From f13f2aeed154da8e48f90b85e720f8ba39b1e881 Mon Sep 17 00:00:00 2001 From: Philip Whineray Date: Sun, 22 Nov 2015 11:35:07 +0000 Subject: [PATCH] netfilter: Set /proc/net entries owner to root in namespace Various files are owned by root with 0440 permission. Reading them is impossible in an unprivileged user namespace, interfering with firewall tools. For instance, iptables-save relies on /proc/net/ip_tables_names contents to dump only loaded tables. This patch assigned ownership of the following files to root in the current namespace: - /proc/net/*_tables_names - /proc/net/*_tables_matches - /proc/net/*_tables_targets - /proc/net/nf_conntrack - /proc/net/nf_conntrack_expect - /proc/net/netfilter/nfnetlink_log A mapping for root must be available, so this order should be followed: unshare(CLONE_NEWUSER); /* Setup the mapping */ unshare(CLONE_NEWNET); Signed-off-by: Philip Whineray Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_expect.c | 7 +++++++ net/netfilter/nf_conntrack_standalone.c | 7 +++++++ net/netfilter/nfnetlink_log.c | 15 +++++++++++++-- net/netfilter/x_tables.c | 12 ++++++++++++ 4 files changed, 39 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index acf5c7b3f378..278927ab0948 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -596,11 +596,18 @@ static int exp_proc_init(struct net *net) { #ifdef CONFIG_NF_CONNTRACK_PROCFS struct proc_dir_entry *proc; + kuid_t root_uid; + kgid_t root_gid; proc = proc_create("nf_conntrack_expect", 0440, net->proc_net, &exp_file_ops); if (!proc) return -ENOMEM; + + root_uid = make_kuid(net->user_ns, 0); + root_gid = make_kgid(net->user_ns, 0); + if (uid_valid(root_uid) && gid_valid(root_gid)) + proc_set_user(proc, root_uid, root_gid); #endif /* CONFIG_NF_CONNTRACK_PROCFS */ return 0; } diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 1fb3cacc04e1..0f1a45bcacb2 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -392,11 +392,18 @@ static const struct file_operations ct_cpu_seq_fops = { static int nf_conntrack_standalone_init_proc(struct net *net) { struct proc_dir_entry *pde; + kuid_t root_uid; + kgid_t root_gid; pde = proc_create("nf_conntrack", 0440, net->proc_net, &ct_file_ops); if (!pde) goto out_nf_conntrack; + root_uid = make_kuid(net->user_ns, 0); + root_gid = make_kgid(net->user_ns, 0); + if (uid_valid(root_uid) && gid_valid(root_gid)) + proc_set_user(pde, root_uid, root_gid); + pde = proc_create("nf_conntrack", S_IRUGO, net->proc_net_stat, &ct_cpu_seq_fops); if (!pde) diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 740cce4685ac..dea467647c90 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -1064,15 +1064,26 @@ static int __net_init nfnl_log_net_init(struct net *net) { unsigned int i; struct nfnl_log_net *log = nfnl_log_pernet(net); +#ifdef CONFIG_PROC_FS + struct proc_dir_entry *proc; + kuid_t root_uid; + kgid_t root_gid; +#endif for (i = 0; i < INSTANCE_BUCKETS; i++) INIT_HLIST_HEAD(&log->instance_table[i]); spin_lock_init(&log->instances_lock); #ifdef CONFIG_PROC_FS - if (!proc_create("nfnetlink_log", 0440, - net->nf.proc_netfilter, &nful_file_ops)) + proc = proc_create("nfnetlink_log", 0440, + net->nf.proc_netfilter, &nful_file_ops); + if (!proc) return -ENOMEM; + + root_uid = make_kuid(net->user_ns, 0); + root_gid = make_kgid(net->user_ns, 0); + if (uid_valid(root_uid) && gid_valid(root_gid)) + proc_set_user(proc, root_uid, root_gid); #endif return 0; } diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index d4aaad747ea9..c8a0b7da5ff4 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -1226,6 +1227,8 @@ int xt_proto_init(struct net *net, u_int8_t af) #ifdef CONFIG_PROC_FS char buf[XT_FUNCTION_MAXNAMELEN]; struct proc_dir_entry *proc; + kuid_t root_uid; + kgid_t root_gid; #endif if (af >= ARRAY_SIZE(xt_prefix)) @@ -1233,12 +1236,17 @@ int xt_proto_init(struct net *net, u_int8_t af) #ifdef CONFIG_PROC_FS + root_uid = make_kuid(net->user_ns, 0); + root_gid = make_kgid(net->user_ns, 0); + strlcpy(buf, xt_prefix[af], sizeof(buf)); strlcat(buf, FORMAT_TABLES, sizeof(buf)); proc = proc_create_data(buf, 0440, net->proc_net, &xt_table_ops, (void *)(unsigned long)af); if (!proc) goto out; + if (uid_valid(root_uid) && gid_valid(root_gid)) + proc_set_user(proc, root_uid, root_gid); strlcpy(buf, xt_prefix[af], sizeof(buf)); strlcat(buf, FORMAT_MATCHES, sizeof(buf)); @@ -1246,6 +1254,8 @@ int xt_proto_init(struct net *net, u_int8_t af) (void *)(unsigned long)af); if (!proc) goto out_remove_tables; + if (uid_valid(root_uid) && gid_valid(root_gid)) + proc_set_user(proc, root_uid, root_gid); strlcpy(buf, xt_prefix[af], sizeof(buf)); strlcat(buf, FORMAT_TARGETS, sizeof(buf)); @@ -1253,6 +1263,8 @@ int xt_proto_init(struct net *net, u_int8_t af) (void *)(unsigned long)af); if (!proc) goto out_remove_matches; + if (uid_valid(root_uid) && gid_valid(root_gid)) + proc_set_user(proc, root_uid, root_gid); #endif return 0; -- 2.20.1