| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "rpmb.h" |
| #include "error_reporting.h" |
| #include "rpmb_protocol.h" |
| |
| #include <assert.h> |
| #include <ctype.h> |
| #include <errno.h> |
| #include <lk/compiler.h> |
| #include <stdbool.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include <openssl/hmac.h> |
| #include <openssl/mem.h> |
| #include <openssl/rand.h> |
| |
| #define RPMB_DEBUG 0 |
| #define MAX_PACKET_COUNT 2 |
| |
| #define RPMB_PROTOCOL_MMC 1 |
| #define RPMB_PROTOCOL_UFS 2 |
| |
| #define RPMB_READ_COUNTER_MAX_RETRIES 3 |
| |
| #if RPMB_PROTOCOL != RPMB_PROTOCOL_MMC && RPMB_PROTOCOL != RPMB_PROTOCOL_UFS |
| #error "invalid RPMB_PROTOCOL!" |
| #endif |
| |
| struct rpmb_state { |
| struct rpmb_key key; |
| void* mmc_handle; |
| uint32_t write_counter; |
| bool first_write_complete; |
| bool verify_failed; |
| }; |
| |
| #if RPMB_DEBUG |
| #define rpmb_dprintf(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__) |
| #else |
| #define rpmb_dprintf(fmt, ...) \ |
| do { \ |
| } while (0) |
| #endif |
| |
| static void rpmb_dprint_buf(const char* prefix, |
| const uint8_t* buf, |
| size_t size) { |
| #if RPMB_DEBUG |
| size_t i, j; |
| |
| rpmb_dprintf("%s", prefix); |
| for (i = 0; i < size; i++) { |
| if (i && i % 32 == 0) { |
| rpmb_dprintf("\n"); |
| j = strlen(prefix); |
| while (j) { |
| rpmb_dprintf(" "); |
| j--; |
| } |
| } |
| rpmb_dprintf(" %02x", buf[i]); |
| } |
| rpmb_dprintf("\n"); |
| #endif |
| } |
| |
| static void rpmb_dprint_u16(const char* prefix, const struct rpmb_u16 u16) { |
| rpmb_dprint_buf(prefix, u16.byte, sizeof(u16.byte)); |
| } |
| |
| static void rpmb_dprint_u32(const char* prefix, const struct rpmb_u32 u32) { |
| rpmb_dprint_buf(prefix, u32.byte, sizeof(u32.byte)); |
| } |
| |
| static void rpmb_dprint_key(const char* prefix, |
| const struct rpmb_key key, |
| const char* expected_prefix, |
| const struct rpmb_key expected_key) { |
| #if RPMB_DEBUG |
| rpmb_dprint_buf(prefix, key.byte, sizeof(key.byte)); |
| if (CRYPTO_memcmp(key.byte, expected_key.byte, sizeof(key.byte))) |
| rpmb_dprint_buf(expected_prefix, expected_key.byte, |
| sizeof(expected_key.byte)); |
| #endif |
| } |
| |
| static struct rpmb_nonce rpmb_nonce_init(void) { |
| struct rpmb_nonce rpmb_nonce; |
| |
| RAND_bytes(rpmb_nonce.byte, sizeof(rpmb_nonce.byte)); |
| |
| return rpmb_nonce; |
| } |
| |
| static int rpmb_mac(struct rpmb_key key, |
| struct rpmb_packet* packet, |
| size_t packet_count, |
| struct rpmb_key* mac) { |
| size_t i; |
| int hmac_ret; |
| unsigned int md_len; |
| HMAC_CTX hmac_ctx; |
| |
| HMAC_CTX_init(&hmac_ctx); |
| hmac_ret = HMAC_Init_ex(&hmac_ctx, &key, sizeof(key), EVP_sha256(), NULL); |
| if (!hmac_ret) { |
| fprintf(stderr, "HMAC_Init_ex failed\n"); |
| goto err; |
| } |
| for (i = 0; i < packet_count; i++) { |
| STATIC_ASSERT(sizeof(*packet) - offsetof(__typeof__(*packet), data) == |
| 284); |
| hmac_ret = HMAC_Update(&hmac_ctx, packet[i].data, 284); |
| if (!hmac_ret) { |
| fprintf(stderr, "HMAC_Update failed\n"); |
| goto err; |
| } |
| } |
| hmac_ret = HMAC_Final(&hmac_ctx, mac->byte, &md_len); |
| if (md_len != sizeof(mac->byte)) { |
| fprintf(stderr, "bad md_len %d != %zd\n", md_len, sizeof(mac->byte)); |
| exit(1); |
| } |
| if (!hmac_ret) { |
| fprintf(stderr, "HMAC_Final failed\n"); |
| goto err; |
| } |
| |
| err: |
| HMAC_CTX_cleanup(&hmac_ctx); |
| return hmac_ret ? 0 : -1; |
| } |
| |
| static int rpmb_check_response(const char* cmd_str, |
| enum rpmb_response response_type, |
| struct rpmb_packet* res, |
| int res_count, |
| struct rpmb_key* mac, |
| struct rpmb_nonce* nonce, |
| uint16_t* addrp, |
| uint32_t write_counter) { |
| int i; |
| for (i = 0; i < res_count; i++) { |
| if (rpmb_get_u16(res[i].req_resp) != response_type) { |
| fprintf(stderr, "%s: Bad response type, 0x%x, expected 0x%x\n", |
| cmd_str, rpmb_get_u16(res[i].req_resp), response_type); |
| return -1; |
| } |
| |
| if (rpmb_get_u16(res[i].result) != RPMB_RES_OK) { |
| if (rpmb_get_u16(res[i].result) == RPMB_RES_ADDR_FAILURE) { |
| fprintf(stderr, "%s: Addr failure, %u\n", cmd_str, |
| rpmb_get_u16(res[i].address)); |
| return -ENOENT; |
| } |
| fprintf(stderr, "%s: Bad result, 0x%x\n", cmd_str, |
| rpmb_get_u16(res[i].result)); |
| return -1; |
| } |
| |
| if (i == res_count - 1 && mac && |
| CRYPTO_memcmp(res[i].key_mac.byte, mac->byte, sizeof(mac->byte))) { |
| fprintf(stderr, "%s: Bad MAC\n", cmd_str); |
| error_report_rpmb_mac_mismatch(); |
| return -1; |
| } |
| |
| if (nonce && CRYPTO_memcmp(res[i].nonce.byte, nonce->byte, |
| sizeof(nonce->byte))) { |
| fprintf(stderr, "%s: Bad nonce\n", cmd_str); |
| return -1; |
| } |
| |
| if (write_counter && |
| write_counter != rpmb_get_u32(res[i].write_counter)) { |
| fprintf(stderr, "%s: Bad write counter, got %u, expected %u\n", |
| cmd_str, rpmb_get_u32(res[i].write_counter), write_counter); |
| error_report_rpmb_counter_mismatch(); |
| return -1; |
| } |
| |
| if (addrp && *addrp != rpmb_get_u16(res[i].address)) { |
| fprintf(stderr, "%s: Bad addr, got %u, expected %u\n", cmd_str, |
| rpmb_get_u16(res[i].address), *addrp); |
| error_report_rpmb_addr_mismatch(); |
| return -1; |
| } |
| } |
| |
| return 0; |
| } |
| |
| int rpmb_program_key(struct rpmb_state* state, const struct rpmb_key* key) { |
| int ret; |
| struct rpmb_packet cmd = { |
| .req_resp = rpmb_u16(RPMB_REQ_PROGRAM_KEY), |
| }; |
| struct rpmb_packet rescmd = { |
| .req_resp = rpmb_u16(RPMB_REQ_RESULT_READ), |
| }; |
| struct rpmb_packet res; |
| |
| memcpy(cmd.key_mac.byte, key->byte, sizeof(cmd.key_mac.byte)); |
| |
| ret = rpmb_send(state->mmc_handle, &cmd, sizeof(cmd), &rescmd, |
| sizeof(rescmd), &res, sizeof(res), false, false); |
| if (ret < 0) |
| return ret; |
| |
| rpmb_dprint_key(" key/mac ", res.key_mac, " expected mac ", |
| res.key_mac); |
| rpmb_dprint_buf(" nonce ", res.nonce.byte, sizeof(res.nonce.byte)); |
| rpmb_dprint_u32(" write_counter ", res.write_counter); |
| rpmb_dprint_u16(" result ", res.result); |
| rpmb_dprint_u16(" req/resp ", res.req_resp); |
| |
| ret = rpmb_check_response("program key", RPMB_RESP_PROGRAM_KEY, &res, 1, |
| NULL, NULL, NULL, 0); |
| return ret; |
| } |
| |
| static int rpmb_read_counter(struct rpmb_state* state, |
| uint32_t* write_counter) { |
| int ret; |
| struct rpmb_key mac; |
| struct rpmb_nonce nonce = rpmb_nonce_init(); |
| struct rpmb_packet cmd = { |
| .nonce = nonce, |
| .req_resp = rpmb_u16(RPMB_REQ_GET_COUNTER), |
| }; |
| struct rpmb_packet res; |
| |
| ret = rpmb_send(state->mmc_handle, NULL, 0, &cmd, sizeof(cmd), &res, |
| sizeof(res), false, false); |
| if (ret < 0) |
| return ret; |
| |
| ret = rpmb_mac(state->key, &res, 1, &mac); |
| if (ret < 0) |
| return ret; |
| |
| rpmb_dprintf("rpmb: read counter response:\n"); |
| rpmb_dprint_key(" key/mac ", res.key_mac, " expected mac ", mac); |
| rpmb_dprint_buf(" nonce ", res.nonce.byte, sizeof(res.nonce.byte)); |
| rpmb_dprint_u32(" write_counter ", res.write_counter); |
| rpmb_dprint_u16(" result ", res.result); |
| rpmb_dprint_u16(" req/resp ", res.req_resp); |
| |
| ret = rpmb_check_response("read counter", RPMB_RESP_GET_COUNTER, &res, 1, |
| &mac, &nonce, NULL, 0); |
| if (ret < 0) |
| return ret; |
| |
| if (write_counter) |
| *write_counter = rpmb_get_u32(res.write_counter); |
| |
| return 0; |
| } |
| |
| static int rpmb_read_counter_retry(struct rpmb_state* state, |
| uint32_t* write_counter) { |
| int retries; |
| int ret = 0; |
| for (retries = 0; retries < RPMB_READ_COUNTER_MAX_RETRIES; retries++) { |
| ret = rpmb_read_counter(state, write_counter); |
| if (ret >= 0) { |
| return ret; |
| } |
| } |
| |
| /* Return the last error */ |
| error_report_rpmb_counter_read_failure(); |
| return ret; |
| } |
| |
| static int rpmb_read_data(struct rpmb_state* state, |
| const void* cmp_buf, |
| void* out_buf, |
| uint16_t addr, |
| uint16_t count, |
| struct rpmb_key* mac) { |
| int i; |
| int ret; |
| struct rpmb_nonce nonce = rpmb_nonce_init(); |
| struct rpmb_packet cmd = { |
| .nonce = nonce, |
| .address = rpmb_u16(addr), |
| #if RPMB_PROTOCOL == RPMB_PROTOCOL_UFS |
| .block_count = rpmb_u16(count), |
| #endif |
| .req_resp = rpmb_u16(RPMB_REQ_DATA_READ), |
| }; |
| struct rpmb_packet res[MAX_PACKET_COUNT]; |
| const uint8_t* cmp_bufp; |
| uint8_t* out_bufp; |
| |
| assert(count <= MAX_PACKET_COUNT); |
| |
| if (!state) |
| return -EINVAL; |
| if (state->verify_failed) |
| return -EIO; |
| |
| ret = rpmb_send(state->mmc_handle, NULL, 0, &cmd, sizeof(cmd), res, |
| sizeof(res[0]) * count, false, false); |
| if (ret < 0) |
| return ret; |
| |
| if (mac) { |
| ret = rpmb_mac(state->key, res, count, mac); |
| if (ret < 0) |
| return ret; |
| } |
| |
| rpmb_dprintf("rpmb: read data, addr %d, count %d, response:\n", addr, |
| count); |
| for (i = 0; i < count; i++) { |
| rpmb_dprintf(" block %d\n", i); |
| if (i == count - 1 && mac) |
| rpmb_dprint_key(" key/mac ", res[i].key_mac, |
| " expected mac ", *mac); |
| rpmb_dprint_buf(" data ", res[i].data, sizeof(res[i].data)); |
| rpmb_dprint_buf(" nonce ", res[i].nonce.byte, |
| sizeof(res[i].nonce.byte)); |
| rpmb_dprint_u16(" address ", res[i].address); |
| rpmb_dprint_u16(" block_count ", res[i].block_count); |
| rpmb_dprint_u16(" result ", res[i].result); |
| rpmb_dprint_u16(" req/resp ", res[i].req_resp); |
| } |
| |
| ret = rpmb_check_response("read data", RPMB_RESP_DATA_READ, res, count, mac, |
| &nonce, &addr, 0); |
| if (ret < 0) |
| return ret; |
| |
| if (cmp_buf) { |
| for (cmp_bufp = cmp_buf, i = 0; i < count; |
| i++, cmp_bufp += sizeof(res[i].data)) { |
| if (memcmp(cmp_bufp, res[i].data, sizeof(res[i].data))) { |
| fprintf(stderr, "verify read: data compare failed\n"); |
| return -1; |
| } |
| } |
| } |
| |
| if (out_buf) { |
| for (out_bufp = out_buf, i = 0; i < count; |
| i++, out_bufp += sizeof(res[i].data)) { |
| memcpy(out_bufp, res[i].data, sizeof(res[i].data)); |
| } |
| } |
| |
| return 0; |
| } |
| |
| int rpmb_read(struct rpmb_state* state, |
| void* buf, |
| uint16_t addr, |
| uint16_t count) { |
| struct rpmb_key mac; |
| return rpmb_read_data(state, NULL, buf, addr, count, &mac); |
| } |
| |
| int rpmb_read_no_mac(struct rpmb_state* state, |
| void* buf, |
| uint16_t addr, |
| uint16_t count) { |
| return rpmb_read_data(state, NULL, buf, addr, count, NULL); |
| } |
| |
| int rpmb_verify(struct rpmb_state* state, |
| const void* buf, |
| uint16_t addr, |
| uint16_t count) { |
| struct rpmb_key mac; |
| return rpmb_read_data(state, buf, NULL, addr, count, &mac); |
| } |
| |
| /** |
| * check_write_counter() - Check that the write counter matches |
| * @expected_write_counter |
| * @state: Current RPMB state |
| * @expected_write_counter: Write counter we expect |
| * |
| * Return: %true if the write counter is confirmed to be |
| * @expected_write_counter |
| */ |
| static bool check_write_counter(struct rpmb_state* state, |
| uint32_t expected_write_counter) { |
| /* |
| * Query the RPMB chip for the current write counter. Although there was |
| * some sort of exceptional condition, we don't actually know if a |
| * write went through and therefore the counter was incremented. |
| */ |
| int ret; |
| uint32_t new_write_counter = 0; |
| ret = rpmb_read_counter_retry(state, &new_write_counter); |
| if (ret == 0) { |
| if (new_write_counter == expected_write_counter) { |
| return true; |
| } else { |
| fprintf(stderr, |
| "%s: Could not resync write counter. " |
| "expected write counter: %u, queried write counter: %u\n", |
| __func__, expected_write_counter, new_write_counter); |
| } |
| } else { |
| fprintf(stderr, "%s: rpmb_read_counter failed: %d\n", __func__, ret); |
| } |
| |
| return false; |
| } |
| |
| static int rpmb_write_data(struct rpmb_state* state, |
| const char* buf, |
| uint16_t addr, |
| uint16_t count, |
| bool sync, |
| bool sync_checkpoint) { |
| int i; |
| int ret; |
| struct rpmb_key mac; |
| struct rpmb_packet cmd[MAX_PACKET_COUNT]; |
| struct rpmb_packet rescmd = { |
| .req_resp = rpmb_u16(RPMB_REQ_RESULT_READ), |
| }; |
| struct rpmb_packet res; |
| |
| assert(count <= MAX_PACKET_COUNT); |
| |
| rpmb_dprintf("rpmb: write data, addr %d, count %d\n", addr, count); |
| for (i = 0; i < count; i++) { |
| memset(&cmd[i], 0, sizeof(cmd[i])); |
| memcpy(cmd[i].data, buf + i * sizeof(cmd[i].data), sizeof(cmd[i].data)); |
| rpmb_dprint_buf(" data ", cmd[i].data, sizeof(cmd[i].data)); |
| cmd[i].write_counter = rpmb_u32(state->write_counter); |
| cmd[i].address = rpmb_u16(addr); |
| cmd[i].block_count = rpmb_u16(count); |
| cmd[i].req_resp = rpmb_u16(RPMB_REQ_DATA_WRITE); |
| } |
| ret = rpmb_mac(state->key, cmd, count, &cmd[count - 1].key_mac); |
| if (ret < 0) { |
| fprintf(stderr, "rpmb command mac failed\n"); |
| return ret; |
| } |
| |
| ret = rpmb_send(state->mmc_handle, cmd, sizeof(cmd[0]) * count, &rescmd, |
| sizeof(rescmd), &res, sizeof(res), sync, sync_checkpoint); |
| if (ret < 0) { |
| fprintf(stderr, "rpmb send failed: %d, result: %hu\n", ret, |
| rpmb_get_u16(res.result)); |
| goto err_sent; |
| } |
| |
| ret = rpmb_mac(state->key, &res, 1, &mac); |
| if (ret < 0) { |
| fprintf(stderr, "rpmb response mac failed\n"); |
| goto err_sent; |
| } |
| |
| rpmb_dprintf( |
| "rpmb: write data, addr %d, count %d, write_counter %d, response\n", |
| addr, count, state->write_counter); |
| rpmb_dprint_key(" key/mac ", res.key_mac, " expected mac ", mac); |
| rpmb_dprint_buf(" nonce ", res.nonce.byte, sizeof(res.nonce.byte)); |
| rpmb_dprint_u32(" write_counter ", res.write_counter); |
| rpmb_dprint_u16(" address ", res.address); |
| rpmb_dprint_u16(" result ", res.result); |
| rpmb_dprint_u16(" req/resp ", res.req_resp); |
| |
| ret = rpmb_check_response("write data", RPMB_RESP_DATA_WRITE, &res, 1, &mac, |
| NULL, &addr, state->write_counter + 1); |
| if (ret < 0) { |
| fprintf(stderr, "rpmb_check_response_failed: %d, result: %hu\n", ret, |
| rpmb_get_u16(res.result)); |
| if (check_write_counter(state, state->write_counter + 1)) { |
| state->write_counter++; |
| |
| fprintf(stderr, |
| "Write was committed with failed response. New write counter: %u\n", |
| state->write_counter); |
| error_report_rpmb_counter_mismatch_recovered(); |
| |
| /* |
| * Indicate to block device that the FS state is unknown and a clean |
| * superblock must be written. |
| */ |
| ret = -EUCLEAN; |
| } |
| |
| goto err_sent; |
| } |
| |
| state->write_counter++; |
| |
| return 0; |
| |
| err_sent: |
| /* |
| * An error occurred after the write request was sent. An attacker might |
| * have saved this write request and might send it to the rpmb device at |
| * any time. Any other write with this write counter value now needs extra |
| * checks to make sure there is no corruption. |
| * |
| * 1. The next write fails. |
| * |
| * 1.1. The failure is a count failure. |
| * A write operation that was previously reported as an error must have |
| * actually been written. The filesystem may now be in a state where is it |
| * not safe to write any other block. The write that actually went through |
| * may have been from a previous write attempt, so we don't know the current |
| * state. |
| * |
| * We pass BLOCK_WRITE_FAILED_UNKNOWN_STATE to block_cache_complete_write() |
| * in this case which causes the block device to queue writes of all |
| * filesystem superblocks before doing any new writes. |
| * |
| * 1.1.1. The block actually written was a super-block. |
| * This means a transaction was committed to disk that the file-system code |
| * thought was aborted. The in-memory view of free blocks will not match the |
| * on disk state. It is not safe to proceed with any other write operations |
| * in this state as the file-system could pick a block to write to that is |
| * not actually free until the super block gets updated again with the |
| * in-memory state. |
| * |
| * We mitigate this case by immediately rewriting a new, valid super-block |
| * with the current in-memory (i.e. not including the current, failing |
| * transaction) state when a super-block write fails. If this second write |
| * fails, we are left with a failed transaction in fs->inital_super_block_tr |
| * and all future writes to this filesystem will fail. If it succeeds we |
| * validate the write in 2.1 below. If the device reboots before completing |
| * the second super-block write attempt, a malicious host can replay this |
| * block on a later boot. In the case of TD filesystems, this can cause |
| * detectable filesystem corruption as data blocks may not match the |
| * super-block now, however, that is allowed. For TP filesystems, the next |
| * data write will be validated as it is the first RPMB write after boot, |
| * and if it fails we abort the service (2.1.1), forcing a reboot and |
| * re-initializing the filesystem state from the now committed super-block. |
| * |
| * It's worth noting that in this case, we may have sent a failed response |
| * to a client for a transaction that was eventually committed. |
| * |
| * 1.1.2. The block actually written was a data block. |
| * |
| * The write must have been to a block that was free, and the transaction |
| * that block was part of could never have been committed. We don't actually |
| * care about this write, but we rewrite the superblock as described in |
| * 1.1.1. because we can't know what was written. |
| * |
| * 1.2. The failure is not reported as count failure. |
| * This can be handled the same way as the inital failure. We now have one |
| * more possible write request that can be saved and written at any time by |
| * an attacker, but it is in the same class as before. |
| * |
| * 2. The next write succeeds. |
| * |
| * 2.1. The same block number and counter value has already been sent. |
| * This success status cannot be trusted. We read back the data to verify. |
| * 2.1.1. Verify failed. |
| * This has the same effect as 1.1. We currently block all further |
| * read/write operations after this point (until reboot or FS re-mount) |
| * because it is not safe to recover from this state in a TP filesystem. |
| * |
| * 2.1.2. Verify passed. |
| * We are back to a normal state. |
| * |
| * 2.2. The same block number and counter has not already been sent. |
| * We are back to a normal state. |
| */ |
| fprintf(stderr, "rpmb: write failed for write counter %u\n", |
| state->write_counter); |
| state->first_write_complete = false; |
| return ret; |
| } |
| |
| int rpmb_write(struct rpmb_state* state, |
| const void* buf, |
| uint16_t addr, |
| uint16_t count, |
| bool sync, |
| bool sync_checkpoint) { |
| int ret; |
| |
| if (!state) |
| return -EINVAL; |
| if (state->verify_failed) |
| return -EIO; |
| |
| ret = rpmb_write_data(state, buf, addr, count, sync, sync_checkpoint); |
| if (ret < 0) |
| return ret; |
| |
| if (!state->first_write_complete) { |
| /* |
| * The first write request after reading the write counter could get a |
| * signed response from a different write request. There is no nonce in |
| * the write request, only a write counter. The response could be from |
| * another valid write request we generated on a previous boot that was |
| * not completed. Read back the data and verify that the correct data |
| * was written for this case. Note that this only works if we never |
| * send more than one write request to the non-secure proxy at once. If |
| * we later add support for pipelining rpmb operation we need to verify |
| * the first n write requests here instead, where n is the max pipeline |
| * depth of any build that may have run on the same device. We would |
| * also need ensure that a superblock write request is not sent until |
| * all other write requests have been validated and that an attacker |
| * cannot have any saved write requests to the same filesystem with a |
| * larger write-counter value than the superblock update (e.g. by |
| * repeating a non-superblock write request until only one write |
| * operation remains to be verified). |
| */ |
| ret = rpmb_verify(state, buf, addr, count); |
| if (ret < 0) { |
| fprintf(stderr, |
| "rpmb write verify failure: %d, addr: %hu, count: %hu\n", |
| ret, addr, count); |
| state->verify_failed = true; |
| return ret; |
| } |
| state->first_write_complete = true; |
| } |
| |
| return 0; |
| } |
| |
| void rpmb_set_key(struct rpmb_state* state, const struct rpmb_key* key) { |
| assert(state); |
| state->key = *key; |
| |
| /* |
| * We need to read the counter before reading the super blocks. If an |
| * attacker writes to a super block after we read it, but before we read the |
| * write counter, or next write would succeed without us detecting that the |
| * in-memory super block does not match the on-disk state. |
| * |
| * We retry reading the write counter several times because |
| * we occasionally get an incorrect response |
| */ |
| int ret; |
| ret = rpmb_read_counter_retry(state, &state->write_counter); |
| if (ret < 0) { |
| fprintf(stderr, "failed to read rpmb write counter\n"); |
| /* |
| * Ignore errors. Any future write will fail since we initialized the |
| * write_counter with the value where it expires. |
| */ |
| } |
| } |
| |
| int rpmb_init(struct rpmb_state** statep, void* mmc_handle) { |
| struct rpmb_state* state = malloc(sizeof(*state)); |
| if (!state) |
| return -ENOMEM; |
| |
| state->mmc_handle = mmc_handle; |
| state->write_counter = RPMB_WRITE_COUNTER_EXPIRED_VALUE; |
| /* |
| * We don't know if the last write before reboot completed successfully. |
| * There may be writes for the current write counter that can be replayed at |
| * this point, so we need to validate our next write. |
| */ |
| state->first_write_complete = false; |
| state->verify_failed = false; |
| |
| *statep = state; |
| |
| return 0; |
| } |
| |
| void rpmb_uninit(struct rpmb_state* statep) { |
| free(statep); |
| } |
