diff options
Diffstat (limited to 'net/rxrpc/rxkad.c')
| -rw-r--r-- | net/rxrpc/rxkad.c | 1267 |
1 files changed, 1267 insertions, 0 deletions
diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c new file mode 100644 index 000000000..b52dedceb --- /dev/null +++ b/net/rxrpc/rxkad.c @@ -0,0 +1,1267 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Kerberos-based RxRPC security + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <crypto/skcipher.h> +#include <linux/module.h> +#include <linux/net.h> +#include <linux/skbuff.h> +#include <linux/udp.h> +#include <linux/scatterlist.h> +#include <linux/ctype.h> +#include <linux/slab.h> +#include <linux/key-type.h> +#include <net/sock.h> +#include <net/af_rxrpc.h> +#include <keys/rxrpc-type.h> +#include "ar-internal.h" + +#define RXKAD_VERSION 2 +#define MAXKRB5TICKETLEN 1024 +#define RXKAD_TKT_TYPE_KERBEROS_V5 256 +#define ANAME_SZ 40 /* size of authentication name */ +#define INST_SZ 40 /* size of principal's instance */ +#define REALM_SZ 40 /* size of principal's auth domain */ +#define SNAME_SZ 40 /* size of service name */ +#define RXKAD_ALIGN 8 + +struct rxkad_level1_hdr { + __be32 data_size; /* true data size (excluding padding) */ +}; + +struct rxkad_level2_hdr { + __be32 data_size; /* true data size (excluding padding) */ + __be32 checksum; /* decrypted data checksum */ +}; + +static int rxkad_prime_packet_security(struct rxrpc_connection *conn, + struct crypto_sync_skcipher *ci); + +/* + * this holds a pinned cipher so that keventd doesn't get called by the cipher + * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE + * packets + */ +static struct crypto_sync_skcipher *rxkad_ci; +static struct skcipher_request *rxkad_ci_req; +static DEFINE_MUTEX(rxkad_ci_mutex); + +/* + * Parse the information from a server key + * + * The data should be the 8-byte secret key. + */ +static int rxkad_preparse_server_key(struct key_preparsed_payload *prep) +{ + struct crypto_skcipher *ci; + + if (prep->datalen != 8) + return -EINVAL; + + memcpy(&prep->payload.data[2], prep->data, 8); + + ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(ci)) { + _leave(" = %ld", PTR_ERR(ci)); + return PTR_ERR(ci); + } + + if (crypto_skcipher_setkey(ci, prep->data, 8) < 0) + BUG(); + + prep->payload.data[0] = ci; + _leave(" = 0"); + return 0; +} + +static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep) +{ + + if (prep->payload.data[0]) + crypto_free_skcipher(prep->payload.data[0]); +} + +static void rxkad_destroy_server_key(struct key *key) +{ + if (key->payload.data[0]) { + crypto_free_skcipher(key->payload.data[0]); + key->payload.data[0] = NULL; + } +} + +/* + * initialise connection security + */ +static int rxkad_init_connection_security(struct rxrpc_connection *conn, + struct rxrpc_key_token *token) +{ + struct crypto_sync_skcipher *ci; + int ret; + + _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key)); + + conn->security_ix = token->security_index; + + ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); + if (IS_ERR(ci)) { + _debug("no cipher"); + ret = PTR_ERR(ci); + goto error; + } + + if (crypto_sync_skcipher_setkey(ci, token->kad->session_key, + sizeof(token->kad->session_key)) < 0) + BUG(); + + switch (conn->security_level) { + case RXRPC_SECURITY_PLAIN: + case RXRPC_SECURITY_AUTH: + case RXRPC_SECURITY_ENCRYPT: + break; + default: + ret = -EKEYREJECTED; + goto error; + } + + ret = rxkad_prime_packet_security(conn, ci); + if (ret < 0) + goto error_ci; + + conn->rxkad.cipher = ci; + return 0; + +error_ci: + crypto_free_sync_skcipher(ci); +error: + _leave(" = %d", ret); + return ret; +} + +/* + * Work out how much data we can put in a packet. + */ +static int rxkad_how_much_data(struct rxrpc_call *call, size_t remain, + size_t *_buf_size, size_t *_data_size, size_t *_offset) +{ + size_t shdr, buf_size, chunk; + + switch (call->conn->security_level) { + default: + buf_size = chunk = min_t(size_t, remain, RXRPC_JUMBO_DATALEN); + shdr = 0; + goto out; + case RXRPC_SECURITY_AUTH: + shdr = sizeof(struct rxkad_level1_hdr); + break; + case RXRPC_SECURITY_ENCRYPT: + shdr = sizeof(struct rxkad_level2_hdr); + break; + } + + buf_size = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN); + + chunk = buf_size - shdr; + if (remain < chunk) + buf_size = round_up(shdr + remain, RXKAD_ALIGN); + +out: + *_buf_size = buf_size; + *_data_size = chunk; + *_offset = shdr; + return 0; +} + +/* + * prime the encryption state with the invariant parts of a connection's + * description + */ +static int rxkad_prime_packet_security(struct rxrpc_connection *conn, + struct crypto_sync_skcipher *ci) +{ + struct skcipher_request *req; + struct rxrpc_key_token *token; + struct scatterlist sg; + struct rxrpc_crypt iv; + __be32 *tmpbuf; + size_t tmpsize = 4 * sizeof(__be32); + + _enter(""); + + if (!conn->key) + return 0; + + tmpbuf = kmalloc(tmpsize, GFP_KERNEL); + if (!tmpbuf) + return -ENOMEM; + + req = skcipher_request_alloc(&ci->base, GFP_NOFS); + if (!req) { + kfree(tmpbuf); + return -ENOMEM; + } + + token = conn->key->payload.data[0]; + memcpy(&iv, token->kad->session_key, sizeof(iv)); + + tmpbuf[0] = htonl(conn->proto.epoch); + tmpbuf[1] = htonl(conn->proto.cid); + tmpbuf[2] = 0; + tmpbuf[3] = htonl(conn->security_ix); + + sg_init_one(&sg, tmpbuf, tmpsize); + skcipher_request_set_sync_tfm(req, ci); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x); + crypto_skcipher_encrypt(req); + skcipher_request_free(req); + + memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv)); + kfree(tmpbuf); + _leave(" = 0"); + return 0; +} + +/* + * Allocate and prepare the crypto request on a call. For any particular call, + * this is called serially for the packets, so no lock should be necessary. + */ +static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call) +{ + struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base; + + return skcipher_request_alloc(tfm, GFP_NOFS); +} + +/* + * Clean up the crypto on a call. + */ +static void rxkad_free_call_crypto(struct rxrpc_call *call) +{ +} + +/* + * partially encrypt a packet (level 1 security) + */ +static int rxkad_secure_packet_auth(const struct rxrpc_call *call, + struct rxrpc_txbuf *txb, + struct skcipher_request *req) +{ + struct rxkad_level1_hdr *hdr = (void *)txb->data; + struct rxrpc_crypt iv; + struct scatterlist sg; + size_t pad; + u16 check; + + _enter(""); + + check = txb->seq ^ ntohl(txb->wire.callNumber); + hdr->data_size = htonl((u32)check << 16 | txb->len); + + txb->len += sizeof(struct rxkad_level1_hdr); + pad = txb->len; + pad = RXKAD_ALIGN - pad; + pad &= RXKAD_ALIGN - 1; + if (pad) { + memset(txb->data + txb->offset, 0, pad); + txb->len += pad; + } + + /* start the encryption afresh */ + memset(&iv, 0, sizeof(iv)); + + sg_init_one(&sg, txb->data, 8); + skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); + crypto_skcipher_encrypt(req); + skcipher_request_zero(req); + + _leave(" = 0"); + return 0; +} + +/* + * wholly encrypt a packet (level 2 security) + */ +static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call, + struct rxrpc_txbuf *txb, + struct skcipher_request *req) +{ + const struct rxrpc_key_token *token; + struct rxkad_level2_hdr *rxkhdr = (void *)txb->data; + struct rxrpc_crypt iv; + struct scatterlist sg; + size_t pad; + u16 check; + int ret; + + _enter(""); + + check = txb->seq ^ ntohl(txb->wire.callNumber); + + rxkhdr->data_size = htonl(txb->len | (u32)check << 16); + rxkhdr->checksum = 0; + + txb->len += sizeof(struct rxkad_level2_hdr); + pad = txb->len; + pad = RXKAD_ALIGN - pad; + pad &= RXKAD_ALIGN - 1; + if (pad) { + memset(txb->data + txb->offset, 0, pad); + txb->len += pad; + } + + /* encrypt from the session key */ + token = call->conn->key->payload.data[0]; + memcpy(&iv, token->kad->session_key, sizeof(iv)); + + sg_init_one(&sg, txb->data, txb->len); + skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, &sg, &sg, txb->len, iv.x); + ret = crypto_skcipher_encrypt(req); + skcipher_request_zero(req); + return ret; +} + +/* + * checksum an RxRPC packet header + */ +static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) +{ + struct skcipher_request *req; + struct rxrpc_crypt iv; + struct scatterlist sg; + union { + __be32 buf[2]; + } crypto __aligned(8); + u32 x, y; + int ret; + + _enter("{%d{%x}},{#%u},%u,", + call->debug_id, key_serial(call->conn->key), + txb->seq, txb->len); + + if (!call->conn->rxkad.cipher) + return 0; + + ret = key_validate(call->conn->key); + if (ret < 0) + return ret; + + req = rxkad_get_call_crypto(call); + if (!req) + return -ENOMEM; + + /* continue encrypting from where we left off */ + memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); + + /* calculate the security checksum */ + x = (ntohl(txb->wire.cid) & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); + x |= txb->seq & 0x3fffffff; + crypto.buf[0] = txb->wire.callNumber; + crypto.buf[1] = htonl(x); + + sg_init_one(&sg, crypto.buf, 8); + skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); + crypto_skcipher_encrypt(req); + skcipher_request_zero(req); + + y = ntohl(crypto.buf[1]); + y = (y >> 16) & 0xffff; + if (y == 0) + y = 1; /* zero checksums are not permitted */ + txb->wire.cksum = htons(y); + + switch (call->conn->security_level) { + case RXRPC_SECURITY_PLAIN: + ret = 0; + break; + case RXRPC_SECURITY_AUTH: + ret = rxkad_secure_packet_auth(call, txb, req); + break; + case RXRPC_SECURITY_ENCRYPT: + ret = rxkad_secure_packet_encrypt(call, txb, req); + break; + default: + ret = -EPERM; + break; + } + + skcipher_request_free(req); + _leave(" = %d [set %x]", ret, y); + return ret; +} + +/* + * decrypt partial encryption on a packet (level 1 security) + */ +static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb, + rxrpc_seq_t seq, + struct skcipher_request *req) +{ + struct rxkad_level1_hdr sechdr; + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + struct rxrpc_crypt iv; + struct scatterlist sg[16]; + u32 data_size, buf; + u16 check; + int ret; + + _enter(""); + + if (sp->len < 8) + return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, + rxkad_abort_1_short_header); + + /* Decrypt the skbuff in-place. TODO: We really want to decrypt + * directly into the target buffer. + */ + sg_init_table(sg, ARRAY_SIZE(sg)); + ret = skb_to_sgvec(skb, sg, sp->offset, 8); + if (unlikely(ret < 0)) + return ret; + + /* start the decryption afresh */ + memset(&iv, 0, sizeof(iv)); + + skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, 8, iv.x); + crypto_skcipher_decrypt(req); + skcipher_request_zero(req); + + /* Extract the decrypted packet length */ + if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) + return rxrpc_abort_eproto(call, skb, RXKADDATALEN, + rxkad_abort_1_short_encdata); + sp->offset += sizeof(sechdr); + sp->len -= sizeof(sechdr); + + buf = ntohl(sechdr.data_size); + data_size = buf & 0xffff; + + check = buf >> 16; + check ^= seq ^ call->call_id; + check &= 0xffff; + if (check != 0) + return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, + rxkad_abort_1_short_check); + if (data_size > sp->len) + return rxrpc_abort_eproto(call, skb, RXKADDATALEN, + rxkad_abort_1_short_data); + sp->len = data_size; + + _leave(" = 0 [dlen=%x]", data_size); + return 0; +} + +/* + * wholly decrypt a packet (level 2 security) + */ +static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb, + rxrpc_seq_t seq, + struct skcipher_request *req) +{ + const struct rxrpc_key_token *token; + struct rxkad_level2_hdr sechdr; + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + struct rxrpc_crypt iv; + struct scatterlist _sg[4], *sg; + u32 data_size, buf; + u16 check; + int nsg, ret; + + _enter(",{%d}", sp->len); + + if (sp->len < 8) + return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, + rxkad_abort_2_short_header); + + /* Decrypt the skbuff in-place. TODO: We really want to decrypt + * directly into the target buffer. + */ + sg = _sg; + nsg = skb_shinfo(skb)->nr_frags + 1; + if (nsg <= 4) { + nsg = 4; + } else { + sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO); + if (!sg) + return -ENOMEM; + } + + sg_init_table(sg, nsg); + ret = skb_to_sgvec(skb, sg, sp->offset, sp->len); + if (unlikely(ret < 0)) { + if (sg != _sg) + kfree(sg); + return ret; + } + + /* decrypt from the session key */ + token = call->conn->key->payload.data[0]; + memcpy(&iv, token->kad->session_key, sizeof(iv)); + + skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x); + crypto_skcipher_decrypt(req); + skcipher_request_zero(req); + if (sg != _sg) + kfree(sg); + + /* Extract the decrypted packet length */ + if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0) + return rxrpc_abort_eproto(call, skb, RXKADDATALEN, + rxkad_abort_2_short_len); + sp->offset += sizeof(sechdr); + sp->len -= sizeof(sechdr); + + buf = ntohl(sechdr.data_size); + data_size = buf & 0xffff; + + check = buf >> 16; + check ^= seq ^ call->call_id; + check &= 0xffff; + if (check != 0) + return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, + rxkad_abort_2_short_check); + + if (data_size > sp->len) + return rxrpc_abort_eproto(call, skb, RXKADDATALEN, + rxkad_abort_2_short_data); + + sp->len = data_size; + _leave(" = 0 [dlen=%x]", data_size); + return 0; +} + +/* + * Verify the security on a received packet and the subpackets therein. + */ +static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb) +{ + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + struct skcipher_request *req; + struct rxrpc_crypt iv; + struct scatterlist sg; + union { + __be32 buf[2]; + } crypto __aligned(8); + rxrpc_seq_t seq = sp->hdr.seq; + int ret; + u16 cksum; + u32 x, y; + + _enter("{%d{%x}},{#%u}", + call->debug_id, key_serial(call->conn->key), seq); + + if (!call->conn->rxkad.cipher) + return 0; + + req = rxkad_get_call_crypto(call); + if (!req) + return -ENOMEM; + + /* continue encrypting from where we left off */ + memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv)); + + /* validate the security checksum */ + x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); + x |= seq & 0x3fffffff; + crypto.buf[0] = htonl(call->call_id); + crypto.buf[1] = htonl(x); + + sg_init_one(&sg, crypto.buf, 8); + skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x); + crypto_skcipher_encrypt(req); + skcipher_request_zero(req); + + y = ntohl(crypto.buf[1]); + cksum = (y >> 16) & 0xffff; + if (cksum == 0) + cksum = 1; /* zero checksums are not permitted */ + + if (cksum != sp->hdr.cksum) { + ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON, + rxkad_abort_bad_checksum); + goto out; + } + + switch (call->conn->security_level) { + case RXRPC_SECURITY_PLAIN: + ret = 0; + break; + case RXRPC_SECURITY_AUTH: + ret = rxkad_verify_packet_1(call, skb, seq, req); + break; + case RXRPC_SECURITY_ENCRYPT: + ret = rxkad_verify_packet_2(call, skb, seq, req); + break; + default: + ret = -ENOANO; + break; + } + +out: + skcipher_request_free(req); + return ret; +} + +/* + * issue a challenge + */ +static int rxkad_issue_challenge(struct rxrpc_connection *conn) +{ + struct rxkad_challenge challenge; + struct rxrpc_wire_header whdr; + struct msghdr msg; + struct kvec iov[2]; + size_t len; + u32 serial; + int ret; + + _enter("{%d}", conn->debug_id); + + get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce)); + + challenge.version = htonl(2); + challenge.nonce = htonl(conn->rxkad.nonce); + challenge.min_level = htonl(0); + challenge.__padding = 0; + + msg.msg_name = &conn->peer->srx.transport; + msg.msg_namelen = conn->peer->srx.transport_len; + msg.msg_control = NULL; + msg.msg_controllen = 0; + msg.msg_flags = 0; + + whdr.epoch = htonl(conn->proto.epoch); + whdr.cid = htonl(conn->proto.cid); + whdr.callNumber = 0; + whdr.seq = 0; + whdr.type = RXRPC_PACKET_TYPE_CHALLENGE; + whdr.flags = conn->out_clientflag; + whdr.userStatus = 0; + whdr.securityIndex = conn->security_ix; + whdr._rsvd = 0; + whdr.serviceId = htons(conn->service_id); + + iov[0].iov_base = &whdr; + iov[0].iov_len = sizeof(whdr); + iov[1].iov_base = &challenge; + iov[1].iov_len = sizeof(challenge); + + len = iov[0].iov_len + iov[1].iov_len; + + serial = atomic_inc_return(&conn->serial); + whdr.serial = htonl(serial); + + ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len); + if (ret < 0) { + trace_rxrpc_tx_fail(conn->debug_id, serial, ret, + rxrpc_tx_point_rxkad_challenge); + return -EAGAIN; + } + + conn->peer->last_tx_at = ktime_get_seconds(); + trace_rxrpc_tx_packet(conn->debug_id, &whdr, + rxrpc_tx_point_rxkad_challenge); + _leave(" = 0"); + return 0; +} + +/* + * send a Kerberos security response + */ +static int rxkad_send_response(struct rxrpc_connection *conn, + struct rxrpc_host_header *hdr, + struct rxkad_response *resp, + const struct rxkad_key *s2) +{ + struct rxrpc_wire_header whdr; + struct msghdr msg; + struct kvec iov[3]; + size_t len; + u32 serial; + int ret; + + _enter(""); + + msg.msg_name = &conn->peer->srx.transport; + msg.msg_namelen = conn->peer->srx.transport_len; + msg.msg_control = NULL; + msg.msg_controllen = 0; + msg.msg_flags = 0; + + memset(&whdr, 0, sizeof(whdr)); + whdr.epoch = htonl(hdr->epoch); + whdr.cid = htonl(hdr->cid); + whdr.type = RXRPC_PACKET_TYPE_RESPONSE; + whdr.flags = conn->out_clientflag; + whdr.securityIndex = hdr->securityIndex; + whdr.serviceId = htons(hdr->serviceId); + + iov[0].iov_base = &whdr; + iov[0].iov_len = sizeof(whdr); + iov[1].iov_base = resp; + iov[1].iov_len = sizeof(*resp); + iov[2].iov_base = (void *)s2->ticket; + iov[2].iov_len = s2->ticket_len; + + len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len; + + serial = atomic_inc_return(&conn->serial); + whdr.serial = htonl(serial); + + rxrpc_local_dont_fragment(conn->local, false); + ret = kernel_sendmsg(conn->local->socket, &msg, iov, 3, len); + rxrpc_local_dont_fragment(conn->local, true); + if (ret < 0) { + trace_rxrpc_tx_fail(conn->debug_id, serial, ret, + rxrpc_tx_point_rxkad_response); + return -EAGAIN; + } + + conn->peer->last_tx_at = ktime_get_seconds(); + _leave(" = 0"); + return 0; +} + +/* + * calculate the response checksum + */ +static void rxkad_calc_response_checksum(struct rxkad_response *response) +{ + u32 csum = 1000003; + int loop; + u8 *p = (u8 *) response; + + for (loop = sizeof(*response); loop > 0; loop--) + csum = csum * 0x10204081 + *p++; + + response->encrypted.checksum = htonl(csum); +} + +/* + * encrypt the response packet + */ +static int rxkad_encrypt_response(struct rxrpc_connection *conn, + struct rxkad_response *resp, + const struct rxkad_key *s2) +{ + struct skcipher_request *req; + struct rxrpc_crypt iv; + struct scatterlist sg[1]; + + req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS); + if (!req) + return -ENOMEM; + + /* continue encrypting from where we left off */ + memcpy(&iv, s2->session_key, sizeof(iv)); + + sg_init_table(sg, 1); + sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); + skcipher_request_set_sync_tfm(req, conn->rxkad.cipher); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); + crypto_skcipher_encrypt(req); + skcipher_request_free(req); + return 0; +} + +/* + * respond to a challenge packet + */ +static int rxkad_respond_to_challenge(struct rxrpc_connection *conn, + struct sk_buff *skb) +{ + const struct rxrpc_key_token *token; + struct rxkad_challenge challenge; + struct rxkad_response *resp; + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + u32 version, nonce, min_level; + int ret = -EPROTO; + + _enter("{%d,%x}", conn->debug_id, key_serial(conn->key)); + + if (!conn->key) + return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO, + rxkad_abort_chall_no_key); + + ret = key_validate(conn->key); + if (ret < 0) + return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret, + rxkad_abort_chall_key_expired); + + if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), + &challenge, sizeof(challenge)) < 0) + return rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, + rxkad_abort_chall_short); + + version = ntohl(challenge.version); + nonce = ntohl(challenge.nonce); + min_level = ntohl(challenge.min_level); + + trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, nonce, min_level); + + if (version != RXKAD_VERSION) + return rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO, + rxkad_abort_chall_version); + + if (conn->security_level < min_level) + return rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES, + rxkad_abort_chall_level); + + token = conn->key->payload.data[0]; + + /* build the response packet */ + resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS); + if (!resp) + return -ENOMEM; + + resp->version = htonl(RXKAD_VERSION); + resp->encrypted.epoch = htonl(conn->proto.epoch); + resp->encrypted.cid = htonl(conn->proto.cid); + resp->encrypted.securityIndex = htonl(conn->security_ix); + resp->encrypted.inc_nonce = htonl(nonce + 1); + resp->encrypted.level = htonl(conn->security_level); + resp->kvno = htonl(token->kad->kvno); + resp->ticket_len = htonl(token->kad->ticket_len); + resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter); + resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter); + resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter); + resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter); + + /* calculate the response checksum and then do the encryption */ + rxkad_calc_response_checksum(resp); + ret = rxkad_encrypt_response(conn, resp, token->kad); + if (ret == 0) + ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad); + kfree(resp); + return ret; +} + +/* + * decrypt the kerberos IV ticket in the response + */ +static int rxkad_decrypt_ticket(struct rxrpc_connection *conn, + struct key *server_key, + struct sk_buff *skb, + void *ticket, size_t ticket_len, + struct rxrpc_crypt *_session_key, + time64_t *_expiry) +{ + struct skcipher_request *req; + struct rxrpc_crypt iv, key; + struct scatterlist sg[1]; + struct in_addr addr; + unsigned int life; + time64_t issue, now; + bool little_endian; + u8 *p, *q, *name, *end; + + _enter("{%d},{%x}", conn->debug_id, key_serial(server_key)); + + *_expiry = 0; + + ASSERT(server_key->payload.data[0] != NULL); + ASSERTCMP((unsigned long) ticket & 7UL, ==, 0); + + memcpy(&iv, &server_key->payload.data[2], sizeof(iv)); + + req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS); + if (!req) + return -ENOMEM; + + sg_init_one(&sg[0], ticket, ticket_len); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x); + crypto_skcipher_decrypt(req); + skcipher_request_free(req); + + p = ticket; + end = p + ticket_len; + +#define Z(field, fieldl) \ + ({ \ + u8 *__str = p; \ + q = memchr(p, 0, end - p); \ + if (!q || q - p > field##_SZ) \ + return rxrpc_abort_conn( \ + conn, skb, RXKADBADTICKET, -EPROTO, \ + rxkad_abort_resp_tkt_##fieldl); \ + for (; p < q; p++) \ + if (!isprint(*p)) \ + return rxrpc_abort_conn( \ + conn, skb, RXKADBADTICKET, -EPROTO, \ + rxkad_abort_resp_tkt_##fieldl); \ + p++; \ + __str; \ + }) + + /* extract the ticket flags */ + _debug("KIV FLAGS: %x", *p); + little_endian = *p & 1; + p++; + + /* extract the authentication name */ + name = Z(ANAME, aname); + _debug("KIV ANAME: %s", name); + + /* extract the principal's instance */ + name = Z(INST, inst); + _debug("KIV INST : %s", name); + + /* extract the principal's authentication domain */ + name = Z(REALM, realm); + _debug("KIV REALM: %s", name); + + if (end - p < 4 + 8 + 4 + 2) + return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO, + rxkad_abort_resp_tkt_short); + + /* get the IPv4 address of the entity that requested the ticket */ + memcpy(&addr, p, sizeof(addr)); + p += 4; + _debug("KIV ADDR : %pI4", &addr); + + /* get the session key from the ticket */ + memcpy(&key, p, sizeof(key)); + p += 8; + _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1])); + memcpy(_session_key, &key, sizeof(key)); + + /* get the ticket's lifetime */ + life = *p++ * 5 * 60; + _debug("KIV LIFE : %u", life); + + /* get the issue time of the ticket */ + if (little_endian) { + __le32 stamp; + memcpy(&stamp, p, 4); + issue = rxrpc_u32_to_time64(le32_to_cpu(stamp)); + } else { + __be32 stamp; + memcpy(&stamp, p, 4); + issue = rxrpc_u32_to_time64(be32_to_cpu(stamp)); + } + p += 4; + now = ktime_get_real_seconds(); + _debug("KIV ISSUE: %llx [%llx]", issue, now); + + /* check the ticket is in date */ + if (issue > now) + return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED, + rxkad_abort_resp_tkt_future); + if (issue < now - life) + return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED, + rxkad_abort_resp_tkt_expired); + + *_expiry = issue + life; + + /* get the service name */ + name = Z(SNAME, sname); + _debug("KIV SNAME: %s", name); + + /* get the service instance name */ + name = Z(INST, sinst); + _debug("KIV SINST: %s", name); + return 0; +} + +/* + * decrypt the response packet + */ +static void rxkad_decrypt_response(struct rxrpc_connection *conn, + struct rxkad_response *resp, + const struct rxrpc_crypt *session_key) +{ + struct skcipher_request *req = rxkad_ci_req; + struct scatterlist sg[1]; + struct rxrpc_crypt iv; + + _enter(",,%08x%08x", + ntohl(session_key->n[0]), ntohl(session_key->n[1])); + + mutex_lock(&rxkad_ci_mutex); + if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x, + sizeof(*session_key)) < 0) + BUG(); + + memcpy(&iv, session_key, sizeof(iv)); + + sg_init_table(sg, 1); + sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted)); + skcipher_request_set_sync_tfm(req, rxkad_ci); + skcipher_request_set_callback(req, 0, NULL, NULL); + skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x); + crypto_skcipher_decrypt(req); + skcipher_request_zero(req); + + mutex_unlock(&rxkad_ci_mutex); + + _leave(""); +} + +/* + * verify a response + */ +static int rxkad_verify_response(struct rxrpc_connection *conn, + struct sk_buff *skb) +{ + struct rxkad_response *response; + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + struct rxrpc_crypt session_key; + struct key *server_key; + time64_t expiry; + void *ticket; + u32 version, kvno, ticket_len, level; + __be32 csum; + int ret, i; + + _enter("{%d}", conn->debug_id); + + server_key = rxrpc_look_up_server_security(conn, skb, 0, 0); + if (IS_ERR(server_key)) { + ret = PTR_ERR(server_key); + switch (ret) { + case -ENOKEY: + return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret, + rxkad_abort_resp_nokey); + case -EKEYEXPIRED: + return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret, + rxkad_abort_resp_key_expired); + default: + return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret, + rxkad_abort_resp_key_rejected); + } + } + + ret = -ENOMEM; + response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS); + if (!response) + goto temporary_error; + + if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), + response, sizeof(*response)) < 0) { + rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, + rxkad_abort_resp_short); + goto protocol_error; + } + + version = ntohl(response->version); + ticket_len = ntohl(response->ticket_len); + kvno = ntohl(response->kvno); + + trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len); + + if (version != RXKAD_VERSION) { + rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO, + rxkad_abort_resp_version); + goto protocol_error; + } + + if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) { + rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO, + rxkad_abort_resp_tkt_len); + goto protocol_error; + } + + if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) { + rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO, + rxkad_abort_resp_unknown_tkt); + goto protocol_error; + } + + /* extract the kerberos ticket and decrypt and decode it */ + ret = -ENOMEM; + ticket = kmalloc(ticket_len, GFP_NOFS); + if (!ticket) + goto temporary_error_free_resp; + + if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response), + ticket, ticket_len) < 0) { + rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO, + rxkad_abort_resp_short_tkt); + goto protocol_error; + } + + ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len, + &session_key, &expiry); + if (ret < 0) + goto temporary_error_free_ticket; + + /* use the session key from inside the ticket to decrypt the + * response */ + rxkad_decrypt_response(conn, response, &session_key); + + if (ntohl(response->encrypted.epoch) != conn->proto.epoch || + ntohl(response->encrypted.cid) != conn->proto.cid || + ntohl(response->encrypted.securityIndex) != conn->security_ix) { + rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, + rxkad_abort_resp_bad_param); + goto protocol_error_free; + } + + csum = response->encrypted.checksum; + response->encrypted.checksum = 0; + rxkad_calc_response_checksum(response); + if (response->encrypted.checksum != csum) { + rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, + rxkad_abort_resp_bad_checksum); + goto protocol_error_free; + } + + for (i = 0; i < RXRPC_MAXCALLS; i++) { + u32 call_id = ntohl(response->encrypted.call_id[i]); + u32 counter = READ_ONCE(conn->channels[i].call_counter); + + if (call_id > INT_MAX) { + rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, + rxkad_abort_resp_bad_callid); + goto protocol_error_free; + } + + if (call_id < counter) { + rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, + rxkad_abort_resp_call_ctr); + goto protocol_error_free; + } + + if (call_id > counter) { + if (conn->channels[i].call) { + rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO, + rxkad_abort_resp_call_state); + goto protocol_error_free; + } + conn->channels[i].call_counter = call_id; + } + } + + if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) { + rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO, + rxkad_abort_resp_ooseq); + goto protocol_error_free; + } + + level = ntohl(response->encrypted.level); + if (level > RXRPC_SECURITY_ENCRYPT) { + rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO, + rxkad_abort_resp_level); + goto protocol_error_free; + } + conn->security_level = level; + + /* create a key to hold the security data and expiration time - after + * this the connection security can be handled in exactly the same way + * as for a client connection */ + ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno); + if (ret < 0) + goto temporary_error_free_ticket; + + kfree(ticket); + kfree(response); + _leave(" = 0"); + return 0; + +protocol_error_free: + kfree(ticket); +protocol_error: + kfree(response); + key_put(server_key); + return -EPROTO; + +temporary_error_free_ticket: + kfree(ticket); +temporary_error_free_resp: + kfree(response); +temporary_error: + /* Ignore the response packet if we got a temporary error such as + * ENOMEM. We just want to send the challenge again. Note that we + * also come out this way if the ticket decryption fails. + */ + key_put(server_key); + return ret; +} + +/* + * clear the connection security + */ +static void rxkad_clear(struct rxrpc_connection *conn) +{ + _enter(""); + + if (conn->rxkad.cipher) + crypto_free_sync_skcipher(conn->rxkad.cipher); +} + +/* + * Initialise the rxkad security service. + */ +static int rxkad_init(void) +{ + struct crypto_sync_skcipher *tfm; + struct skcipher_request *req; + + /* pin the cipher we need so that the crypto layer doesn't invoke + * keventd to go get it */ + tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + req = skcipher_request_alloc(&tfm->base, GFP_KERNEL); + if (!req) + goto nomem_tfm; + + rxkad_ci_req = req; + rxkad_ci = tfm; + return 0; + +nomem_tfm: + crypto_free_sync_skcipher(tfm); + return -ENOMEM; +} + +/* + * Clean up the rxkad security service. + */ +static void rxkad_exit(void) +{ + crypto_free_sync_skcipher(rxkad_ci); + skcipher_request_free(rxkad_ci_req); +} + +/* + * RxRPC Kerberos-based security + */ +const struct rxrpc_security rxkad = { + .name = "rxkad", + .security_index = RXRPC_SECURITY_RXKAD, + .no_key_abort = RXKADUNKNOWNKEY, + .init = rxkad_init, + .exit = rxkad_exit, + .preparse_server_key = rxkad_preparse_server_key, + .free_preparse_server_key = rxkad_free_preparse_server_key, + .destroy_server_key = rxkad_destroy_server_key, + .init_connection_security = rxkad_init_connection_security, + .how_much_data = rxkad_how_much_data, + .secure_packet = rxkad_secure_packet, + .verify_packet = rxkad_verify_packet, + .free_call_crypto = rxkad_free_call_crypto, + .issue_challenge = rxkad_issue_challenge, + .respond_to_challenge = rxkad_respond_to_challenge, + .verify_response = rxkad_verify_response, + .clear = rxkad_clear, +}; |