1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
// SPDX-License-Identifier: GPL-2.0
/*
* Verified Boot for Embedded (VBE) OS request (device tree fixup) functions
*
* Copyright 2022 Google LLC
* Written by Simon Glass <sjg@chromium.org>
*/
#define LOG_CATEGORY LOGC_BOOT
#include <common.h>
#include <dm.h>
#include <event.h>
#include <image.h>
#include <malloc.h>
#include <rng.h>
#include <dm/ofnode.h>
#define VBE_PREFIX "vbe,"
#define VBE_PREFIX_LEN (sizeof(VBE_PREFIX) - 1)
#define VBE_ERR_STR_LEN 128
#define VBE_MAX_RAND_SIZE 256
struct vbe_result {
int errnum;
char err_str[VBE_ERR_STR_LEN];
};
typedef int (*vbe_req_func)(ofnode node, struct vbe_result *result);
static int handle_random_req(ofnode node, int default_size,
struct vbe_result *result)
{
char buf[VBE_MAX_RAND_SIZE];
struct udevice *dev;
u32 size;
int ret;
if (!IS_ENABLED(CONFIG_DM_RNG))
return -ENOTSUPP;
if (ofnode_read_u32(node, "vbe,size", &size)) {
if (!default_size) {
snprintf(result->err_str, VBE_ERR_STR_LEN,
"Missing vbe,size property");
return log_msg_ret("byt", -EINVAL);
}
size = default_size;
}
if (size > VBE_MAX_RAND_SIZE) {
snprintf(result->err_str, VBE_ERR_STR_LEN,
"vbe,size %#x exceeds max size %#x", size,
VBE_MAX_RAND_SIZE);
return log_msg_ret("siz", -E2BIG);
}
ret = uclass_first_device_err(UCLASS_RNG, &dev);
if (ret) {
snprintf(result->err_str, VBE_ERR_STR_LEN,
"Cannot find random-number device (err=%d)", ret);
return log_msg_ret("wr", ret);
}
ret = dm_rng_read(dev, buf, size);
if (ret) {
snprintf(result->err_str, VBE_ERR_STR_LEN,
"Failed to read random-number device (err=%d)", ret);
return log_msg_ret("rd", ret);
}
ret = ofnode_write_prop(node, "data", buf, size, true);
if (ret)
return log_msg_ret("wr", -EINVAL);
return 0;
}
static int vbe_req_random_seed(ofnode node, struct vbe_result *result)
{
return handle_random_req(node, 0, result);
}
static int vbe_req_aslr_move(ofnode node, struct vbe_result *result)
{
return -ENOTSUPP;
}
static int vbe_req_aslr_rand(ofnode node, struct vbe_result *result)
{
return handle_random_req(node, 4, result);
}
static int vbe_req_efi_runtime_rand(ofnode node, struct vbe_result *result)
{
return handle_random_req(node, 4, result);
}
static struct vbe_req {
const char *compat;
vbe_req_func func;
} vbe_reqs[] = {
/* address space layout randomization - move the OS in memory */
{ "aslr-move", vbe_req_aslr_move },
/* provide random data for address space layout randomization */
{ "aslr-rand", vbe_req_aslr_rand },
/* provide random data for EFI-runtime-services address */
{ "efi-runtime-rand", vbe_req_efi_runtime_rand },
/* generate random data bytes to see the OS's rand generator */
{ "random-rand", vbe_req_random_seed },
};
static int vbe_process_request(ofnode node, struct vbe_result *result)
{
const char *compat, *req_name;
int i;
compat = ofnode_read_string(node, "compatible");
if (!compat)
return 0;
if (strlen(compat) <= VBE_PREFIX_LEN ||
strncmp(compat, VBE_PREFIX, VBE_PREFIX_LEN))
return -EINVAL;
req_name = compat + VBE_PREFIX_LEN; /* drop "vbe," prefix */
for (i = 0; i < ARRAY_SIZE(vbe_reqs); i++) {
if (!strcmp(vbe_reqs[i].compat, req_name)) {
int ret;
ret = vbe_reqs[i].func(node, result);
if (ret)
return log_msg_ret("req", ret);
return 0;
}
}
snprintf(result->err_str, VBE_ERR_STR_LEN, "Unknown request: %s",
req_name);
return -ENOTSUPP;
}
/**
* bootmeth_vbe_ft_fixup() - Process VBE OS requests and do device tree fixups
*
* If there are no images provided, this does nothing and returns 0.
*
* @ctx: Context for event
* @event: Event to process
* @return 0 if OK, -ve on error
*/
static int bootmeth_vbe_ft_fixup(void *ctx, struct event *event)
{
const struct event_ft_fixup *fixup = &event->data.ft_fixup;
const struct bootm_headers *images = fixup->images;
ofnode parent, dest_parent, root, node;
oftree fit;
if (!images || !images->fit_hdr_os)
return 0;
/* Get the image node with requests in it */
log_debug("fit=%p, noffset=%d\n", images->fit_hdr_os,
images->fit_noffset_os);
fit = oftree_from_fdt(images->fit_hdr_os);
root = oftree_root(fit);
if (of_live_active()) {
log_warning("Cannot fix up live tree\n");
return 0;
}
if (!ofnode_valid(root))
return log_msg_ret("rt", -EINVAL);
parent = noffset_to_ofnode(root, images->fit_noffset_os);
if (!ofnode_valid(parent))
return log_msg_ret("img", -EINVAL);
dest_parent = oftree_path(fixup->tree, "/chosen");
if (!ofnode_valid(dest_parent))
return log_msg_ret("dst", -EINVAL);
ofnode_for_each_subnode(node, parent) {
const char *name = ofnode_get_name(node);
struct vbe_result result;
ofnode dest;
int ret;
log_debug("copy subnode: %s\n", name);
ret = ofnode_add_subnode(dest_parent, name, &dest);
if (ret && ret != -EEXIST)
return log_msg_ret("add", ret);
ret = ofnode_copy_props(node, dest);
if (ret)
return log_msg_ret("cp", ret);
*result.err_str = '\0';
ret = vbe_process_request(dest, &result);
if (ret) {
result.errnum = ret;
log_warning("Failed to process VBE request %s (err=%d)\n",
ofnode_get_name(dest), ret);
if (*result.err_str) {
char *msg = strdup(result.err_str);
if (!msg)
return log_msg_ret("msg", -ENOMEM);
ret = ofnode_write_string(dest, "vbe,error",
msg);
if (ret) {
free(msg);
return log_msg_ret("str", -ENOMEM);
}
}
if (result.errnum) {
ret = ofnode_write_u32(dest, "vbe,errnum",
result.errnum);
if (ret)
return log_msg_ret("num", -ENOMEM);
if (result.errnum != -ENOTSUPP)
return log_msg_ret("pro",
result.errnum);
if (result.errnum == -ENOTSUPP &&
ofnode_read_bool(dest, "vbe,required")) {
log_err("Cannot handle required request: %s\n",
ofnode_get_name(dest));
return log_msg_ret("req",
result.errnum);
}
}
}
}
return 0;
}
EVENT_SPY_FULL(EVT_FT_FIXUP, bootmeth_vbe_ft_fixup);
|
