Loading...
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/kasan.h>
28#include <linux/bug.h>
29#include <linux/mm.h>
30#include <linux/gfp.h>
31#include <linux/jump_label.h>
32#include <linux/random.h>
33
34#include <asm/text-patching.h>
35#include <asm/page.h>
36#include <asm/pgtable.h>
37#include <asm/setup.h>
38#include <asm/unwind.h>
39
40#if 0
41#define DEBUGP(fmt, ...) \
42 printk(KERN_DEBUG fmt, ##__VA_ARGS__)
43#else
44#define DEBUGP(fmt, ...) \
45do { \
46 if (0) \
47 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
48} while (0)
49#endif
50
51#ifdef CONFIG_RANDOMIZE_BASE
52static unsigned long module_load_offset;
53
54/* Mutex protects the module_load_offset. */
55static DEFINE_MUTEX(module_kaslr_mutex);
56
57static unsigned long int get_module_load_offset(void)
58{
59 if (kaslr_enabled()) {
60 mutex_lock(&module_kaslr_mutex);
61 /*
62 * Calculate the module_load_offset the first time this
63 * code is called. Once calculated it stays the same until
64 * reboot.
65 */
66 if (module_load_offset == 0)
67 module_load_offset =
68 (get_random_int() % 1024 + 1) * PAGE_SIZE;
69 mutex_unlock(&module_kaslr_mutex);
70 }
71 return module_load_offset;
72}
73#else
74static unsigned long int get_module_load_offset(void)
75{
76 return 0;
77}
78#endif
79
80void *module_alloc(unsigned long size)
81{
82 void *p;
83
84 if (PAGE_ALIGN(size) > MODULES_LEN)
85 return NULL;
86
87 p = __vmalloc_node_range(size, MODULE_ALIGN,
88 MODULES_VADDR + get_module_load_offset(),
89 MODULES_END, GFP_KERNEL,
90 PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
91 __builtin_return_address(0));
92 if (p && (kasan_module_alloc(p, size) < 0)) {
93 vfree(p);
94 return NULL;
95 }
96
97 return p;
98}
99
100#ifdef CONFIG_X86_32
101int apply_relocate(Elf32_Shdr *sechdrs,
102 const char *strtab,
103 unsigned int symindex,
104 unsigned int relsec,
105 struct module *me)
106{
107 unsigned int i;
108 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
109 Elf32_Sym *sym;
110 uint32_t *location;
111
112 DEBUGP("Applying relocate section %u to %u\n",
113 relsec, sechdrs[relsec].sh_info);
114 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
115 /* This is where to make the change */
116 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
117 + rel[i].r_offset;
118 /* This is the symbol it is referring to. Note that all
119 undefined symbols have been resolved. */
120 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
121 + ELF32_R_SYM(rel[i].r_info);
122
123 switch (ELF32_R_TYPE(rel[i].r_info)) {
124 case R_386_32:
125 /* We add the value into the location given */
126 *location += sym->st_value;
127 break;
128 case R_386_PC32:
129 /* Add the value, subtract its position */
130 *location += sym->st_value - (uint32_t)location;
131 break;
132 default:
133 pr_err("%s: Unknown relocation: %u\n",
134 me->name, ELF32_R_TYPE(rel[i].r_info));
135 return -ENOEXEC;
136 }
137 }
138 return 0;
139}
140#else /*X86_64*/
141int apply_relocate_add(Elf64_Shdr *sechdrs,
142 const char *strtab,
143 unsigned int symindex,
144 unsigned int relsec,
145 struct module *me)
146{
147 unsigned int i;
148 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
149 Elf64_Sym *sym;
150 void *loc;
151 u64 val;
152
153 DEBUGP("Applying relocate section %u to %u\n",
154 relsec, sechdrs[relsec].sh_info);
155 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
156 /* This is where to make the change */
157 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
158 + rel[i].r_offset;
159
160 /* This is the symbol it is referring to. Note that all
161 undefined symbols have been resolved. */
162 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
163 + ELF64_R_SYM(rel[i].r_info);
164
165 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
166 (int)ELF64_R_TYPE(rel[i].r_info),
167 sym->st_value, rel[i].r_addend, (u64)loc);
168
169 val = sym->st_value + rel[i].r_addend;
170
171 switch (ELF64_R_TYPE(rel[i].r_info)) {
172 case R_X86_64_NONE:
173 break;
174 case R_X86_64_64:
175 if (*(u64 *)loc != 0)
176 goto invalid_relocation;
177 *(u64 *)loc = val;
178 break;
179 case R_X86_64_32:
180 if (*(u32 *)loc != 0)
181 goto invalid_relocation;
182 *(u32 *)loc = val;
183 if (val != *(u32 *)loc)
184 goto overflow;
185 break;
186 case R_X86_64_32S:
187 if (*(s32 *)loc != 0)
188 goto invalid_relocation;
189 *(s32 *)loc = val;
190 if ((s64)val != *(s32 *)loc)
191 goto overflow;
192 break;
193 case R_X86_64_PC32:
194 case R_X86_64_PLT32:
195 if (*(u32 *)loc != 0)
196 goto invalid_relocation;
197 val -= (u64)loc;
198 *(u32 *)loc = val;
199#if 0
200 if ((s64)val != *(s32 *)loc)
201 goto overflow;
202#endif
203 break;
204 default:
205 pr_err("%s: Unknown rela relocation: %llu\n",
206 me->name, ELF64_R_TYPE(rel[i].r_info));
207 return -ENOEXEC;
208 }
209 }
210 return 0;
211
212invalid_relocation:
213 pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
214 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
215 return -ENOEXEC;
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#endif
225
226int module_finalize(const Elf_Ehdr *hdr,
227 const Elf_Shdr *sechdrs,
228 struct module *me)
229{
230 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
231 *para = NULL, *orc = NULL, *orc_ip = NULL;
232 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
233
234 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
235 if (!strcmp(".text", secstrings + s->sh_name))
236 text = s;
237 if (!strcmp(".altinstructions", secstrings + s->sh_name))
238 alt = s;
239 if (!strcmp(".smp_locks", secstrings + s->sh_name))
240 locks = s;
241 if (!strcmp(".parainstructions", secstrings + s->sh_name))
242 para = s;
243 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
244 orc = s;
245 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
246 orc_ip = s;
247 }
248
249 if (alt) {
250 /* patch .altinstructions */
251 void *aseg = (void *)alt->sh_addr;
252 apply_alternatives(aseg, aseg + alt->sh_size);
253 }
254 if (locks && text) {
255 void *lseg = (void *)locks->sh_addr;
256 void *tseg = (void *)text->sh_addr;
257 alternatives_smp_module_add(me, me->name,
258 lseg, lseg + locks->sh_size,
259 tseg, tseg + text->sh_size);
260 }
261
262 if (para) {
263 void *pseg = (void *)para->sh_addr;
264 apply_paravirt(pseg, pseg + para->sh_size);
265 }
266
267 /* make jump label nops */
268 jump_label_apply_nops(me);
269
270 if (orc && orc_ip)
271 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
272 (void *)orc->sh_addr, orc->sh_size);
273
274 return 0;
275}
276
277void module_arch_cleanup(struct module *mod)
278{
279 alternatives_smp_module_del(mod);
280}
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 __apply_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{
139 unsigned int i;
140 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
141 Elf64_Sym *sym;
142 void *loc;
143 u64 val;
144
145 DEBUGP("Applying relocate section %u to %u\n",
146 relsec, sechdrs[relsec].sh_info);
147 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
148 /* This is where to make the change */
149 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
150 + rel[i].r_offset;
151
152 /* This is the symbol it is referring to. Note that all
153 undefined symbols have been resolved. */
154 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
155 + ELF64_R_SYM(rel[i].r_info);
156
157 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
158 (int)ELF64_R_TYPE(rel[i].r_info),
159 sym->st_value, rel[i].r_addend, (u64)loc);
160
161 val = sym->st_value + rel[i].r_addend;
162
163 switch (ELF64_R_TYPE(rel[i].r_info)) {
164 case R_X86_64_NONE:
165 break;
166 case R_X86_64_64:
167 if (*(u64 *)loc != 0)
168 goto invalid_relocation;
169 write(loc, &val, 8);
170 break;
171 case R_X86_64_32:
172 if (*(u32 *)loc != 0)
173 goto invalid_relocation;
174 write(loc, &val, 4);
175 if (val != *(u32 *)loc)
176 goto overflow;
177 break;
178 case R_X86_64_32S:
179 if (*(s32 *)loc != 0)
180 goto invalid_relocation;
181 write(loc, &val, 4);
182 if ((s64)val != *(s32 *)loc)
183 goto overflow;
184 break;
185 case R_X86_64_PC32:
186 case R_X86_64_PLT32:
187 if (*(u32 *)loc != 0)
188 goto invalid_relocation;
189 val -= (u64)loc;
190 write(loc, &val, 4);
191#if 0
192 if ((s64)val != *(s32 *)loc)
193 goto overflow;
194#endif
195 break;
196 case R_X86_64_PC64:
197 if (*(u64 *)loc != 0)
198 goto invalid_relocation;
199 val -= (u64)loc;
200 write(loc, &val, 8);
201 break;
202 default:
203 pr_err("%s: Unknown rela relocation: %llu\n",
204 me->name, ELF64_R_TYPE(rel[i].r_info));
205 return -ENOEXEC;
206 }
207 }
208 return 0;
209
210invalid_relocation:
211 pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
212 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
213 return -ENOEXEC;
214
215overflow:
216 pr_err("overflow in relocation type %d val %Lx\n",
217 (int)ELF64_R_TYPE(rel[i].r_info), val);
218 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
219 me->name);
220 return -ENOEXEC;
221}
222
223int apply_relocate_add(Elf64_Shdr *sechdrs,
224 const char *strtab,
225 unsigned int symindex,
226 unsigned int relsec,
227 struct module *me)
228{
229 int ret;
230 bool early = me->state == MODULE_STATE_UNFORMED;
231 void *(*write)(void *, const void *, size_t) = memcpy;
232
233 if (!early) {
234 write = text_poke;
235 mutex_lock(&text_mutex);
236 }
237
238 ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
239 write);
240
241 if (!early) {
242 text_poke_sync();
243 mutex_unlock(&text_mutex);
244 }
245
246 return ret;
247}
248
249#endif
250
251int module_finalize(const Elf_Ehdr *hdr,
252 const Elf_Shdr *sechdrs,
253 struct module *me)
254{
255 const Elf_Shdr *s, *alt = NULL, *locks = NULL,
256 *para = NULL, *orc = NULL, *orc_ip = NULL,
257 *retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
258 *calls = NULL, *cfi = NULL;
259 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
260
261 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
262 if (!strcmp(".altinstructions", secstrings + s->sh_name))
263 alt = s;
264 if (!strcmp(".smp_locks", secstrings + s->sh_name))
265 locks = s;
266 if (!strcmp(".parainstructions", secstrings + s->sh_name))
267 para = s;
268 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
269 orc = s;
270 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
271 orc_ip = s;
272 if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
273 retpolines = s;
274 if (!strcmp(".return_sites", secstrings + s->sh_name))
275 returns = s;
276 if (!strcmp(".call_sites", secstrings + s->sh_name))
277 calls = s;
278 if (!strcmp(".cfi_sites", secstrings + s->sh_name))
279 cfi = s;
280 if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
281 ibt_endbr = s;
282 }
283
284 /*
285 * See alternative_instructions() for the ordering rules between the
286 * various patching types.
287 */
288 if (para) {
289 void *pseg = (void *)para->sh_addr;
290 apply_paravirt(pseg, pseg + para->sh_size);
291 }
292 if (retpolines || cfi) {
293 void *rseg = NULL, *cseg = NULL;
294 unsigned int rsize = 0, csize = 0;
295
296 if (retpolines) {
297 rseg = (void *)retpolines->sh_addr;
298 rsize = retpolines->sh_size;
299 }
300
301 if (cfi) {
302 cseg = (void *)cfi->sh_addr;
303 csize = cfi->sh_size;
304 }
305
306 apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize);
307 }
308 if (retpolines) {
309 void *rseg = (void *)retpolines->sh_addr;
310 apply_retpolines(rseg, rseg + retpolines->sh_size);
311 }
312 if (returns) {
313 void *rseg = (void *)returns->sh_addr;
314 apply_returns(rseg, rseg + returns->sh_size);
315 }
316 if (alt) {
317 /* patch .altinstructions */
318 void *aseg = (void *)alt->sh_addr;
319 apply_alternatives(aseg, aseg + alt->sh_size);
320 }
321 if (calls || para) {
322 struct callthunk_sites cs = {};
323
324 if (calls) {
325 cs.call_start = (void *)calls->sh_addr;
326 cs.call_end = (void *)calls->sh_addr + calls->sh_size;
327 }
328
329 if (para) {
330 cs.pv_start = (void *)para->sh_addr;
331 cs.pv_end = (void *)para->sh_addr + para->sh_size;
332 }
333
334 callthunks_patch_module_calls(&cs, me);
335 }
336 if (ibt_endbr) {
337 void *iseg = (void *)ibt_endbr->sh_addr;
338 apply_ibt_endbr(iseg, iseg + ibt_endbr->sh_size);
339 }
340 if (locks) {
341 void *lseg = (void *)locks->sh_addr;
342 void *text = me->core_layout.base;
343 void *text_end = text + me->core_layout.text_size;
344 alternatives_smp_module_add(me, me->name,
345 lseg, lseg + locks->sh_size,
346 text, text_end);
347 }
348
349 if (orc && orc_ip)
350 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
351 (void *)orc->sh_addr, orc->sh_size);
352
353 return 0;
354}
355
356void module_arch_cleanup(struct module *mod)
357{
358 alternatives_smp_module_del(mod);
359}