stack= before 6: (bf) r8 = r0")

__flag(BPF_F_TEST_STATE_FREQ)

__naked void precision_two_ids(void)

{

	asm volatile (

	/* r6 = random number up to 0xff

	 * r6.id == r7.id

	 */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	"r6 = r0;"

	"r7 = r0;"

	/* same, but for r{8,9} */

	"call %[bpf_ktime_get_ns];"

	"r0 &= 0xff;"

	"r8 = r0;"

	"r9 = r0;"

	/* clear r0 id */

	"r0 = 0;"

	/* force checkpoint */

	"goto +0;"

	"r3 = r10;"

	/* force r7 to be precise, this also marks r6 */

	"r3 += r7;"

	/* force r9 to be precise, this also marks r8 */

	"r3 += r9;"

	"exit;"

	:

	: __imm(bpf_ktime_get_ns)

	: __clobber_all);

}



char _license[] SEC("license") = "GPL";