Quelle  verifier_spin_lock.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/* Converted from tools/testing/selftests/bpf/verifier/spin_lock.c */

#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"

struct val {
 int cnt;
 struct bpf_spin_lock l;
};

struct {
 __uint(type, BPF_MAP_TYPE_ARRAY);
 __uint(max_entries, 1);
 __type(key, int);
 __type(value, struct val);
} map_spin_lock SEC(".maps");

SEC("cgroup/skb")
__description("spin_lock: test1 success")
__success __failure_unpriv __msg_unpriv("")
__retval(0)
__naked void spin_lock_test1_success(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 r0 = *(u32*)(r6 + 0);    \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test2 direct ld/st")
__failure __msg("cannot be accessed directly")
__failure_unpriv __msg_unpriv("")
__naked void lock_test2_direct_ld_st(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 r0 = *(u32*)(r1 + 0);    \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test3 direct ld/st")
__failure __msg("cannot be accessed directly")
__failure_unpriv __msg_unpriv("")
__flag(BPF_F_ANY_ALIGNMENT)
__naked void lock_test3_direct_ld_st(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 r0 = *(u32*)(r6 + 1);    \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test4 direct ld/st")
__failure __msg("cannot be accessed directly")
__failure_unpriv __msg_unpriv("")
__flag(BPF_F_ANY_ALIGNMENT)
__naked void lock_test4_direct_ld_st(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 r0 = *(u16*)(r6 + 3);    \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test5 call within a locked region")
__failure __msg("calls are not allowed")
__failure_unpriv __msg_unpriv("")
__naked void call_within_a_locked_region(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 call %[bpf_get_prandom_u32];   \
 r1 = r6;     \
 r1 += 4;     \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_get_prandom_u32),
   __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test6 missing unlock")
__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_spin_lock-ed region")
__failure_unpriv __msg_unpriv("")
__naked void spin_lock_test6_missing_unlock(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 r0 = *(u32*)(r6 + 0);    \
 if r0 != 0 goto l1_%=;    \
 call %[bpf_spin_unlock];   \
l1_%=: r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test7 unlock without lock")
__failure __msg("without taking a lock")
__failure_unpriv __msg_unpriv("")
__naked void lock_test7_unlock_without_lock(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 if r1 != 0 goto l1_%=;    \
 call %[bpf_spin_lock];    \
l1_%=: r1 = r6;     \
 r1 += 4;     \
 r0 = *(u32*)(r6 + 0);    \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test8 double lock")
__failure __msg("calls are not allowed")
__failure_unpriv __msg_unpriv("")
__naked void spin_lock_test8_double_lock(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r6;     \
 r1 += 4;     \
 r0 = *(u32*)(r6 + 0);    \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test9 different lock")
__failure __msg("unlock of different lock")
__failure_unpriv __msg_unpriv("")
__naked void spin_lock_test9_different_lock(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l1_%=;    \
 exit;      \
l1_%=: r7 = r0;     \
 r1 = r6;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r1 = r7;     \
 r1 += 4;     \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("cgroup/skb")
__description("spin_lock: test10 lock in subprog without unlock")
__success
__failure_unpriv __msg_unpriv("")
__naked void lock_in_subprog_without_unlock(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r6 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call lock_in_subprog_without_unlock__1;  \
 r1 = r6;     \
 r1 += 4;     \
 call %[bpf_spin_unlock];   \
 r0 = 1;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

static __naked __noinline __attribute__((used))
void lock_in_subprog_without_unlock__1(void)
{
 asm volatile (" \
 call %[bpf_spin_lock];    \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_spin_lock)
 : __clobber_all);
}

SEC("tc")
__description("spin_lock: test11 ld_abs under lock")
__failure __msg("inside bpf_spin_lock")
__naked void test11_ld_abs_under_lock(void)
{
 asm volatile (" \
 r6 = r1;     \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r7 = r0;     \
 r1 = r0;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r0 = *(u8*)skb[0];    \
 r1 = r7;     \
 r1 += 4;     \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("tc")
__description("spin_lock: regsafe compare reg->id for map value")
__failure __msg("bpf_spin_unlock of different lock")
__flag(BPF_F_TEST_STATE_FREQ)
__naked void reg_id_for_map_value(void)
{
 asm volatile (" \
 r6 = r1;     \
 r6 = *(u32*)(r6 + %[__sk_buff_mark]);  \
 r1 = %[map_spin_lock] ll;   \
 r9 = r1;     \
 r2 = 0;      \
 *(u32*)(r10 - 4) = r2;    \
 r2 = r10;     \
 r2 += -4;     \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r7 = r0;     \
 r1 = r9;     \
 r2 = r10;     \
 r2 += -4;     \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l1_%=;    \
 exit;      \
l1_%=: r8 = r0;     \
 r1 = r7;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 if r6 == 0 goto l2_%=;    \
 goto l3_%=;     \
l2_%=: r7 = r8;     \
l3_%=: r1 = r7;     \
 r1 += 4;     \
 call %[bpf_spin_unlock];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock),
   __imm_const(__sk_buff_mark, offsetof(struct __sk_buff, mark))
 : __clobber_all);
}

/* Make sure that regsafe() compares ids for spin lock records using
 * check_ids():
 *  1: r9 = map_lookup_elem(...)  ; r9.id == 1
 *  2: r8 = map_lookup_elem(...)  ; r8.id == 2
 *  3: r7 = ktime_get_ns()
 *  4: r6 = ktime_get_ns()
 *  5: if r6 > r7 goto <9>
 *  6: spin_lock(r8)
 *  7: r9 = r8
 *  8: goto <10>
 *  9: spin_lock(r9)
 * 10: spin_unlock(r9)             ; r9.id == 1 || r9.id == 2 and lock is active,
 *                                 ; second visit to (10) should be considered safe
 *                                 ; if check_ids() is used.
 * 11: exit(0)
 */

SEC("cgroup/skb")
__description("spin_lock: regsafe() check_ids() similar id mappings")
__success __msg("29: safe")
__failure_unpriv __msg_unpriv("")
__log_level(2) __retval(0) __flag(BPF_F_TEST_STATE_FREQ)
__naked void check_ids_similar_id_mappings(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 /* r9 = map_lookup_elem(...) */ \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 == 0 goto l0_%=;    \
 r9 = r0;     \
 /* r8 = map_lookup_elem(...) */ \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_spin_lock] ll;   \
 call %[bpf_map_lookup_elem];   \
 if r0 == 0 goto l1_%=;    \
 r8 = r0;     \
 /* r7 = ktime_get_ns() */ \
 call %[bpf_ktime_get_ns];   \
 r7 = r0;     \
 /* r6 = ktime_get_ns() */ \
 call %[bpf_ktime_get_ns];   \
 r6 = r0;     \
 /* if r6 > r7 goto +5      ; no new information about the state is derived from\
 *                         ; this check, thus produced verifier states differ\
 *                         ; only in 'insn_idx' \
 * spin_lock(r8) \
 * r9 = r8 \
 * goto unlock \
 */
 if r6 > r7 goto l2_%=;    \
 r1 = r8;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
 r9 = r8;     \
 goto l3_%=;     \
l2_%=: /* spin_lock(r9) */ \
 r1 = r9;     \
 r1 += 4;     \
 call %[bpf_spin_lock];    \
l3_%=: /* spin_unlock(r9) */ \
 r1 = r9;     \
 r1 += 4;     \
 call %[bpf_spin_unlock];   \
l0_%=: /* exit(0) */ \
 r0 = 0;      \
l1_%=: exit;      \
" :
 : __imm(bpf_ktime_get_ns),
   __imm(bpf_map_lookup_elem),
   __imm(bpf_spin_lock),
   __imm(bpf_spin_unlock),
   __imm_addr(map_spin_lock)
 : __clobber_all);
}

SEC("tc")
__description("spin_lock: loop within a locked region")
__success __failure_unpriv __msg_unpriv("")
__retval(0)
int bpf_loop_inside_locked_region(void)
{
 const int zero = 0;
 struct val *val;
 int i, j = 0;

 val = bpf_map_lookup_elem(&map_spin_lock, &zero);
 if (!val)
  return -1;

 bpf_spin_lock(&val->l);
 bpf_for(i, 0, 10) {
  j++;
  /* Silence "unused variable" warnings. */
  if (j == 10)
   break;
 }
 bpf_spin_unlock(&val->l);

 return 0;
}

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