1. 20 Nov, 2018 3 commits
  2. 19 Nov, 2018 6 commits
  3. 17 Nov, 2018 9 commits
  4. 11 Nov, 2018 4 commits
    • Alexei Starovoitov's avatar
      Merge branch 'narrow-loads' · 407be8d0
      Alexei Starovoitov authored
      Andrey Ignatov says:
      
      ====================
      This patch set adds support for narrow loads with offset > 0 to BPF
      verifier.
      
      Patch 1 provides more details and is the main patch in the set.
      Patches 2 and 3 add new test cases to test_verifier and test_sock_addr
      selftests.
      
      v1->v2:
      - fix -Wdeclaration-after-statement warning.
      ====================
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      407be8d0
    • Andrey Ignatov's avatar
      selftests/bpf: Test narrow loads with off > 0 for bpf_sock_addr · e7605475
      Andrey Ignatov authored
      Add more test cases for context bpf_sock_addr to test narrow loads with
      offset > 0 for ctx->user_ip4 field (__u32):
      * off=1, size=1;
      * off=2, size=1;
      * off=3, size=1;
      * off=2, size=2.
      Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      e7605475
    • Andrey Ignatov's avatar
      selftests/bpf: Test narrow loads with off > 0 in test_verifier · 6c2afb67
      Andrey Ignatov authored
      Test the following narrow loads in test_verifier for context __sk_buff:
      * off=1, size=1 - ok;
      * off=2, size=1 - ok;
      * off=3, size=1 - ok;
      * off=0, size=2 - ok;
      * off=1, size=2 - fail;
      * off=0, size=2 - ok;
      * off=3, size=2 - fail.
      Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      6c2afb67
    • Andrey Ignatov's avatar
      bpf: Allow narrow loads with offset > 0 · 46f53a65
      Andrey Ignatov authored
      Currently BPF verifier allows narrow loads for a context field only with
      offset zero. E.g. if there is a __u32 field then only the following
      loads are permitted:
        * off=0, size=1 (narrow);
        * off=0, size=2 (narrow);
        * off=0, size=4 (full).
      
      On the other hand LLVM can generate a load with offset different than
      zero that make sense from program logic point of view, but verifier
      doesn't accept it.
      
      E.g. tools/testing/selftests/bpf/sendmsg4_prog.c has code:
      
        #define DST_IP4			0xC0A801FEU /* 192.168.1.254 */
        ...
        	if ((ctx->user_ip4 >> 24) == (bpf_htonl(DST_IP4) >> 24) &&
      
      where ctx is struct bpf_sock_addr.
      
      Some versions of LLVM can produce the following byte code for it:
      
             8:       71 12 07 00 00 00 00 00         r2 = *(u8 *)(r1 + 7)
             9:       67 02 00 00 18 00 00 00         r2 <<= 24
            10:       18 03 00 00 00 00 00 fe 00 00 00 00 00 00 00 00         r3 = 4261412864 ll
            12:       5d 32 07 00 00 00 00 00         if r2 != r3 goto +7 <LBB0_6>
      
      where `*(u8 *)(r1 + 7)` means narrow load for ctx->user_ip4 with size=1
      and offset=3 (7 - sizeof(ctx->user_family) = 3). This load is currently
      rejected by verifier.
      
      Verifier code that rejects such loads is in bpf_ctx_narrow_access_ok()
      what means any is_valid_access implementation, that uses the function,
      works this way, e.g. bpf_skb_is_valid_access() for __sk_buff or
      sock_addr_is_valid_access() for bpf_sock_addr.
      
      The patch makes such loads supported. Offset can be in [0; size_default)
      but has to be multiple of load size. E.g. for __u32 field the following
      loads are supported now:
        * off=0, size=1 (narrow);
        * off=1, size=1 (narrow);
        * off=2, size=1 (narrow);
        * off=3, size=1 (narrow);
        * off=0, size=2 (narrow);
        * off=2, size=2 (narrow);
        * off=0, size=4 (full).
      Reported-by: default avatarYonghong Song <yhs@fb.com>
      Signed-off-by: default avatarAndrey Ignatov <rdna@fb.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      46f53a65
  5. 10 Nov, 2018 18 commits