diff options
| author | Kevin Cernekee | 2017-12-03 12:12:45 -0800 |
|---|---|---|
| committer | Pablo Neira Ayuso | 2017-12-04 11:30:09 +0100 |
| commit | 4b380c42f7d00a395feede754f0bc2292eebe6e5 (patch) | |
| tree | 726c117ca7fb8f101fc0245840972f27ac59b19e | |
| parent | 8b1836c4b64386e9bc580438cae386ed31a43ab9 (diff) | |
netfilter: nfnetlink_cthelper: Add missing permission checks
The capability check in nfnetlink_rcv() verifies that the caller
has CAP_NET_ADMIN in the namespace that "owns" the netlink socket.
However, nfnl_cthelper_list is shared by all net namespaces on the
system. An unprivileged user can create user and net namespaces
in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable()
check:
$ nfct helper list
nfct v1.4.4: netlink error: Operation not permitted
$ vpnns -- nfct helper list
{
.name = ftp,
.queuenum = 0,
.l3protonum = 2,
.l4protonum = 6,
.priv_data_len = 24,
.status = enabled,
};
Add capable() checks in nfnetlink_cthelper, as this is cleaner than
trying to generalize the solution.
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/nfnetlink_cthelper.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c index 41628b393673..d33ce6d5ebce 100644 --- a/net/netfilter/nfnetlink_cthelper.c +++ b/net/netfilter/nfnetlink_cthelper.c @@ -17,6 +17,7 @@ #include <linux/types.h> #include <linux/list.h> #include <linux/errno.h> +#include <linux/capability.h> #include <net/netlink.h> #include <net/sock.h> @@ -407,6 +408,9 @@ static int nfnl_cthelper_new(struct net *net, struct sock *nfnl, struct nfnl_cthelper *nlcth; int ret = 0; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE]) return -EINVAL; @@ -611,6 +615,9 @@ static int nfnl_cthelper_get(struct net *net, struct sock *nfnl, struct nfnl_cthelper *nlcth; bool tuple_set = false; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (nlh->nlmsg_flags & NLM_F_DUMP) { struct netlink_dump_control c = { .dump = nfnl_cthelper_dump_table, @@ -678,6 +685,9 @@ static int nfnl_cthelper_del(struct net *net, struct sock *nfnl, struct nfnl_cthelper *nlcth, *n; int j = 0, ret; + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (tb[NFCTH_NAME]) helper_name = nla_data(tb[NFCTH_NAME]); |