diff options
| author | Kees Cook <keescook@chromium.org> | 2018-05-30 12:17:56 -0700 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-06-01 09:47:42 +0200 |
| commit | 7b7744e2aa93864b2a490fb3533e9417d21cadc0 (patch) | |
| tree | 9bf5e9c52b653f9907ce72e729acda9dc255c639 /net | |
| parent | 2a79fd3908acd88e6cb0e620c314d7b1fee56a02 (diff) | |
netfilter: nfnetlink: Remove VLA usage
In the quest to remove all stack VLA usage from the kernel[1], this
allocates the maximum size expected for all possible attrs and adds
sanity-checks at both registration and usage to make sure nothing
gets out of sync.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/nfnetlink.c | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index 261820627711..4d0da7042aff 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -38,6 +38,8 @@ MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); rcu_dereference_protected(table[(id)].subsys, \ lockdep_nfnl_is_held((id))) +#define NFNL_MAX_ATTR_COUNT 32 + static struct { struct mutex mutex; const struct nfnetlink_subsystem __rcu *subsys; @@ -77,6 +79,13 @@ EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) { + u8 cb_id; + + /* Sanity-check attr_count size to avoid stack buffer overflow. */ + for (cb_id = 0; cb_id < n->cb_count; cb_id++) + if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT)) + return -EINVAL; + nfnl_lock(n->subsys_id); if (table[n->subsys_id].subsys) { nfnl_unlock(n->subsys_id); @@ -186,11 +195,17 @@ replay: { int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); - struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; + struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1]; struct nlattr *attr = (void *)nlh + min_len; int attrlen = nlh->nlmsg_len - min_len; __u8 subsys_id = NFNL_SUBSYS_ID(type); + /* Sanity-check NFNL_MAX_ATTR_COUNT */ + if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) { + rcu_read_unlock(); + return -ENOMEM; + } + err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen, ss->cb[cb_id].policy, extack); if (err < 0) { @@ -387,10 +402,16 @@ replay: { int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type); - struct nlattr *cda[ss->cb[cb_id].attr_count + 1]; + struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1]; struct nlattr *attr = (void *)nlh + min_len; int attrlen = nlh->nlmsg_len - min_len; + /* Sanity-check NFTA_MAX_ATTR */ + if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) { + err = -ENOMEM; + goto ack; + } + err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen, ss->cb[cb_id].policy, NULL); if (err < 0) |