1 /* Copyright 2012 The Chromium OS Authors. All rights reserved. 2 * Use of this source code is governed by a BSD-style license that can be 3 * found in the LICENSE file. 4 * 5 * Exports the kernel commandline from a given partition/image. 6 */ 7 8 #include <stdio.h> 9 #include <string.h> 10 #include <sys/mman.h> 11 #include <sys/fcntl.h> 12 #include <sys/stat.h> 13 #include <sys/types.h> 14 #include <unistd.h> 15 16 #include "host_common.h" 17 #include "kernel_blob.h" 18 #include "vboot_api.h" 19 #include "vboot_host.h" 20 21 #ifdef USE_MTD 22 #include <linux/major.h> 23 #include <mtd/mtd-user.h> 24 #include <mtdutils.h> 25 #endif 26 27 typedef ssize_t (*ReadFullyFn)(void *ctx, void *buf, size_t count); 28 29 static ssize_t ReadFullyWithRead(void *ctx, void *buf, size_t count) 30 { 31 ssize_t nr_read = 0; 32 int fd = *((int*)ctx); 33 while (nr_read < count) { 34 ssize_t to_read = count - nr_read; 35 ssize_t chunk = read(fd, buf + nr_read, to_read); 36 if (chunk < 0) { 37 return -1; 38 } else if (chunk == 0) { 39 break; 40 } 41 nr_read += chunk; 42 } 43 return nr_read; 44 } 45 46 #ifdef USE_MTD 47 static ssize_t ReadFullyWithMtdRead(void *ctx, void *buf, size_t count) 48 { 49 MtdReadContext *mtd_ctx = (MtdReadContext*)ctx; 50 return mtd_read_data(mtd_ctx, buf, count); 51 } 52 #endif 53 54 /* Skip the stream by calling |read_fn| many times. Return 0 on success. */ 55 static int SkipWithRead(void *ctx, ReadFullyFn read_fn, size_t count) 56 { 57 char buf[1024]; 58 ssize_t nr_skipped = 0; 59 while (nr_skipped < count) { 60 ssize_t to_read = count - nr_skipped; 61 if (to_read > sizeof(buf)) { 62 to_read = sizeof(buf); 63 } 64 if (read_fn(ctx, buf, to_read) != to_read) { 65 return -1; 66 } 67 nr_skipped += to_read; 68 } 69 return 0; 70 } 71 72 static char *FindKernelConfigFromStream(void *ctx, ReadFullyFn read_fn, 73 uint64_t kernel_body_load_address) 74 { 75 VbKeyBlockHeader key_block; 76 VbKernelPreambleHeader preamble; 77 uint32_t now = 0; 78 uint32_t offset = 0; 79 80 /* Skip the key block */ 81 if (read_fn(ctx, &key_block, sizeof(key_block)) != sizeof(key_block)) { 82 VbExError("not enough data to fill key block header\n"); 83 return NULL; 84 } 85 ssize_t to_skip = key_block.key_block_size - sizeof(key_block); 86 if (to_skip < 0 || SkipWithRead(ctx, read_fn, to_skip)) { 87 VbExError("key_block_size advances past the end of the blob\n"); 88 return NULL; 89 } 90 now += key_block.key_block_size; 91 92 /* Open up the preamble */ 93 if (read_fn(ctx, &preamble, sizeof(preamble)) != sizeof(preamble)) { 94 VbExError("not enough data to fill preamble\n"); 95 return NULL; 96 } 97 to_skip = preamble.preamble_size - sizeof(preamble); 98 if (to_skip < 0 || SkipWithRead(ctx, read_fn, to_skip)) { 99 VbExError("preamble_size advances past the end of the blob\n"); 100 return NULL; 101 } 102 now += preamble.preamble_size; 103 104 /* Read body_load_address from preamble if no 105 * kernel_body_load_address */ 106 if (kernel_body_load_address == USE_PREAMBLE_LOAD_ADDR) 107 kernel_body_load_address = preamble.body_load_address; 108 109 /* The x86 kernels have a pointer to the kernel commandline in the 110 * zeropage table, but that's irrelevant for ARM. Both types keep the 111 * config blob in the same place, so just go find it. */ 112 offset = preamble.bootloader_address - 113 (kernel_body_load_address + CROS_PARAMS_SIZE + 114 CROS_CONFIG_SIZE) + now; 115 to_skip = offset - now; 116 if (to_skip < 0 || SkipWithRead(ctx, read_fn, to_skip)) { 117 VbExError("params are outside of the memory blob: %x\n", 118 offset); 119 return NULL; 120 } 121 char *ret = malloc(CROS_CONFIG_SIZE); 122 if (!ret) { 123 VbExError("No memory\n"); 124 return NULL; 125 } 126 if (read_fn(ctx, ret, CROS_CONFIG_SIZE) != CROS_CONFIG_SIZE) { 127 VbExError("Cannot read kernel config\n"); 128 free(ret); 129 ret = NULL; 130 } 131 return ret; 132 } 133 134 char *FindKernelConfig(const char *infile, uint64_t kernel_body_load_address) 135 { 136 char *newstr = NULL; 137 138 int fd = open(infile, O_RDONLY | O_CLOEXEC | O_LARGEFILE); 139 if (fd < 0) { 140 VbExError("Cannot open %s\n", infile); 141 return NULL; 142 } 143 144 void *ctx = &fd; 145 ReadFullyFn read_fn = ReadFullyWithRead; 146 147 #ifdef USE_MTD 148 struct stat stat_buf; 149 if (fstat(fd, &stat_buf)) { 150 VbExError("Cannot stat %s\n", infile); 151 return NULL; 152 } 153 154 int is_mtd = (major(stat_buf.st_rdev) == MTD_CHAR_MAJOR); 155 if (is_mtd) { 156 ctx = mtd_read_descriptor(fd, infile); 157 if (!ctx) { 158 VbExError("Cannot read from MTD device %s\n", infile); 159 return NULL; 160 } 161 read_fn = ReadFullyWithMtdRead; 162 } 163 #endif 164 165 newstr = FindKernelConfigFromStream(ctx, read_fn, 166 kernel_body_load_address); 167 168 #ifdef USE_MTD 169 if (is_mtd) { 170 mtd_read_close(ctx); 171 } 172 #endif 173 close(fd); 174 175 return newstr; 176 } 177
