| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * lib80211 crypt: host-based CCMP encryption implementation for lib80211 |
| * |
| * Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi> |
| * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com> |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/err.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/slab.h> |
| #include <linux/random.h> |
| #include <linux/skbuff.h> |
| #include <linux/netdevice.h> |
| #include <linux/if_ether.h> |
| #include <linux/if_arp.h> |
| #include <asm/string.h> |
| #include <linux/wireless.h> |
| |
| #include <linux/ieee80211.h> |
| |
| #include <linux/crypto.h> |
| #include <crypto/aead.h> |
| |
| #include <net/lib80211.h> |
| |
| MODULE_AUTHOR("Jouni Malinen"); |
| MODULE_DESCRIPTION("Host AP crypt: CCMP"); |
| MODULE_LICENSE("GPL"); |
| |
| #define AES_BLOCK_LEN 16 |
| #define CCMP_HDR_LEN 8 |
| #define CCMP_MIC_LEN 8 |
| #define CCMP_TK_LEN 16 |
| #define CCMP_PN_LEN 6 |
| |
| struct lib80211_ccmp_data { |
| u8 key[CCMP_TK_LEN]; |
| int key_set; |
| |
| u8 tx_pn[CCMP_PN_LEN]; |
| u8 rx_pn[CCMP_PN_LEN]; |
| |
| u32 dot11RSNAStatsCCMPFormatErrors; |
| u32 dot11RSNAStatsCCMPReplays; |
| u32 dot11RSNAStatsCCMPDecryptErrors; |
| |
| int key_idx; |
| |
| struct crypto_aead *tfm; |
| |
| /* scratch buffers for virt_to_page() (crypto API) */ |
| u8 tx_aad[2 * AES_BLOCK_LEN]; |
| u8 rx_aad[2 * AES_BLOCK_LEN]; |
| }; |
| |
| static void *lib80211_ccmp_init(int key_idx) |
| { |
| struct lib80211_ccmp_data *priv; |
| |
| priv = kzalloc(sizeof(*priv), GFP_ATOMIC); |
| if (priv == NULL) |
| goto fail; |
| priv->key_idx = key_idx; |
| |
| priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC); |
| if (IS_ERR(priv->tfm)) { |
| priv->tfm = NULL; |
| goto fail; |
| } |
| |
| return priv; |
| |
| fail: |
| if (priv) { |
| if (priv->tfm) |
| crypto_free_aead(priv->tfm); |
| kfree(priv); |
| } |
| |
| return NULL; |
| } |
| |
| static void lib80211_ccmp_deinit(void *priv) |
| { |
| struct lib80211_ccmp_data *_priv = priv; |
| if (_priv && _priv->tfm) |
| crypto_free_aead(_priv->tfm); |
| kfree(priv); |
| } |
| |
| static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr, |
| const u8 *pn, u8 *iv, u8 *aad) |
| { |
| u8 *pos, qc = 0; |
| size_t aad_len; |
| int a4_included, qc_included; |
| |
| a4_included = ieee80211_has_a4(hdr->frame_control); |
| qc_included = ieee80211_is_data_qos(hdr->frame_control); |
| |
| aad_len = 22; |
| if (a4_included) |
| aad_len += 6; |
| if (qc_included) { |
| pos = (u8 *) & hdr->addr4; |
| if (a4_included) |
| pos += 6; |
| qc = *pos & 0x0f; |
| aad_len += 2; |
| } |
| |
| /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC |
| * mode authentication are not allowed to collide, yet both are derived |
| * from the same vector. We only set L := 1 here to indicate that the |
| * data size can be represented in (L+1) bytes. The CCM layer will take |
| * care of storing the data length in the top (L+1) bytes and setting |
| * and clearing the other bits as is required to derive the two IVs. |
| */ |
| iv[0] = 0x1; |
| |
| /* Nonce: QC | A2 | PN */ |
| iv[1] = qc; |
| memcpy(iv + 2, hdr->addr2, ETH_ALEN); |
| memcpy(iv + 8, pn, CCMP_PN_LEN); |
| |
| /* AAD: |
| * FC with bits 4..6 and 11..13 masked to zero; 14 is always one |
| * A1 | A2 | A3 |
| * SC with bits 4..15 (seq#) masked to zero |
| * A4 (if present) |
| * QC (if present) |
| */ |
| pos = (u8 *) hdr; |
| aad[0] = pos[0] & 0x8f; |
| aad[1] = pos[1] & 0xc7; |
| memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN); |
| pos = (u8 *) & hdr->seq_ctrl; |
| aad[20] = pos[0] & 0x0f; |
| aad[21] = 0; /* all bits masked */ |
| memset(aad + 22, 0, 8); |
| if (a4_included) |
| memcpy(aad + 22, hdr->addr4, ETH_ALEN); |
| if (qc_included) { |
| aad[a4_included ? 28 : 22] = qc; |
| /* rest of QC masked */ |
| } |
| return aad_len; |
| } |
| |
| static int lib80211_ccmp_hdr(struct sk_buff *skb, int hdr_len, |
| u8 *aeskey, int keylen, void *priv) |
| { |
| struct lib80211_ccmp_data *key = priv; |
| int i; |
| u8 *pos; |
| |
| if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len) |
| return -1; |
| |
| if (aeskey != NULL && keylen >= CCMP_TK_LEN) |
| memcpy(aeskey, key->key, CCMP_TK_LEN); |
| |
| pos = skb_push(skb, CCMP_HDR_LEN); |
| memmove(pos, pos + CCMP_HDR_LEN, hdr_len); |
| pos += hdr_len; |
| |
| i = CCMP_PN_LEN - 1; |
| while (i >= 0) { |
| key->tx_pn[i]++; |
| if (key->tx_pn[i] != 0) |
| break; |
| i--; |
| } |
| |
| *pos++ = key->tx_pn[5]; |
| *pos++ = key->tx_pn[4]; |
| *pos++ = 0; |
| *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ; |
| *pos++ = key->tx_pn[3]; |
| *pos++ = key->tx_pn[2]; |
| *pos++ = key->tx_pn[1]; |
| *pos++ = key->tx_pn[0]; |
| |
| return CCMP_HDR_LEN; |
| } |
| |
| static int lib80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv) |
| { |
| struct lib80211_ccmp_data *key = priv; |
| struct ieee80211_hdr *hdr; |
| struct aead_request *req; |
| struct scatterlist sg[2]; |
| u8 *aad = key->tx_aad; |
| u8 iv[AES_BLOCK_LEN]; |
| int len, data_len, aad_len; |
| int ret; |
| |
| if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len) |
| return -1; |
| |
| data_len = skb->len - hdr_len; |
| len = lib80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv); |
| if (len < 0) |
| return -1; |
| |
| req = aead_request_alloc(key->tfm, GFP_ATOMIC); |
| if (!req) |
| return -ENOMEM; |
| |
| hdr = (struct ieee80211_hdr *)skb->data; |
| aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad); |
| |
| skb_put(skb, CCMP_MIC_LEN); |
| |
| sg_init_table(sg, 2); |
| sg_set_buf(&sg[0], aad, aad_len); |
| sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN, |
| data_len + CCMP_MIC_LEN); |
| |
| aead_request_set_callback(req, 0, NULL, NULL); |
| aead_request_set_ad(req, aad_len); |
| aead_request_set_crypt(req, sg, sg, data_len, iv); |
| |
| ret = crypto_aead_encrypt(req); |
| aead_request_free(req); |
| |
| return ret; |
| } |
| |
| /* |
| * deal with seq counter wrapping correctly. |
| * refer to timer_after() for jiffies wrapping handling |
| */ |
| static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o) |
| { |
| u32 iv32_n, iv16_n; |
| u32 iv32_o, iv16_o; |
| |
| iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3]; |
| iv16_n = (pn_n[4] << 8) | pn_n[5]; |
| |
| iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3]; |
| iv16_o = (pn_o[4] << 8) | pn_o[5]; |
| |
| if ((s32)iv32_n - (s32)iv32_o < 0 || |
| (iv32_n == iv32_o && iv16_n <= iv16_o)) |
| return 1; |
| return 0; |
| } |
| |
| static int lib80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv) |
| { |
| struct lib80211_ccmp_data *key = priv; |
| u8 keyidx, *pos; |
| struct ieee80211_hdr *hdr; |
| struct aead_request *req; |
| struct scatterlist sg[2]; |
| u8 *aad = key->rx_aad; |
| u8 iv[AES_BLOCK_LEN]; |
| u8 pn[6]; |
| int aad_len, ret; |
| size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN; |
| |
| if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) { |
| key->dot11RSNAStatsCCMPFormatErrors++; |
| return -1; |
| } |
| |
| hdr = (struct ieee80211_hdr *)skb->data; |
| pos = skb->data + hdr_len; |
| keyidx = pos[3]; |
| if (!(keyidx & (1 << 5))) { |
| net_dbg_ratelimited("CCMP: received packet without ExtIV flag from %pM\n", |
| hdr->addr2); |
| key->dot11RSNAStatsCCMPFormatErrors++; |
| return -2; |
| } |
| keyidx >>= 6; |
| if (key->key_idx != keyidx) { |
| net_dbg_ratelimited("CCMP: RX tkey->key_idx=%d frame keyidx=%d\n", |
| key->key_idx, keyidx); |
| return -6; |
| } |
| if (!key->key_set) { |
| net_dbg_ratelimited("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n", |
| hdr->addr2, keyidx); |
| return -3; |
| } |
| |
| pn[0] = pos[7]; |
| pn[1] = pos[6]; |
| pn[2] = pos[5]; |
| pn[3] = pos[4]; |
| pn[4] = pos[1]; |
| pn[5] = pos[0]; |
| pos += 8; |
| |
| if (ccmp_replay_check(pn, key->rx_pn)) { |
| #ifdef CONFIG_LIB80211_DEBUG |
| net_dbg_ratelimited("CCMP: replay detected: STA=%pM previous PN %02x%02x%02x%02x%02x%02x received PN %02x%02x%02x%02x%02x%02x\n", |
| hdr->addr2, |
| key->rx_pn[0], key->rx_pn[1], key->rx_pn[2], |
| key->rx_pn[3], key->rx_pn[4], key->rx_pn[5], |
| pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]); |
| #endif |
| key->dot11RSNAStatsCCMPReplays++; |
| return -4; |
| } |
| |
| req = aead_request_alloc(key->tfm, GFP_ATOMIC); |
| if (!req) |
| return -ENOMEM; |
| |
| aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad); |
| |
| sg_init_table(sg, 2); |
| sg_set_buf(&sg[0], aad, aad_len); |
| sg_set_buf(&sg[1], pos, data_len); |
| |
| aead_request_set_callback(req, 0, NULL, NULL); |
| aead_request_set_ad(req, aad_len); |
| aead_request_set_crypt(req, sg, sg, data_len, iv); |
| |
| ret = crypto_aead_decrypt(req); |
| aead_request_free(req); |
| |
| if (ret) { |
| net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM (%d)\n", |
| hdr->addr2, ret); |
| key->dot11RSNAStatsCCMPDecryptErrors++; |
| return -5; |
| } |
| |
| memcpy(key->rx_pn, pn, CCMP_PN_LEN); |
| |
| /* Remove hdr and MIC */ |
| memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len); |
| skb_pull(skb, CCMP_HDR_LEN); |
| skb_trim(skb, skb->len - CCMP_MIC_LEN); |
| |
| return keyidx; |
| } |
| |
| static int lib80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv) |
| { |
| struct lib80211_ccmp_data *data = priv; |
| int keyidx; |
| struct crypto_aead *tfm = data->tfm; |
| |
| keyidx = data->key_idx; |
| memset(data, 0, sizeof(*data)); |
| data->key_idx = keyidx; |
| data->tfm = tfm; |
| if (len == CCMP_TK_LEN) { |
| memcpy(data->key, key, CCMP_TK_LEN); |
| data->key_set = 1; |
| if (seq) { |
| data->rx_pn[0] = seq[5]; |
| data->rx_pn[1] = seq[4]; |
| data->rx_pn[2] = seq[3]; |
| data->rx_pn[3] = seq[2]; |
| data->rx_pn[4] = seq[1]; |
| data->rx_pn[5] = seq[0]; |
| } |
| if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) || |
| crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN)) |
| return -1; |
| } else if (len == 0) |
| data->key_set = 0; |
| else |
| return -1; |
| |
| return 0; |
| } |
| |
| static int lib80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv) |
| { |
| struct lib80211_ccmp_data *data = priv; |
| |
| if (len < CCMP_TK_LEN) |
| return -1; |
| |
| if (!data->key_set) |
| return 0; |
| memcpy(key, data->key, CCMP_TK_LEN); |
| |
| if (seq) { |
| seq[0] = data->tx_pn[5]; |
| seq[1] = data->tx_pn[4]; |
| seq[2] = data->tx_pn[3]; |
| seq[3] = data->tx_pn[2]; |
| seq[4] = data->tx_pn[1]; |
| seq[5] = data->tx_pn[0]; |
| } |
| |
| return CCMP_TK_LEN; |
| } |
| |
| static void lib80211_ccmp_print_stats(struct seq_file *m, void *priv) |
| { |
| struct lib80211_ccmp_data *ccmp = priv; |
| |
| seq_printf(m, |
| "key[%d] alg=CCMP key_set=%d " |
| "tx_pn=%02x%02x%02x%02x%02x%02x " |
| "rx_pn=%02x%02x%02x%02x%02x%02x " |
| "format_errors=%d replays=%d decrypt_errors=%d\n", |
| ccmp->key_idx, ccmp->key_set, |
| ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2], |
| ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5], |
| ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2], |
| ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5], |
| ccmp->dot11RSNAStatsCCMPFormatErrors, |
| ccmp->dot11RSNAStatsCCMPReplays, |
| ccmp->dot11RSNAStatsCCMPDecryptErrors); |
| } |
| |
| static struct lib80211_crypto_ops lib80211_crypt_ccmp = { |
| .name = "CCMP", |
| .init = lib80211_ccmp_init, |
| .deinit = lib80211_ccmp_deinit, |
| .encrypt_mpdu = lib80211_ccmp_encrypt, |
| .decrypt_mpdu = lib80211_ccmp_decrypt, |
| .encrypt_msdu = NULL, |
| .decrypt_msdu = NULL, |
| .set_key = lib80211_ccmp_set_key, |
| .get_key = lib80211_ccmp_get_key, |
| .print_stats = lib80211_ccmp_print_stats, |
| .extra_mpdu_prefix_len = CCMP_HDR_LEN, |
| .extra_mpdu_postfix_len = CCMP_MIC_LEN, |
| .owner = THIS_MODULE, |
| }; |
| |
| static int __init lib80211_crypto_ccmp_init(void) |
| { |
| return lib80211_register_crypto_ops(&lib80211_crypt_ccmp); |
| } |
| |
| static void __exit lib80211_crypto_ccmp_exit(void) |
| { |
| lib80211_unregister_crypto_ops(&lib80211_crypt_ccmp); |
| } |
| |
| module_init(lib80211_crypto_ccmp_init); |
| module_exit(lib80211_crypto_ccmp_exit); |