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 
106 	/* Message sending file descriptor to a temporary file. */
107 	GOT_IMSG_TMPFD,
108 
109 	/* Messages related to gitconfig files. */
110 	GOT_IMSG_GITCONFIG_PARSE_REQUEST,
111 	GOT_IMSG_GITCONFIG_REPOSITORY_FORMAT_VERSION_REQUEST,
112 	GOT_IMSG_GITCONFIG_AUTHOR_NAME_REQUEST,
113 	GOT_IMSG_GITCONFIG_AUTHOR_EMAIL_REQUEST,
114 	GOT_IMSG_GITCONFIG_REMOTES_REQUEST,
115 	GOT_IMSG_GITCONFIG_INT_VAL,
116 	GOT_IMSG_GITCONFIG_STR_VAL,
117 	GOT_IMSG_GITCONFIG_REMOTES,
118 	GOT_IMSG_GITCONFIG_REMOTE,
119 };
120 
121 /* Structure for GOT_IMSG_ERROR. */
122 struct got_imsg_error {
123 	int code; /* an error code from got_error.h */
124 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
125 } __attribute__((__packed__));
126 
127 /*
128  * Structure for GOT_IMSG_TREE_REQUEST and GOT_IMSG_OBJECT data.
129  */
130 struct got_imsg_object {
131 	uint8_t id[SHA1_DIGEST_LENGTH];
132 
133 	/* These fields are the same as in struct got_object. */
134 	int type;
135 	int flags;
136 	size_t hdrlen;
137 	size_t size;
138 	off_t pack_offset;
139 	int pack_idx;
140 }  __attribute__((__packed__));
141 
142 /* Structure for GOT_IMSG_COMMIT data. */
143 struct got_imsg_commit_object {
144 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
145 	size_t author_len;
146 	time_t author_time;
147 	time_t author_gmtoff;
148 	size_t committer_len;
149 	time_t committer_time;
150 	time_t committer_gmtoff;
151 	size_t logmsg_len;
152 	int nparents;
153 
154 	/*
155 	 * Followed by author_len + committer_len data bytes
156 	 */
157 
158 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
159 
160 	/*
161 	 * Followed by 'logmsg_len' bytes of commit log message data in
162 	 * one or more GOT_IMSG_COMMIT_LOGMSG messages.
163 	 */
164 } __attribute__((__packed__));
165 
166 
167 /* Structure for GOT_IMSG_TREE_ENTRY. */
168 struct got_imsg_tree_entry {
169 	char id[SHA1_DIGEST_LENGTH];
170 	mode_t mode;
171 	/* Followed by entry's name in remaining data of imsg buffer. */
172 } __attribute__((__packed__));
173 
174 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
175 struct got_imsg_tree_object {
176 	int nentries; /* This many TREE_ENTRY messages follow. */
177 };
178 
179 /* Structure for GOT_IMSG_BLOB. */
180 struct got_imsg_blob {
181 	size_t size;
182 	size_t hdrlen;
183 
184 	/*
185 	 * If size <= GOT_PRIVSEP_INLINE_BLOB_DATA_MAX, blob data follows
186 	 * in the imsg buffer. Otherwise, blob data has been written to a
187 	 * file descriptor passed via the GOT_IMSG_BLOB_OUTFD imsg.
188 	 */
189 #define GOT_PRIVSEP_INLINE_BLOB_DATA_MAX \
190 	(MAX_IMSGSIZE - IMSG_HEADER_SIZE - sizeof(struct got_imsg_blob))
191 };
192 
193 
194 /* Structure for GOT_IMSG_TAG data. */
195 struct got_imsg_tag_object {
196 	uint8_t id[SHA1_DIGEST_LENGTH];
197 	int obj_type;
198 	size_t tag_len;
199 	size_t tagger_len;
200 	time_t tagger_time;
201 	time_t tagger_gmtoff;
202 	size_t tagmsg_len;
203 
204 	/*
205 	 * Followed by tag_len + tagger_len data bytes
206 	 */
207 
208 	/*
209 	 * Followed by 'tagmsg_len' bytes of tag message data in
210 	 * one or more GOT_IMSG_TAG_TAGMSG messages.
211 	 */
212 } __attribute__((__packed__));
213 
214 /* Structure for GOT_IMSG_PACKIDX. */
215 struct got_imsg_packidx {
216 	size_t len;
217 	/* Additionally, a file desciptor is passed via imsg. */
218 };
219 
220 /* Structure for GOT_IMSG_PACK. */
221 struct got_imsg_pack {
222 	char path_packfile[PATH_MAX];
223 	size_t filesize;
224 	/* Additionally, a file desciptor is passed via imsg. */
225 } __attribute__((__packed__));
226 
227 /*
228  * Structure for GOT_IMSG_PACKED_OBJECT_REQUEST data.
229  */
230 struct got_imsg_packed_object {
231 	uint8_t id[SHA1_DIGEST_LENGTH];
232 	int idx;
233 } __attribute__((__packed__));
234 
235 /*
236  * Structure for GOT_IMSG_GITCONFIG_REMOTE data.
237  */
238 struct got_imsg_remote {
239 	size_t name_len;
240 	size_t url_len;
241 
242 	/* Followed by name_len + url_len data bytes. */
243 };
244 
245 /*
246  * Structure for GOT_IMSG_GITCONFIG_REMOTES data.
247  */
248 struct got_imsg_remotes {
249 	int nremotes; /* This many GOT_IMSG_GITCONFIG_REMOTE messages follow. */
250 };
251 
252 struct got_remote_repo;
253 struct got_pack;
254 struct got_packidx;
255 struct got_pathlist_head;
256 
257 const struct got_error *got_privsep_wait_for_child(pid_t);
258 const struct got_error *got_privsep_send_stop(int);
259 const struct got_error *got_privsep_recv_imsg(struct imsg *, struct imsgbuf *,
260     size_t);
261 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
262 const struct got_error *got_privsep_send_obj_req(struct imsgbuf *, int);
263 const struct got_error *got_privsep_send_commit_req(struct imsgbuf *, int,
264     struct got_object_id *, int);
265 const struct got_error *got_privsep_send_tree_req(struct imsgbuf *, int,
266     struct got_object_id *, int);
267 const struct got_error *got_privsep_send_tag_req(struct imsgbuf *, int,
268     struct got_object_id *, int);
269 const struct got_error *got_privsep_send_blob_req(struct imsgbuf *, int,
270     struct got_object_id *, int);
271 const struct got_error *got_privsep_send_blob_outfd(struct imsgbuf *, int);
272 const struct got_error *got_privsep_send_tmpfd(struct imsgbuf *, int);
273 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
274     struct got_object *);
275 const struct got_error *got_privsep_get_imsg_obj(struct got_object **,
276     struct imsg *, struct imsgbuf *);
277 const struct got_error *got_privsep_recv_obj(struct got_object **,
278     struct imsgbuf *);
279 const struct got_error *got_privsep_send_commit(struct imsgbuf *,
280     struct got_commit_object *);
281 const struct got_error *got_privsep_recv_commit(struct got_commit_object **,
282     struct imsgbuf *);
283 const struct got_error *got_privsep_recv_tree(struct got_tree_object **,
284     struct imsgbuf *);
285 const struct got_error *got_privsep_send_tree(struct imsgbuf *,
286     struct got_pathlist_head *, int);
287 const struct got_error *got_privsep_send_blob(struct imsgbuf *, size_t, size_t,
288     const uint8_t *);
289 const struct got_error *got_privsep_recv_blob(uint8_t **, size_t *, size_t *,
290     struct imsgbuf *);
291 const struct got_error *got_privsep_send_tag(struct imsgbuf *,
292     struct got_tag_object *);
293 const struct got_error *got_privsep_recv_tag(struct got_tag_object **,
294     struct imsgbuf *);
295 const struct got_error *got_privsep_init_pack_child(struct imsgbuf *,
296     struct got_pack *, struct got_packidx *);
297 const struct got_error *got_privsep_send_packed_obj_req(struct imsgbuf *, int,
298     struct got_object_id *);
299 const struct got_error *got_privsep_send_pack_child_ready(struct imsgbuf *);
300 
301 const struct got_error *got_privsep_send_gitconfig_parse_req(struct imsgbuf *,
302     int);
303 const struct got_error *
304     got_privsep_send_gitconfig_repository_format_version_req(struct imsgbuf *);
305 const struct got_error *got_privsep_send_gitconfig_author_name_req(
306     struct imsgbuf *);
307 const struct got_error *got_privsep_send_gitconfig_author_email_req(
308     struct imsgbuf *);
309 const struct got_error *got_privsep_send_gitconfig_remotes_req(
310     struct imsgbuf *);
311 const struct got_error *got_privsep_send_gitconfig_str(struct imsgbuf *,
312     const char *);
313 const struct got_error *got_privsep_recv_gitconfig_str(char **,
314     struct imsgbuf *);
315 const struct got_error *got_privsep_send_gitconfig_int(struct imsgbuf *, int);
316 const struct got_error *got_privsep_recv_gitconfig_int(int *, struct imsgbuf *);
317 const struct got_error *got_privsep_send_gitconfig_remotes(struct imsgbuf *,
318     struct got_remote_repo *, int);
319 const struct got_error *got_privsep_recv_gitconfig_remotes(
320     struct got_remote_repo **, int *, struct imsgbuf *);
321 
322 void got_privsep_exec_child(int[2], const char *, const char *);