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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Kernel module help for x86.
3 Copyright (C) 2001 Rusty Russell.
4
5*/
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/moduleloader.h>
10#include <linux/elf.h>
11#include <linux/vmalloc.h>
12#include <linux/fs.h>
13#include <linux/string.h>
14#include <linux/kernel.h>
15#include <linux/kasan.h>
16#include <linux/bug.h>
17#include <linux/mm.h>
18#include <linux/gfp.h>
19#include <linux/jump_label.h>
20#include <linux/random.h>
21#include <linux/memory.h>
22
23#include <asm/text-patching.h>
24#include <asm/page.h>
25#include <asm/setup.h>
26#include <asm/unwind.h>
27
28#if 0
29#define DEBUGP(fmt, ...) \
30 printk(KERN_DEBUG fmt, ##__VA_ARGS__)
31#else
32#define DEBUGP(fmt, ...) \
33do { \
34 if (0) \
35 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
36} while (0)
37#endif
38
39#ifdef CONFIG_RANDOMIZE_BASE
40static unsigned long module_load_offset;
41
42/* Mutex protects the module_load_offset. */
43static DEFINE_MUTEX(module_kaslr_mutex);
44
45static unsigned long int get_module_load_offset(void)
46{
47 if (kaslr_enabled()) {
48 mutex_lock(&module_kaslr_mutex);
49 /*
50 * Calculate the module_load_offset the first time this
51 * code is called. Once calculated it stays the same until
52 * reboot.
53 */
54 if (module_load_offset == 0)
55 module_load_offset =
56 get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
57 mutex_unlock(&module_kaslr_mutex);
58 }
59 return module_load_offset;
60}
61#else
62static unsigned long int get_module_load_offset(void)
63{
64 return 0;
65}
66#endif
67
68void *module_alloc(unsigned long size)
69{
70 gfp_t gfp_mask = GFP_KERNEL;
71 void *p;
72
73 if (PAGE_ALIGN(size) > MODULES_LEN)
74 return NULL;
75
76 p = __vmalloc_node_range(size, MODULE_ALIGN,
77 MODULES_VADDR + get_module_load_offset(),
78 MODULES_END, gfp_mask, PAGE_KERNEL,
79 VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
80 NUMA_NO_NODE, __builtin_return_address(0));
81
82 if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
83 vfree(p);
84 return NULL;
85 }
86
87 return p;
88}
89
90#ifdef CONFIG_X86_32
91int apply_relocate(Elf32_Shdr *sechdrs,
92 const char *strtab,
93 unsigned int symindex,
94 unsigned int relsec,
95 struct module *me)
96{
97 unsigned int i;
98 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
99 Elf32_Sym *sym;
100 uint32_t *location;
101
102 DEBUGP("Applying relocate section %u to %u\n",
103 relsec, sechdrs[relsec].sh_info);
104 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
105 /* This is where to make the change */
106 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
107 + rel[i].r_offset;
108 /* This is the symbol it is referring to. Note that all
109 undefined symbols have been resolved. */
110 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
111 + ELF32_R_SYM(rel[i].r_info);
112
113 switch (ELF32_R_TYPE(rel[i].r_info)) {
114 case R_386_32:
115 /* We add the value into the location given */
116 *location += sym->st_value;
117 break;
118 case R_386_PC32:
119 case R_386_PLT32:
120 /* Add the value, subtract its position */
121 *location += sym->st_value - (uint32_t)location;
122 break;
123 default:
124 pr_err("%s: Unknown relocation: %u\n",
125 me->name, ELF32_R_TYPE(rel[i].r_info));
126 return -ENOEXEC;
127 }
128 }
129 return 0;
130}
131#else /*X86_64*/
132static int __write_relocate_add(Elf64_Shdr *sechdrs,
133 const char *strtab,
134 unsigned int symindex,
135 unsigned int relsec,
136 struct module *me,
137 void *(*write)(void *dest, const void *src, size_t len),
138 bool apply)
139{
140 unsigned int i;
141 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
142 Elf64_Sym *sym;
143 void *loc;
144 u64 val;
145 u64 zero = 0ULL;
146
147 DEBUGP("%s relocate section %u to %u\n",
148 apply ? "Applying" : "Clearing",
149 relsec, sechdrs[relsec].sh_info);
150 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
151 size_t size;
152
153 /* This is where to make the change */
154 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
155 + rel[i].r_offset;
156
157 /* This is the symbol it is referring to. Note that all
158 undefined symbols have been resolved. */
159 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
160 + ELF64_R_SYM(rel[i].r_info);
161
162 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
163 (int)ELF64_R_TYPE(rel[i].r_info),
164 sym->st_value, rel[i].r_addend, (u64)loc);
165
166 val = sym->st_value + rel[i].r_addend;
167
168 switch (ELF64_R_TYPE(rel[i].r_info)) {
169 case R_X86_64_NONE:
170 continue; /* nothing to write */
171 case R_X86_64_64:
172 size = 8;
173 break;
174 case R_X86_64_32:
175 if (val != *(u32 *)&val)
176 goto overflow;
177 size = 4;
178 break;
179 case R_X86_64_32S:
180 if ((s64)val != *(s32 *)&val)
181 goto overflow;
182 size = 4;
183 break;
184 case R_X86_64_PC32:
185 case R_X86_64_PLT32:
186 val -= (u64)loc;
187 size = 4;
188 break;
189 case R_X86_64_PC64:
190 val -= (u64)loc;
191 size = 8;
192 break;
193 default:
194 pr_err("%s: Unknown rela relocation: %llu\n",
195 me->name, ELF64_R_TYPE(rel[i].r_info));
196 return -ENOEXEC;
197 }
198
199 if (apply) {
200 if (memcmp(loc, &zero, size)) {
201 pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
202 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
203 return -ENOEXEC;
204 }
205 write(loc, &val, size);
206 } else {
207 if (memcmp(loc, &val, size)) {
208 pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
209 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
210 return -ENOEXEC;
211 }
212 write(loc, &zero, size);
213 }
214 }
215 return 0;
216
217overflow:
218 pr_err("overflow in relocation type %d val %Lx\n",
219 (int)ELF64_R_TYPE(rel[i].r_info), val);
220 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
221 me->name);
222 return -ENOEXEC;
223}
224
225static int write_relocate_add(Elf64_Shdr *sechdrs,
226 const char *strtab,
227 unsigned int symindex,
228 unsigned int relsec,
229 struct module *me,
230 bool apply)
231{
232 int ret;
233 bool early = me->state == MODULE_STATE_UNFORMED;
234 void *(*write)(void *, const void *, size_t) = memcpy;
235
236 if (!early) {
237 write = text_poke;
238 mutex_lock(&text_mutex);
239 }
240
241 ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
242 write, apply);
243
244 if (!early) {
245 text_poke_sync();
246 mutex_unlock(&text_mutex);
247 }
248
249 return ret;
250}
251
252int apply_relocate_add(Elf64_Shdr *sechdrs,
253 const char *strtab,
254 unsigned int symindex,
255 unsigned int relsec,
256 struct module *me)
257{
258 return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);
259}
260
261#ifdef CONFIG_LIVEPATCH
262void clear_relocate_add(Elf64_Shdr *sechdrs,
263 const char *strtab,
264 unsigned int symindex,
265 unsigned int relsec,
266 struct module *me)
267{
268 write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
269}
270#endif
271
272#endif
273
274int module_finalize(const Elf_Ehdr *hdr,
275 const Elf_Shdr *sechdrs,
276 struct module *me)
277{
278 const Elf_Shdr *s, *alt = NULL, *locks = NULL,
279 *orc = NULL, *orc_ip = NULL,
280 *retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
281 *calls = NULL, *cfi = NULL;
282 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
283
284 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
285 if (!strcmp(".altinstructions", secstrings + s->sh_name))
286 alt = s;
287 if (!strcmp(".smp_locks", secstrings + s->sh_name))
288 locks = s;
289 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
290 orc = s;
291 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
292 orc_ip = s;
293 if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
294 retpolines = s;
295 if (!strcmp(".return_sites", secstrings + s->sh_name))
296 returns = s;
297 if (!strcmp(".call_sites", secstrings + s->sh_name))
298 calls = s;
299 if (!strcmp(".cfi_sites", secstrings + s->sh_name))
300 cfi = s;
301 if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
302 ibt_endbr = s;
303 }
304
305 if (retpolines || cfi) {
306 void *rseg = NULL, *cseg = NULL;
307 unsigned int rsize = 0, csize = 0;
308
309 if (retpolines) {
310 rseg = (void *)retpolines->sh_addr;
311 rsize = retpolines->sh_size;
312 }
313
314 if (cfi) {
315 cseg = (void *)cfi->sh_addr;
316 csize = cfi->sh_size;
317 }
318
319 apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize);
320 }
321 if (retpolines) {
322 void *rseg = (void *)retpolines->sh_addr;
323 apply_retpolines(rseg, rseg + retpolines->sh_size);
324 }
325 if (returns) {
326 void *rseg = (void *)returns->sh_addr;
327 apply_returns(rseg, rseg + returns->sh_size);
328 }
329 if (alt) {
330 /* patch .altinstructions */
331 void *aseg = (void *)alt->sh_addr;
332 apply_alternatives(aseg, aseg + alt->sh_size);
333 }
334 if (calls || alt) {
335 struct callthunk_sites cs = {};
336
337 if (calls) {
338 cs.call_start = (void *)calls->sh_addr;
339 cs.call_end = (void *)calls->sh_addr + calls->sh_size;
340 }
341
342 if (alt) {
343 cs.alt_start = (void *)alt->sh_addr;
344 cs.alt_end = (void *)alt->sh_addr + alt->sh_size;
345 }
346
347 callthunks_patch_module_calls(&cs, me);
348 }
349 if (ibt_endbr) {
350 void *iseg = (void *)ibt_endbr->sh_addr;
351 apply_seal_endbr(iseg, iseg + ibt_endbr->sh_size);
352 }
353 if (locks) {
354 void *lseg = (void *)locks->sh_addr;
355 void *text = me->mem[MOD_TEXT].base;
356 void *text_end = text + me->mem[MOD_TEXT].size;
357 alternatives_smp_module_add(me, me->name,
358 lseg, lseg + locks->sh_size,
359 text, text_end);
360 }
361
362 if (orc && orc_ip)
363 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
364 (void *)orc->sh_addr, orc->sh_size);
365
366 return 0;
367}
368
369void module_arch_cleanup(struct module *mod)
370{
371 alternatives_smp_module_del(mod);
372}
1/* Kernel module help for x86.
2 Copyright (C) 2001 Rusty Russell.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17*/
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/moduleloader.h>
22#include <linux/elf.h>
23#include <linux/vmalloc.h>
24#include <linux/fs.h>
25#include <linux/string.h>
26#include <linux/kernel.h>
27#include <linux/bug.h>
28#include <linux/mm.h>
29#include <linux/gfp.h>
30#include <linux/jump_label.h>
31#include <linux/random.h>
32
33#include <asm/page.h>
34#include <asm/pgtable.h>
35
36#if 0
37#define DEBUGP(fmt, ...) \
38 printk(KERN_DEBUG fmt, ##__VA_ARGS__)
39#else
40#define DEBUGP(fmt, ...) \
41do { \
42 if (0) \
43 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
44} while (0)
45#endif
46
47#ifdef CONFIG_RANDOMIZE_BASE
48static unsigned long module_load_offset;
49static int randomize_modules = 1;
50
51/* Mutex protects the module_load_offset. */
52static DEFINE_MUTEX(module_kaslr_mutex);
53
54static int __init parse_nokaslr(char *p)
55{
56 randomize_modules = 0;
57 return 0;
58}
59early_param("nokaslr", parse_nokaslr);
60
61static unsigned long int get_module_load_offset(void)
62{
63 if (randomize_modules) {
64 mutex_lock(&module_kaslr_mutex);
65 /*
66 * Calculate the module_load_offset the first time this
67 * code is called. Once calculated it stays the same until
68 * reboot.
69 */
70 if (module_load_offset == 0)
71 module_load_offset =
72 (get_random_int() % 1024 + 1) * PAGE_SIZE;
73 mutex_unlock(&module_kaslr_mutex);
74 }
75 return module_load_offset;
76}
77#else
78static unsigned long int get_module_load_offset(void)
79{
80 return 0;
81}
82#endif
83
84void *module_alloc(unsigned long size)
85{
86 if (PAGE_ALIGN(size) > MODULES_LEN)
87 return NULL;
88 return __vmalloc_node_range(size, 1,
89 MODULES_VADDR + get_module_load_offset(),
90 MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
91 PAGE_KERNEL_EXEC, NUMA_NO_NODE,
92 __builtin_return_address(0));
93}
94
95#ifdef CONFIG_X86_32
96int apply_relocate(Elf32_Shdr *sechdrs,
97 const char *strtab,
98 unsigned int symindex,
99 unsigned int relsec,
100 struct module *me)
101{
102 unsigned int i;
103 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
104 Elf32_Sym *sym;
105 uint32_t *location;
106
107 DEBUGP("Applying relocate section %u to %u\n",
108 relsec, sechdrs[relsec].sh_info);
109 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
110 /* This is where to make the change */
111 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
112 + rel[i].r_offset;
113 /* This is the symbol it is referring to. Note that all
114 undefined symbols have been resolved. */
115 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
116 + ELF32_R_SYM(rel[i].r_info);
117
118 switch (ELF32_R_TYPE(rel[i].r_info)) {
119 case R_386_32:
120 /* We add the value into the location given */
121 *location += sym->st_value;
122 break;
123 case R_386_PC32:
124 /* Add the value, subtract its position */
125 *location += sym->st_value - (uint32_t)location;
126 break;
127 default:
128 pr_err("%s: Unknown relocation: %u\n",
129 me->name, ELF32_R_TYPE(rel[i].r_info));
130 return -ENOEXEC;
131 }
132 }
133 return 0;
134}
135#else /*X86_64*/
136int apply_relocate_add(Elf64_Shdr *sechdrs,
137 const char *strtab,
138 unsigned int symindex,
139 unsigned int relsec,
140 struct module *me)
141{
142 unsigned int i;
143 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
144 Elf64_Sym *sym;
145 void *loc;
146 u64 val;
147
148 DEBUGP("Applying relocate section %u to %u\n",
149 relsec, sechdrs[relsec].sh_info);
150 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
151 /* This is where to make the change */
152 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
153 + rel[i].r_offset;
154
155 /* This is the symbol it is referring to. Note that all
156 undefined symbols have been resolved. */
157 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
158 + ELF64_R_SYM(rel[i].r_info);
159
160 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
161 (int)ELF64_R_TYPE(rel[i].r_info),
162 sym->st_value, rel[i].r_addend, (u64)loc);
163
164 val = sym->st_value + rel[i].r_addend;
165
166 switch (ELF64_R_TYPE(rel[i].r_info)) {
167 case R_X86_64_NONE:
168 break;
169 case R_X86_64_64:
170 *(u64 *)loc = val;
171 break;
172 case R_X86_64_32:
173 *(u32 *)loc = val;
174 if (val != *(u32 *)loc)
175 goto overflow;
176 break;
177 case R_X86_64_32S:
178 *(s32 *)loc = val;
179 if ((s64)val != *(s32 *)loc)
180 goto overflow;
181 break;
182 case R_X86_64_PC32:
183 val -= (u64)loc;
184 *(u32 *)loc = val;
185#if 0
186 if ((s64)val != *(s32 *)loc)
187 goto overflow;
188#endif
189 break;
190 default:
191 pr_err("%s: Unknown rela relocation: %llu\n",
192 me->name, ELF64_R_TYPE(rel[i].r_info));
193 return -ENOEXEC;
194 }
195 }
196 return 0;
197
198overflow:
199 pr_err("overflow in relocation type %d val %Lx\n",
200 (int)ELF64_R_TYPE(rel[i].r_info), val);
201 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
202 me->name);
203 return -ENOEXEC;
204}
205#endif
206
207int module_finalize(const Elf_Ehdr *hdr,
208 const Elf_Shdr *sechdrs,
209 struct module *me)
210{
211 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
212 *para = NULL;
213 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
214
215 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
216 if (!strcmp(".text", secstrings + s->sh_name))
217 text = s;
218 if (!strcmp(".altinstructions", secstrings + s->sh_name))
219 alt = s;
220 if (!strcmp(".smp_locks", secstrings + s->sh_name))
221 locks = s;
222 if (!strcmp(".parainstructions", secstrings + s->sh_name))
223 para = s;
224 }
225
226 if (alt) {
227 /* patch .altinstructions */
228 void *aseg = (void *)alt->sh_addr;
229 apply_alternatives(aseg, aseg + alt->sh_size);
230 }
231 if (locks && text) {
232 void *lseg = (void *)locks->sh_addr;
233 void *tseg = (void *)text->sh_addr;
234 alternatives_smp_module_add(me, me->name,
235 lseg, lseg + locks->sh_size,
236 tseg, tseg + text->sh_size);
237 }
238
239 if (para) {
240 void *pseg = (void *)para->sh_addr;
241 apply_paravirt(pseg, pseg + para->sh_size);
242 }
243
244 /* make jump label nops */
245 jump_label_apply_nops(me);
246
247 return 0;
248}
249
250void module_arch_cleanup(struct module *mod)
251{
252 alternatives_smp_module_del(mod);
253}