summaryrefslogtreecommitdiff
path: root/lib/libalpm/signing.c
blob: 2301bba4e94e6ad350b5feff207f93fa47e14ffe (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
/*
 *  signing.c
 *
 *  Copyright (c) 2008-2011 Pacman Development Team <pacman-dev@archlinux.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <locale.h> /* setlocale() */
#include <gpgme.h>

/* libalpm */
#include "signing.h"
#include "package.h"
#include "util.h"
#include "log.h"
#include "alpm.h"

#define CHECK_ERR(void) do { \
		if(err != GPG_ERR_NO_ERROR) { goto error; } \
	} while(0)

static int gpgme_init(void)
{
	static int init = 0;
	const char *version;
	gpgme_error_t err;
	gpgme_engine_info_t enginfo;

	ALPM_LOG_FUNC;

	if(init) {
		/* we already successfully initialized the library */
		return 0;
	}

	if(!alpm_option_get_signaturedir()) {
		RET_ERR(PM_ERR_SIG_MISSINGDIR, 1);
	}

	/* calling gpgme_check_version() returns the current version and runs
	 * some internal library setup code */
	version = gpgme_check_version(NULL);
	_alpm_log(PM_LOG_DEBUG, "GPGME version: %s\n", version);
	gpgme_set_locale(NULL, LC_CTYPE, setlocale(LC_CTYPE, NULL));
#ifdef LC_MESSAGES
	gpgme_set_locale(NULL, LC_MESSAGES, setlocale(LC_MESSAGES, NULL));
#endif
	/* NOTE:
	 * The GPGME library installs a SIGPIPE signal handler automatically if
	 * the default signal hander is in use. The only time we set a handler
	 * for SIGPIPE is in dload.c, and we reset it when we are done. Given that
	 * we do this, we can let GPGME do its automagic. However, if we install
	 * a library-wide SIGPIPE handler, we will have to be careful.
	 */

	/* check for OpenPGP support (should be a no-brainer, but be safe) */
	err = gpgme_engine_check_version(GPGME_PROTOCOL_OpenPGP);
	CHECK_ERR();

	/* set and check engine information */
	err = gpgme_set_engine_info(GPGME_PROTOCOL_OpenPGP, NULL,
			alpm_option_get_signaturedir());
	CHECK_ERR();
	err = gpgme_get_engine_info(&enginfo);
	CHECK_ERR();
	_alpm_log(PM_LOG_DEBUG, "GPGME engine info: file=%s, home=%s\n",
			enginfo->file_name, enginfo->home_dir);

	init = 1;
	return 0;

error:
	_alpm_log(PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
	RET_ERR(PM_ERR_GPGME, 1);
}

/**
 * Check the PGP package signature for the given file.
 * @param path the full path to a file
 * @param sig PGP signature data in raw form (already decoded)
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
 */
int _alpm_gpgme_checksig(const char *path, const pmpgpsig_t *sig)
{
	int ret = 0;
	gpgme_error_t err;
	gpgme_ctx_t ctx;
	gpgme_data_t filedata, sigdata;
	gpgme_verify_result_t result;
	gpgme_signature_t gpgsig;
	FILE *file = NULL, *sigfile = NULL;

	ALPM_LOG_FUNC;

	if(!sig || !sig->rawdata) {
		 RET_ERR(PM_ERR_SIG_UNKNOWN, -1);
	}
	if(!path || access(path, R_OK) != 0) {
		RET_ERR(PM_ERR_NOT_A_FILE, -1);
	}
	if(gpgme_init()) {
		/* pm_errno was set in gpgme_init() */
		return -1;
	}

	_alpm_log(PM_LOG_DEBUG, "checking signature for %s\n", path);

	memset(&ctx, 0, sizeof(ctx));
	memset(&sigdata, 0, sizeof(sigdata));
	memset(&filedata, 0, sizeof(filedata));

	err = gpgme_new(&ctx);
	CHECK_ERR();

	/* create our necessary data objects to verify the signature */
	file = fopen(path, "rb");
	if(file == NULL) {
		pm_errno = PM_ERR_NOT_A_FILE;
		ret = -1;
		goto error;
	}
	err = gpgme_data_new_from_stream(&filedata, file);
	CHECK_ERR();

	/* next create data object for the signature */
	err = gpgme_data_new_from_mem(&sigdata, (char *)sig->rawdata, sig->rawlen, 0);
	CHECK_ERR();

	/* here's where the magic happens */
	err = gpgme_op_verify(ctx, sigdata, filedata, NULL);
	CHECK_ERR();
	result = gpgme_op_verify_result(ctx);
	gpgsig = result->signatures;
	if (!gpgsig || gpgsig->next) {
		_alpm_log(PM_LOG_ERROR, _("Unexpected number of signatures\n"));
		ret = -1;
		goto error;
	}
	_alpm_log(PM_LOG_DEBUG, "summary=%x\n", gpgsig->summary);
	_alpm_log(PM_LOG_DEBUG, "fpr=%s\n", gpgsig->fpr);
	_alpm_log(PM_LOG_DEBUG, "status=%d\n", gpgsig->status);
	_alpm_log(PM_LOG_DEBUG, "timestamp=%lu\n", gpgsig->timestamp);
	_alpm_log(PM_LOG_DEBUG, "wrong_key_usage=%u\n", gpgsig->wrong_key_usage);
	_alpm_log(PM_LOG_DEBUG, "pka_trust=%u\n", gpgsig->pka_trust);
	_alpm_log(PM_LOG_DEBUG, "chain_model=%u\n", gpgsig->chain_model);
	_alpm_log(PM_LOG_DEBUG, "validity=%d\n", gpgsig->validity);
	_alpm_log(PM_LOG_DEBUG, "validity_reason=%d\n", gpgsig->validity_reason);
	_alpm_log(PM_LOG_DEBUG, "key=%d\n", gpgsig->pubkey_algo);
	_alpm_log(PM_LOG_DEBUG, "hash=%d\n", gpgsig->hash_algo);

	if(gpgsig->summary & GPGME_SIGSUM_VALID) {
		/* good signature, continue */
		_alpm_log(PM_LOG_DEBUG, _("File %s has a valid signature.\n"),
				path);
	} else if(gpgsig->summary & GPGME_SIGSUM_GREEN) {
		/* 'green' signature, not sure what to do here */
		_alpm_log(PM_LOG_WARNING, _("File %s has a green signature.\n"),
				path);
	} else if(gpgsig->summary & GPGME_SIGSUM_KEY_MISSING) {
		pm_errno = PM_ERR_SIG_UNKNOWN;
		_alpm_log(PM_LOG_WARNING, _("File %s has a signature from an unknown key.\n"),
				path);
		ret = -1;
	} else {
		/* we'll capture everything else here */
		pm_errno = PM_ERR_SIG_INVALID;
		_alpm_log(PM_LOG_ERROR, _("File %s has an invalid signature.\n"),
				path);
		ret = 1;
	}

error:
	gpgme_data_release(sigdata);
	gpgme_data_release(filedata);
	gpgme_release(ctx);
	if(sigfile) {
		fclose(sigfile);
	}
	if(file) {
		fclose(file);
	}
	if(err != GPG_ERR_NO_ERROR) {
		_alpm_log(PM_LOG_ERROR, _("GPGME error: %s\n"), gpgme_strerror(err));
		RET_ERR(PM_ERR_GPGME, -1);
	}
	return ret;
}

/**
 * Load the signature from the given path into the provided struct.
 * @param sigfile the signature to attempt to load
 * @param pgpsig the struct to place the data in
 *
 * @return 0 on success, 1 on file not found, -1 on error
 */
int _alpm_load_signature(const char *sigfile, pmpgpsig_t *pgpsig) {
	struct stat st;

	if(access(sigfile, R_OK) == 0 && stat(sigfile, &st) == 0) {
		FILE *f;
		size_t bytes_read;

		if(st.st_size > 4096) {
			return -1;
		}

		if((f = fopen(sigfile, "rb")) == NULL) {
			return -1;
		}
		CALLOC(pgpsig->rawdata, st.st_size, sizeof(unsigned char),
				RET_ERR(PM_ERR_MEMORY, -1));
		bytes_read = fread(pgpsig->rawdata, sizeof(char), st.st_size, f);
		if(bytes_read == (size_t)st.st_size) {
			pgpsig->rawlen = bytes_read;
			_alpm_log(PM_LOG_DEBUG, "loaded gpg signature file, location %s\n",
					sigfile);
		} else {
			_alpm_log(PM_LOG_WARNING, _("Failed reading PGP signature file %s"),
					sigfile);
			FREE(pgpsig->rawdata);
			return -1;
		}

		fclose(f);
	} else {
		_alpm_log(PM_LOG_DEBUG, "signature file %s not found\n", sigfile);
		/* not fatal...we return a different error code here */
		return 1;
	}

	return 0;
}

/**
 * Check the PGP package signature for the given package file.
 * @param pkg the package to check
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
 */
int SYMEXPORT alpm_pkg_check_pgp_signature(pmpkg_t *pkg)
{
	ALPM_LOG_FUNC;
	ASSERT(pkg != NULL, return 0);

	return _alpm_gpgme_checksig(alpm_pkg_get_filename(pkg),
			alpm_pkg_get_pgpsig(pkg));
}

/**
 * Check the PGP package signature for the given database.
 * @param db the database to check
 * @return a int value : 0 (valid), 1 (invalid), -1 (an error occured)
 */
int SYMEXPORT alpm_db_check_pgp_signature(pmdb_t *db)
{
	ALPM_LOG_FUNC;
	ASSERT(db != NULL, return(0));

	return _alpm_gpgme_checksig(_alpm_db_path(db),
			_alpm_db_pgpsig(db));
}


/* vim: set ts=2 sw=2 noet: */