linux/kernel/bpf
Daniel Borkmann b4e432f100 bpf: enable BPF_J{LT, LE, SLT, SLE} opcodes in verifier
Enable the newly added jump opcodes, main parts are in two
different areas, namely direct packet access and dynamic map
value access. For the direct packet access, we now allow for
the following two new patterns to match in order to trigger
markings with find_good_pkt_pointers():

Variant 1 (access ok when taking the branch):

  0: (61) r2 = *(u32 *)(r1 +76)
  1: (61) r3 = *(u32 *)(r1 +80)
  2: (bf) r0 = r2
  3: (07) r0 += 8
  4: (ad) if r0 < r3 goto pc+2
  R0=pkt(id=0,off=8,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
  R3=pkt_end R10=fp
  5: (b7) r0 = 0
  6: (95) exit

  from 4 to 7: R0=pkt(id=0,off=8,r=8) R1=ctx
               R2=pkt(id=0,off=0,r=8) R3=pkt_end R10=fp
  7: (71) r0 = *(u8 *)(r2 +0)
  8: (05) goto pc-4
  5: (b7) r0 = 0
  6: (95) exit
  processed 11 insns, stack depth 0

Variant 2 (access ok on fall-through):

  0: (61) r2 = *(u32 *)(r1 +76)
  1: (61) r3 = *(u32 *)(r1 +80)
  2: (bf) r0 = r2
  3: (07) r0 += 8
  4: (bd) if r3 <= r0 goto pc+1
  R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8)
  R3=pkt_end R10=fp
  5: (71) r0 = *(u8 *)(r2 +0)
  6: (b7) r0 = 1
  7: (95) exit

  from 4 to 6: R0=pkt(id=0,off=8,r=0) R1=ctx
               R2=pkt(id=0,off=0,r=0) R3=pkt_end R10=fp
  6: (b7) r0 = 1
  7: (95) exit
  processed 10 insns, stack depth 0

The above two basically just swap the branches where we need
to handle an exception and allow packet access compared to the
two already existing variants for find_good_pkt_pointers().

For the dynamic map value access, we add the new instructions
to reg_set_min_max() and reg_set_min_max_inv() in order to
learn bounds. Verifier test cases for both are added in a
follow-up patch.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-09 16:53:57 -07:00
..
arraymap.c bpf: Add syscall lookup support for fd array and htab 2017-06-29 13:13:25 -04:00
bpf_lru_list.c bpf: lru: Lower the PERCPU_NR_SCANS from 16 to 4 2017-04-17 13:55:52 -04:00
bpf_lru_list.h bpf: Add percpu LRU list 2016-11-15 11:50:20 -05:00
cgroup.c bpf: BPF support for sock_ops 2017-07-01 16:15:13 -07:00
core.c bpf: add BPF_J{LT,LE,SLT,SLE} instructions 2017-08-09 16:53:56 -07:00
devmap.c bpf: devmap fix mutex in rcu critical section 2017-08-07 14:13:04 -07:00
hashtab.c bpf: Add syscall lookup support for fd array and htab 2017-06-29 13:13:25 -04:00
helpers.c bpf: rename ARG_PTR_TO_STACK 2017-01-09 16:56:27 -05:00
inode.c bpf: Implement show_options 2017-07-06 03:31:46 -04:00
lpm_trie.c bpf: fix wrong exposure of map_flags into fdinfo for lpm 2017-05-25 13:44:28 -04:00
Makefile bpf/verifier: rework value tracking 2017-08-08 17:51:34 -07:00
map_in_map.c bpf: Add syscall lookup support for fd array and htab 2017-06-29 13:13:25 -04:00
map_in_map.h bpf: Add syscall lookup support for fd array and htab 2017-06-29 13:13:25 -04:00
percpu_freelist.c bpf: introduce percpu_freelist 2016-03-08 15:28:31 -05:00
percpu_freelist.h bpf: introduce percpu_freelist 2016-03-08 15:28:31 -05:00
stackmap.c bpf: fix wrong exposure of map_flags into fdinfo for lpm 2017-05-25 13:44:28 -04:00
syscall.c bpf: Extend check_uarg_tail_zero() checks 2017-08-08 18:11:17 -07:00
tnum.c bpf/verifier: track signed and unsigned min/max values 2017-08-08 17:51:34 -07:00
verifier.c bpf: enable BPF_J{LT, LE, SLT, SLE} opcodes in verifier 2017-08-09 16:53:57 -07:00