/* Kerberos-based RxRPC security * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * 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. */ #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 <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 */ 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 */ }; /* * 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_skcipher *rxkad_ci; static DEFINE_MUTEX(rxkad_ci_mutex); /* * initialise connection security */ static int rxkad_init_connection_security(struct rxrpc_connection *conn) { struct crypto_skcipher *ci; struct rxrpc_key_token *token; int ret; _enter("{%d},{%x}", conn->debug_id, key_serial(conn->params.key)); token = conn->params.key->payload.data[0]; conn->security_ix = token->security_index; ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC); if (IS_ERR(ci)) { _debug("no cipher"); ret = PTR_ERR(ci); goto error; } if (crypto_skcipher_setkey(ci, token->kad->session_key, sizeof(token->kad->session_key)) < 0) BUG(); switch (conn->params.security_level) { case RXRPC_SECURITY_PLAIN: break; case RXRPC_SECURITY_AUTH: conn->size_align = 8; conn->security_size = sizeof(struct rxkad_level1_hdr); break; case RXRPC_SECURITY_ENCRYPT: conn->size_align = 8; conn->security_size = sizeof(struct rxkad_level2_hdr); break; default: ret = -EKEYREJECTED; goto error; } conn->cipher = ci; ret = 0; error: _leave(" = %d", ret); return ret; } /* * prime the encryption state with the invariant parts of a connection's * description */ static int rxkad_prime_packet_security(struct rxrpc_connection *conn) { struct rxrpc_key_token *token; SKCIPHER_REQUEST_ON_STACK(req, conn->cipher); struct scatterlist sg; struct rxrpc_crypt iv; __be32 *tmpbuf; size_t tmpsize = 4 * sizeof(__be32); _enter(""); if (!conn->params.key) return 0; tmpbuf = kmalloc(tmpsize, GFP_KERNEL); if (!tmpbuf) return -ENOMEM; token = conn->params.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_tfm(req, conn->cipher); skcipher_request_set_callback(req, 0, NULL, NULL); skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x); crypto_skcipher_encrypt(req); skcipher_request_zero(req); memcpy(&conn->csum_iv, tmpbuf + 2, sizeof(conn->csum_iv)); kfree(tmpbuf); _leave(" = 0"); return 0; } /* * partially encrypt a packet (level 1 security) */ static int rxkad_secure_packet_auth(const struct rxrpc_call *call, struct sk_buff *skb, u32 data_size, void *sechdr) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher); struct rxkad_level1_hdr hdr; struct rxrpc_crypt iv; struct scatterlist sg; u16 check; _enter(""); check = sp->hdr.seq ^ call->call_id; data_size |= (u32)check << 16; hdr.data_size = htonl(data_size); memcpy(sechdr, &hdr, sizeof(hdr)); /* start the encryption afresh */ memset(&iv, 0, sizeof(iv)); sg_init_one(&sg, sechdr, 8); skcipher_request_set_tfm(req, call->conn->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 sk_buff *skb, u32 data_size, void *sechdr) { const struct rxrpc_key_token *token; struct rxkad_level2_hdr rxkhdr; struct rxrpc_skb_priv *sp; SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher); struct rxrpc_crypt iv; struct scatterlist sg[16]; struct sk_buff *trailer; unsigned int len; u16 check; int nsg; int err; sp = rxrpc_skb(skb); _enter(""); check = sp->hdr.seq ^ call->call_id; rxkhdr.data_size = htonl(data_size | (u32)check << 16); rxkhdr.checksum = 0; memcpy(sechdr, &rxkhdr, sizeof(rxkhdr)); /* encrypt from the session key */ token = call->conn->params.key->payload.data[0]; memcpy(&iv, token->kad->session_key, sizeof(iv)); sg_init_one(&sg[0], sechdr, sizeof(rxkhdr)); skcipher_request_set_tfm(req, call->conn->cipher); skcipher_request_set_callback(req, 0, NULL, NULL); skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x); crypto_skcipher_encrypt(req); /* we want to encrypt the skbuff in-place */ nsg = skb_cow_data(skb, 0, &trailer); err = -ENOMEM; if (nsg < 0 || nsg > 16) goto out; len = data_size + call->conn->size_align - 1; len &= ~(call->conn->size_align - 1); sg_init_table(sg, nsg); skb_to_sgvec(skb, sg, 0, len); skcipher_request_set_crypt(req, sg, sg, len, iv.x); crypto_skcipher_encrypt(req); _leave(" = 0"); err = 0; out: skcipher_request_zero(req); return err; } /* * checksum an RxRPC packet header */ static int rxkad_secure_packet(struct rxrpc_call *call, struct sk_buff *skb, size_t data_size, void *sechdr) { struct rxrpc_skb_priv *sp; SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher); struct rxrpc_crypt iv; struct scatterlist sg; u32 x, y; int ret; sp = rxrpc_skb(skb); _enter("{%d{%x}},{#%u},%zu,", call->debug_id, key_serial(call->conn->params.key), sp->hdr.seq, data_size); if (!call->conn->cipher) return 0; ret = key_validate(call->conn->params.key); if (ret < 0) return ret; /* continue encrypting from where we left off */ memcpy(&iv, call->conn->csum_iv.x, sizeof(iv)); /* calculate the security checksum */ x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); x |= sp->hdr.seq & 0x3fffffff; call->crypto_buf[0] = htonl(call->call_id); call->crypto_buf[1] = htonl(x); sg_init_one(&sg, call->crypto_buf, 8); skcipher_request_set_tfm(req, call->conn->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(call->crypto_buf[1]); y = (y >> 16) & 0xffff; if (y == 0) y = 1; /* zero checksums are not permitted */ sp->hdr.cksum = y; switch (call->conn->params.security_level) { case RXRPC_SECURITY_PLAIN: ret = 0; break; case RXRPC_SECURITY_AUTH: ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr); break; case RXRPC_SECURITY_ENCRYPT: ret = rxkad_secure_packet_encrypt(call, skb, data_size, sechdr); break; default: ret = -EPERM; break; } _leave(" = %d [set %hx]", 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, unsigned int offset, unsigned int len, rxrpc_seq_t seq) { struct rxkad_level1_hdr sechdr; SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher); struct rxrpc_crypt iv; struct scatterlist sg[16]; struct sk_buff *trailer; bool aborted; u32 data_size, buf; u16 check; int nsg; _enter(""); if (len < 8) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_hdr", "V1H", RXKADSEALEDINCON); goto protocol_error; } /* Decrypt the skbuff in-place. TODO: We really want to decrypt * directly into the target buffer. */ nsg = skb_cow_data(skb, 0, &trailer); if (nsg < 0 || nsg > 16) goto nomem; sg_init_table(sg, nsg); skb_to_sgvec(skb, sg, offset, 8); /* start the decryption afresh */ memset(&iv, 0, sizeof(iv)); skcipher_request_set_tfm(req, call->conn->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, offset, &sechdr, sizeof(sechdr)) < 0) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_len", "XV1", RXKADDATALEN); goto protocol_error; } offset += sizeof(sechdr); 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) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_check", "V1C", RXKADSEALEDINCON); goto protocol_error; } if (data_size > len) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_datalen", "V1L", RXKADDATALEN); goto protocol_error; } _leave(" = 0 [dlen=%x]", data_size); return 0; protocol_error: if (aborted) rxrpc_send_abort_packet(call); return -EPROTO; nomem: _leave(" = -ENOMEM"); return -ENOMEM; } /* * wholly decrypt a packet (level 2 security) */ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb, unsigned int offset, unsigned int len, rxrpc_seq_t seq) { const struct rxrpc_key_token *token; struct rxkad_level2_hdr sechdr; SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher); struct rxrpc_crypt iv; struct scatterlist _sg[4], *sg; struct sk_buff *trailer; bool aborted; u32 data_size, buf; u16 check; int nsg; _enter(",{%d}", skb->len); if (len < 8) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_hdr", "V2H", RXKADSEALEDINCON); goto protocol_error; } /* Decrypt the skbuff in-place. TODO: We really want to decrypt * directly into the target buffer. */ nsg = skb_cow_data(skb, 0, &trailer); if (nsg < 0) goto nomem; sg = _sg; if (unlikely(nsg > 4)) { sg = kmalloc(sizeof(*sg) * nsg, GFP_NOIO); if (!sg) goto nomem; } sg_init_table(sg, nsg); skb_to_sgvec(skb, sg, offset, len); /* decrypt from the session key */ token = call->conn->params.key->payload.data[0]; memcpy(&iv, token->kad->session_key, sizeof(iv)); skcipher_request_set_tfm(req, call->conn->cipher); skcipher_request_set_callback(req, 0, NULL, NULL); skcipher_request_set_crypt(req, sg, sg, 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, offset, &sechdr, sizeof(sechdr)) < 0) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_len", "XV2", RXKADDATALEN); goto protocol_error; } offset += sizeof(sechdr); 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) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_check", "V2C", RXKADSEALEDINCON); goto protocol_error; } if (data_size > len) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_datalen", "V2L", RXKADDATALEN); goto protocol_error; } _leave(" = 0 [dlen=%x]", data_size); return 0; protocol_error: if (aborted) rxrpc_send_abort_packet(call); return -EPROTO; nomem: _leave(" = -ENOMEM"); return -ENOMEM; } /* * Verify the security on a received packet or subpacket (if part of a * jumbo packet). */ static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb, unsigned int offset, unsigned int len, rxrpc_seq_t seq, u16 expected_cksum) { SKCIPHER_REQUEST_ON_STACK(req, call->conn->cipher); struct rxrpc_crypt iv; struct scatterlist sg; bool aborted; u16 cksum; u32 x, y; _enter("{%d{%x}},{#%u}", call->debug_id, key_serial(call->conn->params.key), seq); if (!call->conn->cipher) return 0; /* continue encrypting from where we left off */ memcpy(&iv, call->conn->csum_iv.x, sizeof(iv)); /* validate the security checksum */ x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT); x |= seq & 0x3fffffff; call->crypto_buf[0] = htonl(call->call_id); call->crypto_buf[1] = htonl(x); sg_init_one(&sg, call->crypto_buf, 8); skcipher_request_set_tfm(req, call->conn->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(call->crypto_buf[1]); cksum = (y >> 16) & 0xffff; if (cksum == 0) cksum = 1; /* zero checksums are not permitted */ if (cksum != expected_cksum) { aborted = rxrpc_abort_eproto(call, skb, "rxkad_csum", "VCK", RXKADSEALEDINCON); goto protocol_error; } switch (call->conn->params.security_level) { case RXRPC_SECURITY_PLAIN: return 0; case RXRPC_SECURITY_AUTH: return rxkad_verify_packet_1(call, skb, offset, len, seq); case RXRPC_SECURITY_ENCRYPT: return rxkad_verify_packet_2(call, skb, offset, len, seq); default: return -ENOANO; } protocol_error: if (aborted) rxrpc_send_abort_packet(call); return -EPROTO; } /* * Locate the data contained in a packet that was partially encrypted. */ static void rxkad_locate_data_1(struct rxrpc_call *call, struct sk_buff *skb, unsigned int *_offset, unsigned int *_len) { struct rxkad_level1_hdr sechdr; if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0) BUG(); *_offset += sizeof(sechdr); *_len = ntohl(sechdr.data_size) & 0xffff; } /* * Locate the data contained in a packet that was completely encrypted. */ static void rxkad_locate_data_2(struct rxrpc_call *call, struct sk_buff *skb, unsigned int *_offset, unsigned int *_len) { struct rxkad_level2_hdr sechdr; if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0) BUG(); *_offset += sizeof(sechdr); *_len = ntohl(sechdr.data_size) & 0xffff; } /* * Locate the data contained in an already decrypted packet. */ static void rxkad_locate_data(struct rxrpc_call *call, struct sk_buff *skb, unsigned int *_offset, unsigned int *_len) { switch (call->conn->params.security_level) { case RXRPC_SECURITY_AUTH: rxkad_locate_data_1(call, skb, _offset, _len); return; case RXRPC_SECURITY_ENCRYPT: rxkad_locate_data_2(call, skb, _offset, _len); return; default: return; } } /* * 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,%x}", conn->debug_id, key_serial(conn->params.key)); ret = key_validate(conn->params.key); if (ret < 0) return ret; get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce)); challenge.version = htonl(2); challenge.nonce = htonl(conn->security_nonce); challenge.min_level = htonl(0); challenge.__padding = 0; msg.msg_name = &conn->params.peer->srx.transport.sin; msg.msg_namelen = sizeof(conn->params.peer->srx.transport.sin); 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->params.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); _proto("Tx CHALLENGE %%%u", serial); ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len); if (ret < 0) { _debug("sendmsg failed: %d", ret); return -EAGAIN; } _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->params.peer->srx.transport.sin; msg.msg_namelen = sizeof(conn->params.peer->srx.transport.sin); 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); _proto("Tx RESPONSE %%%u", serial); ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 3, len); if (ret < 0) { _debug("sendmsg failed: %d", ret); return -EAGAIN; } _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 void rxkad_encrypt_response(struct rxrpc_connection *conn, struct rxkad_response *resp, const struct rxkad_key *s2) { SKCIPHER_REQUEST_ON_STACK(req, conn->cipher); struct rxrpc_crypt iv; struct scatterlist sg[1]; /* 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_tfm(req, conn->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_zero(req); } /* * respond to a challenge packet */ static int rxkad_respond_to_challenge(struct rxrpc_connection *conn, struct sk_buff *skb, u32 *_abort_code) { const struct rxrpc_key_token *token; struct rxkad_challenge challenge; struct rxkad_response resp __attribute__((aligned(8))); /* must be aligned for crypto */ struct rxrpc_skb_priv *sp = rxrpc_skb(skb); const char *eproto; u32 version, nonce, min_level, abort_code; int ret; _enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key)); eproto = tracepoint_string("chall_no_key"); abort_code = RX_PROTOCOL_ERROR; if (!conn->params.key) goto protocol_error; abort_code = RXKADEXPIRED; ret = key_validate(conn->params.key); if (ret < 0) goto other_error; eproto = tracepoint_string("chall_short"); abort_code = RXKADPACKETSHORT; if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), &challenge, sizeof(challenge)) < 0) goto protocol_error; version = ntohl(challenge.version); nonce = ntohl(challenge.nonce); min_level = ntohl(challenge.min_level); _proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }", sp->hdr.serial, version, nonce, min_level); eproto = tracepoint_string("chall_ver"); abort_code = RXKADINCONSISTENCY; if (version != RXKAD_VERSION) goto protocol_error; abort_code = RXKADLEVELFAIL; ret = -EACCES; if (conn->params.security_level < min_level) goto other_error; token = conn->params.key->payload.data[0]; /* build the response packet */ memset(&resp, 0, sizeof(resp)); 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->params.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); rxkad_encrypt_response(conn, &resp, token->kad); return rxkad_send_response(conn, &sp->hdr, &resp, token->kad); protocol_error: trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto); ret = -EPROTO; other_error: *_abort_code = abort_code; return ret; } /* * decrypt the kerberos IV ticket in the response */ static int rxkad_decrypt_ticket(struct rxrpc_connection *conn, struct sk_buff *skb, void *ticket, size_t ticket_len, struct rxrpc_crypt *_session_key, time_t *_expiry, u32 *_abort_code) { struct skcipher_request *req; struct rxrpc_skb_priv *sp = rxrpc_skb(skb); struct rxrpc_crypt iv, key; struct scatterlist sg[1]; struct in_addr addr; unsigned int life; const char *eproto; time_t issue, now; bool little_endian; int ret; u32 abort_code; u8 *p, *q, *name, *end; _enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key)); *_expiry = 0; ret = key_validate(conn->server_key); if (ret < 0) { switch (ret) { case -EKEYEXPIRED: abort_code = RXKADEXPIRED; goto other_error; default: abort_code = RXKADNOAUTH; goto other_error; } } ASSERT(conn->server_key->payload.data[0] != NULL); ASSERTCMP((unsigned long) ticket & 7UL, ==, 0); memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv)); ret = -ENOMEM; req = skcipher_request_alloc(conn->server_key->payload.data[0], GFP_NOFS); if (!req) goto temporary_error; 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) \ ({ \ u8 *__str = p; \ eproto = tracepoint_string("rxkad_bad_"#field); \ q = memchr(p, 0, end - p); \ if (!q || q - p > (field##_SZ)) \ goto bad_ticket; \ for (; p < q; p++) \ if (!isprint(*p)) \ goto bad_ticket; \ p++; \ __str; \ }) /* extract the ticket flags */ _debug("KIV FLAGS: %x", *p); little_endian = *p & 1; p++; /* extract the authentication name */ name = Z(ANAME); _debug("KIV ANAME: %s", name); /* extract the principal's instance */ name = Z(INST); _debug("KIV INST : %s", name); /* extract the principal's authentication domain */ name = Z(REALM); _debug("KIV REALM: %s", name); eproto = tracepoint_string("rxkad_bad_len"); if (end - p < 4 + 8 + 4 + 2) goto bad_ticket; /* 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 = le32_to_cpu(stamp); } else { __be32 stamp; memcpy(&stamp, p, 4); issue = be32_to_cpu(stamp); } p += 4; now = get_seconds(); _debug("KIV ISSUE: %lx [%lx]", issue, now); /* check the ticket is in date */ if (issue > now) { abort_code = RXKADNOAUTH; ret = -EKEYREJECTED; goto other_error; } if (issue < now - life) { abort_code = RXKADEXPIRED; ret = -EKEYEXPIRED; goto other_error; } *_expiry = issue + life; /* get the service name */ name = Z(SNAME); _debug("KIV SNAME: %s", name); /* get the service instance name */ name = Z(INST); _debug("KIV SINST: %s", name); return 0; bad_ticket: trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto); abort_code = RXKADBADTICKET; ret = -EPROTO; other_error: *_abort_code = abort_code; return ret; temporary_error: return ret; } /* * decrypt the response packet */ static void rxkad_decrypt_response(struct rxrpc_connection *conn, struct rxkad_response *resp, const struct rxrpc_crypt *session_key) { SKCIPHER_REQUEST_ON_STACK(req, rxkad_ci); struct scatterlist sg[1]; struct rxrpc_crypt iv; _enter(",,%08x%08x", ntohl(session_key->n[0]), ntohl(session_key->n[1])); ASSERT(rxkad_ci != NULL); mutex_lock(&rxkad_ci_mutex); if (crypto_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_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, u32 *_abort_code) { struct rxkad_response response __attribute__((aligned(8))); /* must be aligned for crypto */ struct rxrpc_skb_priv *sp = rxrpc_skb(skb); struct rxrpc_crypt session_key; const char *eproto; time_t expiry; void *ticket; u32 abort_code, version, kvno, ticket_len, level; __be32 csum; int ret, i; _enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key)); eproto = tracepoint_string("rxkad_rsp_short"); abort_code = RXKADPACKETSHORT; if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), &response, sizeof(response)) < 0) goto protocol_error; if (!pskb_pull(skb, sizeof(response))) BUG(); version = ntohl(response.version); ticket_len = ntohl(response.ticket_len); kvno = ntohl(response.kvno); _proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }", sp->hdr.serial, version, kvno, ticket_len); eproto = tracepoint_string("rxkad_rsp_ver"); abort_code = RXKADINCONSISTENCY; if (version != RXKAD_VERSION) goto protocol_error; eproto = tracepoint_string("rxkad_rsp_tktlen"); abort_code = RXKADTICKETLEN; if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) goto protocol_error; eproto = tracepoint_string("rxkad_rsp_unkkey"); abort_code = RXKADUNKNOWNKEY; if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) 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; eproto = tracepoint_string("rxkad_tkt_short"); abort_code = RXKADPACKETSHORT; if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header), ticket, ticket_len) < 0) goto protocol_error_free; ret = rxkad_decrypt_ticket(conn, skb, ticket, ticket_len, &session_key, &expiry, _abort_code); if (ret < 0) goto temporary_error_free; /* use the session key from inside the ticket to decrypt the * response */ rxkad_decrypt_response(conn, &response, &session_key); eproto = tracepoint_string("rxkad_rsp_param"); abort_code = RXKADSEALEDINCON; if (ntohl(response.encrypted.epoch) != conn->proto.epoch) goto protocol_error_free; if (ntohl(response.encrypted.cid) != conn->proto.cid) goto protocol_error_free; if (ntohl(response.encrypted.securityIndex) != conn->security_ix) goto protocol_error_free; csum = response.encrypted.checksum; response.encrypted.checksum = 0; rxkad_calc_response_checksum(&response); eproto = tracepoint_string("rxkad_rsp_csum"); if (response.encrypted.checksum != csum) goto protocol_error_free; spin_lock(&conn->channel_lock); for (i = 0; i < RXRPC_MAXCALLS; i++) { struct rxrpc_call *call; u32 call_id = ntohl(response.encrypted.call_id[i]); eproto = tracepoint_string("rxkad_rsp_callid"); if (call_id > INT_MAX) goto protocol_error_unlock; eproto = tracepoint_string("rxkad_rsp_callctr"); if (call_id < conn->channels[i].call_counter) goto protocol_error_unlock; eproto = tracepoint_string("rxkad_rsp_callst"); if (call_id > conn->channels[i].call_counter) { call = rcu_dereference_protected( conn->channels[i].call, lockdep_is_held(&conn->channel_lock)); if (call && call->state < RXRPC_CALL_COMPLETE) goto protocol_error_unlock; conn->channels[i].call_counter = call_id; } } spin_unlock(&conn->channel_lock); eproto = tracepoint_string("rxkad_rsp_seq"); abort_code = RXKADOUTOFSEQUENCE; if (ntohl(response.encrypted.inc_nonce) != conn->security_nonce + 1) goto protocol_error_free; eproto = tracepoint_string("rxkad_rsp_level"); abort_code = RXKADLEVELFAIL; level = ntohl(response.encrypted.level); if (level > RXRPC_SECURITY_ENCRYPT) goto protocol_error_free; conn->params.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; kfree(ticket); _leave(" = 0"); return 0; protocol_error_unlock: spin_unlock(&conn->channel_lock); protocol_error_free: kfree(ticket); protocol_error: trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto); *_abort_code = abort_code; return -EPROTO; temporary_error_free: kfree(ticket); 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. */ return ret; } /* * clear the connection security */ static void rxkad_clear(struct rxrpc_connection *conn) { _enter(""); if (conn->cipher) crypto_free_skcipher(conn->cipher); } /* * Initialise the rxkad security service. */ static int rxkad_init(void) { /* pin the cipher we need so that the crypto layer doesn't invoke * keventd to go get it */ rxkad_ci = crypto_alloc_skcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC); return PTR_ERR_OR_ZERO(rxkad_ci); } /* * Clean up the rxkad security service. */ static void rxkad_exit(void) { if (rxkad_ci) crypto_free_skcipher(rxkad_ci); } /* * RxRPC Kerberos-based security */ const struct rxrpc_security rxkad = { .name = "rxkad", .security_index = RXRPC_SECURITY_RXKAD, .init = rxkad_init, .exit = rxkad_exit, .init_connection_security = rxkad_init_connection_security, .prime_packet_security = rxkad_prime_packet_security, .secure_packet = rxkad_secure_packet, .verify_packet = rxkad_verify_packet, .locate_data = rxkad_locate_data, .issue_challenge = rxkad_issue_challenge, .respond_to_challenge = rxkad_respond_to_challenge, .verify_response = rxkad_verify_response, .clear = rxkad_clear, };