1 /*-
2 * Copyright (c) 2018, Juniper Networks, Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
14 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
15 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
16 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
17 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
18 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
19 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25 #include <sys/cdefs.h>
26 __FBSDID("$FreeBSD$");
27
28 #ifndef _STANDALONE
29 /* Avoid unwanted userlandish components */
30 #define _KERNEL
31 #include <sys/errno.h>
32 #undef _KERNEL
33 #endif
34
35 #include "libsecureboot-priv.h"
36 #include <verify_file.h>
37
38 /**
39 * @file vectx.c
40 * @brief api to verify file while reading
41 *
42 * This API allows the hash of a file to be computed as it is read.
43 * Key to this is seeking by reading.
44 *
45 * On close an indication of the verification result is returned.
46 */
47
48 struct vectx {
49 br_hash_compat_context vec_ctx; /* hash ctx */
50 const br_hash_class *vec_md; /* hash method */
51 const char *vec_path; /* path we are verifying */
52 const char *vec_want; /* hash value we want */
53 off_t vec_off; /* current offset */
54 off_t vec_hashed; /* where we have hashed to */
55 size_t vec_size; /* size of path */
56 size_t vec_hashsz; /* size of hash */
57 int vec_fd; /* file descriptor */
58 int vec_status; /* verification status */
59 };
60
61
62 /**
63 * @brief
64 * verify an open file as we read it
65 *
66 * If the file has no fingerprint to match, we will still return a
67 * verification context containing little more than the file
68 * descriptor, and an error code in @c error.
69 *
70 * @param[in] fd
71 * open descriptor
72 *
73 * @param[in] path
74 * pathname to open
75 *
76 * @param[in] off
77 * current offset
78 *
79 * @param[in] stp
80 * pointer to struct stat
81 *
82 * @param[out] error
83 * @li 0 all is good
84 * @li ENOMEM out of memory
85 * @li VE_FINGERPRINT_NONE no entry found
86 * @li VE_FINGERPRINT_UNKNOWN no fingerprint in entry
87 *
88 * @return ctx or NULL on error.
89 * NULL is only returned for non-files or out-of-memory.
90 */
91 struct vectx *
vectx_open(int fd,const char * path,off_t off,struct stat * stp,int * error,const char * caller)92 vectx_open(int fd, const char *path, off_t off, struct stat *stp,
93 int *error, const char *caller)
94 {
95 struct vectx *ctx;
96 struct stat st;
97 size_t hashsz;
98 char *cp;
99 int rc;
100
101 if (!stp)
102 stp = &st;
103
104 rc = verify_prep(fd, path, off, stp, __func__);
105
106 DEBUG_PRINTF(2,
107 ("vectx_open: caller=%s,fd=%d,name='%s',prep_rc=%d\n",
108 caller, fd, path, rc));
109
110 switch (rc) {
111 case VE_FINGERPRINT_NONE:
112 case VE_FINGERPRINT_UNKNOWN:
113 case VE_FINGERPRINT_WRONG:
114 *error = rc;
115 return (NULL);
116 }
117 ctx = malloc(sizeof(struct vectx));
118 if (!ctx)
119 goto enomem;
120 ctx->vec_fd = fd;
121 ctx->vec_path = path;
122 ctx->vec_size = stp->st_size;
123 ctx->vec_off = 0;
124 ctx->vec_hashed = 0;
125 ctx->vec_want = NULL;
126 ctx->vec_status = 0;
127 ctx->vec_hashsz = hashsz = 0;
128
129 if (rc == 0) {
130 /* we are not verifying this */
131 *error = 0;
132 return (ctx);
133 }
134 cp = fingerprint_info_lookup(fd, path);
135 if (!cp) {
136 ctx->vec_status = VE_FINGERPRINT_NONE;
137 ve_error_set("%s: no entry", path);
138 } else {
139 if (strncmp(cp, "no_hash", 7) == 0) {
140 ctx->vec_status = VE_FINGERPRINT_IGNORE;
141 hashsz = 0;
142 } else if (strncmp(cp, "sha256=", 7) == 0) {
143 ctx->vec_md = &br_sha256_vtable;
144 hashsz = br_sha256_SIZE;
145 cp += 7;
146 #ifdef VE_SHA1_SUPPORT
147 } else if (strncmp(cp, "sha1=", 5) == 0) {
148 ctx->vec_md = &br_sha1_vtable;
149 hashsz = br_sha1_SIZE;
150 cp += 5;
151 #endif
152 #ifdef VE_SHA384_SUPPORT
153 } else if (strncmp(cp, "sha384=", 7) == 0) {
154 ctx->vec_md = &br_sha384_vtable;
155 hashsz = br_sha384_SIZE;
156 cp += 7;
157 #endif
158 #ifdef VE_SHA512_SUPPORT
159 } else if (strncmp(cp, "sha512=", 7) == 0) {
160 ctx->vec_md = &br_sha512_vtable;
161 hashsz = br_sha512_SIZE;
162 cp += 7;
163 #endif
164 } else {
165 ctx->vec_status = VE_FINGERPRINT_UNKNOWN;
166 ve_error_set("%s: no supported fingerprint", path);
167 }
168 }
169 *error = ctx->vec_status;
170 ctx->vec_hashsz = hashsz;
171 ctx->vec_want = cp;
172 if (hashsz > 0) {
173 ctx->vec_md->init(&ctx->vec_ctx.vtable);
174
175 if (off > 0) {
176 lseek(fd, 0, SEEK_SET);
177 vectx_lseek(ctx, off, SEEK_SET);
178 }
179 }
180 DEBUG_PRINTF(2,
181 ("vectx_open: caller=%s,name='%s',hashsz=%lu,status=%d\n",
182 caller, path, (unsigned long)ctx->vec_hashsz,
183 ctx->vec_status));
184 return (ctx);
185
186 enomem: /* unlikely */
187 *error = ENOMEM;
188 free(ctx);
189 return (NULL);
190 }
191
192 /**
193 * @brief
194 * read bytes from file and update hash
195 *
196 * It is critical that all file I/O comes through here.
197 * We keep track of current offset.
198 * We also track what offset we have hashed to,
199 * so we won't replay data if we seek backwards.
200 *
201 * @param[in] pctx
202 * pointer to ctx
203 *
204 * @param[in] buf
205 *
206 * @param[in] nbytes
207 *
208 * @return bytes read or error.
209 */
210 ssize_t
vectx_read(struct vectx * ctx,void * buf,size_t nbytes)211 vectx_read(struct vectx *ctx, void *buf, size_t nbytes)
212 {
213 unsigned char *bp = buf;
214 int d;
215 int n;
216 int delta;
217 int x;
218 size_t off;
219
220 if (ctx->vec_hashsz == 0) /* nothing to do */
221 return (read(ctx->vec_fd, buf, nbytes));
222
223 off = 0;
224 do {
225 /*
226 * Do this in reasonable chunks so
227 * we don't timeout if doing tftp
228 */
229 x = nbytes - off;
230 x = MIN(PAGE_SIZE, x);
231 d = n = read(ctx->vec_fd, &bp[off], x);
232 if (n < 0) {
233 return (n);
234 }
235 if (d > 0) {
236 /* we may have seeked backwards! */
237 delta = ctx->vec_hashed - ctx->vec_off;
238 if (delta > 0) {
239 x = MIN(delta, d);
240 off += x;
241 d -= x;
242 ctx->vec_off += x;
243 }
244 if (d > 0) {
245 ctx->vec_md->update(&ctx->vec_ctx.vtable, &bp[off], d);
246 off += d;
247 ctx->vec_off += d;
248 ctx->vec_hashed += d;
249 }
250 }
251 } while (n > 0 && off < nbytes);
252 return (off);
253 }
254
255 /**
256 * @brief
257 * vectx equivalent of lseek
258 *
259 * When seeking forwards we actually call vectx_read
260 * to reach the desired offset.
261 *
262 * We support seeking backwards.
263 *
264 * @param[in] pctx
265 * pointer to ctx
266 *
267 * @param[in] off
268 * desired offset
269 *
270 * @param[in] whence
271 * We try to convert whence to ``SEEK_SET``.
272 * We do not support ``SEEK_DATA`` or ``SEEK_HOLE``.
273 *
274 * @return offset or error.
275 */
276 off_t
vectx_lseek(struct vectx * ctx,off_t off,int whence)277 vectx_lseek(struct vectx *ctx, off_t off, int whence)
278 {
279 unsigned char buf[PAGE_SIZE];
280 size_t delta;
281 ssize_t n;
282
283 if (ctx->vec_hashsz == 0) /* nothing to do */
284 return (lseek(ctx->vec_fd, off, whence));
285
286 /*
287 * Convert whence to SEEK_SET
288 */
289 if (whence == SEEK_END && off <= 0) {
290 whence = SEEK_SET;
291 off += ctx->vec_size;
292 } else if (whence == SEEK_CUR) {
293 whence = SEEK_SET;
294 off += ctx->vec_off;
295 }
296 if (whence != SEEK_SET ||
297 (size_t)off > ctx->vec_size) {
298 printf("ERROR: %s: unsupported operation: whence=%d off=%lld -> %lld\n",
299 __func__, whence, (long long)ctx->vec_off, (long long)off);
300 return (-1);
301 }
302 if (off < ctx->vec_hashed) {
303 /* seeking backwards! just do it */
304 ctx->vec_off = lseek(ctx->vec_fd, off, whence);
305 return (ctx->vec_off);
306 }
307 n = 0;
308 do {
309 delta = off - ctx->vec_off;
310 if (delta > 0) {
311 delta = MIN(PAGE_SIZE, delta);
312 n = vectx_read(ctx, buf, delta);
313 if (n < 0)
314 return (n);
315 }
316 } while (ctx->vec_off < off && n > 0);
317 return (ctx->vec_off);
318 }
319
320 /**
321 * @brief
322 * check that hashes match and cleanup
323 *
324 * We have finished reading file, compare the hash with what
325 * we wanted.
326 *
327 * Be sure to call this before closing the file, since we may
328 * need to seek to the end to ensure hashing is complete.
329 *
330 * @param[in] pctx
331 * pointer to ctx
332 *
333 * @return 0 or an error.
334 */
335 int
vectx_close(struct vectx * ctx,int severity,const char * caller)336 vectx_close(struct vectx *ctx, int severity, const char *caller)
337 {
338 int rc;
339
340 if (ctx->vec_hashsz == 0) {
341 rc = ctx->vec_status;
342 } else {
343 #ifdef VE_PCR_SUPPORT
344 /*
345 * Only update pcr with things that must verify
346 * these tend to be processed in a more deterministic
347 * order, which makes our pseudo pcr more useful.
348 */
349 ve_pcr_updating_set((severity == VE_MUST));
350 #endif
351 /* make sure we have hashed it all */
352 vectx_lseek(ctx, 0, SEEK_END);
353 rc = ve_check_hash(&ctx->vec_ctx, ctx->vec_md,
354 ctx->vec_path, ctx->vec_want, ctx->vec_hashsz);
355 }
356 DEBUG_PRINTF(2,
357 ("vectx_close: caller=%s,name='%s',rc=%d,severity=%d\n",
358 caller,ctx->vec_path, rc, severity));
359 if (rc == VE_FINGERPRINT_WRONG) {
360 printf("Unverified: %s\n", ve_error_get());
361 #if !defined(UNIT_TEST) && !defined(DEBUG_VECTX)
362 /* we are generally called with VE_MUST */
363 if (severity > VE_WANT)
364 panic("cannot continue");
365 #endif
366 } else if (severity > VE_WANT) {
367 printf("%serified %s\n", (rc <= 0) ? "Unv" : "V",
368 ctx->vec_path);
369 }
370 free(ctx);
371 return ((rc < 0) ? rc : 0);
372 }
373