diff options
| author | Rabin Vincent <rabin@rab.in> | 2016-01-05 16:23:07 +0100 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-02-15 15:42:43 -0500 |
| commit | 03a115644c4a6dd0f7efec7e9b28b2dbebd7c018 (patch) | |
| tree | 5bd1f74fcc5736fc23f638033bb30020499fe285 /include | |
| parent | 7e95dfd637e49b49f3e3383fc28db48004103184 (diff) | |
net: filter: make JITs zero A for SKF_AD_ALU_XOR_X
[ Upstream commit 55795ef5469290f89f04e12e662ded604909e462 ]
The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data
instructions since it XORs A with X while all the others replace A with
some loaded value. All the BPF JITs fail to clear A if this is used as
the first instruction in a filter. This was found using american fuzzy
lop.
Add a helper to determine if A needs to be cleared given the first
instruction in a filter, and use this in the JITs. Except for ARM, the
rest have only been compile-tested.
Fixes: 3480593131e0 ("net: filter: get rid of BPF_S_* enum")
Signed-off-by: Rabin Vincent <rabin@rab.in>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/filter.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index ca95abd2bed1..c80b1a9d0715 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -427,6 +427,25 @@ static inline void bpf_jit_free(struct bpf_prog *fp) #define BPF_ANC BIT(15) +static inline bool bpf_needs_clear_a(const struct sock_filter *first) +{ + switch (first->code) { + case BPF_RET | BPF_K: + case BPF_LD | BPF_W | BPF_LEN: + return false; + + case BPF_LD | BPF_W | BPF_ABS: + case BPF_LD | BPF_H | BPF_ABS: + case BPF_LD | BPF_B | BPF_ABS: + if (first->k == SKF_AD_OFF + SKF_AD_ALU_XOR_X) + return true; + return false; + + default: + return true; + } +} + static inline u16 bpf_anc_helper(const struct sock_filter *ftest) { BUG_ON(ftest->code & BPF_ANC); |