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