Quelle  verifier_map_in_map.c   Sprache: C

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

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

struct {
 __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
 __uint(max_entries, 1);
 __type(key, int);
 __type(value, int);
 __array(values, struct {
  __uint(type, BPF_MAP_TYPE_ARRAY);
  __uint(max_entries, 1);
  __type(key, int);
  __type(value, int);
 });
} map_in_map SEC(".maps");

SEC("socket")
__description("map in map access")
__success __success_unpriv __retval(0)
__naked void map_in_map_access(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 if r0 == 0 goto l0_%=;    \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = r0;     \
 call %[bpf_map_lookup_elem];   \
l0_%=: r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

SEC("xdp")
__description("map in map state pruning")
__success __msg("processed 15 insns")
__log_level(2) __retval(0) __flag(BPF_F_TEST_STATE_FREQ)
__naked void map_in_map_state_pruning(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r6 = r10;     \
 r6 += -4;     \
 r2 = r6;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: r2 = r6;     \
 r1 = r0;     \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l1_%=;    \
 r2 = r6;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l2_%=;    \
 exit;      \
l2_%=: r2 = r6;     \
 r1 = r0;     \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l1_%=;    \
 exit;      \
l1_%=: r0 = *(u32*)(r0 + 0);    \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

SEC("socket")
__description("invalid inner map pointer")
__failure __msg("R1 pointer arithmetic on map_ptr prohibited")
__failure_unpriv
__naked void invalid_inner_map_pointer(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 if r0 == 0 goto l0_%=;    \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = r0;     \
 r1 += 8;     \
 call %[bpf_map_lookup_elem];   \
l0_%=: r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

SEC("socket")
__description("forgot null checking on the inner map pointer")
__failure __msg("R1 type=map_value_or_null expected=map_ptr")
__failure_unpriv
__naked void on_the_inner_map_pointer(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = r0;     \
 call %[bpf_map_lookup_elem];   \
 r0 = 0;      \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

SEC("socket")
__description("map_ptr is never null")
__success
__naked void map_ptr_is_never_null(void)
{
 asm volatile (" \
 r0 = 0;      \
 r1 = %[map_in_map] ll;    \
 if r1 != 0 goto l0_%=;    \
 r10 = 42;     \
l0_%=: exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

SEC("socket")
__description("map_ptr is never null inner")
__success
__naked void map_ptr_is_never_null_inner(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 if r0 == 0 goto l0_%=;    \
 if r0 != 0 goto l0_%=;    \
 r10 = 42;     \
l0_%=:  exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

SEC("socket")
__description("map_ptr is never null inner spill fill")
__success
__naked void map_ptr_is_never_null_inner_spill_fill(void)
{
 asm volatile (" \
 r1 = 0;      \
 *(u32*)(r10 - 4) = r1;    \
 r2 = r10;     \
 r2 += -4;     \
 r1 = %[map_in_map] ll;    \
 call %[bpf_map_lookup_elem];   \
 if r0 != 0 goto l0_%=;    \
 exit;      \
l0_%=: *(u64 *)(r10 -16) = r0;    \
 r1 = *(u64 *)(r10 -16);    \
 if r1 == 0 goto l1_%=;    \
 exit;      \
l1_%=: r10 = 42;     \
 exit;      \
" :
 : __imm(bpf_map_lookup_elem),
   __imm_addr(map_in_map)
 : __clobber_all);
}

struct {
 __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
 __uint(max_entries, 1);
 __type(key, int);
 __type(value, int);
 __array(values, struct {
  __uint(type, BPF_MAP_TYPE_RINGBUF);
  __uint(max_entries, 64 * 1024);
 });
} rb_in_map SEC(".maps");

struct rb_ctx {
 void *rb;
 struct bpf_dynptr dptr;
};

static __always_inline struct rb_ctx __rb_event_reserve(__u32 sz)
{
 struct rb_ctx rb_ctx = {};
 void *rb;
 __u32 cpu = bpf_get_smp_processor_id();
 __u32 rb_slot = cpu & 1;

 rb = bpf_map_lookup_elem(&rb_in_map, &rb_slot);
 if (!rb)
  return rb_ctx;

 rb_ctx.rb = rb;
 bpf_ringbuf_reserve_dynptr(rb, sz, 0, &rb_ctx.dptr);

 return rb_ctx;
}

static __noinline void __rb_event_submit(struct rb_ctx *ctx)
{
 if (!ctx->rb)
  return;

 /* If the verifier (incorrectly) concludes that ctx->rb can be
 * NULL at this point, we'll get "BPF_EXIT instruction in main
 * prog would lead to reference leak" error
 */
 bpf_ringbuf_submit_dynptr(&ctx->dptr, 0);
}

SEC("socket")
int map_ptr_is_never_null_rb(void *ctx)
{
 struct rb_ctx event_ctx = __rb_event_reserve(256);
 __rb_event_submit(&event_ctx);
 return 0;
}

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