decode.c

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/*
 *   This program is 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.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * @file src/lib/eap_aka_sim/decode.c
 * @brief Code common to EAP-SIM/AKA/AKA' clients and servers.
 *
 * The development of the EAP-SIM support was funded by Internet Foundation
 * Austria (http://www.nic.at/ipa).
 *
 * @copyright 2003 Michael Richardson (mcr@sandelman.ottawa.on.ca)
 * @copyright 2003-2016 The FreeRADIUS server project
 */
 
RCSID("$Id: 19d84ce007b785dfb83e8f717a5e7145eb9f6530 $")
 
#include <freeradius-devel/io/test_point.h>
#include <freeradius-devel/server/module.h>
#include <freeradius-devel/tls/strerror.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/sha1.h>
#include <freeradius-devel/util/decode.h>
 
#include <freeradius-devel/eap/types.h>
#include "attrs.h"
#include "base.h"
#include "crypto_priv.h"
 
/*
 *  EAP-SIM/AKA/AKA' PACKET FORMAT
 *  ---------------- ------ ------
 *
 * EAP Request and Response Packet Format
 * --- ------- --- -------- ------ ------
 *  0              1               2               3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |     Code      |  Identifier   |        Length           |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |     Type      |    AT-Type    |   AT-Length   |     value ... |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * With AT-Type/AT-Length/Value... repeating. Length is in units
 * of 32 bits, and includes the Type/Length fields.
 */
 
static ssize_t sim_decode_pair_internal(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                                           uint8_t const *data, size_t data_len, void *decode_ctx);
 
static ssize_t sim_decode_pair_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                                     uint8_t const *data, size_t const attr_len, size_t const data_len,
                                     void *decode_ctx);
 
/** Extract the IV value from an AT_IV attribute
 *
 * SIM uses padding at the start of the attribute to make it a multiple of 4.
 * We need to strip packet_ctx and check that it was set to zero.
 *
 * @param[out] out      Where to write IV.
 * @param[in] in        value of AT_IV attribute.
 * @param[in] in_len    the length of the AT_IV attribute (should be 18).
 * @return
 *      - 0 on success.
 *      - < 0 on failure (bad IV).
 */
static inline int sim_iv_extract(uint8_t out[AKA_SIM_IV_SIZE], uint8_t const *in, size_t in_len)
{
        /*
         *      Two bytes are reserved, so although
         *      the IV is actually 16 bytes, we
         *      check for 18.
         */
        if (in_len != (AKA_SIM_IV_SIZE + 2)) {
                fr_strerror_printf("%s: Invalid IV length, expected %u got %zu",
                                   __FUNCTION__, (AKA_SIM_IV_SIZE + 2), in_len);
                return -1;
        }
 
        if ((in[0] != 0x00) || (in[1] != 0x00)) {
                fr_strerror_printf("%s: Reserved bytes in IV are not zeroed", __FUNCTION__);
                return -1;
        }
 
        /* skip reserved bytes */
        memcpy(out, in + 2, AKA_SIM_IV_SIZE);
 
        return 0;
}
 
/** Decrypt an AES-128-CBC encrypted attribute
 *
 * @param[in] ctx               to allocate decr buffer in.
 * @param[out] out              where to write pointer to decr buffer.
 * @param[in] data              to decrypt.
 * @param[in] attr_len          length of encrypted data.
 * @param[in] data_len          length of data remaining in the packet.
 * @param[in] decode_ctx        containing keys, and the IV (if we already found it).
 * @return
 *      - Number of decr bytes decrypted on success.
 *      - < 0 on failure.
 */
static ssize_t sim_value_decrypt(TALLOC_CTX *ctx, uint8_t **out,
                                 uint8_t const *data, size_t const attr_len, size_t const data_len,
                                 void *decode_ctx)
{
        fr_aka_sim_ctx_t        *packet_ctx = decode_ctx;
        EVP_CIPHER_CTX          *evp_ctx;
        EVP_CIPHER const        *evp_cipher = EVP_aes_128_cbc();
        size_t                  block_size = EVP_CIPHER_block_size(evp_cipher);
        size_t                  len = 0, decr_len = 0;
        uint8_t                 *decr = NULL;
 
        if (!fr_cond_assert(attr_len <= data_len)) return -1;
 
        FR_PROTO_HEX_DUMP(data, attr_len, "ciphertext");
 
        /*
         *      Encrypted values must be a multiple of 16.
         *
         *      There's a padding attribute to ensure they
         *      always can be...
         */
        if (attr_len % block_size) {
                fr_strerror_printf("%s: Encrypted attribute is not a multiple of cipher's block size (%zu)",
                                   __FUNCTION__, block_size);
                return -1;
        }
 
        /*
         *      Ugh, now we have to go hunting for it....
         */
        if (!packet_ctx->have_iv) {
                uint8_t const   *p = data + attr_len;   /* Skip to the end of packet_ctx attribute */
                uint8_t const   *end = data + data_len;
 
                while ((size_t)(end - p) >= sizeof(uint32_t)) {
                        uint8_t  sim_at = p[0];
                        size_t   sim_at_len = p[1] * sizeof(uint32_t);
 
                        if (sim_at_len == 0) {
                                fr_strerror_printf("%s: Failed IV search.  AT Length field is zero", __FUNCTION__);
                                return -1;
                        }
 
                        if ((p + sim_at_len) > end) {
                                fr_strerror_printf("%s: Invalid IV length, longer than remaining data", __FUNCTION__);
                                return -1;
                        }
 
                        if (sim_at == FR_IV) {
                                if (sim_iv_extract(&(packet_ctx->iv[0]), p + 2, sim_at_len - 2) < 0) return -1;
                                packet_ctx->have_iv = true;
                                break;
                        }
                        p += sim_at_len;
                }
 
                if (!packet_ctx->have_iv) {
                        fr_strerror_printf("%s: No IV present in packet, can't decrypt data", __FUNCTION__);
                        return -1;
                }
        }
 
        if (unlikely(!packet_ctx->k_encr)) {
                fr_strerror_printf("%s: No k_encr set, cannot decrypt attributes", __FUNCTION__);
                return PAIR_DECODE_FATAL_ERROR;
        }
 
        evp_ctx = aka_sim_crypto_cipher_ctx();
        if (!EVP_DecryptInit_ex(evp_ctx, evp_cipher, NULL, packet_ctx->k_encr, packet_ctx->iv)) {
                fr_tls_strerror_printf("%s: Failed setting decryption parameters", __FUNCTION__);
        error:
                talloc_free(decr);
                return -1;
        }
 
        MEM(decr = talloc_zero_array(ctx, uint8_t, attr_len));
 
        /*
         *      By default OpenSSL expects 16 bytes of cleartext
         *      to produce 32 bytes of ciphertext, due to padding
         *      being added if the decr is a multiple of 16.
         *
         *      There's no way for OpenSSL to determine if a
         *      16 byte ciphertext was padded or not, so we need to
         *      inform OpenSSL explicitly that there's no padding.
         */
        EVP_CIPHER_CTX_set_padding(evp_ctx, 0);
        if (!EVP_DecryptUpdate(evp_ctx, decr, (int *)&len, data, attr_len)) {
                fr_tls_strerror_printf("%s: Failed decrypting attribute", __FUNCTION__);
                goto error;
        }
        decr_len = len;
 
        if (!EVP_DecryptFinal_ex(evp_ctx, decr + decr_len, (int *)&len)) {
                fr_tls_strerror_printf("%s: Failed decrypting attribute", __FUNCTION__);
                goto error;
        }
        decr_len += len;
 
        /*
         *      Note: packet_ctx implicitly validates the length of the padding
         *      attribute (if present), so we don't have to do it later.
         */
        if (decr_len % block_size) {
                fr_strerror_printf("%s: Expected decrypted value length to be multiple of %zu, got %zu",
                                   __FUNCTION__, block_size, decr_len);
                goto error;
        }
 
        /*
         *      Ciphertext should be same length as plaintext.
         */
        if (unlikely(attr_len != decr_len)) {
                fr_strerror_printf("%s: Invalid plaintext length, expected %zu, got %zu",
                                   __FUNCTION__, attr_len, decr_len);
                goto error;
        }
 
        FR_PROTO_TRACE("decryption successful, got %zu bytes of cleartext", decr_len);
        FR_PROTO_HEX_DUMP(decr, decr_len, "cleartext");
 
        *out = decr;
 
        return decr_len;
}
 
/** Returns the number of array members for arrays with fixed element sizes
 *
 * @param[out] out      The element length.
 * @param[in] len       the total length of the array.
 * @param[in] da        the specifying the array type.
 * @return
 *      - The number of elements in the array on success.
 *      - < 0 on error (array length not a multiple of element size).
 */
static int sim_array_members(size_t *out, size_t len, fr_dict_attr_t const *da)
{
        size_t          element_len;
 
        /*
         *      Could be an array of bytes, integers, etc.
         */
        switch (da->type) {
        case FR_TYPE_OCTETS:
                if (da->flags.length == 0) {
                        fr_strerror_printf("%s: Octets array must have fixed length elements", __FUNCTION__);
                        return -1;
                }
                element_len = da->flags.length;
                break;
 
        default:
                element_len = fr_aka_sim_attr_sizes[da->type][0];
                break;
        }
 
        if (element_len == 1) {
                *out = 1;
                return 1;       /* Fast path */
        }
 
        if (!fr_cond_assert(element_len > 0)) return -1;
 
        if (element_len > len) {
                fr_strerror_printf("%s: Element length (%zu) > array length (%zu)", __FUNCTION__,
                                   element_len, len);
                return -1;
        }
 
        /*
         *      Number of elements must divide exactly
         */
        if (len % element_len) {
                fr_strerror_printf("%s: Expected array actual length to be multiple of %zu, got %zu",
                                   __FUNCTION__, element_len, len);
                return -1;
        }
        *out = element_len;
 
        return len / element_len;
}
 
static ssize_t sim_decode_array(TALLOC_CTX *ctx, fr_pair_list_t *out,
                                fr_dict_attr_t const *parent,
                                uint8_t const *data, size_t const attr_len, UNUSED size_t data_len,
                                void *decode_ctx)
{
        uint8_t const   *p = data, *end = p + attr_len;
        uint16_t        actual_len;
        int             elements, i;
        size_t          element_len;
        ssize_t         ret;
 
        FR_PROTO_TRACE("Array attribute");
 
        fr_assert(parent->flags.array);
        fr_assert(attr_len >= 2);               /* Should have been caught earlier */
 
        /*
         *      Arrays with fixed length members that
         *      are a multiple of 4 don't need an
         *      actual_len value, as we can get the
         *      number of elements from the attribute
         *      length.
         */
        if (!parent->flags.length || (parent->flags.length % 4)) {
                actual_len = fr_nbo_to_uint16(p);
                if (actual_len > (attr_len - 2)) {
                        fr_strerror_printf("%s: Actual length field value (%hu) > attribute value length (%zu)",
                                           __FUNCTION__, actual_len, attr_len - 2);
                        return -1;
                }
        } else {
                actual_len = attr_len - 2;      /* -2 for the reserved bytes */
        }
        p += 2;
 
        /*
         *      Zero length array
         */
        if (!actual_len) return p - data;
 
        /*
         *      Get the number of elements
         */
        elements = sim_array_members(&element_len, actual_len, parent);
        if (elements < 0) return elements;
 
        for (i = 0; i < elements; i++) {
                ret = sim_decode_pair_value(ctx, out, parent, p, element_len, end - p, decode_ctx);
                if (ret < 0) return ret;
 
                p += ret;
 
                if (!fr_cond_assert(p <= end)) break;
        }
 
        return attr_len;        /* Say we consumed attr_len because it may have padding */
}
 
/** Break apart a TLV attribute into individual attributes
 *
 * @param[in] ctx               to allocate new attributes in.
 * @param[in] out               to add new attributes to.
 * @param[in] parent            the current attribute TLV attribute we're processing.
 * @param[in] data              to parse. Points to the data field of the attribute.
 * @param[in] attr_len          length of the TLV attribute.
 * @param[in] data_len          remaining data in the packet.
 * @param[in] decode_ctx        IVs, keys etc...
 * @return
 *      - Length on success.
 *      - < 0 on malformed attribute.
 */
static ssize_t sim_decode_tlv(TALLOC_CTX *ctx, fr_pair_list_t *out,
                              fr_dict_attr_t const *parent,
                              uint8_t const *data, size_t const attr_len, size_t data_len,
                              void *decode_ctx)
{
        uint8_t const           *p = data, *end = p + attr_len;
        uint8_t                 *decr = NULL;
        ssize_t                 decr_len;
        fr_dict_attr_t const    *child;
        fr_pair_t               *tlv;
        ssize_t                 ret;
 
        if (data_len < 2) {
                fr_strerror_printf("%s: Insufficient data", __FUNCTION__);
                return -1; /* minimum attr size */
        }
 
        tlv = fr_pair_afrom_da(ctx, parent);
        if (!tlv) return PAIR_DECODE_OOM;
 
        /*
         *      We have an AES-128-CBC encrypted attribute
         *
         *      IV is from AT_IV, key is from k_encr.
         *
         *      unfortunately the ordering of these two attributes
         *      aren't specified, so we may have to hunt for the IV.
         */
        if (!parent->flags.extra && parent->flags.subtype) {
                FR_PROTO_TRACE("found encrypted attribute '%s'", parent->name);
 
                decr_len = sim_value_decrypt(ctx, &decr, p + 2,
                                             attr_len - 2, data_len - 2, decode_ctx);   /* Skip reserved */
                if (decr_len < 0) return -1;
 
                p = decr;
                end = p + decr_len;
        } else {
                p += 2; /* Skip the reserved bytes */
        }
 
        FR_PROTO_HEX_DUMP(p, end - p, "tlvs");
 
        /*
         *  Record where we were in the list when packet_ctx function was called
         */
        while ((size_t)(end - p) >= sizeof(uint32_t)) {
                uint8_t sim_at = p[0];
                size_t  sim_at_len = ((size_t)p[1]) << 2;
                fr_dict_attr_t const *unknown_child = NULL;
 
                if ((p + sim_at_len) > end) {
                        fr_strerror_printf("%s: Malformed nested attribute %d: Length field (%zu bytes) value "
                                           "longer than remaining data in parent (%zu bytes)",
                                           __FUNCTION__, sim_at, sim_at_len, end - p);
 
                error:
                        talloc_free(decr);
                        talloc_free(tlv);
                        return -1;
                }
 
                if (sim_at_len == 0) {
                        fr_strerror_printf("%s: Malformed nested attribute %d: Length field 0", __FUNCTION__, sim_at);
                        goto error;
                }
 
                /*
                 *      Padding attributes are cleartext inside of
                 *      encrypted TLVs to pad out the value to the
                 *      correct length for the block cipher
                 *      (16 in the case of AES-128-CBC).
                 */
                if (sim_at == FR_PADDING) {
                        uint8_t zero = 0;
                        uint8_t i;
 
                        if (!parent->flags.subtype) {
                                fr_strerror_printf("%s: Found padding attribute outside of an encrypted TLV",
                                                   __FUNCTION__);
                                goto error;
                        }
 
                        if (!fr_cond_assert(data_len % 4)) goto error;
 
                        if (sim_at_len > 12) {
                                fr_strerror_printf("%s: Expected padding attribute length <= 12 bytes, got %zu bytes",
                                                   __FUNCTION__, sim_at_len);
                                goto error;
                        }
 
                        /*
                         *      RFC says we MUST verify that FR_PADDING
                         *      data is zeroed out.
                         */
                        for (i = 2; i < sim_at_len; i++) zero |= p[i];
                        if (zero) {
                                fr_strerror_printf("%s: Padding attribute value not zeroed 0x%pH", __FUNCTION__,
                                                   fr_box_octets(p + 2, sim_at_len - 2));
                                goto error;
                        }
 
                        p += sim_at_len;
                        continue;
                }
 
                child = fr_dict_attr_child_by_num(parent, p[0]);
                if (!child) {
                        FR_PROTO_TRACE("Failed to find child %u of TLV %s", p[0], parent->name);
 
                        /*
                         *      Encountered none skippable attribute
                         *
                         *      RFC says we need to die on these if we don't
                         *      understand them.  non-skippables are < 128.
                         */
                        if (sim_at <= AKA_SIM_SKIPPABLE_MAX) {
                                fr_strerror_printf("%s: Unknown (non-skippable) attribute %i",
                                                   __FUNCTION__, sim_at);
                                goto error;
                        }
 
                        /*
                         *      Build an unknown attr
                         */
                        unknown_child = fr_dict_unknown_attr_afrom_num(ctx, parent, p[0]);
                        if (!unknown_child) goto error;
                        child = unknown_child;
                }
                FR_PROTO_TRACE("decode context changed %s -> %s", parent->name, child->name);
 
                ret = sim_decode_pair_value(tlv, &tlv->vp_group, child, p + 2, sim_at_len - 2, (end - p) - 2,
                                            decode_ctx);
                fr_dict_unknown_free(&unknown_child);
                if (ret < 0) goto error;
                p += sim_at_len;
        }
        fr_pair_append(out, tlv);
 
        talloc_free(decr);
 
        return attr_len;
}
 
/** Create any kind of VP from the attribute contents
 *
 * @param[in] ctx               to allocate new attributes in.
 * @param[in] out               to add new attributes to.
 * @param[in] parent            the current attribute we're processing.
 * @param[in] data              to parse. Points to the data field of the attribute.
 * @param[in] attr_len          length of the attribute being parsed.
 * @param[in] data_len          length of the remaining data in the packet.
 * @param[in] decode_ctx        IVs, keys etc...
 * @return
 *      - Length on success.
 *      - -1 on failure.
 */
static ssize_t sim_decode_pair_value(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                                     uint8_t const *data, size_t const attr_len, size_t const data_len,
                                     void *decode_ctx)
{
        fr_pair_t               *vp;
        uint8_t const           *p = data;
        size_t                  prefix = 0;
 
        fr_aka_sim_ctx_t        *packet_ctx = decode_ctx;
 
        if (!fr_cond_assert(attr_len <= data_len)) return -1;
        if (!fr_cond_assert(parent)) return -1;
 
        FR_PROTO_TRACE("Parent %s len %zu", parent->name, attr_len);
        FR_PROTO_HEX_DUMP(data, attr_len, __FUNCTION__ );
 
        FR_PROTO_TRACE("Type \"%s\" (%u)", fr_type_to_str(parent->type), parent->type);
 
        /*
         *      Special cases, attributes that either have odd formats, or need
         *      have information we need to decode the packet.
         */
        switch (parent->attr) {
        /*
         *      We need to record packet_ctx so we can decrypt AT_ENCR attributes.
         *
         *      If we don't find it before, then that's fine, we'll try and
         *      find it in the rest of the packet after the encrypted
         *      attribute.
         *
         *      0                   1                   2                   3
         *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |     AT_IV     | Length = 5    |           Reserved            |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |                                                               |
         *      |                 Initialization Vector                         |
         *      |                                                               |
         *      |                                                               |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         */
        case FR_IV:
                if (sim_iv_extract(&packet_ctx->iv[0], data, attr_len) < 0) return -1;
                packet_ctx->have_iv = true;
                break;  /* Now create the attribute */
 
        /*
         *      AT_RES - Special case (RES length is in bits)
         *
         *      0                   1                   2                   3
         *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |     AT_RES    |    Length     |          RES Length           |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
         *      |                                                               |
         *      |                             RES                               |
         *      |                                                               |
         *      |                                                               |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         */
        case FR_RES:
        {
                uint16_t res_len;
 
                if (attr_len < 2) goto raw;     /* Need at least two bytes for the length field */
 
                res_len = fr_nbo_to_uint16(p);
                if (res_len % 8) {
                        fr_strerror_printf("%s: RES Length (%hu) is not a multiple of 8",
                                           __FUNCTION__, res_len);
                        return -1;
                }
                res_len /= 8;
 
                if (res_len > (attr_len - 2)) {
                        fr_strerror_printf("%s: RES Length field value (%u bits) > attribute value length (%zu bits)",
                                           __FUNCTION__, res_len * 8, (attr_len - 2) * 8);
                        return -1;
                }
 
                if ((res_len < 4) || (res_len > 16)) {
                        fr_strerror_printf("%s: RES Length field value must be between 32-128 bits, got %u bits",
                                           __FUNCTION__, (res_len * 8));
                        return -1;
                }
 
                vp = fr_pair_afrom_da(ctx, parent);
                if (!vp) return -1;
 
                fr_pair_value_memdup(vp, p + 2, res_len, true);
        }
                goto done;
 
        /*
         *      AT_CHECKCODE - Special case (Variable length with no length field)
         *
         *      0                   1                   2                   3
         *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      | AT_CHECKCODE  | Length        |           Reserved            |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |                                                               |
         *      |                     Checkcode (0 or 20 bytes)                 |
         *      |                                                               |
         *      |                                                               |
         *      |                                                               |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         */
        case FR_CHECKCODE:
                if (attr_len < 2) goto raw;     /* Need at least two bytes for reserved field */
 
                vp = fr_pair_afrom_da(ctx, parent);
                if (!vp) return -1;
 
                fr_pair_value_memdup(vp, p + 2, attr_len - 2, true);
                goto done;
 
        default:
                break;
        }
 
        switch (parent->type) {
        case FR_TYPE_STRING:
                if (attr_len < 2) goto raw;     /* Need at least two bytes for the length field */
                if (parent->flags.length && (attr_len != parent->flags.length)) {
                wrong_len:
                        fr_strerror_printf("%s: Attribute \"%s\" needs a value of exactly %zu bytes, "
                                           "but value was %zu bytes", __FUNCTION__,
                                           parent->name, (size_t)parent->flags.length, attr_len);
                        goto raw;
                }
                break;
 
        case FR_TYPE_OCTETS:
                if (parent->flags.is_unknown) goto raw;
 
                /*
                 *      Get the number of bytes we expect before the value
                 */
                prefix = fr_aka_sim_octets_prefix_len(parent);
                if (attr_len < prefix) goto raw;
                if (parent->flags.length && (attr_len != (parent->flags.length + prefix))) goto wrong_len;
                break;
 
        case FR_TYPE_BOOL:
        case FR_TYPE_UINT8:
        case FR_TYPE_UINT16:
        case FR_TYPE_UINT32:
        case FR_TYPE_UINT64:
                if (attr_len != fr_aka_sim_attr_sizes[parent->type][0]) goto raw;
                break;
 
        case FR_TYPE_TLV:
                if (attr_len < 2) goto raw;
 
                /*
                 *      We presume that the TLVs all fit into one
                 *      attribute, OR they've already been grouped
                 *      into a contiguous memory buffer.
                 */
                return sim_decode_tlv(ctx, out, parent, p, attr_len, data_len, decode_ctx);
 
        default:
        raw:
                /*
                 *      We can't create unknowns for non-skippable attributes
                 *      as we're prohibited from continuing by the SIM RFCs.
                 */
                if (parent->attr <= AKA_SIM_SKIPPABLE_MAX) {
                        fr_strerror_printf_push("%s: Failed parsing non-skippable attribute '%s'",
                                                __FUNCTION__, parent->name);
                        return -1;
                }
 
#ifdef STATIC_ANALYZER
                if (!parent->parent) return -1; /* stupid static analyzers */
#endif
                fr_assert(parent->parent);
 
                if (fr_pair_raw_from_network(ctx, out, parent, p, attr_len) < 0) return -1;
 
                return attr_len;
        }
 
        fr_assert(!parent->flags.is_unknown);
 
        vp = fr_pair_afrom_da(ctx, parent);
        if (!vp) return -1;
 
        switch (parent->type) {
        /*
         *      0                   1                   2                   3
         *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      | AT_<STRING>   | Length        |    Actual <STRING> Length     |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |                                                               |
         *      .                           String                              .
         *      .                                                               .
         *      |                                                               |
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         */
        case FR_TYPE_STRING:
        {
                uint16_t actual_len = fr_nbo_to_uint16(p);
 
                if (actual_len > (attr_len - 2)) {
                        fr_strerror_printf("%s: Actual length field value (%hu) > attribute value length (%zu)",
                                           __FUNCTION__, actual_len, attr_len - 2);
                        return -1;
                }
 
                fr_pair_value_bstrndup(vp, (char const *)p + 2, actual_len, true);
        }
                break;
 
        case FR_TYPE_OCTETS:
                /*
                 *      Variable length octets buffer
                 */
                if (!parent->flags.length) {
                        uint16_t actual_len = fr_nbo_to_uint16(p);
 
                        if (actual_len > (attr_len - prefix)) {
                                fr_strerror_printf("%s: Actual length field value (%hu) > attribute value length (%zu)",
                                                   __FUNCTION__, actual_len, attr_len - 2);
                                return -1;
                        }
 
                        fr_pair_value_memdup(vp, p + prefix, actual_len, true);
                /*
                 *      Fixed length octets buffer
                 */
                } else {
                        fr_pair_value_memdup(vp, p + prefix, attr_len - prefix, true);
                }
                break;
 
        /*
         *      Not proper bool. We Use packet_ctx to represent
         *      flag attributes like AT_FULLAUTH_ID_REQ
         *
         *      0                   1                   2                   3
         *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |   AT_<BOOL>   | Length = 1    |           Reserved            |
         *      +---------------+---------------+-------------------------------+
         */
        case FR_TYPE_BOOL:
                vp->vp_bool = true;
                break;
 
        /*
         *      Numbers are network byte order.
         *
         *      In the base RFCs only short (16bit) unsigned integers are used.
         *      We add support for more, just for completeness.
         *
         *      0                   1                   2                   3
         *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
         *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         *      |   AT_<SHORT>  | Length = 1    |    Short 1    |    Short 2    |
         *      +---------------+---------------+-------------------------------+
         */
        case FR_TYPE_UINT8:
                vp->vp_uint8 = p[0];
                break;
 
        case FR_TYPE_UINT16:
                vp->vp_uint16 = fr_nbo_to_uint16(p);
                break;
 
        case FR_TYPE_UINT32:
                vp->vp_uint32 = fr_nbo_to_uint32(p);
                break;
 
        case FR_TYPE_UINT64:
                vp->vp_uint64 = fr_nbo_to_uint64(p);
                break;
 
        default:
                talloc_free(&vp);
                fr_strerror_printf_push("%s[%d]: Internal sanity check failed", __FUNCTION__, __LINE__);
                return -1;
        }
 
done:
        fr_pair_append(out, vp);
 
        return attr_len;
}
 
/** Decode SIM/AKA/AKA' attributes
 *
 * @param[in] ctx               to allocate attributes in.
 * @param[in] out               where to insert the attributes.
 * @param[in] parent            of current attribute being decoded.
 * @param[in] data              data to parse.
 * @param[in] data_len          length of data.  For top level attributes packet_ctx must be the length
 *                              of the packet (so we can hunt for AT_IV), for Sub-TLVs it should
 *                              be the length of the container value.
 * @param[in] decode_ctx        extra context to pass to the decoder.
 * @return
 *      - The number of bytes parsed.
 *      - -1 on error.
 */
static ssize_t sim_decode_pair_internal(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                                        uint8_t const *data, size_t data_len, void *decode_ctx)
{
        uint8_t                 sim_at;
        size_t                  sim_at_len;
 
        ssize_t                 ret;
        fr_dict_attr_t const    *da;
 
 
        /*
         *      We need at least 2 bytes.  We really need 4 but it's
         *      useful to print the attribute number in the errors.
         */
        if (data_len < 2) {
                fr_strerror_printf("%s: Insufficient data: Expected >= 2 bytes, got %zu bytes",
                                   __FUNCTION__, data_len);
                return -1;
        }
 
        sim_at = data[0];
 
        sim_at_len = ((size_t)data[1]) << 2;
        if (sim_at_len > data_len) {
                fr_strerror_printf("%s: Insufficient data for attribute %d: Length field %zu, remaining data %zu",
                                   __FUNCTION__, sim_at, sim_at_len, data_len);
                return -1;
        }
 
        if (sim_at_len == 0) {
                fr_strerror_printf("%s: Malformed attribute %d: Length field 0", __FUNCTION__, sim_at);
                return -1;
        }
 
        da = fr_dict_attr_child_by_num(parent, sim_at);
        if (!da) {
                FR_PROTO_TRACE("Unknown attribute %u", sim_at);
 
                /*
                 *      Encountered none skippable attribute
                 *
                 *      RFC says we need to die on these if we don't
                 *      understand them.  non-skippables are < 128.
                 */
                if (sim_at <= AKA_SIM_SKIPPABLE_MAX) {
                        fr_strerror_printf("Unknown (non-skippable) attribute %i", sim_at);
                        return -1;
                }
                da = fr_dict_unknown_attr_afrom_num(ctx, parent, sim_at);
        }
        if (!da) return -1;
 
        FR_PROTO_TRACE("decode context changed %s -> %s", da->parent->name, da->name);
 
        if (da->flags.array) {
                ret = sim_decode_array(ctx, out, da, data + 2, sim_at_len - 2, data_len - 2, decode_ctx);
        } else {
                ret = sim_decode_pair_value(ctx, out, da, data + 2, sim_at_len - 2, data_len - 2, decode_ctx);
        }
        if (ret < 0) return ret;
 
        return 2 + ret;
}
 
/** Decode SIM/AKA/AKA' attributes
 *
 * @param[in] ctx               to allocate attributes in.
 * @param[in] out               where to insert the attributes.
 * @param[in] parent            for looking up attributes.
 * @param[in] data              data to parse.
 * @param[in] data_len          length of data.  For top level attributes packet_ctx must be the length
 *                              of the packet (so we can hunt for AT_IV), for Sub-TLVs it should
 *                              be the length of the container value.
 * @param[in] decode_ctx        extra context to pass to the decoder.
 * @return
 *      - The number of bytes parsed.
 *      - -1 on error.
 */
ssize_t fr_aka_sim_decode_pair(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                               uint8_t const *data, size_t data_len, void *decode_ctx)
{
        return sim_decode_pair_internal(ctx, out, parent, data, data_len, decode_ctx);
}
 
/** Decode SIM/AKA/AKA' specific packet data
 *
 * @note data should point to the subtype field in the EAP packet.
 *
 * Extracts the SUBTYPE and adds it an attribute, then decodes any TLVs in the
 * SIM/AKA/AKA' packet.
 *
 *   0                   1                   2                   3
 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |     Code      |  Identifier   |            Length             |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |     Type      |    Subtype    |           Reserved            |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * The first byte of the data pointer should be the subtype.
 *
 * @param[in] ctx               where to allocate the pairs.
 * @param[in] out               where to write out attributes.
 * @param[in] dict              for looking up attributes.
 * @param[in] data              to convert to pairs.
 * @param[in] data_len          length of data to convert.
 * @param[in] decode_ctx        holds the state of the decoder.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int fr_aka_sim_decode(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_t const *dict,
                      uint8_t const *data, size_t data_len, fr_aka_sim_ctx_t *decode_ctx)
{
        ssize_t                 ret;
        uint8_t const           *p = data;
        uint8_t const           *end = p + data_len;
        fr_dict_attr_t const    *parent;
 
        /*
         *      We need at least enough data for the subtype
         *      and reserved bytes.
         *
         *      Note: Not all packets should contain attrs.
         *      When the client acknowledges an
         *      AKA-Notification from the server, the
         *      AKA-Notification is returns contains no
         *      attributes.
         */
        if (data_len < 3) {
                fr_strerror_printf("Packet data too small, expected at least 3 bytes got %zu bytes", data_len);
                return -1;
        }
        p += 3;
        parent = fr_dict_root(dict);
 
        /*
         *      Loop over all the attributes decoding
         *      them into the appropriate attributes
         *      in the SIM/AKA/AKA' dict.
         */
        while (p < end) {
                ret = fr_aka_sim_decode_pair(ctx, out, parent, p, end - p, decode_ctx);
                if (ret <= 0) {
                        fr_strerror_const_push("Failed decoding AT");
                error:
                        fr_pair_list_free(out); /* Free any attributes we added */
                        return -1;
                }
 
                p += ret;
                fr_assert(p <= end);
        }
 
        /*
         *      No point in doing packet_ctx until we known the rest
         *      of the data is OK!
         */
        {
                fr_pair_t *vp;
 
                vp = fr_pair_afrom_child_num(ctx, parent, FR_SUBTYPE);
                if (!vp) {
                        fr_strerror_const("Failed allocating subtype attribute");
                        goto error;
                }
                vp->vp_uint32 = data[0];
                fr_pair_append(out, vp);
        }
 
        return 0;
}
 
static int _test_ctx_free(UNUSED fr_aka_sim_ctx_t *ctx)
{
        fr_aka_sim_free();
 
        return 0;
}
 
static fr_aka_sim_ctx_t *test_ctx_init(TALLOC_CTX *ctx, uint8_t const *k_encr, size_t k_encr_len)
{
        fr_aka_sim_ctx_t        *test_ctx;
 
        if (fr_aka_sim_init() < 0) return NULL;
 
        test_ctx = talloc_zero(ctx, fr_aka_sim_ctx_t);
        test_ctx->k_encr = talloc_memdup(test_ctx, k_encr, k_encr_len);
        talloc_set_destructor(test_ctx, _test_ctx_free);
 
        return test_ctx;
}
/*
 *      Test ctx data
 */
static int decode_test_ctx_sim(void **out, TALLOC_CTX *ctx)
{
        fr_aka_sim_ctx_t        *test_ctx;
        static uint8_t          k_encr[] = { 0x00, 0x01, 0x02, 0x03, 0x04 ,0x05, 0x06, 0x07,
                                             0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
 
        test_ctx = test_ctx_init(ctx, k_encr, sizeof(k_encr));
        if (!test_ctx) return -1;
 
        test_ctx->have_iv = true;       /* Ensures IV is all zeros */
 
        *out = test_ctx;
 
        return 0;
}
 
 
static int decode_test_ctx_aka(void **out, TALLOC_CTX *ctx)
{
        fr_aka_sim_ctx_t *test_ctx;
        static uint8_t          k_encr[] = { 0x00, 0x01, 0x02, 0x03, 0x04 ,0x05, 0x06, 0x07,
                                             0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
 
        test_ctx = test_ctx_init(ctx, k_encr, sizeof(k_encr));
        if (!test_ctx) return -1;
 
        test_ctx->have_iv = true;       /* Ensures IV is all zeros */
 
        *out = test_ctx;
 
        return 0;
}
 
static int decode_test_ctx_sim_rfc4186(void **out, TALLOC_CTX *ctx)
{
        fr_aka_sim_ctx_t *test_ctx;
        static uint8_t          k_encr[] = { 0x53, 0x6e, 0x5e, 0xbc, 0x44 ,0x65, 0x58, 0x2a,
                                             0xa6, 0xa8, 0xec, 0x99, 0x86, 0xeb, 0xb6, 0x20 };
 
        test_ctx = test_ctx_init(ctx, k_encr, sizeof(k_encr));
        if (!test_ctx) return -1;
 
        *out = test_ctx;
 
        return 0;
}
 
/*
 *      Test points
 */
extern fr_test_point_pair_decode_t sim_tp_decode;
fr_test_point_pair_decode_t sim_tp_decode = {
        .test_ctx       = decode_test_ctx_sim,
        .func           = fr_aka_sim_decode_pair
};
 
extern fr_test_point_pair_decode_t sim_tp_decode_rfc4186;
fr_test_point_pair_decode_t sim_tp_decode_rfc4186 = {
        .test_ctx       = decode_test_ctx_sim_rfc4186,
        .func           = fr_aka_sim_decode_pair
};
 
extern fr_test_point_pair_decode_t aka_tp_decode;
fr_test_point_pair_decode_t aka_tp_decode = {
        .test_ctx       = decode_test_ctx_aka,
        .func           = fr_aka_sim_decode_pair
};