diff options
| author | Alexei Starovoitov <ast@plumgrid.com> | 2014-09-26 00:17:03 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-26 15:05:15 -0400 |
| commit | cbd357008604925355ae7b54a09137dabb81b580 (patch) | |
| tree | 85e57d37ffdb0e743ce71c7124e07c1c9e5c3317 /include | |
| parent | 51580e798cb61b0fc63fa3aa6c5c975375aa0550 (diff) | |
| download | linux-cbd357008604925355ae7b54a09137dabb81b580.tar.bz2 | |
bpf: verifier (add ability to receive verification log)
add optional attributes for BPF_PROG_LOAD syscall:
union bpf_attr {
struct {
...
__u32 log_level; /* verbosity level of eBPF verifier */
__u32 log_size; /* size of user buffer */
__aligned_u64 log_buf; /* user supplied 'char *buffer' */
};
};
when log_level > 0 the verifier will return its verification log in the user
supplied buffer 'log_buf' which can be used by program author to analyze why
verifier rejected given program.
'Understanding eBPF verifier messages' section of Documentation/networking/filter.txt
provides several examples of these messages, like the program:
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_LD_MAP_FD(BPF_REG_1, 0),
BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem),
BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
BPF_ST_MEM(BPF_DW, BPF_REG_0, 4, 0),
BPF_EXIT_INSN(),
will be rejected with the following multi-line message in log_buf:
0: (7a) *(u64 *)(r10 -8) = 0
1: (bf) r2 = r10
2: (07) r2 += -8
3: (b7) r1 = 0
4: (85) call 1
5: (15) if r0 == 0x0 goto pc+1
R0=map_ptr R10=fp
6: (7a) *(u64 *)(r0 +4) = 0
misaligned access off 4 size 8
The format of the output can change at any time as verifier evolves.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/linux/bpf.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 424f442016e7..31b0ac208a52 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -138,6 +138,9 @@ union bpf_attr { __u32 insn_cnt; __aligned_u64 insns; __aligned_u64 license; + __u32 log_level; /* verbosity level of verifier */ + __u32 log_size; /* size of user buffer */ + __aligned_u64 log_buf; /* user supplied buffer */ }; } __attribute__((aligned(8))); |