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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/bpf.h>
   4 #include <bpf/bpf_helpers.h>
   5 #include "bpf_misc.h"
   6
   7 SEC("socket")
   8 __description("check w reg equal if r reg upper32 bits 0")
   9 __success
  10 __naked void subreg_equality_1(void)
  11 {
  12         asm volatile ("                                 \
  13         call %[bpf_ktime_get_ns];                       \
  14         *(u64 *)(r10 - 8) = r0;                         \
  15         r2 = *(u32 *)(r10 - 8);                         \
  16         /* At this point upper 4-bytes of r2 are 0,     \
  17          * thus insn w3 = w2 should propagate reg id,   \
  18          * and w2 < 9 comparison would also propagate   \
  19          * the range for r3.                            \
  20          */                                             \
  21         w3 = w2;                                        \
  22         if w2 < 9 goto l0_%=;                           \
  23         exit;                                           \
  24 l0_%=:  if r3 < 9 goto l1_%=;                           \
  25         /* r1 read is illegal at this point */          \
  26         r0 -= r1;                                       \
  27 l1_%=:  exit;                                           \
  28 "       :
  29         : __imm(bpf_ktime_get_ns)
  30         : __clobber_all);
  31 }
  32
  33 SEC("socket")
  34 __description("check w reg not equal if r reg upper32 bits not 0")
  35 __failure __msg("R1 !read_ok")
  36 __naked void subreg_equality_2(void)
  37 {
  38         asm volatile ("                                 \
  39         call %[bpf_ktime_get_ns];                       \
  40         r2 = r0;                                        \
  41         /* Upper 4-bytes of r2 may not be 0, thus insn  \
  42          * w3 = w2 should not propagate reg id, and     \
  43          * w2 < 9 comparison should not propagate       \
  44          * the range for r3 either.                     \
  45          */                                             \
  46         w3 = w2;                                        \
  47         if w2 < 9 goto l0_%=;                           \
  48         exit;                                           \
  49 l0_%=:  if r3 < 9 goto l1_%=;                           \
  50         /* r1 read is illegal at this point */          \
  51         r0 -= r1;                                       \
  52 l1_%=:  exit;                                           \
  53 "       :
  54         : __imm(bpf_ktime_get_ns)
  55         : __clobber_all);
  56 }
  57
  58 char _license[] SEC("license") = "GPL";