/* Copyright 2012 The Chromium OS Authors. All rights reserved. * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. * * Exports the kernel commandline from a given partition/image. */ #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <sys/fcntl.h> #include <sys/stat.h> #include <sys/types.h> #include <unistd.h> #include "host_common.h" #include "kernel_blob.h" #include "vboot_api.h" #include "vboot_host.h" #ifdef USE_MTD #include <linux/major.h> #include <mtd/mtd-user.h> #include <mtdutils.h> #endif typedef ssize_t (*ReadFullyFn)(void *ctx, void *buf, size_t count); static ssize_t ReadFullyWithRead(void *ctx, void *buf, size_t count) { ssize_t nr_read = 0; int fd = *((int*)ctx); while (nr_read < count) { ssize_t to_read = count - nr_read; ssize_t chunk = read(fd, buf + nr_read, to_read); if (chunk < 0) { return -1; } else if (chunk == 0) { break; } nr_read += chunk; } return nr_read; } #ifdef USE_MTD static ssize_t ReadFullyWithMtdRead(void *ctx, void *buf, size_t count) { MtdReadContext *mtd_ctx = (MtdReadContext*)ctx; return mtd_read_data(mtd_ctx, buf, count); } #endif /* Skip the stream by calling |read_fn| many times. Return 0 on success. */ static int SkipWithRead(void *ctx, ReadFullyFn read_fn, size_t count) { char buf[1024]; ssize_t nr_skipped = 0; while (nr_skipped < count) { ssize_t to_read = count - nr_skipped; if (to_read > sizeof(buf)) { to_read = sizeof(buf); } if (read_fn(ctx, buf, to_read) != to_read) { return -1; } nr_skipped += to_read; } return 0; } static char *FindKernelConfigFromStream(void *ctx, ReadFullyFn read_fn, uint64_t kernel_body_load_address) { VbKeyBlockHeader key_block; VbKernelPreambleHeader preamble; uint32_t now = 0; uint32_t offset = 0; /* Skip the key block */ if (read_fn(ctx, &key_block, sizeof(key_block)) != sizeof(key_block)) { VbExError("not enough data to fill key block header\n"); return NULL; } ssize_t to_skip = key_block.key_block_size - sizeof(key_block); if (to_skip < 0 || SkipWithRead(ctx, read_fn, to_skip)) { VbExError("key_block_size advances past the end of the blob\n"); return NULL; } now += key_block.key_block_size; /* Open up the preamble */ if (read_fn(ctx, &preamble, sizeof(preamble)) != sizeof(preamble)) { VbExError("not enough data to fill preamble\n"); return NULL; } to_skip = preamble.preamble_size - sizeof(preamble); if (to_skip < 0 || SkipWithRead(ctx, read_fn, to_skip)) { VbExError("preamble_size advances past the end of the blob\n"); return NULL; } now += preamble.preamble_size; /* Read body_load_address from preamble if no * kernel_body_load_address */ if (kernel_body_load_address == USE_PREAMBLE_LOAD_ADDR) kernel_body_load_address = preamble.body_load_address; /* The x86 kernels have a pointer to the kernel commandline in the * zeropage table, but that's irrelevant for ARM. Both types keep the * config blob in the same place, so just go find it. */ offset = preamble.bootloader_address - (kernel_body_load_address + CROS_PARAMS_SIZE + CROS_CONFIG_SIZE) + now; to_skip = offset - now; if (to_skip < 0 || SkipWithRead(ctx, read_fn, to_skip)) { VbExError("params are outside of the memory blob: %x\n", offset); return NULL; } char *ret = malloc(CROS_CONFIG_SIZE); if (!ret) { VbExError("No memory\n"); return NULL; } if (read_fn(ctx, ret, CROS_CONFIG_SIZE) != CROS_CONFIG_SIZE) { VbExError("Cannot read kernel config\n"); free(ret); ret = NULL; } return ret; } char *FindKernelConfig(const char *infile, uint64_t kernel_body_load_address) { char *newstr = NULL; int fd = open(infile, O_RDONLY | O_CLOEXEC | O_LARGEFILE); if (fd < 0) { VbExError("Cannot open %s\n", infile); return NULL; } void *ctx = &fd; ReadFullyFn read_fn = ReadFullyWithRead; #ifdef USE_MTD struct stat stat_buf; if (fstat(fd, &stat_buf)) { VbExError("Cannot stat %s\n", infile); return NULL; } int is_mtd = (major(stat_buf.st_rdev) == MTD_CHAR_MAJOR); if (is_mtd) { ctx = mtd_read_descriptor(fd, infile); if (!ctx) { VbExError("Cannot read from MTD device %s\n", infile); return NULL; } read_fn = ReadFullyWithMtdRead; } #endif newstr = FindKernelConfigFromStream(ctx, read_fn, kernel_body_load_address); #ifdef USE_MTD if (is_mtd) { mtd_read_close(ctx); } #endif close(fd); return newstr; }