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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kexec.c - kexec_load system call
4 * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/capability.h>
10#include <linux/mm.h>
11#include <linux/file.h>
12#include <linux/security.h>
13#include <linux/kexec.h>
14#include <linux/mutex.h>
15#include <linux/list.h>
16#include <linux/syscalls.h>
17#include <linux/vmalloc.h>
18#include <linux/slab.h>
19
20#include "kexec_internal.h"
21
22static int copy_user_segment_list(struct kimage *image,
23 unsigned long nr_segments,
24 struct kexec_segment __user *segments)
25{
26 int ret;
27 size_t segment_bytes;
28
29 /* Read in the segments */
30 image->nr_segments = nr_segments;
31 segment_bytes = nr_segments * sizeof(*segments);
32 ret = copy_from_user(image->segment, segments, segment_bytes);
33 if (ret)
34 ret = -EFAULT;
35
36 return ret;
37}
38
39static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
40 unsigned long nr_segments,
41 struct kexec_segment __user *segments,
42 unsigned long flags)
43{
44 int ret;
45 struct kimage *image;
46 bool kexec_on_panic = flags & KEXEC_ON_CRASH;
47
48 if (kexec_on_panic) {
49 /* Verify we have a valid entry point */
50 if ((entry < phys_to_boot_phys(crashk_res.start)) ||
51 (entry > phys_to_boot_phys(crashk_res.end)))
52 return -EADDRNOTAVAIL;
53 }
54
55 /* Allocate and initialize a controlling structure */
56 image = do_kimage_alloc_init();
57 if (!image)
58 return -ENOMEM;
59
60 image->start = entry;
61
62 ret = copy_user_segment_list(image, nr_segments, segments);
63 if (ret)
64 goto out_free_image;
65
66 if (kexec_on_panic) {
67 /* Enable special crash kernel control page alloc policy. */
68 image->control_page = crashk_res.start;
69 image->type = KEXEC_TYPE_CRASH;
70 }
71
72 ret = sanity_check_segment_list(image);
73 if (ret)
74 goto out_free_image;
75
76 /*
77 * Find a location for the control code buffer, and add it
78 * the vector of segments so that it's pages will also be
79 * counted as destination pages.
80 */
81 ret = -ENOMEM;
82 image->control_code_page = kimage_alloc_control_pages(image,
83 get_order(KEXEC_CONTROL_PAGE_SIZE));
84 if (!image->control_code_page) {
85 pr_err("Could not allocate control_code_buffer\n");
86 goto out_free_image;
87 }
88
89 if (!kexec_on_panic) {
90 image->swap_page = kimage_alloc_control_pages(image, 0);
91 if (!image->swap_page) {
92 pr_err("Could not allocate swap buffer\n");
93 goto out_free_control_pages;
94 }
95 }
96
97 *rimage = image;
98 return 0;
99out_free_control_pages:
100 kimage_free_page_list(&image->control_pages);
101out_free_image:
102 kfree(image);
103 return ret;
104}
105
106static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
107 struct kexec_segment __user *segments, unsigned long flags)
108{
109 struct kimage **dest_image, *image;
110 unsigned long i;
111 int ret;
112
113 if (flags & KEXEC_ON_CRASH) {
114 dest_image = &kexec_crash_image;
115 if (kexec_crash_image)
116 arch_kexec_unprotect_crashkres();
117 } else {
118 dest_image = &kexec_image;
119 }
120
121 if (nr_segments == 0) {
122 /* Uninstall image */
123 kimage_free(xchg(dest_image, NULL));
124 return 0;
125 }
126 if (flags & KEXEC_ON_CRASH) {
127 /*
128 * Loading another kernel to switch to if this one
129 * crashes. Free any current crash dump kernel before
130 * we corrupt it.
131 */
132 kimage_free(xchg(&kexec_crash_image, NULL));
133 }
134
135 ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
136 if (ret)
137 return ret;
138
139 if (flags & KEXEC_PRESERVE_CONTEXT)
140 image->preserve_context = 1;
141
142 ret = machine_kexec_prepare(image);
143 if (ret)
144 goto out;
145
146 /*
147 * Some architecture(like S390) may touch the crash memory before
148 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
149 */
150 ret = kimage_crash_copy_vmcoreinfo(image);
151 if (ret)
152 goto out;
153
154 for (i = 0; i < nr_segments; i++) {
155 ret = kimage_load_segment(image, &image->segment[i]);
156 if (ret)
157 goto out;
158 }
159
160 kimage_terminate(image);
161
162 /* Install the new kernel and uninstall the old */
163 image = xchg(dest_image, image);
164
165out:
166 if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
167 arch_kexec_protect_crashkres();
168
169 kimage_free(image);
170 return ret;
171}
172
173/*
174 * Exec Kernel system call: for obvious reasons only root may call it.
175 *
176 * This call breaks up into three pieces.
177 * - A generic part which loads the new kernel from the current
178 * address space, and very carefully places the data in the
179 * allocated pages.
180 *
181 * - A generic part that interacts with the kernel and tells all of
182 * the devices to shut down. Preventing on-going dmas, and placing
183 * the devices in a consistent state so a later kernel can
184 * reinitialize them.
185 *
186 * - A machine specific part that includes the syscall number
187 * and then copies the image to it's final destination. And
188 * jumps into the image at entry.
189 *
190 * kexec does not sync, or unmount filesystems so if you need
191 * that to happen you need to do that yourself.
192 */
193
194static inline int kexec_load_check(unsigned long nr_segments,
195 unsigned long flags)
196{
197 int result;
198
199 /* We only trust the superuser with rebooting the system. */
200 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
201 return -EPERM;
202
203 /* Permit LSMs and IMA to fail the kexec */
204 result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
205 if (result < 0)
206 return result;
207
208 /*
209 * kexec can be used to circumvent module loading restrictions, so
210 * prevent loading in that case
211 */
212 result = security_locked_down(LOCKDOWN_KEXEC);
213 if (result)
214 return result;
215
216 /*
217 * Verify we have a legal set of flags
218 * This leaves us room for future extensions.
219 */
220 if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
221 return -EINVAL;
222
223 /* Put an artificial cap on the number
224 * of segments passed to kexec_load.
225 */
226 if (nr_segments > KEXEC_SEGMENT_MAX)
227 return -EINVAL;
228
229 return 0;
230}
231
232SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
233 struct kexec_segment __user *, segments, unsigned long, flags)
234{
235 int result;
236
237 result = kexec_load_check(nr_segments, flags);
238 if (result)
239 return result;
240
241 /* Verify we are on the appropriate architecture */
242 if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
243 ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
244 return -EINVAL;
245
246 /* Because we write directly to the reserved memory
247 * region when loading crash kernels we need a mutex here to
248 * prevent multiple crash kernels from attempting to load
249 * simultaneously, and to prevent a crash kernel from loading
250 * over the top of a in use crash kernel.
251 *
252 * KISS: always take the mutex.
253 */
254 if (!mutex_trylock(&kexec_mutex))
255 return -EBUSY;
256
257 result = do_kexec_load(entry, nr_segments, segments, flags);
258
259 mutex_unlock(&kexec_mutex);
260
261 return result;
262}
263
264#ifdef CONFIG_COMPAT
265COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
266 compat_ulong_t, nr_segments,
267 struct compat_kexec_segment __user *, segments,
268 compat_ulong_t, flags)
269{
270 struct compat_kexec_segment in;
271 struct kexec_segment out, __user *ksegments;
272 unsigned long i, result;
273
274 result = kexec_load_check(nr_segments, flags);
275 if (result)
276 return result;
277
278 /* Don't allow clients that don't understand the native
279 * architecture to do anything.
280 */
281 if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
282 return -EINVAL;
283
284 ksegments = compat_alloc_user_space(nr_segments * sizeof(out));
285 for (i = 0; i < nr_segments; i++) {
286 result = copy_from_user(&in, &segments[i], sizeof(in));
287 if (result)
288 return -EFAULT;
289
290 out.buf = compat_ptr(in.buf);
291 out.bufsz = in.bufsz;
292 out.mem = in.mem;
293 out.memsz = in.memsz;
294
295 result = copy_to_user(&ksegments[i], &out, sizeof(out));
296 if (result)
297 return -EFAULT;
298 }
299
300 /* Because we write directly to the reserved memory
301 * region when loading crash kernels we need a mutex here to
302 * prevent multiple crash kernels from attempting to load
303 * simultaneously, and to prevent a crash kernel from loading
304 * over the top of a in use crash kernel.
305 *
306 * KISS: always take the mutex.
307 */
308 if (!mutex_trylock(&kexec_mutex))
309 return -EBUSY;
310
311 result = do_kexec_load(entry, nr_segments, ksegments, flags);
312
313 mutex_unlock(&kexec_mutex);
314
315 return result;
316}
317#endif
1/*
2 * kexec.c - kexec_load system call
3 * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
4 *
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/capability.h>
12#include <linux/mm.h>
13#include <linux/file.h>
14#include <linux/kexec.h>
15#include <linux/mutex.h>
16#include <linux/list.h>
17#include <linux/syscalls.h>
18#include <linux/vmalloc.h>
19#include <linux/slab.h>
20
21#include "kexec_internal.h"
22
23static int copy_user_segment_list(struct kimage *image,
24 unsigned long nr_segments,
25 struct kexec_segment __user *segments)
26{
27 int ret;
28 size_t segment_bytes;
29
30 /* Read in the segments */
31 image->nr_segments = nr_segments;
32 segment_bytes = nr_segments * sizeof(*segments);
33 ret = copy_from_user(image->segment, segments, segment_bytes);
34 if (ret)
35 ret = -EFAULT;
36
37 return ret;
38}
39
40static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
41 unsigned long nr_segments,
42 struct kexec_segment __user *segments,
43 unsigned long flags)
44{
45 int ret;
46 struct kimage *image;
47 bool kexec_on_panic = flags & KEXEC_ON_CRASH;
48
49 if (kexec_on_panic) {
50 /* Verify we have a valid entry point */
51 if ((entry < phys_to_boot_phys(crashk_res.start)) ||
52 (entry > phys_to_boot_phys(crashk_res.end)))
53 return -EADDRNOTAVAIL;
54 }
55
56 /* Allocate and initialize a controlling structure */
57 image = do_kimage_alloc_init();
58 if (!image)
59 return -ENOMEM;
60
61 image->start = entry;
62
63 ret = copy_user_segment_list(image, nr_segments, segments);
64 if (ret)
65 goto out_free_image;
66
67 if (kexec_on_panic) {
68 /* Enable special crash kernel control page alloc policy. */
69 image->control_page = crashk_res.start;
70 image->type = KEXEC_TYPE_CRASH;
71 }
72
73 ret = sanity_check_segment_list(image);
74 if (ret)
75 goto out_free_image;
76
77 /*
78 * Find a location for the control code buffer, and add it
79 * the vector of segments so that it's pages will also be
80 * counted as destination pages.
81 */
82 ret = -ENOMEM;
83 image->control_code_page = kimage_alloc_control_pages(image,
84 get_order(KEXEC_CONTROL_PAGE_SIZE));
85 if (!image->control_code_page) {
86 pr_err("Could not allocate control_code_buffer\n");
87 goto out_free_image;
88 }
89
90 if (!kexec_on_panic) {
91 image->swap_page = kimage_alloc_control_pages(image, 0);
92 if (!image->swap_page) {
93 pr_err("Could not allocate swap buffer\n");
94 goto out_free_control_pages;
95 }
96 }
97
98 *rimage = image;
99 return 0;
100out_free_control_pages:
101 kimage_free_page_list(&image->control_pages);
102out_free_image:
103 kfree(image);
104 return ret;
105}
106
107static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
108 struct kexec_segment __user *segments, unsigned long flags)
109{
110 struct kimage **dest_image, *image;
111 unsigned long i;
112 int ret;
113
114 if (flags & KEXEC_ON_CRASH) {
115 dest_image = &kexec_crash_image;
116 if (kexec_crash_image)
117 arch_kexec_unprotect_crashkres();
118 } else {
119 dest_image = &kexec_image;
120 }
121
122 if (nr_segments == 0) {
123 /* Uninstall image */
124 kimage_free(xchg(dest_image, NULL));
125 return 0;
126 }
127 if (flags & KEXEC_ON_CRASH) {
128 /*
129 * Loading another kernel to switch to if this one
130 * crashes. Free any current crash dump kernel before
131 * we corrupt it.
132 */
133 kimage_free(xchg(&kexec_crash_image, NULL));
134 }
135
136 ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
137 if (ret)
138 return ret;
139
140 if (flags & KEXEC_PRESERVE_CONTEXT)
141 image->preserve_context = 1;
142
143 ret = machine_kexec_prepare(image);
144 if (ret)
145 goto out;
146
147 /*
148 * Some architecture(like S390) may touch the crash memory before
149 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
150 */
151 ret = kimage_crash_copy_vmcoreinfo(image);
152 if (ret)
153 goto out;
154
155 for (i = 0; i < nr_segments; i++) {
156 ret = kimage_load_segment(image, &image->segment[i]);
157 if (ret)
158 goto out;
159 }
160
161 kimage_terminate(image);
162
163 /* Install the new kernel and uninstall the old */
164 image = xchg(dest_image, image);
165
166out:
167 if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
168 arch_kexec_protect_crashkres();
169
170 kimage_free(image);
171 return ret;
172}
173
174/*
175 * Exec Kernel system call: for obvious reasons only root may call it.
176 *
177 * This call breaks up into three pieces.
178 * - A generic part which loads the new kernel from the current
179 * address space, and very carefully places the data in the
180 * allocated pages.
181 *
182 * - A generic part that interacts with the kernel and tells all of
183 * the devices to shut down. Preventing on-going dmas, and placing
184 * the devices in a consistent state so a later kernel can
185 * reinitialize them.
186 *
187 * - A machine specific part that includes the syscall number
188 * and then copies the image to it's final destination. And
189 * jumps into the image at entry.
190 *
191 * kexec does not sync, or unmount filesystems so if you need
192 * that to happen you need to do that yourself.
193 */
194
195static inline int kexec_load_check(unsigned long nr_segments,
196 unsigned long flags)
197{
198 /* We only trust the superuser with rebooting the system. */
199 if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
200 return -EPERM;
201
202 /*
203 * Verify we have a legal set of flags
204 * This leaves us room for future extensions.
205 */
206 if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
207 return -EINVAL;
208
209 /* Put an artificial cap on the number
210 * of segments passed to kexec_load.
211 */
212 if (nr_segments > KEXEC_SEGMENT_MAX)
213 return -EINVAL;
214
215 return 0;
216}
217
218SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
219 struct kexec_segment __user *, segments, unsigned long, flags)
220{
221 int result;
222
223 result = kexec_load_check(nr_segments, flags);
224 if (result)
225 return result;
226
227 /* Verify we are on the appropriate architecture */
228 if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
229 ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
230 return -EINVAL;
231
232 /* Because we write directly to the reserved memory
233 * region when loading crash kernels we need a mutex here to
234 * prevent multiple crash kernels from attempting to load
235 * simultaneously, and to prevent a crash kernel from loading
236 * over the top of a in use crash kernel.
237 *
238 * KISS: always take the mutex.
239 */
240 if (!mutex_trylock(&kexec_mutex))
241 return -EBUSY;
242
243 result = do_kexec_load(entry, nr_segments, segments, flags);
244
245 mutex_unlock(&kexec_mutex);
246
247 return result;
248}
249
250#ifdef CONFIG_COMPAT
251COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
252 compat_ulong_t, nr_segments,
253 struct compat_kexec_segment __user *, segments,
254 compat_ulong_t, flags)
255{
256 struct compat_kexec_segment in;
257 struct kexec_segment out, __user *ksegments;
258 unsigned long i, result;
259
260 result = kexec_load_check(nr_segments, flags);
261 if (result)
262 return result;
263
264 /* Don't allow clients that don't understand the native
265 * architecture to do anything.
266 */
267 if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
268 return -EINVAL;
269
270 ksegments = compat_alloc_user_space(nr_segments * sizeof(out));
271 for (i = 0; i < nr_segments; i++) {
272 result = copy_from_user(&in, &segments[i], sizeof(in));
273 if (result)
274 return -EFAULT;
275
276 out.buf = compat_ptr(in.buf);
277 out.bufsz = in.bufsz;
278 out.mem = in.mem;
279 out.memsz = in.memsz;
280
281 result = copy_to_user(&ksegments[i], &out, sizeof(out));
282 if (result)
283 return -EFAULT;
284 }
285
286 /* Because we write directly to the reserved memory
287 * region when loading crash kernels we need a mutex here to
288 * prevent multiple crash kernels from attempting to load
289 * simultaneously, and to prevent a crash kernel from loading
290 * over the top of a in use crash kernel.
291 *
292 * KISS: always take the mutex.
293 */
294 if (!mutex_trylock(&kexec_mutex))
295 return -EBUSY;
296
297 result = do_kexec_load(entry, nr_segments, ksegments, flags);
298
299 mutex_unlock(&kexec_mutex);
300
301 return result;
302}
303#endif