diff options
Diffstat (limited to 'net/netfilter/xt_owner.c')
| -rw-r--r-- | net/netfilter/xt_owner.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/net/netfilter/xt_owner.c b/net/netfilter/xt_owner.c new file mode 100644 index 000000000..50332888c --- /dev/null +++ b/net/netfilter/xt_owner.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel module to match various things tied to sockets associated with + * locally generated outgoing packets. + * + * (C) 2000 Marc Boucher <marc@mbsi.ca> + * + * Copyright © CC Computer Consultants GmbH, 2007 - 2008 + */ +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/file.h> +#include <linux/cred.h> + +#include <net/sock.h> +#include <net/inet_sock.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_owner.h> + +static int owner_check(const struct xt_mtchk_param *par) +{ + struct xt_owner_match_info *info = par->matchinfo; + struct net *net = par->net; + + if (info->match & ~XT_OWNER_MASK) + return -EINVAL; + + /* Only allow the common case where the userns of the writer + * matches the userns of the network namespace. + */ + if ((info->match & (XT_OWNER_UID|XT_OWNER_GID)) && + (current_user_ns() != net->user_ns)) + return -EINVAL; + + /* Ensure the uids are valid */ + if (info->match & XT_OWNER_UID) { + kuid_t uid_min = make_kuid(net->user_ns, info->uid_min); + kuid_t uid_max = make_kuid(net->user_ns, info->uid_max); + + if (!uid_valid(uid_min) || !uid_valid(uid_max) || + (info->uid_max < info->uid_min) || + uid_lt(uid_max, uid_min)) { + return -EINVAL; + } + } + + /* Ensure the gids are valid */ + if (info->match & XT_OWNER_GID) { + kgid_t gid_min = make_kgid(net->user_ns, info->gid_min); + kgid_t gid_max = make_kgid(net->user_ns, info->gid_max); + + if (!gid_valid(gid_min) || !gid_valid(gid_max) || + (info->gid_max < info->gid_min) || + gid_lt(gid_max, gid_min)) { + return -EINVAL; + } + } + + return 0; +} + +static bool +owner_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_owner_match_info *info = par->matchinfo; + const struct file *filp; + struct sock *sk = skb_to_full_sk(skb); + struct net *net = xt_net(par); + + if (!sk || !sk->sk_socket || !net_eq(net, sock_net(sk))) + return (info->match ^ info->invert) == 0; + else if (info->match & info->invert & XT_OWNER_SOCKET) + /* + * Socket exists but user wanted ! --socket-exists. + * (Single ampersands intended.) + */ + return false; + + read_lock_bh(&sk->sk_callback_lock); + filp = sk->sk_socket ? sk->sk_socket->file : NULL; + if (filp == NULL) { + read_unlock_bh(&sk->sk_callback_lock); + return ((info->match ^ info->invert) & + (XT_OWNER_UID | XT_OWNER_GID)) == 0; + } + + if (info->match & XT_OWNER_UID) { + kuid_t uid_min = make_kuid(net->user_ns, info->uid_min); + kuid_t uid_max = make_kuid(net->user_ns, info->uid_max); + if ((uid_gte(filp->f_cred->fsuid, uid_min) && + uid_lte(filp->f_cred->fsuid, uid_max)) ^ + !(info->invert & XT_OWNER_UID)) { + read_unlock_bh(&sk->sk_callback_lock); + return false; + } + } + + if (info->match & XT_OWNER_GID) { + unsigned int i, match = false; + kgid_t gid_min = make_kgid(net->user_ns, info->gid_min); + kgid_t gid_max = make_kgid(net->user_ns, info->gid_max); + struct group_info *gi = filp->f_cred->group_info; + + if (gid_gte(filp->f_cred->fsgid, gid_min) && + gid_lte(filp->f_cred->fsgid, gid_max)) + match = true; + + if (!match && (info->match & XT_OWNER_SUPPL_GROUPS) && gi) { + for (i = 0; i < gi->ngroups; ++i) { + kgid_t group = gi->gid[i]; + + if (gid_gte(group, gid_min) && + gid_lte(group, gid_max)) { + match = true; + break; + } + } + } + + if (match ^ !(info->invert & XT_OWNER_GID)) { + read_unlock_bh(&sk->sk_callback_lock); + return false; + } + } + + read_unlock_bh(&sk->sk_callback_lock); + return true; +} + +static struct xt_match owner_mt_reg __read_mostly = { + .name = "owner", + .revision = 1, + .family = NFPROTO_UNSPEC, + .checkentry = owner_check, + .match = owner_mt, + .matchsize = sizeof(struct xt_owner_match_info), + .hooks = (1 << NF_INET_LOCAL_OUT) | + (1 << NF_INET_POST_ROUTING), + .me = THIS_MODULE, +}; + +static int __init owner_mt_init(void) +{ + return xt_register_match(&owner_mt_reg); +} + +static void __exit owner_mt_exit(void) +{ + xt_unregister_match(&owner_mt_reg); +} + +module_init(owner_mt_init); +module_exit(owner_mt_exit); +MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); +MODULE_DESCRIPTION("Xtables: socket owner matching"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_owner"); +MODULE_ALIAS("ip6t_owner"); |