diff options
| author | Yonghong Song <yhs@fb.com> | 2017-06-22 15:07:39 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-23 14:04:11 -0400 |
| commit | 239946314e57711d7da546b67964d0b387a3ee42 (patch) | |
| tree | 958d35fbbbc439b561832c75de22f5fdfa825f7c /include/linux/bpf.h | |
| parent | 72de46556f8a291b2c72ea1fa22275ffef85e4f9 (diff) | |
bpf: possibly avoid extra masking for narrower load in verifier
Commit 31fd85816dbe ("bpf: permits narrower load from bpf program
context fields") permits narrower load for certain ctx fields.
The commit however will already generate a masking even if
the prog-specific ctx conversion produces the result with
narrower size.
For example, for __sk_buff->protocol, the ctx conversion
loads the data into register with 2-byte load.
A narrower 2-byte load should not generate masking.
For __sk_buff->vlan_present, the conversion function
set the result as either 0 or 1, essentially a byte.
The narrower 2-byte or 1-byte load should not generate masking.
To avoid unnecessary masking, prog-specific *_is_valid_access
now passes converted_op_size back to verifier, which indicates
the valid data width after perceived future conversion.
Based on this information, verifier is able to avoid
unnecessary marking.
Since we want more information back from prog-specific
*_is_valid_access checking, all of them are packed into
one data structure for more clarity.
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/bpf.h')
| -rw-r--r-- | include/linux/bpf.h | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1bcbf0a71f75..deca4e7f2845 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -149,6 +149,15 @@ enum bpf_reg_type { struct bpf_prog; +/* The information passed from prog-specific *_is_valid_access + * back to the verifier. + */ +struct bpf_insn_access_aux { + enum bpf_reg_type reg_type; + int ctx_field_size; + int converted_op_size; +}; + struct bpf_verifier_ops { /* return eBPF function prototype for verification */ const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id); @@ -157,7 +166,7 @@ struct bpf_verifier_ops { * with 'type' (read or write) is allowed */ bool (*is_valid_access)(int off, int size, enum bpf_access_type type, - enum bpf_reg_type *reg_type, int *ctx_field_size); + struct bpf_insn_access_aux *info); int (*gen_prologue)(struct bpf_insn *insn, bool direct_write, const struct bpf_prog *prog); u32 (*convert_ctx_access)(enum bpf_access_type type, |