1 /*
2  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
3  * Copyright (c) 2019, Ori Bernstein <ori@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 /*
19  * All code runs under the same UID but sensitive code paths are
20  * run in a separate process with tighter pledge(2) promises.
21  * Data is communicated between processes via imsg_flush(3) and imsg_read(3).
22  * This behaviour is transparent to users of the library.
23  *
24  * We generally transmit data in imsg buffers, split across several messages
25  * if necessary. File descriptors are used in cases where this is impractical,
26  * such as when accessing pack files or when transferring large blobs.
27  *
28  * We exec(2) after a fork(2). Parts of our library functionality are
29  * accessible via separate executables in a libexec directory.
30  */
31 
32 #define GOT_IMSG_FD_CHILD (STDERR_FILENO + 1)
33 
34 #ifndef GOT_LIBEXECDIR
35 #define GOT_LIBEXECDIR /usr/libexec
36 #endif
37 
38 /* Names of helper programs in libexec directory */
39 #define GOT_PROG_READ_OBJECT	got-read-object
40 #define GOT_PROG_READ_TREE	got-read-tree
41 #define GOT_PROG_READ_COMMIT	got-read-commit
42 #define GOT_PROG_READ_BLOB	got-read-blob
43 #define GOT_PROG_READ_TAG	got-read-tag
44 #define GOT_PROG_READ_PACK	got-read-pack
45 #define GOT_PROG_READ_GITCONFIG	got-read-gitconfig
46 #define GOT_PROG_FETCH_PACK	got-fetch-pack
47 #define GOT_PROG_INDEX_PACK	got-index-pack
48 #define GOT_PROG_SEND_PACK	got-send-pack
49 
50 #define GOT_STRINGIFY(x) #x
51 #define GOT_STRINGVAL(x) GOT_STRINGIFY(x)
52 
53 /* Paths to helper programs in libexec directory */
54 #define GOT_PATH_PROG_READ_OBJECT \
55 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_OBJECT)
56 #define GOT_PATH_PROG_READ_TREE \
57 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_TREE)
58 #define GOT_PATH_PROG_READ_COMMIT \
59 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_COMMIT)
60 #define GOT_PATH_PROG_READ_BLOB \
61 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_BLOB)
62 #define GOT_PATH_PROG_READ_TAG \
63 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_TAG)
64 #define GOT_PATH_PROG_READ_PACK \
65 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_PACK)
66 #define GOT_PATH_PROG_READ_GITCONFIG \
67 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_GITCONFIG)
68 #define GOT_PATH_PROG_FETCH_PACK \
69 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_FETCH_PACK)
70 #define GOT_PATH_PROG_SEND_PACK \
71 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_SEND_PACK)
72 #define GOT_PATH_PROG_INDEX_PACK \
73 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_INDEX_PACK)
74 
75 struct got_privsep_child {
76 	int imsg_fd;
77 	pid_t pid;
78 	struct imsgbuf *ibuf;
79 };
80 
81 enum got_imsg_type {
82 	/* An error occured while processing a request. */
83 	GOT_IMSG_ERROR,
84 
85 	/* Stop the child process. */
86 	GOT_IMSG_STOP,
87 
88 	/*
89 	 * Messages concerned with read access to objects in a repository.
90 	 * Object and pack files are opened by the main process, where
91 	 * data may be read as a byte string but without any interpretation.
92 	 * Decompression and parsing of object and pack files occurs in a
93 	 * separate process which runs under pledge("stdio recvfd").
94 	 * This sandboxes our own repository parsing code, as well as zlib.
95 	 */
96 	GOT_IMSG_OBJECT_REQUEST,
97 	GOT_IMSG_OBJECT,
98 	GOT_IMSG_COMMIT_REQUEST,
99 	GOT_IMSG_COMMIT,
100 	GOT_IMSG_COMMIT_LOGMSG,
101 	GOT_IMSG_TREE_REQUEST,
102 	GOT_IMSG_TREE,
103 	GOT_IMSG_TREE_ENTRY,
104 	GOT_IMSG_BLOB_REQUEST,
105 	GOT_IMSG_BLOB_OUTFD,
106 	GOT_IMSG_BLOB,
107 	GOT_IMSG_TAG_REQUEST,
108 	GOT_IMSG_TAG,
109 	GOT_IMSG_TAG_TAGMSG,
110 
111 	/* Messages related to networking. */
112 	GOT_IMSG_FETCH_REQUEST,
113 	GOT_IMSG_FETCH_SYMREFS,
114 	GOT_IMSG_FETCH_REF,
115 	GOT_IMSG_FETCH_SERVER_PROGRESS,
116 	GOT_IMSG_FETCH_DONE,
117 	GOT_IMSG_IDXPACK_REQUEST,
118 	GOT_IMSG_IDXPACK_DONE,
119 
120 	/* Messages related to pack files. */
121 	GOT_IMSG_PACKIDX,
122 	GOT_IMSG_PACK,
123 	GOT_IMSG_PACKED_OBJECT_REQUEST,
124 	GOT_IMSG_COMMIT_TRAVERSAL_REQUEST,
125 	GOT_IMSG_TRAVERSED_COMMITS,
126 	GOT_IMSG_COMMIT_TRAVERSAL_DONE,
127 
128 	/* Message sending file descriptor to a temporary file. */
129 	GOT_IMSG_TMPFD,
130 
131 	/* Messages related to gitconfig files. */
132 	GOT_IMSG_GITCONFIG_PARSE_REQUEST,
133 	GOT_IMSG_GITCONFIG_REPOSITORY_FORMAT_VERSION_REQUEST,
134 	GOT_IMSG_GITCONFIG_AUTHOR_NAME_REQUEST,
135 	GOT_IMSG_GITCONFIG_AUTHOR_EMAIL_REQUEST,
136 	GOT_IMSG_GITCONFIG_REMOTES_REQUEST,
137 	GOT_IMSG_GITCONFIG_INT_VAL,
138 	GOT_IMSG_GITCONFIG_STR_VAL,
139 	GOT_IMSG_GITCONFIG_REMOTES,
140 	GOT_IMSG_GITCONFIG_REMOTE,
141 	GOT_IMSG_GITCONFIG_OWNER_REQUEST,
142 	GOT_IMSG_GITCONFIG_OWNER,
143 };
144 
145 /* Structure for GOT_IMSG_ERROR. */
146 struct got_imsg_error {
147 	int code; /* an error code from got_error.h */
148 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
149 } __attribute__((__packed__));
150 
151 /*
152  * Structure for GOT_IMSG_TREE_REQUEST and GOT_IMSG_OBJECT data.
153  */
154 struct got_imsg_object {
155 	uint8_t id[SHA1_DIGEST_LENGTH];
156 
157 	/* These fields are the same as in struct got_object. */
158 	int type;
159 	int flags;
160 	size_t hdrlen;
161 	size_t size;
162 	off_t pack_offset;
163 	int pack_idx;
164 }  __attribute__((__packed__));
165 
166 /* Structure for GOT_IMSG_COMMIT data. */
167 struct got_imsg_commit_object {
168 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
169 	size_t author_len;
170 	time_t author_time;
171 	time_t author_gmtoff;
172 	size_t committer_len;
173 	time_t committer_time;
174 	time_t committer_gmtoff;
175 	size_t logmsg_len;
176 	int nparents;
177 
178 	/*
179 	 * Followed by author_len + committer_len data bytes
180 	 */
181 
182 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
183 
184 	/*
185 	 * Followed by 'logmsg_len' bytes of commit log message data in
186 	 * one or more GOT_IMSG_COMMIT_LOGMSG messages.
187 	 */
188 } __attribute__((__packed__));
189 
190 
191 /* Structure for GOT_IMSG_TREE_ENTRY. */
192 struct got_imsg_tree_entry {
193 	char id[SHA1_DIGEST_LENGTH];
194 	mode_t mode;
195 	/* Followed by entry's name in remaining data of imsg buffer. */
196 } __attribute__((__packed__));
197 
198 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
199 struct got_imsg_tree_object {
200 	int nentries; /* This many TREE_ENTRY messages follow. */
201 };
202 
203 /* Structure for GOT_IMSG_BLOB. */
204 struct got_imsg_blob {
205 	size_t size;
206 	size_t hdrlen;
207 
208 	/*
209 	 * If size <= GOT_PRIVSEP_INLINE_BLOB_DATA_MAX, blob data follows
210 	 * in the imsg buffer. Otherwise, blob data has been written to a
211 	 * file descriptor passed via the GOT_IMSG_BLOB_OUTFD imsg.
212 	 */
213 #define GOT_PRIVSEP_INLINE_BLOB_DATA_MAX \
214 	(MAX_IMSGSIZE - IMSG_HEADER_SIZE - sizeof(struct got_imsg_blob))
215 };
216 
217 
218 /* Structure for GOT_IMSG_TAG data. */
219 struct got_imsg_tag_object {
220 	uint8_t id[SHA1_DIGEST_LENGTH];
221 	int obj_type;
222 	size_t tag_len;
223 	size_t tagger_len;
224 	time_t tagger_time;
225 	time_t tagger_gmtoff;
226 	size_t tagmsg_len;
227 
228 	/*
229 	 * Followed by tag_len + tagger_len data bytes
230 	 */
231 
232 	/*
233 	 * Followed by 'tagmsg_len' bytes of tag message data in
234 	 * one or more GOT_IMSG_TAG_TAGMSG messages.
235 	 */
236 } __attribute__((__packed__));
237 
238 /* Structures for GOT_IMSG_FETCH_REQUEST data. */
239 struct got_imsg_fetch_have_ref {
240 	uint8_t id[SHA1_DIGEST_LENGTH];
241 	size_t name_len;
242 	/* Followed by name_len data bytes. */
243 };
244 struct got_imsg_fetch_have_refs {
245 	size_t n_have_refs;
246 	/* Followed by n_have_refs times of got_imsg_fetch_have_ref data. */
247 };
248 
249 /* Structures for GOT_IMSG_FETCH_SYMREFS data. */
250 struct got_imsg_fetch_symref {
251 	size_t name_len;
252 	size_t target_len;
253 
254 	/*
255 	 * Followed by name_len + target_len data bytes.
256 	 */
257 } __attribute__((__packed__));
258 
259 struct got_imsg_fetch_symrefs {
260 	size_t nsymrefs;
261 
262 	/* Followed by nsymrefs times of got_imsg_fetch_symref data. */
263 } __attribute__((__packed__));
264 
265 /* Structure for GOT_IMSG_FETCH_REF data. */
266 struct got_imsg_fetch_ref {
267 	/* Describes a reference which will be fetched. */
268 	uint8_t refid[SHA1_DIGEST_LENGTH];
269 	/* Followed by reference name in remaining data of imsg buffer. */
270 };
271 
272 /* Structure for GOT_IMSG_PACKIDX. */
273 struct got_imsg_packidx {
274 	size_t len;
275 	/* Additionally, a file desciptor is passed via imsg. */
276 };
277 
278 /* Structure for GOT_IMSG_PACK. */
279 struct got_imsg_pack {
280 	char path_packfile[PATH_MAX];
281 	size_t filesize;
282 	/* Additionally, a file desciptor is passed via imsg. */
283 } __attribute__((__packed__));
284 
285 /*
286  * Structure for GOT_IMSG_PACKED_OBJECT_REQUEST data.
287  */
288 struct got_imsg_packed_object {
289 	uint8_t id[SHA1_DIGEST_LENGTH];
290 	int idx;
291 } __attribute__((__packed__));
292 
293 /* Structure for GOT_IMSG_COMMIT_TRAVERSAL_REQUEST  */
294 struct got_imsg_commit_traversal_request {
295 	uint8_t id[SHA1_DIGEST_LENGTH];
296 	int idx;
297 	size_t path_len;
298 	/* Followed by path_len bytes of path data */
299 } __attribute__((__packed__));
300 
301 /* Structure for GOT_IMSG_TRAVERSED_COMMITS  */
302 struct got_imsg_traversed_commits {
303 	size_t ncommits;
304 	/* Followed by ncommit IDs of SHA1_DIGEST_LENGTH each */
305 } __attribute__((__packed__));
306 
307 /*
308  * Structure for GOT_IMSG_GITCONFIG_REMOTE data.
309  */
310 struct got_imsg_remote {
311 	size_t name_len;
312 	size_t url_len;
313 
314 	/* Followed by name_len + url_len data bytes. */
315 };
316 
317 /*
318  * Structure for GOT_IMSG_GITCONFIG_REMOTES data.
319  */
320 struct got_imsg_remotes {
321 	int nremotes; /* This many GOT_IMSG_GITCONFIG_REMOTE messages follow. */
322 };
323 
324 struct got_remote_repo;
325 struct got_pack;
326 struct got_packidx;
327 struct got_pathlist_head;
328 
329 const struct got_error *got_send_ack(pid_t);
330 const struct got_error *got_privsep_wait_for_child(pid_t);
331 const struct got_error *got_privsep_send_stop(int);
332 const struct got_error *got_privsep_recv_imsg(struct imsg *, struct imsgbuf *,
333     size_t);
334 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
335 const struct got_error *got_privsep_send_ack(struct imsgbuf *);
336 const struct got_error *got_privsep_wait_ack(struct imsgbuf *);
337 const struct got_error *got_privsep_send_obj_req(struct imsgbuf *, int);
338 const struct got_error *got_privsep_send_commit_req(struct imsgbuf *, int,
339     struct got_object_id *, int);
340 const struct got_error *got_privsep_send_tree_req(struct imsgbuf *, int,
341     struct got_object_id *, int);
342 const struct got_error *got_privsep_send_tag_req(struct imsgbuf *, int,
343     struct got_object_id *, int);
344 const struct got_error *got_privsep_send_blob_req(struct imsgbuf *, int,
345     struct got_object_id *, int);
346 const struct got_error *got_privsep_send_blob_outfd(struct imsgbuf *, int);
347 const struct got_error *got_privsep_send_tmpfd(struct imsgbuf *, int);
348 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
349     struct got_object *);
350 const struct got_error *got_privsep_send_index_pack_req(struct imsgbuf *, int,
351     struct got_object_id *);
352 const struct got_error *got_privsep_send_index_pack_done(struct imsgbuf *);
353 const struct got_error *got_privsep_wait_index_pack_done(struct imsgbuf *);
354 const struct got_error *got_privsep_send_fetch_req(struct imsgbuf *, int,
355     struct got_pathlist_head *);
356 const struct got_error *got_privsep_send_fetch_symrefs(struct imsgbuf *,
357     struct got_pathlist_head *);
358 const struct got_error *got_privsep_send_fetch_ref(struct imsgbuf *,
359     struct got_object_id *, const char *);
360 const struct got_error *got_privsep_send_fetch_server_progress(struct imsgbuf *,
361     const char *, size_t);
362 const struct got_error *got_privsep_recv_fetch_progress(int *,
363     struct got_object_id **, char **, struct got_pathlist_head *,
364     char **, struct imsgbuf *);
365 const struct got_error *got_privsep_send_fetch_done(struct imsgbuf *,
366     struct got_object_id);
367 const struct got_error *got_privsep_get_imsg_obj(struct got_object **,
368     struct imsg *, struct imsgbuf *);
369 const struct got_error *got_privsep_recv_obj(struct got_object **,
370     struct imsgbuf *);
371 const struct got_error *got_privsep_send_commit(struct imsgbuf *,
372     struct got_commit_object *);
373 const struct got_error *got_privsep_recv_commit(struct got_commit_object **,
374     struct imsgbuf *);
375 const struct got_error *got_privsep_recv_tree(struct got_tree_object **,
376     struct imsgbuf *);
377 const struct got_error *got_privsep_send_tree(struct imsgbuf *,
378     struct got_pathlist_head *, int);
379 const struct got_error *got_privsep_send_blob(struct imsgbuf *, size_t, size_t,
380     const uint8_t *);
381 const struct got_error *got_privsep_recv_blob(uint8_t **, size_t *, size_t *,
382     struct imsgbuf *);
383 const struct got_error *got_privsep_send_tag(struct imsgbuf *,
384     struct got_tag_object *);
385 const struct got_error *got_privsep_recv_tag(struct got_tag_object **,
386     struct imsgbuf *);
387 const struct got_error *got_privsep_init_pack_child(struct imsgbuf *,
388     struct got_pack *, struct got_packidx *);
389 const struct got_error *got_privsep_send_packed_obj_req(struct imsgbuf *, int,
390     struct got_object_id *);
391 const struct got_error *got_privsep_send_pack_child_ready(struct imsgbuf *);
392 
393 const struct got_error *got_privsep_send_gitconfig_parse_req(struct imsgbuf *,
394     int);
395 const struct got_error *
396     got_privsep_send_gitconfig_repository_format_version_req(struct imsgbuf *);
397 const struct got_error *got_privsep_send_gitconfig_author_name_req(
398     struct imsgbuf *);
399 const struct got_error *got_privsep_send_gitconfig_author_email_req(
400     struct imsgbuf *);
401 const struct got_error *got_privsep_send_gitconfig_remotes_req(
402     struct imsgbuf *);
403 const struct got_error *got_privsep_send_gitconfig_owner_req(struct imsgbuf *);
404 const struct got_error *got_privsep_send_gitconfig_str(struct imsgbuf *,
405     const char *);
406 const struct got_error *got_privsep_recv_gitconfig_str(char **,
407     struct imsgbuf *);
408 const struct got_error *got_privsep_send_gitconfig_int(struct imsgbuf *, int);
409 const struct got_error *got_privsep_recv_gitconfig_int(int *, struct imsgbuf *);
410 const struct got_error *got_privsep_send_gitconfig_remotes(struct imsgbuf *,
411     struct got_remote_repo *, int);
412 const struct got_error *got_privsep_recv_gitconfig_remotes(
413     struct got_remote_repo **, int *, struct imsgbuf *);
414 
415 const struct got_error *got_privsep_send_commit_traversal_request(
416     struct imsgbuf *, struct got_object_id *, int, const char *);
417 const struct got_error *got_privsep_recv_traversed_commits(
418     struct got_commit_object **, struct got_object_id **,
419     struct got_object_id_queue *, struct imsgbuf *);
420 const struct got_error *got_privsep_send_traversed_commits(
421     struct got_object_id *, size_t, struct imsgbuf *);
422 const struct got_error *got_privsep_send_commit_traversal_done(
423     struct imsgbuf *);
424 
425 void got_privsep_exec_child(int[2], const char *, const char *);