From f32815d21d4d8287336fb9cef4d2d9e0866214c2 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Mon, 2 Jan 2017 17:19:40 -0500 Subject: xtables: add xt_match, xt_target and data copy_to_user functions xt_entry_target, xt_entry_match and their private data may contain kernel data. Introduce helper functions xt_match_to_user, xt_target_to_user and xt_data_to_user that copy only the expected fields. These replace existing logic that calls copy_to_user on entire structs, then overwrites select fields. Private data is defined in xt_match and xt_target. All matches and targets that maintain kernel data store this at the tail of their private structure. Extend xt_match and xt_target with .usersize to limit how many bytes of data are copied. The remainder is cleared. If compatsize is specified, usersize can only safely be used if all fields up to usersize use platform-independent types. Otherwise, the compat_to_user callback must be defined. This patch does not yet enable the support logic. Signed-off-by: Willem de Bruijn Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/x_tables.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux/netfilter') diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 5117e4d2ddfa..be378cf47fcc 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -167,6 +167,7 @@ struct xt_match { const char *table; unsigned int matchsize; + unsigned int usersize; #ifdef CONFIG_COMPAT unsigned int compatsize; #endif @@ -207,6 +208,7 @@ struct xt_target { const char *table; unsigned int targetsize; + unsigned int usersize; #ifdef CONFIG_COMPAT unsigned int compatsize; #endif @@ -287,6 +289,13 @@ int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto, int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto, bool inv_proto); +int xt_match_to_user(const struct xt_entry_match *m, + struct xt_entry_match __user *u); +int xt_target_to_user(const struct xt_entry_target *t, + struct xt_entry_target __user *u); +int xt_data_to_user(void __user *dst, const void *src, + int usersize, int size); + void *xt_copy_counters_from_user(const void __user *user, unsigned int len, struct xt_counters_info *info, bool compat); -- cgit v1.2.3 From 8c4d4e8b5626fec965fd5034e5bd5e57790f243f Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Fri, 10 Feb 2017 12:08:17 +0100 Subject: netfilter: nfnetlink: allow to check for generation ID This patch allows userspace to specify the generation ID that has been used to build an incremental batch update. If userspace specifies the generation ID in the batch message as attribute, then nfnetlink compares it to the current generation ID so you make sure that you work against the right baseline. Otherwise, bail out with ERESTART so userspace knows that its changeset is stale and needs to respin. Userspace can do this transparently at the cost of taking slightly more time to refresh caches and rework the changeset. This check is optional, if there is no NFNL_BATCH_GENID attribute in the batch begin message, then no check is performed. Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/nfnetlink.h | 1 + include/uapi/linux/netfilter/nfnetlink.h | 12 ++++++++++++ net/netfilter/nfnetlink.c | 31 +++++++++++++++++++++++++++---- 3 files changed, 40 insertions(+), 4 deletions(-) (limited to 'include/linux/netfilter') diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h index 1d82dd5e9a08..1b49209dd5c7 100644 --- a/include/linux/netfilter/nfnetlink.h +++ b/include/linux/netfilter/nfnetlink.h @@ -28,6 +28,7 @@ struct nfnetlink_subsystem { const struct nfnl_callback *cb; /* callback for individual types */ int (*commit)(struct net *net, struct sk_buff *skb); int (*abort)(struct net *net, struct sk_buff *skb); + bool (*valid_genid)(struct net *net, u32 genid); }; int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n); diff --git a/include/uapi/linux/netfilter/nfnetlink.h b/include/uapi/linux/netfilter/nfnetlink.h index 4bb8cb7730e7..a09906a30d77 100644 --- a/include/uapi/linux/netfilter/nfnetlink.h +++ b/include/uapi/linux/netfilter/nfnetlink.h @@ -65,4 +65,16 @@ struct nfgenmsg { #define NFNL_MSG_BATCH_BEGIN NLMSG_MIN_TYPE #define NFNL_MSG_BATCH_END NLMSG_MIN_TYPE+1 +/** + * enum nfnl_batch_attributes - nfnetlink batch netlink attributes + * + * @NFNL_BATCH_GENID: generation ID for this changeset (NLA_U32) + */ +enum nfnl_batch_attributes { + NFNL_BATCH_UNSPEC, + NFNL_BATCH_GENID, + __NFNL_BATCH_MAX +}; +#define NFNL_BATCH_MAX (__NFNL_BATCH_MAX - 1) + #endif /* _UAPI_NFNETLINK_H */ diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index ca645a3b1375..a2148d0bc50e 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -3,7 +3,7 @@ * * (C) 2001 by Jay Schulist , * (C) 2002-2005 by Harald Welte - * (C) 2005,2007 by Pablo Neira Ayuso + * (C) 2005-2017 by Pablo Neira Ayuso * * Initial netfilter messages via netlink development funded and * generally made possible by Network Robots, Inc. (www.networkrobots.com) @@ -273,7 +273,7 @@ enum { }; static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh, - u16 subsys_id) + u16 subsys_id, u32 genid) { struct sk_buff *oskb = skb; struct net *net = sock_net(skb->sk); @@ -315,6 +315,12 @@ replay: return kfree_skb(skb); } + if (genid && ss->valid_genid && !ss->valid_genid(net, genid)) { + nfnl_unlock(subsys_id); + netlink_ack(oskb, nlh, -ERESTART); + return kfree_skb(skb); + } + while (skb->len >= nlmsg_total_size(0)) { int msglen, type; @@ -436,11 +442,20 @@ done: kfree_skb(skb); } +static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = { + [NFNL_BATCH_GENID] = { .type = NLA_U32 }, +}; + static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh) { + int min_len = nlmsg_total_size(sizeof(struct nfgenmsg)); + struct nlattr *attr = (void *)nlh + min_len; + struct nlattr *cda[NFNL_BATCH_MAX + 1]; + int attrlen = nlh->nlmsg_len - min_len; struct nfgenmsg *nfgenmsg; + int msglen, err; + u32 gen_id = 0; u16 res_id; - int msglen; msglen = NLMSG_ALIGN(nlh->nlmsg_len); if (msglen > skb->len) @@ -450,6 +465,14 @@ static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh) skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) return; + err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy); + if (err < 0) { + netlink_ack(skb, nlh, err); + return; + } + if (cda[NFNL_BATCH_GENID]) + gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID])); + nfgenmsg = nlmsg_data(nlh); skb_pull(skb, msglen); /* Work around old nft using host byte order */ @@ -458,7 +481,7 @@ static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh) else res_id = ntohs(nfgenmsg->res_id); - nfnetlink_rcv_batch(skb, nlh, res_id); + nfnetlink_rcv_batch(skb, nlh, res_id, gen_id); } static void nfnetlink_rcv(struct sk_buff *skb) -- cgit v1.2.3