| 1 | /* |
| 2 | * EAP common peer/server definitions |
| 3 | * Copyright (c) 2004-2012, Jouni Malinen <j@w1.fi> |
| 4 | * |
| 5 | * This software may be distributed under the terms of the BSD license. |
| 6 | * See README for more details. |
| 7 | */ |
| 8 | |
| 9 | #include "includes.h" |
| 10 | |
| 11 | #include "common.h" |
| 12 | #include "eap_defs.h" |
| 13 | #include "eap_common.h" |
| 14 | |
| 15 | /** |
| 16 | * eap_hdr_len_valid - Validate EAP header length field |
| 17 | * @msg: EAP frame (starting with EAP header) |
| 18 | * @min_payload: Minimum payload length needed |
| 19 | * Returns: 1 for valid header, 0 for invalid |
| 20 | * |
| 21 | * This is a helper function that does minimal validation of EAP messages. The |
| 22 | * length field is verified to be large enough to include the header and not |
| 23 | * too large to go beyond the end of the buffer. |
| 24 | */ |
| 25 | int eap_hdr_len_valid(const struct wpabuf *msg, size_t min_payload) |
| 26 | { |
| 27 | const struct eap_hdr *hdr; |
| 28 | size_t len; |
| 29 | |
| 30 | if (msg == NULL) |
| 31 | return 0; |
| 32 | |
| 33 | hdr = wpabuf_head(msg); |
| 34 | |
| 35 | if (wpabuf_len(msg) < sizeof(*hdr)) { |
| 36 | wpa_printf(MSG_INFO, "EAP: Too short EAP frame"); |
| 37 | return 0; |
| 38 | } |
| 39 | |
| 40 | len = be_to_host16(hdr->length); |
| 41 | if (len < sizeof(*hdr) + min_payload || len > wpabuf_len(msg)) { |
| 42 | wpa_printf(MSG_INFO, "EAP: Invalid EAP length"); |
| 43 | return 0; |
| 44 | } |
| 45 | |
| 46 | return 1; |
| 47 | } |
| 48 | |
| 49 | |
| 50 | /** |
| 51 | * eap_hdr_validate - Validate EAP header |
| 52 | * @vendor: Expected EAP Vendor-Id (0 = IETF) |
| 53 | * @eap_type: Expected EAP type number |
| 54 | * @msg: EAP frame (starting with EAP header) |
| 55 | * @plen: Pointer to variable to contain the returned payload length |
| 56 | * Returns: Pointer to EAP payload (after type field), or %NULL on failure |
| 57 | * |
| 58 | * This is a helper function for EAP method implementations. This is usually |
| 59 | * called in the beginning of struct eap_method::process() function to verify |
| 60 | * that the received EAP request packet has a valid header. This function is |
| 61 | * able to process both legacy and expanded EAP headers and in most cases, the |
| 62 | * caller can just use the returned payload pointer (into *plen) for processing |
| 63 | * the payload regardless of whether the packet used the expanded EAP header or |
| 64 | * not. |
| 65 | */ |
| 66 | const u8 * eap_hdr_validate(int vendor, EapType eap_type, |
| 67 | const struct wpabuf *msg, size_t *plen) |
| 68 | { |
| 69 | const struct eap_hdr *hdr; |
| 70 | const u8 *pos; |
| 71 | size_t len; |
| 72 | |
| 73 | if (!eap_hdr_len_valid(msg, 1)) |
| 74 | return NULL; |
| 75 | |
| 76 | hdr = wpabuf_head(msg); |
| 77 | len = be_to_host16(hdr->length); |
| 78 | pos = (const u8 *) (hdr + 1); |
| 79 | |
| 80 | if (*pos == EAP_TYPE_EXPANDED) { |
| 81 | int exp_vendor; |
| 82 | u32 exp_type; |
| 83 | if (len < sizeof(*hdr) + 8) { |
| 84 | wpa_printf(MSG_INFO, "EAP: Invalid expanded EAP " |
| 85 | "length"); |
| 86 | return NULL; |
| 87 | } |
| 88 | pos++; |
| 89 | exp_vendor = WPA_GET_BE24(pos); |
| 90 | pos += 3; |
| 91 | exp_type = WPA_GET_BE32(pos); |
| 92 | pos += 4; |
| 93 | if (exp_vendor != vendor || exp_type != (u32) eap_type) { |
| 94 | wpa_printf(MSG_INFO, "EAP: Invalid expanded frame " |
| 95 | "type"); |
| 96 | return NULL; |
| 97 | } |
| 98 | |
| 99 | *plen = len - sizeof(*hdr) - 8; |
| 100 | return pos; |
| 101 | } else { |
| 102 | if (vendor != EAP_VENDOR_IETF || *pos != eap_type) { |
| 103 | wpa_printf(MSG_INFO, "EAP: Invalid frame type"); |
| 104 | return NULL; |
| 105 | } |
| 106 | *plen = len - sizeof(*hdr) - 1; |
| 107 | return pos + 1; |
| 108 | } |
| 109 | } |
| 110 | |
| 111 | |
| 112 | /** |
| 113 | * eap_msg_alloc - Allocate a buffer for an EAP message |
| 114 | * @vendor: Vendor-Id (0 = IETF) |
| 115 | * @type: EAP type |
| 116 | * @payload_len: Payload length in bytes (data after Type) |
| 117 | * @code: Message Code (EAP_CODE_*) |
| 118 | * @identifier: Identifier |
| 119 | * Returns: Pointer to the allocated message buffer or %NULL on error |
| 120 | * |
| 121 | * This function can be used to allocate a buffer for an EAP message and fill |
| 122 | * in the EAP header. This function is automatically using expanded EAP header |
| 123 | * if the selected Vendor-Id is not IETF. In other words, most EAP methods do |
| 124 | * not need to separately select which header type to use when using this |
| 125 | * function to allocate the message buffers. The returned buffer has room for |
| 126 | * payload_len bytes and has the EAP header and Type field already filled in. |
| 127 | */ |
| 128 | struct wpabuf * eap_msg_alloc(int vendor, EapType type, size_t payload_len, |
| 129 | u8 code, u8 identifier) |
| 130 | { |
| 131 | struct wpabuf *buf; |
| 132 | struct eap_hdr *hdr; |
| 133 | size_t len; |
| 134 | |
| 135 | len = sizeof(struct eap_hdr) + (vendor == EAP_VENDOR_IETF ? 1 : 8) + |
| 136 | payload_len; |
| 137 | buf = wpabuf_alloc(len); |
| 138 | if (buf == NULL) |
| 139 | return NULL; |
| 140 | |
| 141 | hdr = wpabuf_put(buf, sizeof(*hdr)); |
| 142 | hdr->code = code; |
| 143 | hdr->identifier = identifier; |
| 144 | hdr->length = host_to_be16(len); |
| 145 | |
| 146 | if (vendor == EAP_VENDOR_IETF) { |
| 147 | wpabuf_put_u8(buf, type); |
| 148 | } else { |
| 149 | wpabuf_put_u8(buf, EAP_TYPE_EXPANDED); |
| 150 | wpabuf_put_be24(buf, vendor); |
| 151 | wpabuf_put_be32(buf, type); |
| 152 | } |
| 153 | |
| 154 | return buf; |
| 155 | } |
| 156 | |
| 157 | |
| 158 | /** |
| 159 | * eap_update_len - Update EAP header length |
| 160 | * @msg: EAP message from eap_msg_alloc |
| 161 | * |
| 162 | * This function updates the length field in the EAP header to match with the |
| 163 | * current length for the buffer. This allows eap_msg_alloc() to be used to |
| 164 | * allocate a larger buffer than the exact message length (e.g., if exact |
| 165 | * message length is not yet known). |
| 166 | */ |
| 167 | void eap_update_len(struct wpabuf *msg) |
| 168 | { |
| 169 | struct eap_hdr *hdr; |
| 170 | hdr = wpabuf_mhead(msg); |
| 171 | if (wpabuf_len(msg) < sizeof(*hdr)) |
| 172 | return; |
| 173 | hdr->length = host_to_be16(wpabuf_len(msg)); |
| 174 | } |
| 175 | |
| 176 | |
| 177 | /** |
| 178 | * eap_get_id - Get EAP Identifier from wpabuf |
| 179 | * @msg: Buffer starting with an EAP header |
| 180 | * Returns: The Identifier field from the EAP header |
| 181 | */ |
| 182 | u8 eap_get_id(const struct wpabuf *msg) |
| 183 | { |
| 184 | const struct eap_hdr *eap; |
| 185 | |
| 186 | if (wpabuf_len(msg) < sizeof(*eap)) |
| 187 | return 0; |
| 188 | |
| 189 | eap = wpabuf_head(msg); |
| 190 | return eap->identifier; |
| 191 | } |
| 192 | |
| 193 | |
| 194 | /** |
| 195 | * eap_get_id - Get EAP Type from wpabuf |
| 196 | * @msg: Buffer starting with an EAP header |
| 197 | * Returns: The EAP Type after the EAP header |
| 198 | */ |
| 199 | EapType eap_get_type(const struct wpabuf *msg) |
| 200 | { |
| 201 | if (wpabuf_len(msg) < sizeof(struct eap_hdr) + 1) |
| 202 | return EAP_TYPE_NONE; |
| 203 | |
| 204 | return ((const u8 *) wpabuf_head(msg))[sizeof(struct eap_hdr)]; |
| 205 | } |