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authorStanislav Fomichev <sdf@google.com>2019-04-01 13:57:33 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2019-04-03 16:49:48 +0200
commit2ee7fba0d62d638d8b6dbe30cada3a531ec042af (patch)
tree885eee23a75ca15ab8336bca87f53edc65fc0836 /net
parentb9e9c8599f0f23e3d2051befc9966a84b639f64f (diff)
flow_dissector: allow access only to a subset of __sk_buff fields
Use whitelist instead of a blacklist and allow only a small set of fields that might be relevant in the context of flow dissector: * data * data_end * flow_keys This is required for the eth_get_headlen case where we have only a chunk of data to dissect (i.e. trying to read the other skb fields doesn't make sense). Note, that it is a breaking API change! However, we've provided flow_keys->n_proto as a substitute for skb->protocol; and there is no need to manually handle skb->vlan_present. So even if we break somebody, the migration is trivial. Unfortunately, we can't support eth_get_headlen use-case without those breaking changes. Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/filter.c16
1 files changed, 3 insertions, 13 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 647c63a7b25b..fc92ebc4e200 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6613,14 +6613,8 @@ static bool flow_dissector_is_valid_access(int off, int size,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
- if (type == BPF_WRITE) {
- switch (off) {
- case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]):
- break;
- default:
- return false;
- }
- }
+ if (type == BPF_WRITE)
+ return false;
switch (off) {
case bpf_ctx_range(struct __sk_buff, data):
@@ -6632,11 +6626,7 @@ static bool flow_dissector_is_valid_access(int off, int size,
case bpf_ctx_range_ptr(struct __sk_buff, flow_keys):
info->reg_type = PTR_TO_FLOW_KEYS;
break;
- case bpf_ctx_range(struct __sk_buff, tc_classid):
- case bpf_ctx_range(struct __sk_buff, data_meta):
- case bpf_ctx_range_till(struct __sk_buff, family, local_port):
- case bpf_ctx_range(struct __sk_buff, tstamp):
- case bpf_ctx_range(struct __sk_buff, wire_len):
+ default:
return false;
}