// 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";
Codebase Browser
linux