diff options
| author | Alexei Starovoitov <ast@fb.com> | 2016-06-16 04:25:38 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-06-16 09:37:54 +0300 |
| commit | 19de99f70b87fcc3338da52a89c439b088cbff71 (patch) | |
| tree | 43b5ff80043ee9ea62e09fe568502c9d68a188ee /include | |
| parent | e582615ad33dbd39623084a02e95567b116e1eea (diff) | |
| download | linux-19de99f70b87fcc3338da52a89c439b088cbff71.tar.xz | |
bpf: fix matching of data/data_end in verifier
The ctx structure passed into bpf programs is different depending on bpf
program type. The verifier incorrectly marked ctx->data and ctx->data_end
access based on ctx offset only. That caused loads in tracing programs
int bpf_prog(struct pt_regs *ctx) { .. ctx->ax .. }
to be incorrectly marked as PTR_TO_PACKET which later caused verifier
to reject the program that was actually valid in tracing context.
Fix this by doing program type specific matching of ctx offsets.
Fixes: 969bf05eb3ce ("bpf: direct packet access")
Reported-by: Sasha Goldshtein <goldshtn@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bpf.h | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 8ee27b8afe81..8269cafc6eb1 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -111,6 +111,31 @@ enum bpf_access_type { BPF_WRITE = 2 }; +/* types of values stored in eBPF registers */ +enum bpf_reg_type { + NOT_INIT = 0, /* nothing was written into register */ + UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */ + PTR_TO_CTX, /* reg points to bpf_context */ + CONST_PTR_TO_MAP, /* reg points to struct bpf_map */ + PTR_TO_MAP_VALUE, /* reg points to map element value */ + PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */ + FRAME_PTR, /* reg == frame_pointer */ + PTR_TO_STACK, /* reg == frame_pointer + imm */ + CONST_IMM, /* constant integer value */ + + /* PTR_TO_PACKET represents: + * skb->data + * skb->data + imm + * skb->data + (u16) var + * skb->data + (u16) var + imm + * if (range > 0) then [ptr, ptr + range - off) is safe to access + * if (id > 0) means that some 'var' was added + * if (off > 0) menas that 'imm' was added + */ + PTR_TO_PACKET, + PTR_TO_PACKET_END, /* skb->data + headlen */ +}; + struct bpf_prog; struct bpf_verifier_ops { @@ -120,7 +145,8 @@ struct bpf_verifier_ops { /* return true if 'size' wide access at offset 'off' within bpf_context * with 'type' (read or write) is allowed */ - bool (*is_valid_access)(int off, int size, enum bpf_access_type type); + bool (*is_valid_access)(int off, int size, enum bpf_access_type type, + enum bpf_reg_type *reg_type); u32 (*convert_ctx_access)(enum bpf_access_type type, int dst_reg, int src_reg, int ctx_off, |