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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
22#include <asm/text-patching.h>
23#include <asm/page.h>
24#include <asm/pgtable.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_int() % 1024 + 1) * 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 void *p;
71
72 if (PAGE_ALIGN(size) > MODULES_LEN)
73 return NULL;
74
75 p = __vmalloc_node_range(size, MODULE_ALIGN,
76 MODULES_VADDR + get_module_load_offset(),
77 MODULES_END, GFP_KERNEL,
78 PAGE_KERNEL, 0, NUMA_NO_NODE,
79 __builtin_return_address(0));
80 if (p && (kasan_module_alloc(p, size) < 0)) {
81 vfree(p);
82 return NULL;
83 }
84
85 return p;
86}
87
88#ifdef CONFIG_X86_32
89int apply_relocate(Elf32_Shdr *sechdrs,
90 const char *strtab,
91 unsigned int symindex,
92 unsigned int relsec,
93 struct module *me)
94{
95 unsigned int i;
96 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
97 Elf32_Sym *sym;
98 uint32_t *location;
99
100 DEBUGP("Applying relocate section %u to %u\n",
101 relsec, sechdrs[relsec].sh_info);
102 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
103 /* This is where to make the change */
104 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
105 + rel[i].r_offset;
106 /* This is the symbol it is referring to. Note that all
107 undefined symbols have been resolved. */
108 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
109 + ELF32_R_SYM(rel[i].r_info);
110
111 switch (ELF32_R_TYPE(rel[i].r_info)) {
112 case R_386_32:
113 /* We add the value into the location given */
114 *location += sym->st_value;
115 break;
116 case R_386_PC32:
117 /* Add the value, subtract its position */
118 *location += sym->st_value - (uint32_t)location;
119 break;
120 default:
121 pr_err("%s: Unknown relocation: %u\n",
122 me->name, ELF32_R_TYPE(rel[i].r_info));
123 return -ENOEXEC;
124 }
125 }
126 return 0;
127}
128#else /*X86_64*/
129int apply_relocate_add(Elf64_Shdr *sechdrs,
130 const char *strtab,
131 unsigned int symindex,
132 unsigned int relsec,
133 struct module *me)
134{
135 unsigned int i;
136 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
137 Elf64_Sym *sym;
138 void *loc;
139 u64 val;
140
141 DEBUGP("Applying relocate section %u to %u\n",
142 relsec, sechdrs[relsec].sh_info);
143 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
144 /* This is where to make the change */
145 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
146 + rel[i].r_offset;
147
148 /* This is the symbol it is referring to. Note that all
149 undefined symbols have been resolved. */
150 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
151 + ELF64_R_SYM(rel[i].r_info);
152
153 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
154 (int)ELF64_R_TYPE(rel[i].r_info),
155 sym->st_value, rel[i].r_addend, (u64)loc);
156
157 val = sym->st_value + rel[i].r_addend;
158
159 switch (ELF64_R_TYPE(rel[i].r_info)) {
160 case R_X86_64_NONE:
161 break;
162 case R_X86_64_64:
163 if (*(u64 *)loc != 0)
164 goto invalid_relocation;
165 *(u64 *)loc = val;
166 break;
167 case R_X86_64_32:
168 if (*(u32 *)loc != 0)
169 goto invalid_relocation;
170 *(u32 *)loc = val;
171 if (val != *(u32 *)loc)
172 goto overflow;
173 break;
174 case R_X86_64_32S:
175 if (*(s32 *)loc != 0)
176 goto invalid_relocation;
177 *(s32 *)loc = val;
178 if ((s64)val != *(s32 *)loc)
179 goto overflow;
180 break;
181 case R_X86_64_PC32:
182 case R_X86_64_PLT32:
183 if (*(u32 *)loc != 0)
184 goto invalid_relocation;
185 val -= (u64)loc;
186 *(u32 *)loc = val;
187#if 0
188 if ((s64)val != *(s32 *)loc)
189 goto overflow;
190#endif
191 break;
192 case R_X86_64_PC64:
193 if (*(u64 *)loc != 0)
194 goto invalid_relocation;
195 val -= (u64)loc;
196 *(u64 *)loc = val;
197 break;
198 default:
199 pr_err("%s: Unknown rela relocation: %llu\n",
200 me->name, ELF64_R_TYPE(rel[i].r_info));
201 return -ENOEXEC;
202 }
203 }
204 return 0;
205
206invalid_relocation:
207 pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
208 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
209 return -ENOEXEC;
210
211overflow:
212 pr_err("overflow in relocation type %d val %Lx\n",
213 (int)ELF64_R_TYPE(rel[i].r_info), val);
214 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
215 me->name);
216 return -ENOEXEC;
217}
218#endif
219
220int module_finalize(const Elf_Ehdr *hdr,
221 const Elf_Shdr *sechdrs,
222 struct module *me)
223{
224 const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
225 *para = NULL, *orc = NULL, *orc_ip = NULL;
226 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
227
228 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
229 if (!strcmp(".text", secstrings + s->sh_name))
230 text = s;
231 if (!strcmp(".altinstructions", secstrings + s->sh_name))
232 alt = s;
233 if (!strcmp(".smp_locks", secstrings + s->sh_name))
234 locks = s;
235 if (!strcmp(".parainstructions", secstrings + s->sh_name))
236 para = s;
237 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
238 orc = s;
239 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
240 orc_ip = s;
241 }
242
243 if (alt) {
244 /* patch .altinstructions */
245 void *aseg = (void *)alt->sh_addr;
246 apply_alternatives(aseg, aseg + alt->sh_size);
247 }
248 if (locks && text) {
249 void *lseg = (void *)locks->sh_addr;
250 void *tseg = (void *)text->sh_addr;
251 alternatives_smp_module_add(me, me->name,
252 lseg, lseg + locks->sh_size,
253 tseg, tseg + text->sh_size);
254 }
255
256 if (para) {
257 void *pseg = (void *)para->sh_addr;
258 apply_paravirt(pseg, pseg + para->sh_size);
259 }
260
261 /* make jump label nops */
262 jump_label_apply_nops(me);
263
264 if (orc && orc_ip)
265 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
266 (void *)orc->sh_addr, orc->sh_size);
267
268 return 0;
269}
270
271void module_arch_cleanup(struct module *mod)
272{
273 alternatives_smp_module_del(mod);
274}
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_X86_32
40int apply_relocate(Elf32_Shdr *sechdrs,
41 const char *strtab,
42 unsigned int symindex,
43 unsigned int relsec,
44 struct module *me)
45{
46 unsigned int i;
47 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
48 Elf32_Sym *sym;
49 uint32_t *location;
50
51 DEBUGP("Applying relocate section %u to %u\n",
52 relsec, sechdrs[relsec].sh_info);
53 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
54 /* This is where to make the change */
55 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
56 + rel[i].r_offset;
57 /* This is the symbol it is referring to. Note that all
58 undefined symbols have been resolved. */
59 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
60 + ELF32_R_SYM(rel[i].r_info);
61
62 switch (ELF32_R_TYPE(rel[i].r_info)) {
63 case R_386_32:
64 /* We add the value into the location given */
65 *location += sym->st_value;
66 break;
67 case R_386_PC32:
68 case R_386_PLT32:
69 /* Add the value, subtract its position */
70 *location += sym->st_value - (uint32_t)location;
71 break;
72 default:
73 pr_err("%s: Unknown relocation: %u\n",
74 me->name, ELF32_R_TYPE(rel[i].r_info));
75 return -ENOEXEC;
76 }
77 }
78 return 0;
79}
80#else /*X86_64*/
81static int __write_relocate_add(Elf64_Shdr *sechdrs,
82 const char *strtab,
83 unsigned int symindex,
84 unsigned int relsec,
85 struct module *me,
86 void *(*write)(void *dest, const void *src, size_t len),
87 bool apply)
88{
89 unsigned int i;
90 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
91 Elf64_Sym *sym;
92 void *loc;
93 u64 val;
94 u64 zero = 0ULL;
95
96 DEBUGP("%s relocate section %u to %u\n",
97 apply ? "Applying" : "Clearing",
98 relsec, sechdrs[relsec].sh_info);
99 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
100 size_t size;
101
102 /* This is where to make the change */
103 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
104 + rel[i].r_offset;
105
106 /* This is the symbol it is referring to. Note that all
107 undefined symbols have been resolved. */
108 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
109 + ELF64_R_SYM(rel[i].r_info);
110
111 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
112 (int)ELF64_R_TYPE(rel[i].r_info),
113 sym->st_value, rel[i].r_addend, (u64)loc);
114
115 val = sym->st_value + rel[i].r_addend;
116
117 switch (ELF64_R_TYPE(rel[i].r_info)) {
118 case R_X86_64_NONE:
119 continue; /* nothing to write */
120 case R_X86_64_64:
121 size = 8;
122 break;
123 case R_X86_64_32:
124 if (val != *(u32 *)&val)
125 goto overflow;
126 size = 4;
127 break;
128 case R_X86_64_32S:
129 if ((s64)val != *(s32 *)&val)
130 goto overflow;
131 size = 4;
132 break;
133 case R_X86_64_PC32:
134 case R_X86_64_PLT32:
135 val -= (u64)loc;
136 size = 4;
137 break;
138 case R_X86_64_PC64:
139 val -= (u64)loc;
140 size = 8;
141 break;
142 default:
143 pr_err("%s: Unknown rela relocation: %llu\n",
144 me->name, ELF64_R_TYPE(rel[i].r_info));
145 return -ENOEXEC;
146 }
147
148 if (apply) {
149 void *wr_loc = module_writable_address(me, loc);
150
151 if (memcmp(wr_loc, &zero, size)) {
152 pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
153 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
154 return -ENOEXEC;
155 }
156 write(wr_loc, &val, size);
157 } else {
158 if (memcmp(loc, &val, size)) {
159 pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
160 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
161 return -ENOEXEC;
162 }
163 /* FIXME: needs care for ROX module allocations */
164 write(loc, &zero, size);
165 }
166 }
167 return 0;
168
169overflow:
170 pr_err("overflow in relocation type %d val %Lx\n",
171 (int)ELF64_R_TYPE(rel[i].r_info), val);
172 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
173 me->name);
174 return -ENOEXEC;
175}
176
177static int write_relocate_add(Elf64_Shdr *sechdrs,
178 const char *strtab,
179 unsigned int symindex,
180 unsigned int relsec,
181 struct module *me,
182 bool apply)
183{
184 int ret;
185 bool early = me->state == MODULE_STATE_UNFORMED;
186 void *(*write)(void *, const void *, size_t) = memcpy;
187
188 if (!early) {
189 write = text_poke;
190 mutex_lock(&text_mutex);
191 }
192
193 ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
194 write, apply);
195
196 if (!early) {
197 text_poke_sync();
198 mutex_unlock(&text_mutex);
199 }
200
201 return ret;
202}
203
204int apply_relocate_add(Elf64_Shdr *sechdrs,
205 const char *strtab,
206 unsigned int symindex,
207 unsigned int relsec,
208 struct module *me)
209{
210 return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);
211}
212
213#ifdef CONFIG_LIVEPATCH
214void clear_relocate_add(Elf64_Shdr *sechdrs,
215 const char *strtab,
216 unsigned int symindex,
217 unsigned int relsec,
218 struct module *me)
219{
220 write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
221}
222#endif
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, *alt = NULL,
231 *orc = NULL, *orc_ip = NULL,
232 *retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
233 *calls = NULL, *cfi = NULL;
234 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
235
236 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
237 if (!strcmp(".altinstructions", secstrings + s->sh_name))
238 alt = s;
239 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
240 orc = s;
241 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
242 orc_ip = s;
243 if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
244 retpolines = s;
245 if (!strcmp(".return_sites", secstrings + s->sh_name))
246 returns = s;
247 if (!strcmp(".call_sites", secstrings + s->sh_name))
248 calls = s;
249 if (!strcmp(".cfi_sites", secstrings + s->sh_name))
250 cfi = s;
251 if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
252 ibt_endbr = s;
253 }
254
255 if (retpolines || cfi) {
256 void *rseg = NULL, *cseg = NULL;
257 unsigned int rsize = 0, csize = 0;
258
259 if (retpolines) {
260 rseg = (void *)retpolines->sh_addr;
261 rsize = retpolines->sh_size;
262 }
263
264 if (cfi) {
265 cseg = (void *)cfi->sh_addr;
266 csize = cfi->sh_size;
267 }
268
269 apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize, me);
270 }
271 if (retpolines) {
272 void *rseg = (void *)retpolines->sh_addr;
273 apply_retpolines(rseg, rseg + retpolines->sh_size, me);
274 }
275 if (returns) {
276 void *rseg = (void *)returns->sh_addr;
277 apply_returns(rseg, rseg + returns->sh_size, me);
278 }
279 if (alt) {
280 /* patch .altinstructions */
281 void *aseg = (void *)alt->sh_addr;
282 apply_alternatives(aseg, aseg + alt->sh_size, me);
283 }
284 if (calls || alt) {
285 struct callthunk_sites cs = {};
286
287 if (calls) {
288 cs.call_start = (void *)calls->sh_addr;
289 cs.call_end = (void *)calls->sh_addr + calls->sh_size;
290 }
291
292 if (alt) {
293 cs.alt_start = (void *)alt->sh_addr;
294 cs.alt_end = (void *)alt->sh_addr + alt->sh_size;
295 }
296
297 callthunks_patch_module_calls(&cs, me);
298 }
299 if (ibt_endbr) {
300 void *iseg = (void *)ibt_endbr->sh_addr;
301 apply_seal_endbr(iseg, iseg + ibt_endbr->sh_size, me);
302 }
303
304 if (orc && orc_ip)
305 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
306 (void *)orc->sh_addr, orc->sh_size);
307
308 return 0;
309}
310
311int module_post_finalize(const Elf_Ehdr *hdr,
312 const Elf_Shdr *sechdrs,
313 struct module *me)
314{
315 const Elf_Shdr *s, *locks = NULL;
316 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
317
318 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
319 if (!strcmp(".smp_locks", secstrings + s->sh_name))
320 locks = s;
321 }
322
323 if (locks) {
324 void *lseg = (void *)locks->sh_addr;
325 void *text = me->mem[MOD_TEXT].base;
326 void *text_end = text + me->mem[MOD_TEXT].size;
327 alternatives_smp_module_add(me, me->name,
328 lseg, lseg + locks->sh_size,
329 text, text_end);
330 }
331
332 return 0;
333}
334
335void module_arch_cleanup(struct module *mod)
336{
337 alternatives_smp_module_del(mod);
338}