444 lines
9.5 KiB
C
444 lines
9.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* SR-IPv6 implementation -- HMAC functions
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*
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* Author:
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* David Lebrun <david.lebrun@uclouvain.be>
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*/
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <linux/netdevice.h>
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#include <linux/in6.h>
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#include <linux/icmpv6.h>
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#include <linux/mroute6.h>
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#include <linux/slab.h>
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#include <linux/rhashtable.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv6.h>
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#include <net/sock.h>
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#include <net/snmp.h>
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#include <net/ipv6.h>
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#include <net/protocol.h>
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#include <net/transp_v6.h>
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#include <net/rawv6.h>
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#include <net/ndisc.h>
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#include <net/ip6_route.h>
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#include <net/addrconf.h>
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#include <net/xfrm.h>
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#include <linux/cryptohash.h>
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#include <crypto/hash.h>
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#include <crypto/sha.h>
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#include <net/seg6.h>
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#include <net/genetlink.h>
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#include <net/seg6_hmac.h>
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#include <linux/random.h>
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static DEFINE_PER_CPU(char [SEG6_HMAC_RING_SIZE], hmac_ring);
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static int seg6_hmac_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
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{
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const struct seg6_hmac_info *hinfo = obj;
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return (hinfo->hmackeyid != *(__u32 *)arg->key);
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}
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static inline void seg6_hinfo_release(struct seg6_hmac_info *hinfo)
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{
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kfree_rcu(hinfo, rcu);
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}
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static void seg6_free_hi(void *ptr, void *arg)
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{
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struct seg6_hmac_info *hinfo = (struct seg6_hmac_info *)ptr;
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if (hinfo)
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seg6_hinfo_release(hinfo);
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}
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static const struct rhashtable_params rht_params = {
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.head_offset = offsetof(struct seg6_hmac_info, node),
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.key_offset = offsetof(struct seg6_hmac_info, hmackeyid),
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.key_len = sizeof(u32),
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.automatic_shrinking = true,
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.obj_cmpfn = seg6_hmac_cmpfn,
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};
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static struct seg6_hmac_algo hmac_algos[] = {
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{
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.alg_id = SEG6_HMAC_ALGO_SHA1,
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.name = "hmac(sha1)",
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},
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{
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.alg_id = SEG6_HMAC_ALGO_SHA256,
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.name = "hmac(sha256)",
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},
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};
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static struct sr6_tlv_hmac *seg6_get_tlv_hmac(struct ipv6_sr_hdr *srh)
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{
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struct sr6_tlv_hmac *tlv;
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if (srh->hdrlen < (srh->first_segment + 1) * 2 + 5)
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return NULL;
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if (!sr_has_hmac(srh))
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return NULL;
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tlv = (struct sr6_tlv_hmac *)
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((char *)srh + ((srh->hdrlen + 1) << 3) - 40);
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if (tlv->tlvhdr.type != SR6_TLV_HMAC || tlv->tlvhdr.len != 38)
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return NULL;
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return tlv;
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}
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static struct seg6_hmac_algo *__hmac_get_algo(u8 alg_id)
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{
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struct seg6_hmac_algo *algo;
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int i, alg_count;
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alg_count = ARRAY_SIZE(hmac_algos);
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for (i = 0; i < alg_count; i++) {
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algo = &hmac_algos[i];
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if (algo->alg_id == alg_id)
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return algo;
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}
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return NULL;
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}
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static int __do_hmac(struct seg6_hmac_info *hinfo, const char *text, u8 psize,
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u8 *output, int outlen)
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{
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struct seg6_hmac_algo *algo;
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struct crypto_shash *tfm;
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struct shash_desc *shash;
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int ret, dgsize;
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algo = __hmac_get_algo(hinfo->alg_id);
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if (!algo)
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return -ENOENT;
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tfm = *this_cpu_ptr(algo->tfms);
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dgsize = crypto_shash_digestsize(tfm);
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if (dgsize > outlen) {
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pr_debug("sr-ipv6: __do_hmac: digest size too big (%d / %d)\n",
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dgsize, outlen);
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return -ENOMEM;
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}
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ret = crypto_shash_setkey(tfm, hinfo->secret, hinfo->slen);
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if (ret < 0) {
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pr_debug("sr-ipv6: crypto_shash_setkey failed: err %d\n", ret);
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goto failed;
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}
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shash = *this_cpu_ptr(algo->shashs);
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shash->tfm = tfm;
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ret = crypto_shash_digest(shash, text, psize, output);
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if (ret < 0) {
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pr_debug("sr-ipv6: crypto_shash_digest failed: err %d\n", ret);
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goto failed;
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}
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return dgsize;
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failed:
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return ret;
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}
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int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr,
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struct in6_addr *saddr, u8 *output)
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{
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__be32 hmackeyid = cpu_to_be32(hinfo->hmackeyid);
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u8 tmp_out[SEG6_HMAC_MAX_DIGESTSIZE];
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int plen, i, dgsize, wrsize;
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char *ring, *off;
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/* a 160-byte buffer for digest output allows to store highest known
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* hash function (RadioGatun) with up to 1216 bits
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*/
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/* saddr(16) + first_seg(1) + flags(1) + keyid(4) + seglist(16n) */
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plen = 16 + 1 + 1 + 4 + (hdr->first_segment + 1) * 16;
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/* this limit allows for 14 segments */
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if (plen >= SEG6_HMAC_RING_SIZE)
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return -EMSGSIZE;
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/* Let's build the HMAC text on the ring buffer. The text is composed
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* as follows, in order:
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*
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* 1. Source IPv6 address (128 bits)
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* 2. first_segment value (8 bits)
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* 3. Flags (8 bits)
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* 4. HMAC Key ID (32 bits)
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* 5. All segments in the segments list (n * 128 bits)
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*/
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local_bh_disable();
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ring = this_cpu_ptr(hmac_ring);
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off = ring;
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/* source address */
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memcpy(off, saddr, 16);
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off += 16;
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/* first_segment value */
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*off++ = hdr->first_segment;
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/* flags */
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*off++ = hdr->flags;
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/* HMAC Key ID */
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memcpy(off, &hmackeyid, 4);
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off += 4;
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/* all segments in the list */
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for (i = 0; i < hdr->first_segment + 1; i++) {
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memcpy(off, hdr->segments + i, 16);
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off += 16;
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}
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dgsize = __do_hmac(hinfo, ring, plen, tmp_out,
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SEG6_HMAC_MAX_DIGESTSIZE);
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local_bh_enable();
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if (dgsize < 0)
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return dgsize;
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wrsize = SEG6_HMAC_FIELD_LEN;
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if (wrsize > dgsize)
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wrsize = dgsize;
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memset(output, 0, SEG6_HMAC_FIELD_LEN);
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memcpy(output, tmp_out, wrsize);
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return 0;
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}
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EXPORT_SYMBOL(seg6_hmac_compute);
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/* checks if an incoming SR-enabled packet's HMAC status matches
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* the incoming policy.
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*
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* called with rcu_read_lock()
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*/
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bool seg6_hmac_validate_skb(struct sk_buff *skb)
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{
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u8 hmac_output[SEG6_HMAC_FIELD_LEN];
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struct net *net = dev_net(skb->dev);
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struct seg6_hmac_info *hinfo;
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struct sr6_tlv_hmac *tlv;
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struct ipv6_sr_hdr *srh;
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struct inet6_dev *idev;
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idev = __in6_dev_get(skb->dev);
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srh = (struct ipv6_sr_hdr *)skb_transport_header(skb);
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tlv = seg6_get_tlv_hmac(srh);
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/* mandatory check but no tlv */
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if (idev->cnf.seg6_require_hmac > 0 && !tlv)
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return false;
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/* no check */
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if (idev->cnf.seg6_require_hmac < 0)
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return true;
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/* check only if present */
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if (idev->cnf.seg6_require_hmac == 0 && !tlv)
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return true;
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/* now, seg6_require_hmac >= 0 && tlv */
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hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid));
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if (!hinfo)
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return false;
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if (seg6_hmac_compute(hinfo, srh, &ipv6_hdr(skb)->saddr, hmac_output))
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return false;
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if (memcmp(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN) != 0)
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return false;
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return true;
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}
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EXPORT_SYMBOL(seg6_hmac_validate_skb);
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/* called with rcu_read_lock() */
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struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key)
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{
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struct seg6_pernet_data *sdata = seg6_pernet(net);
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struct seg6_hmac_info *hinfo;
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hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params);
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return hinfo;
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}
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EXPORT_SYMBOL(seg6_hmac_info_lookup);
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int seg6_hmac_info_add(struct net *net, u32 key, struct seg6_hmac_info *hinfo)
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{
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struct seg6_pernet_data *sdata = seg6_pernet(net);
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int err;
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err = rhashtable_lookup_insert_fast(&sdata->hmac_infos, &hinfo->node,
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rht_params);
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return err;
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}
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EXPORT_SYMBOL(seg6_hmac_info_add);
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int seg6_hmac_info_del(struct net *net, u32 key)
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{
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struct seg6_pernet_data *sdata = seg6_pernet(net);
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struct seg6_hmac_info *hinfo;
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int err = -ENOENT;
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hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params);
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if (!hinfo)
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goto out;
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err = rhashtable_remove_fast(&sdata->hmac_infos, &hinfo->node,
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rht_params);
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if (err)
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goto out;
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seg6_hinfo_release(hinfo);
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out:
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return err;
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}
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EXPORT_SYMBOL(seg6_hmac_info_del);
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int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
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struct ipv6_sr_hdr *srh)
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{
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struct seg6_hmac_info *hinfo;
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struct sr6_tlv_hmac *tlv;
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int err = -ENOENT;
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tlv = seg6_get_tlv_hmac(srh);
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if (!tlv)
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return -EINVAL;
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rcu_read_lock();
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hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid));
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if (!hinfo)
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goto out;
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memset(tlv->hmac, 0, SEG6_HMAC_FIELD_LEN);
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err = seg6_hmac_compute(hinfo, srh, saddr, tlv->hmac);
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out:
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rcu_read_unlock();
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return err;
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}
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EXPORT_SYMBOL(seg6_push_hmac);
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static int seg6_hmac_init_algo(void)
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{
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struct seg6_hmac_algo *algo;
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struct crypto_shash *tfm;
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struct shash_desc *shash;
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int i, alg_count, cpu;
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alg_count = ARRAY_SIZE(hmac_algos);
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for (i = 0; i < alg_count; i++) {
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struct crypto_shash **p_tfm;
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int shsize;
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algo = &hmac_algos[i];
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algo->tfms = alloc_percpu(struct crypto_shash *);
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if (!algo->tfms)
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return -ENOMEM;
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for_each_possible_cpu(cpu) {
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tfm = crypto_alloc_shash(algo->name, 0, 0);
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if (IS_ERR(tfm))
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return PTR_ERR(tfm);
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p_tfm = per_cpu_ptr(algo->tfms, cpu);
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*p_tfm = tfm;
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}
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p_tfm = raw_cpu_ptr(algo->tfms);
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tfm = *p_tfm;
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shsize = sizeof(*shash) + crypto_shash_descsize(tfm);
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algo->shashs = alloc_percpu(struct shash_desc *);
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if (!algo->shashs)
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return -ENOMEM;
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for_each_possible_cpu(cpu) {
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shash = kzalloc_node(shsize, GFP_KERNEL,
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cpu_to_node(cpu));
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if (!shash)
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return -ENOMEM;
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*per_cpu_ptr(algo->shashs, cpu) = shash;
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}
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}
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return 0;
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}
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int __init seg6_hmac_init(void)
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{
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return seg6_hmac_init_algo();
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}
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int __net_init seg6_hmac_net_init(struct net *net)
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{
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struct seg6_pernet_data *sdata = seg6_pernet(net);
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rhashtable_init(&sdata->hmac_infos, &rht_params);
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return 0;
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}
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void seg6_hmac_exit(void)
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{
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struct seg6_hmac_algo *algo = NULL;
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int i, alg_count, cpu;
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alg_count = ARRAY_SIZE(hmac_algos);
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for (i = 0; i < alg_count; i++) {
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algo = &hmac_algos[i];
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for_each_possible_cpu(cpu) {
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struct crypto_shash *tfm;
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struct shash_desc *shash;
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shash = *per_cpu_ptr(algo->shashs, cpu);
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kfree(shash);
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tfm = *per_cpu_ptr(algo->tfms, cpu);
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crypto_free_shash(tfm);
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}
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free_percpu(algo->tfms);
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free_percpu(algo->shashs);
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}
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}
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EXPORT_SYMBOL(seg6_hmac_exit);
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void __net_exit seg6_hmac_net_exit(struct net *net)
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{
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struct seg6_pernet_data *sdata = seg6_pernet(net);
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rhashtable_free_and_destroy(&sdata->hmac_infos, seg6_free_hi, NULL);
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}
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EXPORT_SYMBOL(seg6_hmac_net_exit);
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