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
ReadFullyWithRead(void * ctx,void * buf,size_t count)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
ReadFullyWithMtdRead(void * ctx,void * buf,size_t count)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. */
SkipWithRead(void * ctx,ReadFullyFn read_fn,size_t count)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
FindKernelConfigFromStream(void * ctx,ReadFullyFn read_fn,uint64_t kernel_body_load_address)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
FindKernelConfig(const char * infile,uint64_t kernel_body_load_address)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