projects/linux·blob master · refs

370 lines · 7.7 KiB

1// SPDX-License-Identifier: GPL-2.0
2/* Copyright(c) 2016-20 Intel Corporation. */
3
4#include <assert.h>
5#include <elf.h>
6#include <errno.h>
7#include <fcntl.h>
8#include <stdbool.h>
9#include <stdio.h>
10#include <stdint.h>
11#include <stdlib.h>
12#include <string.h>
13#include <unistd.h>
14#include <sys/ioctl.h>
15#include <sys/mman.h>
16#include <sys/stat.h>
17#include <sys/time.h>
18#include <sys/types.h>
19#include "defines.h"
20#include "main.h"
21
22void encl_delete(struct encl *encl)
23{
24 struct encl_segment *heap_seg;
25
26 if (encl->encl_base)
27 munmap((void *)encl->encl_base, encl->encl_size);
28
29 if (encl->bin)
30 munmap(encl->bin, encl->bin_size);
31
32 if (encl->fd)
33 close(encl->fd);
34
35 if (encl->segment_tbl) {
36 heap_seg = &encl->segment_tbl[encl->nr_segments - 1];
37 munmap(heap_seg->src, heap_seg->size);
38 free(encl->segment_tbl);
39 }
40
41 memset(encl, 0, sizeof(*encl));
42}
43
44static bool encl_map_bin(const char *path, struct encl *encl)
45{
46 struct stat sb;
47 void *bin;
48 int ret;
49 int fd;
50
51 fd = open(path, O_RDONLY);
52 if (fd == -1) {
53 perror("enclave executable open()");
54 return false;
55 }
56
57 ret = stat(path, &sb);
58 if (ret) {
59 perror("enclave executable stat()");
60 goto err;
61 }
62
63 bin = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
64 if (bin == MAP_FAILED) {
65 perror("enclave executable mmap()");
66 goto err;
67 }
68
69 encl->bin = bin;
70 encl->bin_size = sb.st_size;
71
72 close(fd);
73 return true;
74
75err:
76 close(fd);
77 return false;
78}
79
80static bool encl_ioc_create(struct encl *encl)
81{
82 struct sgx_secs *secs = &encl->secs;
83 struct sgx_enclave_create ioc;
84 int rc;
85
86 assert(encl->encl_base != 0);
87
88 memset(secs, 0, sizeof(*secs));
89 secs->ssa_frame_size = 1;
90 secs->attributes = SGX_ATTR_MODE64BIT;
91 secs->xfrm = 3;
92 secs->base = encl->encl_base;
93 secs->size = encl->encl_size;
94
95 ioc.src = (unsigned long)secs;
96 rc = ioctl(encl->fd, SGX_IOC_ENCLAVE_CREATE, &ioc);
97 if (rc) {
98 perror("SGX_IOC_ENCLAVE_CREATE failed");
99 munmap((void *)secs->base, encl->encl_size);
100 return false;
101 }
102
103 return true;
104}
105
106static bool encl_ioc_add_pages(struct encl *encl, struct encl_segment *seg)
107{
108 struct sgx_enclave_add_pages ioc;
109 struct sgx_secinfo secinfo;
110 int rc;
111
112 memset(&secinfo, 0, sizeof(secinfo));
113 secinfo.flags = seg->flags;
114
115 ioc.src = (uint64_t)seg->src;
116 ioc.offset = seg->offset;
117 ioc.length = seg->size;
118 ioc.secinfo = (unsigned long)&secinfo;
119 if (seg->measure)
120 ioc.flags = SGX_PAGE_MEASURE;
121 else
122 ioc.flags = 0;
123
124 rc = ioctl(encl->fd, SGX_IOC_ENCLAVE_ADD_PAGES, &ioc);
125 if (rc < 0) {
126 perror("SGX_IOC_ENCLAVE_ADD_PAGES failed");
127 return false;
128 }
129
130 return true;
131}
132
133/*
134 * Parse the enclave code's symbol table to locate and return address of
135 * the provided symbol
136 */
137uint64_t encl_get_entry(struct encl *encl, const char *symbol)
138{
139 Elf64_Sym *symtab = NULL;
140 char *sym_names = NULL;
141 Elf64_Shdr *sections;
142 Elf64_Ehdr *ehdr;
143 int num_sym = 0;
144 int i;
145
146 ehdr = encl->bin;
147 sections = encl->bin + ehdr->e_shoff;
148
149 for (i = 0; i < ehdr->e_shnum; i++) {
150 if (sections[i].sh_type == SHT_SYMTAB) {
151 symtab = (Elf64_Sym *)((char *)encl->bin + sections[i].sh_offset);
152 num_sym = sections[i].sh_size / sections[i].sh_entsize;
153 break;
154 }
155 }
156
157 for (i = 0; i < ehdr->e_shnum; i++) {
158 if (sections[i].sh_type == SHT_STRTAB) {
159 sym_names = (char *)encl->bin + sections[i].sh_offset;
160 break;
161 }
162 }
163
164 if (!symtab || !sym_names)
165 return 0;
166
167 for (i = 0; i < num_sym; i++) {
168 Elf64_Sym *sym = &symtab[i];
169
170 if (!strcmp(symbol, sym_names + sym->st_name))
171 return (uint64_t)sym->st_value;
172 }
173
174 return 0;
175}
176
177bool encl_load(const char *path, struct encl *encl, unsigned long heap_size)
178{
179 const char device_path[] = "/dev/sgx_enclave";
180 struct encl_segment *seg;
181 Elf64_Phdr *phdr_tbl;
182 off_t src_offset;
183 Elf64_Ehdr *ehdr;
184 struct stat sb;
185 void *ptr;
186 int i, j;
187 int ret;
188 int fd = -1;
189
190 memset(encl, 0, sizeof(*encl));
191
192 fd = open(device_path, O_RDWR);
193 if (fd < 0) {
194 perror("Unable to open /dev/sgx_enclave");
195 goto err;
196 }
197
198 ret = stat(device_path, &sb);
199 if (ret) {
200 perror("device file stat()");
201 goto err;
202 }
203
204 ptr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, fd, 0);
205 if (ptr == (void *)-1) {
206 perror("mmap for read");
207 goto err;
208 }
209 munmap(ptr, PAGE_SIZE);
210
211#define ERR_MSG \
212"mmap() succeeded for PROT_READ, but failed for PROT_EXEC.\n" \
213" Check that /dev does not have noexec set:\n" \
214" \tmount | grep \"/dev .*noexec\"\n" \
215" If so, remount it executable: mount -o remount,exec /dev\n\n"
216
217 ptr = mmap(NULL, PAGE_SIZE, PROT_EXEC, MAP_SHARED, fd, 0);
218 if (ptr == (void *)-1) {
219 fprintf(stderr, ERR_MSG);
220 goto err;
221 }
222 munmap(ptr, PAGE_SIZE);
223
224 encl->fd = fd;
225
226 if (!encl_map_bin(path, encl))
227 goto err;
228
229 ehdr = encl->bin;
230 phdr_tbl = encl->bin + ehdr->e_phoff;
231
232 encl->nr_segments = 1; /* one for the heap */
233
234 for (i = 0; i < ehdr->e_phnum; i++) {
235 Elf64_Phdr *phdr = &phdr_tbl[i];
236
237 if (phdr->p_type == PT_LOAD)
238 encl->nr_segments++;
239 }
240
241 encl->segment_tbl = calloc(encl->nr_segments,
242 sizeof(struct encl_segment));
243 if (!encl->segment_tbl)
244 goto err;
245
246 for (i = 0, j = 0; i < ehdr->e_phnum; i++) {
247 Elf64_Phdr *phdr = &phdr_tbl[i];
248 unsigned int flags = phdr->p_flags;
249
250 if (phdr->p_type != PT_LOAD)
251 continue;
252
253 seg = &encl->segment_tbl[j];
254
255 if (!!(flags & ~(PF_R | PF_W | PF_X))) {
256 fprintf(stderr,
257 "%d has invalid segment flags 0x%02x.\n", i,
258 phdr->p_flags);
259 goto err;
260 }
261
262 if (j == 0 && flags != (PF_R | PF_W)) {
263 fprintf(stderr,
264 "TCS has invalid segment flags 0x%02x.\n",
265 phdr->p_flags);
266 goto err;
267 }
268
269 if (j == 0) {
270 src_offset = phdr->p_offset & PAGE_MASK;
271 encl->src = encl->bin + src_offset;
272
273 seg->prot = PROT_READ | PROT_WRITE;
274 seg->flags = SGX_PAGE_TYPE_TCS << 8;
275 } else {
276 seg->prot = (phdr->p_flags & PF_R) ? PROT_READ : 0;
277 seg->prot |= (phdr->p_flags & PF_W) ? PROT_WRITE : 0;
278 seg->prot |= (phdr->p_flags & PF_X) ? PROT_EXEC : 0;
279 seg->flags = (SGX_PAGE_TYPE_REG << 8) | seg->prot;
280 }
281
282 seg->offset = (phdr->p_offset & PAGE_MASK) - src_offset;
283 seg->size = (phdr->p_filesz + PAGE_SIZE - 1) & PAGE_MASK;
284 seg->src = encl->src + seg->offset;
285 seg->measure = true;
286
287 j++;
288 }
289
290 assert(j == encl->nr_segments - 1);
291
292 seg = &encl->segment_tbl[j];
293 seg->offset = encl->segment_tbl[j - 1].offset + encl->segment_tbl[j - 1].size;
294 seg->size = heap_size;
295 seg->src = mmap(NULL, heap_size, PROT_READ | PROT_WRITE,
296 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
297 seg->prot = PROT_READ | PROT_WRITE;
298 seg->flags = (SGX_PAGE_TYPE_REG << 8) | seg->prot;
299 seg->measure = false;
300
301 if (seg->src == MAP_FAILED)
302 goto err;
303
304 encl->src_size = encl->segment_tbl[j].offset + encl->segment_tbl[j].size;
305
306 for (encl->encl_size = 4096; encl->encl_size < encl->src_size; )
307 encl->encl_size <<= 1;
308
309 return true;
310
311err:
312 if (fd != -1)
313 close(fd);
314 encl_delete(encl);
315 return false;
316}
317
318static bool encl_map_area(struct encl *encl)
319{
320 size_t encl_size = encl->encl_size;
321 void *area;
322
323 area = mmap(NULL, encl_size * 2, PROT_NONE,
324 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
325 if (area == MAP_FAILED) {
326 perror("reservation mmap()");
327 return false;
328 }
329
330 encl->encl_base = ((uint64_t)area + encl_size - 1) & ~(encl_size - 1);
331
332 munmap(area, encl->encl_base - (uint64_t)area);
333 munmap((void *)(encl->encl_base + encl_size),
334 (uint64_t)area + encl_size - encl->encl_base);
335
336 return true;
337}
338
339bool encl_build(struct encl *encl)
340{
341 struct sgx_enclave_init ioc;
342 int ret;
343 int i;
344
345 if (!encl_map_area(encl))
346 return false;
347
348 if (!encl_ioc_create(encl))
349 return false;
350
351 /*
352 * Pages must be added before mapping VMAs because their permissions
353 * cap the VMA permissions.
354 */
355 for (i = 0; i < encl->nr_segments; i++) {
356 struct encl_segment *seg = &encl->segment_tbl[i];
357
358 if (!encl_ioc_add_pages(encl, seg))
359 return false;
360 }
361
362 ioc.sigstruct = (uint64_t)&encl->sigstruct;
363 ret = ioctl(encl->fd, SGX_IOC_ENCLAVE_INIT, &ioc);
364 if (ret) {
365 perror("SGX_IOC_ENCLAVE_INIT failed");
366 return false;
367 }
368
369 return true;
370}