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Message-ID: <1476715350-18983-5-git-send-email-david.lebrun@uclouvain.be>
Date: Mon, 17 Oct 2016 16:42:25 +0200
From: David Lebrun <david.lebrun@...ouvain.be>
To: <netdev@...r.kernel.org>
CC: David Lebrun <david.lebrun@...ouvain.be>
Subject: [PATCH 4/9] ipv6: sr: add core files for SR HMAC support
This patch adds the necessary functions to compute and check the HMAC signature
of an SR-enabled packet. Two HMAC algorithms are supported: hmac(sha1) and
hmac(sha256).
In order to avoid dynamic memory allocation for each HMAC computation,
a per-cpu ring buffer is allocated for this purpose.
Signed-off-by: David Lebrun <david.lebrun@...ouvain.be>
---
include/linux/seg6_hmac.h | 6 +
include/net/seg6_hmac.h | 61 ++++++
include/uapi/linux/seg6_hmac.h | 20 ++
net/ipv6/seg6_hmac.c | 432 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 519 insertions(+)
create mode 100644 include/linux/seg6_hmac.h
create mode 100644 include/net/seg6_hmac.h
create mode 100644 include/uapi/linux/seg6_hmac.h
create mode 100644 net/ipv6/seg6_hmac.c
diff --git a/include/linux/seg6_hmac.h b/include/linux/seg6_hmac.h
new file mode 100644
index 0000000..da437eb
--- /dev/null
+++ b/include/linux/seg6_hmac.h
@@ -0,0 +1,6 @@
+#ifndef _LINUX_SEG6_HMAC_H
+#define _LINUX_SEG6_HMAC_H
+
+#include <uapi/linux/seg6_hmac.h>
+
+#endif
diff --git a/include/net/seg6_hmac.h b/include/net/seg6_hmac.h
new file mode 100644
index 0000000..6e5ee6a
--- /dev/null
+++ b/include/net/seg6_hmac.h
@@ -0,0 +1,61 @@
+/*
+ * SR-IPv6 implementation
+ *
+ * Author:
+ * David Lebrun <david.lebrun@...ouvain.be>
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _NET_SEG6_HMAC_H
+#define _NET_SEG6_HMAC_H
+
+#include <net/flow.h>
+#include <net/ip6_fib.h>
+#include <net/sock.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/route.h>
+#include <net/seg6.h>
+#include <linux/seg6_hmac.h>
+
+#define SEG6_HMAC_MAX_DIGESTSIZE 160
+#define SEG6_HMAC_RING_SIZE 256
+
+struct seg6_hmac_info {
+ struct list_head list;
+
+ u32 hmackeyid;
+ char secret[SEG6_HMAC_SECRET_LEN];
+ u8 slen;
+ u8 alg_id;
+};
+
+struct seg6_hmac_algo {
+ u8 alg_id;
+ char name[64];
+ struct crypto_shash * __percpu *tfms;
+ struct shash_desc * __percpu *shashs;
+};
+
+extern int seg6_hmac_compute(struct seg6_hmac_info *hinfo,
+ struct ipv6_sr_hdr *hdr, struct in6_addr *saddr,
+ u8 *output);
+extern struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key);
+extern int seg6_hmac_info_add(struct net *net, u32 key,
+ struct seg6_hmac_info *hinfo);
+extern int seg6_hmac_info_del(struct net *net, u32 key,
+ struct seg6_hmac_info *hinfo);
+extern int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
+ struct ipv6_sr_hdr *srh);
+extern bool seg6_hmac_validate_skb(struct sk_buff *skb);
+extern int seg6_hmac_init(void);
+extern void seg6_hmac_exit(void);
+extern int seg6_hmac_net_init(struct net *net);
+extern void seg6_hmac_net_exit(struct net *net);
+
+#endif
diff --git a/include/uapi/linux/seg6_hmac.h b/include/uapi/linux/seg6_hmac.h
new file mode 100644
index 0000000..0b5eda7
--- /dev/null
+++ b/include/uapi/linux/seg6_hmac.h
@@ -0,0 +1,20 @@
+#ifndef _UAPI_LINUX_SEG6_HMAC_H
+#define _UAPI_LINUX_SEG6_HMAC_H
+
+#define SEG6_HMAC_SECRET_LEN 64
+#define SEG6_HMAC_FIELD_LEN 32
+
+struct sr6_tlv_hmac {
+ __u8 type;
+ __u8 len;
+ __u16 reserved;
+ __be32 hmackeyid;
+ __u8 hmac[SEG6_HMAC_FIELD_LEN];
+} __attribute__((packed));
+
+enum {
+ SEG6_HMAC_ALGO_SHA1 = 1,
+ SEG6_HMAC_ALGO_SHA256 = 2,
+};
+
+#endif
diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c
new file mode 100644
index 0000000..91bd59a
--- /dev/null
+++ b/net/ipv6/seg6_hmac.c
@@ -0,0 +1,432 @@
+/*
+ * SR-IPv6 implementation -- HMAC functions
+ *
+ * Author:
+ * David Lebrun <david.lebrun@...ouvain.be>
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/in6.h>
+#include <linux/icmpv6.h>
+#include <linux/mroute6.h>
+#include <linux/slab.h>
+
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/rawv6.h>
+#include <net/ndisc.h>
+#include <net/ip6_route.h>
+#include <net/addrconf.h>
+#include <net/xfrm.h>
+
+#include <linux/cryptohash.h>
+#include <crypto/hash.h>
+#include <crypto/sha.h>
+#include <net/seg6.h>
+#include <net/genetlink.h>
+#include <net/seg6_hmac.h>
+#include <linux/random.h>
+
+static char * __percpu *hmac_ring;
+
+static struct seg6_hmac_algo hmac_algos[] = {
+ {
+ .alg_id = SEG6_HMAC_ALGO_SHA1,
+ .name = "hmac(sha1)",
+ },
+ {
+ .alg_id = SEG6_HMAC_ALGO_SHA256,
+ .name = "hmac(sha256)",
+ },
+};
+
+static struct seg6_hmac_algo *__hmac_get_algo(u8 alg_id)
+{
+ int i, alg_count;
+ struct seg6_hmac_algo *algo;
+
+ alg_count = sizeof(hmac_algos) / sizeof(struct seg6_hmac_algo);
+ for (i = 0; i < alg_count; i++) {
+ algo = &hmac_algos[i];
+ if (algo->alg_id == alg_id)
+ return algo;
+ }
+
+ return NULL;
+}
+
+static int __do_hmac(struct seg6_hmac_info *hinfo, const char *text, u8 psize,
+ u8 *output, int outlen)
+{
+ struct crypto_shash *tfm;
+ struct shash_desc *shash;
+ struct seg6_hmac_algo *algo;
+ int ret, dgsize;
+
+ algo = __hmac_get_algo(hinfo->alg_id);
+ if (!algo)
+ return -ENOENT;
+
+ tfm = *this_cpu_ptr(algo->tfms);
+
+ dgsize = crypto_shash_digestsize(tfm);
+ if (dgsize > outlen) {
+ pr_debug("sr-ipv6: __do_hmac: digest size too big (%d / %d)\n",
+ dgsize, outlen);
+ return -ENOMEM;
+ }
+
+ ret = crypto_shash_setkey(tfm, hinfo->secret, hinfo->slen);
+ if (ret < 0) {
+ pr_debug("sr-ipv6: crypto_shash_setkey failed: err %d\n", ret);
+ goto failed;
+ }
+
+ shash = *this_cpu_ptr(algo->shashs);
+ shash->tfm = tfm;
+
+ ret = crypto_shash_digest(shash, text, psize, output);
+ if (ret < 0) {
+ pr_debug("sr-ipv6: crypto_shash_digest failed: err %d\n", ret);
+ goto failed;
+ }
+
+ return dgsize;
+
+failed:
+ return ret;
+}
+
+int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr,
+ struct in6_addr *saddr, u8 *output)
+{
+ int plen, i, dgsize, wrsize;
+ char *ring, *off;
+ u8 tmp_out[SEG6_HMAC_MAX_DIGESTSIZE];
+ __be32 hmackeyid = cpu_to_be32(hinfo->hmackeyid);
+
+ /* a 160-byte buffer for digest output allows to store highest known
+ * hash function (RadioGatun) with up to 1216 bits
+ */
+
+ /* saddr(16) + first_seg(1) + cleanup(1) + keyid(4) + seglist(16n) */
+ plen = 16 + 1 + 1 + 4 + (hdr->first_segment + 1) * 16;
+
+ /* this limit allows for 14 segments */
+ if (plen >= SEG6_HMAC_RING_SIZE)
+ return -EMSGSIZE;
+
+ local_bh_disable();
+ ring = *this_cpu_ptr(hmac_ring);
+ off = ring;
+ memcpy(off, saddr, 16);
+ off += 16;
+ *off++ = hdr->first_segment;
+ *off++ = !!(sr_get_flags(hdr) & SR6_FLAG_CLEANUP) << 7;
+ memcpy(off, &hmackeyid, 4);
+ off += 4;
+
+ for (i = 0; i < hdr->first_segment + 1; i++) {
+ memcpy(off, hdr->segments + i, 16);
+ off += 16;
+ }
+
+ dgsize = __do_hmac(hinfo, ring, plen, tmp_out,
+ SEG6_HMAC_MAX_DIGESTSIZE);
+ local_bh_enable();
+
+ if (dgsize < 0)
+ return dgsize;
+
+ wrsize = SEG6_HMAC_FIELD_LEN;
+ if (wrsize > dgsize)
+ wrsize = dgsize;
+
+ memset(output, 0, SEG6_HMAC_FIELD_LEN);
+ memcpy(output, tmp_out, wrsize);
+
+ return 0;
+}
+EXPORT_SYMBOL(seg6_hmac_compute);
+
+/* checks if an incoming SR-enabled packet's HMAC status matches
+ * the incoming policy.
+ *
+ * called with rcu_read_lock()
+ */
+bool seg6_hmac_validate_skb(struct sk_buff *skb)
+{
+ struct inet6_dev *idev;
+ struct ipv6_sr_hdr *srh;
+ struct sr6_tlv_hmac *tlv;
+ struct seg6_hmac_info *hinfo;
+ struct net *net = dev_net(skb->dev);
+ u8 hmac_output[SEG6_HMAC_FIELD_LEN];
+
+ idev = __in6_dev_get(skb->dev);
+
+ srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
+
+ tlv = seg6_get_tlv_hmac(srh);
+
+ /* mandatory check but no tlv */
+ if (idev->cnf.seg6_require_hmac > 0 && !tlv)
+ return false;
+
+ /* no check */
+ if (idev->cnf.seg6_require_hmac < 0)
+ return true;
+
+ /* check only if present */
+ if (idev->cnf.seg6_require_hmac == 0 && !tlv)
+ return true;
+
+ /* now, seg6_require_hmac >= 0 && tlv */
+
+ hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid));
+ if (!hinfo)
+ return false;
+
+ if (seg6_hmac_compute(hinfo, srh, &ipv6_hdr(skb)->saddr, hmac_output))
+ return false;
+
+ if (memcmp(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN) != 0)
+ return false;
+
+ return true;
+}
+
+/* called with rcu_read_lock() */
+struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key)
+{
+ struct seg6_pernet_data *sdata = seg6_pernet(net);
+ struct seg6_hmac_info *hinfo;
+
+ list_for_each_entry_rcu(hinfo, &sdata->hmac_infos, list) {
+ if (hinfo->hmackeyid == key)
+ return hinfo;
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL(seg6_hmac_info_lookup);
+
+int seg6_hmac_info_add(struct net *net, u32 key, struct seg6_hmac_info *hinfo)
+{
+ struct seg6_pernet_data *sdata = seg6_pernet(net);
+ struct seg6_hmac_info *old_hinfo;
+
+ old_hinfo = seg6_hmac_info_lookup(net, key);
+ if (old_hinfo)
+ return -EEXIST;
+
+ list_add_rcu(&hinfo->list, &sdata->hmac_infos);
+
+ return 0;
+}
+EXPORT_SYMBOL(seg6_hmac_info_add);
+
+int seg6_hmac_info_del(struct net *net, u32 key, struct seg6_hmac_info *hinfo)
+{
+ struct seg6_hmac_info *tmp;
+
+ tmp = seg6_hmac_info_lookup(net, key);
+ if (!tmp)
+ return -ENOENT;
+
+ /* entry was replaced, ignore deletion */
+ if (tmp != hinfo)
+ return -ENOENT;
+
+ list_del_rcu(&hinfo->list);
+ synchronize_net();
+
+ return 0;
+}
+EXPORT_SYMBOL(seg6_hmac_info_del);
+
+static void seg6_hmac_info_flush(struct net *net)
+{
+ struct seg6_pernet_data *sdata = seg6_pernet(net);
+ struct seg6_hmac_info *hinfo;
+
+ seg6_pernet_lock(net);
+ while ((hinfo = list_first_or_null_rcu(&sdata->hmac_infos,
+ struct seg6_hmac_info,
+ list)) != NULL) {
+ list_del_rcu(&hinfo->list);
+ seg6_pernet_unlock(net);
+ synchronize_net();
+ kfree(hinfo);
+ seg6_pernet_lock(net);
+ }
+
+ seg6_pernet_unlock(net);
+}
+
+int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
+ struct ipv6_sr_hdr *srh)
+{
+ struct seg6_hmac_info *hinfo;
+ int err = -ENOENT;
+ struct sr6_tlv_hmac *tlv;
+
+ tlv = seg6_get_tlv(srh, SR6_TLV_HMAC);
+ if (!tlv)
+ return -EINVAL;
+
+ rcu_read_lock();
+
+ hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid));
+ if (!hinfo)
+ goto out;
+
+ memset(tlv->hmac, 0, SEG6_HMAC_FIELD_LEN);
+ err = seg6_hmac_compute(hinfo, srh, saddr, tlv->hmac);
+
+out:
+ rcu_read_unlock();
+ return err;
+}
+EXPORT_SYMBOL(seg6_push_hmac);
+
+static int seg6_hmac_init_ring(void)
+{
+ int i;
+
+ hmac_ring = alloc_percpu(char *);
+
+ if (!hmac_ring)
+ return -ENOMEM;
+
+ for_each_possible_cpu(i) {
+ char *ring = kzalloc(SEG6_HMAC_RING_SIZE, GFP_KERNEL);
+
+ if (!ring)
+ return -ENOMEM;
+
+ *per_cpu_ptr(hmac_ring, i) = ring;
+ }
+
+ return 0;
+}
+
+static int seg6_hmac_init_algo(void)
+{
+ int i, alg_count, cpu;
+ struct seg6_hmac_algo *algo;
+ struct crypto_shash *tfm;
+ struct shash_desc *shash;
+
+ alg_count = sizeof(hmac_algos) / sizeof(struct seg6_hmac_algo);
+
+ for (i = 0; i < alg_count; i++) {
+ int shsize;
+ struct crypto_shash **p_tfm;
+
+ algo = &hmac_algos[i];
+ algo->tfms = alloc_percpu(struct crypto_shash *);
+ if (!algo->tfms)
+ return -ENOMEM;
+
+ for_each_possible_cpu(cpu) {
+ tfm = crypto_alloc_shash(algo->name, 0, GFP_KERNEL);
+ if (IS_ERR(tfm))
+ return PTR_ERR(tfm);
+ p_tfm = per_cpu_ptr(algo->tfms, cpu);
+ *p_tfm = tfm;
+ }
+
+ p_tfm = this_cpu_ptr(algo->tfms);
+ tfm = *p_tfm;
+
+ shsize = sizeof(*shash) + crypto_shash_descsize(tfm);
+
+ algo->shashs = alloc_percpu(struct shash_desc *);
+ if (!algo->shashs)
+ return -ENOMEM;
+
+ for_each_possible_cpu(cpu) {
+ shash = kzalloc(shsize, GFP_KERNEL);
+ if (!shash)
+ return -ENOMEM;
+ *per_cpu_ptr(algo->shashs, cpu) = shash;
+ }
+ }
+
+ return 0;
+}
+
+int __init seg6_hmac_init(void)
+{
+ int ret;
+
+ ret = seg6_hmac_init_ring();
+ if (ret < 0)
+ goto out;
+
+ ret = seg6_hmac_init_algo();
+
+out:
+ return ret;
+}
+
+int __net_init seg6_hmac_net_init(struct net *net)
+{
+ struct seg6_pernet_data *sdata = seg6_pernet(net);
+
+ INIT_LIST_HEAD(&sdata->hmac_infos);
+ return 0;
+}
+
+void __exit seg6_hmac_exit(void)
+{
+ int i, alg_count, cpu;
+ struct seg6_hmac_algo *algo = NULL;
+
+ for_each_possible_cpu(i) {
+ char *ring = *per_cpu_ptr(hmac_ring, i);
+
+ kfree(ring);
+ }
+ free_percpu(hmac_ring);
+
+ alg_count = sizeof(hmac_algos) / sizeof(struct seg6_hmac_algo);
+ for (i = 0; i < alg_count; i++) {
+ algo = &hmac_algos[i];
+ for_each_possible_cpu(cpu) {
+ struct crypto_shash *tfm;
+ struct shash_desc *shash;
+
+ shash = *per_cpu_ptr(algo->shashs, cpu);
+ kfree(shash);
+ tfm = *per_cpu_ptr(algo->tfms, cpu);
+ crypto_free_shash(tfm);
+ }
+ free_percpu(algo->tfms);
+ free_percpu(algo->shashs);
+ }
+}
+
+void __net_exit seg6_hmac_net_exit(struct net *net)
+{
+ seg6_hmac_info_flush(net);
+}
--
2.7.3
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