Commit a5828e31 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

selftests/bpf: verifier/jeq_infer_not_null converted to inline assembly 



Test verifier/jeq_infer_not_null automatically converted to use inline assembly.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230421174234.2391278-9-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0a372c9c

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

+2 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include "verifier_helper_restricted.skel.h"

#include "verifier_helper_value_access.skel.h"

#include "verifier_int_ptr.skel.h"

#include "verifier_jeq_infer_not_null.skel.h"

#include "verifier_ld_ind.skel.h"

#include "verifier_leak_ptr.skel.h"

#include "verifier_map_ptr.skel.h"
@@ -111,6 +112,7 @@ void test_verifier_helper_packet_access(void) { RUN(verifier_helper_packet_acces 
void test_verifier_helper_restricted(void)    { RUN(verifier_helper_restricted); }

void test_verifier_helper_value_access(void)  { RUN(verifier_helper_value_access); }

void test_verifier_int_ptr(void)              { RUN(verifier_int_ptr); }

void test_verifier_jeq_infer_not_null(void)   { RUN(verifier_jeq_infer_not_null); }

void test_verifier_ld_ind(void)               { RUN(verifier_ld_ind); }

void test_verifier_leak_ptr(void)             { RUN(verifier_leak_ptr); }

void test_verifier_map_ptr(void)              { RUN(verifier_map_ptr); }

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

0 → 100644
+213 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Converted from tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c */



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"



struct {

	__uint(type, BPF_MAP_TYPE_XSKMAP);

	__uint(max_entries, 1);

	__type(key, int);

	__type(value, int);

} map_xskmap SEC(".maps");



/* This is equivalent to the following program:

 *

 *   r6 = skb->sk;

 *   r7 = sk_fullsock(r6);

 *   r0 = sk_fullsock(r6);

 *   if (r0 == 0) return 0;    (a)

 *   if (r0 != r7) return 0;   (b)

 *   *r7->type;                (c)

 *   return 0;

 *

 * It is safe to dereference r7 at point (c), because of (a) and (b).

 * The test verifies that relation r0 == r7 is propagated from (b) to (c).

 */

SEC("cgroup/skb")

__description("jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL -> PTR_TO_SOCKET for JNE false branch")

__success __failure_unpriv __msg_unpriv("R7 pointer comparison")

__retval(0)

__naked void socket_for_jne_false_branch(void)

{

	asm volatile ("					\

	/* r6 = skb->sk; */				\

	r6 = *(u64*)(r1 + %[__sk_buff_sk]);		\

	/* if (r6 == 0) return 0; */			\

	if r6 == 0 goto l0_%=;				\

	/* r7 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	r7 = r0;					\

	/* r0 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	/* if (r0 == null) return 0; */			\

	if r0 == 0 goto l0_%=;				\

	/* if (r0 == r7) r0 = *(r7->type); */		\

	if r0 != r7 goto l0_%=;		/* Use ! JNE ! */\

	r0 = *(u32*)(r7 + %[bpf_sock_type]);		\

l0_%=:	/* return 0 */					\

	r0 = 0;						\

	exit;						\

"	:

	: __imm(bpf_sk_fullsock),

	  __imm_const(__sk_buff_sk, offsetof(struct __sk_buff, sk)),

	  __imm_const(bpf_sock_type, offsetof(struct bpf_sock, type))

	: __clobber_all);

}



/* Same as above, but verify that another branch of JNE still

 * prohibits access to PTR_MAYBE_NULL.

 */

SEC("cgroup/skb")

__description("jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL unchanged for JNE true branch")

__failure __msg("R7 invalid mem access 'sock_or_null'")

__failure_unpriv __msg_unpriv("R7 pointer comparison")

__naked void unchanged_for_jne_true_branch(void)

{

	asm volatile ("					\

	/* r6 = skb->sk */				\

	r6 = *(u64*)(r1 + %[__sk_buff_sk]);		\

	/* if (r6 == 0) return 0; */			\

	if r6 == 0 goto l0_%=;				\

	/* r7 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	r7 = r0;					\

	/* r0 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	/* if (r0 == null) return 0; */			\

	if r0 != 0 goto l0_%=;				\

	/* if (r0 == r7) return 0; */			\

	if r0 != r7 goto l1_%=;		/* Use ! JNE ! */\

	goto l0_%=;					\

l1_%=:	/* r0 = *(r7->type); */				\

	r0 = *(u32*)(r7 + %[bpf_sock_type]);		\

l0_%=:	/* return 0 */					\

	r0 = 0;						\

	exit;						\

"	:

	: __imm(bpf_sk_fullsock),

	  __imm_const(__sk_buff_sk, offsetof(struct __sk_buff, sk)),

	  __imm_const(bpf_sock_type, offsetof(struct bpf_sock, type))

	: __clobber_all);

}



/* Same as a first test, but not null should be inferred for JEQ branch */

SEC("cgroup/skb")

__description("jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL -> PTR_TO_SOCKET for JEQ true branch")

__success __failure_unpriv __msg_unpriv("R7 pointer comparison")

__retval(0)

__naked void socket_for_jeq_true_branch(void)

{

	asm volatile ("					\

	/* r6 = skb->sk; */				\

	r6 = *(u64*)(r1 + %[__sk_buff_sk]);		\

	/* if (r6 == null) return 0; */			\

	if r6 == 0 goto l0_%=;				\

	/* r7 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	r7 = r0;					\

	/* r0 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	/* if (r0 == null) return 0; */			\

	if r0 == 0 goto l0_%=;				\

	/* if (r0 != r7) return 0; */			\

	if r0 == r7 goto l1_%=;		/* Use ! JEQ ! */\

	goto l0_%=;					\

l1_%=:	/* r0 = *(r7->type); */				\

	r0 = *(u32*)(r7 + %[bpf_sock_type]);		\

l0_%=:	/* return 0; */					\

	r0 = 0;						\

	exit;						\

"	:

	: __imm(bpf_sk_fullsock),

	  __imm_const(__sk_buff_sk, offsetof(struct __sk_buff, sk)),

	  __imm_const(bpf_sock_type, offsetof(struct bpf_sock, type))

	: __clobber_all);

}



/* Same as above, but verify that another branch of JNE still

 * prohibits access to PTR_MAYBE_NULL.

 */

SEC("cgroup/skb")

__description("jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL unchanged for JEQ false branch")

__failure __msg("R7 invalid mem access 'sock_or_null'")

__failure_unpriv __msg_unpriv("R7 pointer comparison")

__naked void unchanged_for_jeq_false_branch(void)

{

	asm volatile ("					\

	/* r6 = skb->sk; */				\

	r6 = *(u64*)(r1 + %[__sk_buff_sk]);		\

	/* if (r6 == null) return 0; */			\

	if r6 == 0 goto l0_%=;				\

	/* r7 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	r7 = r0;					\

	/* r0 = sk_fullsock(skb); */			\

	r1 = r6;					\

	call %[bpf_sk_fullsock];			\

	/* if (r0 == null) return 0; */			\

	if r0 == 0 goto l0_%=;				\

	/* if (r0 != r7) r0 = *(r7->type); */		\

	if r0 == r7 goto l0_%=;		/* Use ! JEQ ! */\

	r0 = *(u32*)(r7 + %[bpf_sock_type]);		\

l0_%=:	/* return 0; */					\

	r0 = 0;						\

	exit;						\

"	:

	: __imm(bpf_sk_fullsock),

	  __imm_const(__sk_buff_sk, offsetof(struct __sk_buff, sk)),

	  __imm_const(bpf_sock_type, offsetof(struct bpf_sock, type))

	: __clobber_all);

}



/* Maps are treated in a different branch of `mark_ptr_not_null_reg`,

 * so separate test for maps case.

 */

SEC("xdp")

__description("jne/jeq infer not null, PTR_TO_MAP_VALUE_OR_NULL -> PTR_TO_MAP_VALUE")

__success __retval(0)

__naked void null_ptr_to_map_value(void)

{

	asm volatile ("					\

	/* r9 = &some stack to use as key */		\

	r1 = 0;						\

	*(u32*)(r10 - 8) = r1;				\

	r9 = r10;					\

	r9 += -8;					\

	/* r8 = process local map */			\

	r8 = %[map_xskmap] ll;				\

	/* r6 = map_lookup_elem(r8, r9); */		\

	r1 = r8;					\

	r2 = r9;					\

	call %[bpf_map_lookup_elem];			\

	r6 = r0;					\

	/* r7 = map_lookup_elem(r8, r9); */		\

	r1 = r8;					\

	r2 = r9;					\

	call %[bpf_map_lookup_elem];			\

	r7 = r0;					\

	/* if (r6 == 0) return 0; */			\

	if r6 == 0 goto l0_%=;				\

	/* if (r6 != r7) return 0; */			\

	if r6 != r7 goto l0_%=;				\

	/* read *r7; */					\

	r0 = *(u32*)(r7 + %[bpf_xdp_sock_queue_id]);	\

l0_%=:	/* return 0; */					\

	r0 = 0;						\

	exit;						\

"	:

	: __imm(bpf_map_lookup_elem),

	  __imm_addr(map_xskmap),

	  __imm_const(bpf_xdp_sock_queue_id, offsetof(struct bpf_xdp_sock, queue_id))

	: __clobber_all);

}



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

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

deleted100644 → 0
+0 −174
Original line number Diff line number Diff line 
{

	/* This is equivalent to the following program:

	 *

	 *   r6 = skb->sk;

	 *   r7 = sk_fullsock(r6);

	 *   r0 = sk_fullsock(r6);

	 *   if (r0 == 0) return 0;    (a)

	 *   if (r0 != r7) return 0;   (b)

	 *   *r7->type;                (c)

	 *   return 0;

	 *

	 * It is safe to dereference r7 at point (c), because of (a) and (b).

	 * The test verifies that relation r0 == r7 is propagated from (b) to (c).

	 */

	"jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL -> PTR_TO_SOCKET for JNE false branch",

	.insns = {

	/* r6 = skb->sk; */

	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)),

	/* if (r6 == 0) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 8),

	/* r7 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),

	/* r0 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	/* if (r0 == null) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),

	/* if (r0 == r7) r0 = *(r7->type); */

	BPF_JMP_REG(BPF_JNE, BPF_REG_0, BPF_REG_7, 1), /* Use ! JNE ! */

	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)),

	/* return 0 */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_EXIT_INSN(),

	},

	.prog_type = BPF_PROG_TYPE_CGROUP_SKB,

	.result = ACCEPT,

	.result_unpriv = REJECT,

	.errstr_unpriv = "R7 pointer comparison",

},

{

	/* Same as above, but verify that another branch of JNE still

	 * prohibits access to PTR_MAYBE_NULL.

	 */

	"jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL unchanged for JNE true branch",

	.insns = {

	/* r6 = skb->sk */

	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)),

	/* if (r6 == 0) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 9),

	/* r7 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),

	/* r0 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	/* if (r0 == null) return 0; */

	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 3),

	/* if (r0 == r7) return 0; */

	BPF_JMP_REG(BPF_JNE, BPF_REG_0, BPF_REG_7, 1), /* Use ! JNE ! */

	BPF_JMP_IMM(BPF_JA, 0, 0, 1),

	/* r0 = *(r7->type); */

	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)),

	/* return 0 */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_EXIT_INSN(),

	},

	.prog_type = BPF_PROG_TYPE_CGROUP_SKB,

	.result = REJECT,

	.errstr = "R7 invalid mem access 'sock_or_null'",

	.result_unpriv = REJECT,

	.errstr_unpriv = "R7 pointer comparison",

},

{

	/* Same as a first test, but not null should be inferred for JEQ branch */

	"jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL -> PTR_TO_SOCKET for JEQ true branch",

	.insns = {

	/* r6 = skb->sk; */

	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)),

	/* if (r6 == null) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 9),

	/* r7 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),

	/* r0 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	/* if (r0 == null) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),

	/* if (r0 != r7) return 0; */

	BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_7, 1), /* Use ! JEQ ! */

	BPF_JMP_IMM(BPF_JA, 0, 0, 1),

	/* r0 = *(r7->type); */

	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)),

	/* return 0; */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_EXIT_INSN(),

	},

	.prog_type = BPF_PROG_TYPE_CGROUP_SKB,

	.result = ACCEPT,

	.result_unpriv = REJECT,

	.errstr_unpriv = "R7 pointer comparison",

},

{

	/* Same as above, but verify that another branch of JNE still

	 * prohibits access to PTR_MAYBE_NULL.

	 */

	"jne/jeq infer not null, PTR_TO_SOCKET_OR_NULL unchanged for JEQ false branch",

	.insns = {

	/* r6 = skb->sk; */

	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct __sk_buff, sk)),

	/* if (r6 == null) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 8),

	/* r7 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),

	/* r0 = sk_fullsock(skb); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),

	BPF_EMIT_CALL(BPF_FUNC_sk_fullsock),

	/* if (r0 == null) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),

	/* if (r0 != r7) r0 = *(r7->type); */

	BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_7, 1), /* Use ! JEQ ! */

	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_sock, type)),

	/* return 0; */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_EXIT_INSN(),

	},

	.prog_type = BPF_PROG_TYPE_CGROUP_SKB,

	.result = REJECT,

	.errstr = "R7 invalid mem access 'sock_or_null'",

	.result_unpriv = REJECT,

	.errstr_unpriv = "R7 pointer comparison",

},

{

	/* Maps are treated in a different branch of `mark_ptr_not_null_reg`,

	 * so separate test for maps case.

	 */

	"jne/jeq infer not null, PTR_TO_MAP_VALUE_OR_NULL -> PTR_TO_MAP_VALUE",

	.insns = {

	/* r9 = &some stack to use as key */

	BPF_ST_MEM(BPF_W, BPF_REG_10, -8, 0),

	BPF_MOV64_REG(BPF_REG_9, BPF_REG_10),

	BPF_ALU64_IMM(BPF_ADD, BPF_REG_9, -8),

	/* r8 = process local map */

	BPF_LD_MAP_FD(BPF_REG_8, 0),

	/* r6 = map_lookup_elem(r8, r9); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),

	BPF_MOV64_REG(BPF_REG_2, BPF_REG_9),

	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),

	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),

	/* r7 = map_lookup_elem(r8, r9); */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),

	BPF_MOV64_REG(BPF_REG_2, BPF_REG_9),

	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),

	BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),

	/* if (r6 == 0) return 0; */

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 2),

	/* if (r6 != r7) return 0; */

	BPF_JMP_REG(BPF_JNE, BPF_REG_6, BPF_REG_7, 1),

	/* read *r7; */

	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, offsetof(struct bpf_xdp_sock, queue_id)),

	/* return 0; */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_EXIT_INSN(),

	},

	.fixup_map_xskmap = { 3 },

	.prog_type = BPF_PROG_TYPE_XDP,

	.result = ACCEPT,

},