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