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authorDaniel Borkmann <dborkman@redhat.com>2015-01-22 10:41:01 +0100
committerDavid S. Miller <davem@davemloft.net>2015-01-26 15:50:18 -0800
commit7913ecf69e24bd7575e0d0325eda3b43c8cfa749 (patch)
treed0911f553eb198eafc444f29be35dfeb268b93d2
parent9e79ce66c6e930e815e1d3ad3b875b56dbe99c46 (diff)
net: cls_bpf: fix size mismatch on filter preparation
In cls_bpf_modify_existing(), we read out the number of filter blocks, do some sanity checks, allocate a block on that size, and copy over the BPF instruction blob from user space, then pass everything through the classic BPF checker prior to installation of the classifier. We should reject mismatches here, there are 2 scenarios: the number of filter blocks could be smaller than the provided instruction blob, so we do a partial copy of the BPF program, and thus the instructions will either be rejected from the verifier or a valid BPF program will be run; in the other case, we'll end up copying more than we're supposed to, and most likely the trailing garbage will be rejected by the verifier as well (i.e. we need to fit instruction pattern, ret {A,K} needs to be last instruction, load/stores must be correct, etc); in case not, we would leak memory when dumping back instruction patterns. The code should have only used nla_len() as Dave noted to avoid this from the beginning. Anyway, lets fix it by rejecting such load attempts. Fixes: 7d1d65cb84e1 ("net: sched: cls_bpf: add BPF-based classifier") Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Acked-by: Jiri Pirko <jiri@resnulli.us> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/cls_bpf.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 84c8219c3e1c..49e5fa8795ae 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -180,6 +180,11 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
}
bpf_size = bpf_len * sizeof(*bpf_ops);
+ if (bpf_size != nla_len(tb[TCA_BPF_OPS])) {
+ ret = -EINVAL;
+ goto errout;
+ }
+
bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
if (bpf_ops == NULL) {
ret = -ENOMEM;