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441 lines
9.5 KiB
441 lines
9.5 KiB
// 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 <[email protected]> |
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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 <crypto/hash.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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EXPORT_SYMBOL(seg6_hmac_init); |
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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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return rhashtable_init(&sdata->hmac_infos, &rht_params); |
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} |
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EXPORT_SYMBOL(seg6_hmac_net_init); |
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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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