1 /*
2  * Copyright (c) 2018 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 
45 #define GOT_STRINGIFY(x) #x
46 #define GOT_STRINGVAL(x) GOT_STRINGIFY(x)
47 
48 /* Paths to helper programs in libexec directory */
49 #define GOT_PATH_PROG_READ_OBJECT \
50 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_OBJECT)
51 #define GOT_PATH_PROG_READ_TREE \
52 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_TREE)
53 #define GOT_PATH_PROG_READ_COMMIT \
54 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_COMMIT)
55 #define GOT_PATH_PROG_READ_BLOB \
56 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_BLOB)
57 #define GOT_PATH_PROG_READ_TAG \
58 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_TAG)
59 #define GOT_PATH_PROG_READ_PACK \
60 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_PACK)
61 
62 struct got_privsep_child {
63 	int imsg_fd;
64 	pid_t pid;
65 	struct imsgbuf *ibuf;
66 };
67 
68 enum got_imsg_type {
69 	/* An error occured while processing a request. */
70 	GOT_IMSG_ERROR,
71 
72 	/* Stop the child process. */
73 	GOT_IMSG_STOP,
74 
75 	/*
76 	 * Messages concerned with read access to objects in a repository.
77 	 * Object and pack files are opened by the main process, where
78 	 * data may be read as a byte string but without any interpretation.
79 	 * Decompression and parsing of object and pack files occurs in a
80 	 * separate process which runs under pledge("stdio recvfd").
81 	 * This sandboxes our own repository parsing code, as well as zlib.
82 	 */
83 	GOT_IMSG_OBJECT_REQUEST,
84 	GOT_IMSG_OBJECT,
85 	GOT_IMSG_COMMIT_REQUEST,
86 	GOT_IMSG_COMMIT,
87 	GOT_IMSG_COMMIT_LOGMSG,
88 	GOT_IMSG_TREE_REQUEST,
89 	GOT_IMSG_TREE,
90 	GOT_IMSG_TREE_ENTRY,
91 	GOT_IMSG_BLOB_REQUEST,
92 	GOT_IMSG_BLOB_OUTFD,
93 	GOT_IMSG_BLOB,
94 	GOT_IMSG_TAG_REQUEST,
95 	GOT_IMSG_TAG,
96 	GOT_IMSG_TAG_TAGMSG,
97 
98 	/* Messages related to pack files. */
99 	GOT_IMSG_PACKIDX,
100 	GOT_IMSG_PACK,
101 	GOT_IMSG_PACKED_OBJECT_REQUEST,
102 
103 	/* Message sending file desciprtor to a temporary file. */
104 	GOT_IMSG_TMPFD,
105 };
106 
107 /* Structure for GOT_IMSG_ERROR. */
108 struct got_imsg_error {
109 	int code; /* an error code from got_error.h */
110 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
111 } __attribute__((__packed__));
112 
113 /*
114  * Structure for GOT_IMSG_TREE_REQUEST, GOT_IMSG_COMMIT_REQUEST,
115  * and GOT_IMSG_OBJECT data.
116  */
117 struct got_imsg_object {
118 	uint8_t id[SHA1_DIGEST_LENGTH];
119 
120 	/* These fields are the same as in struct got_object. */
121 	int type;
122 	int flags;
123 	size_t hdrlen;
124 	size_t size;
125 	off_t pack_offset;
126 	int pack_idx;
127 }  __attribute__((__packed__));
128 
129 /* Structure for GOT_IMSG_COMMIT data. */
130 struct got_imsg_commit_object {
131 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
132 	size_t author_len;
133 	time_t author_time;
134 	time_t author_gmtoff;
135 	size_t committer_len;
136 	time_t committer_time;
137 	time_t committer_gmtoff;
138 	size_t logmsg_len;
139 	int nparents;
140 
141 	/*
142 	 * Followed by author_len + committer_len data bytes
143 	 */
144 
145 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
146 
147 	/*
148 	 * Followed by 'logmsg_len' bytes of commit log message data in
149 	 * one or more GOT_IMSG_COMMIT_LOGMSG messages.
150 	 */
151 } __attribute__((__packed__));
152 
153 
154 /* Structure for GOT_IMSG_TREE_ENTRY. */
155 struct got_imsg_tree_entry {
156 	char id[SHA1_DIGEST_LENGTH];
157 	mode_t mode;
158 	/* Followed by entry's name in remaining data of imsg buffer. */
159 } __attribute__((__packed__));
160 
161 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
162 struct got_imsg_tree_object {
163 	int nentries; /* This many TREE_ENTRY messages follow. */
164 };
165 
166 /* Structure for GOT_IMSG_BLOB. */
167 struct got_imsg_blob {
168 	size_t size;
169 };
170 
171 /* Structure for GOT_IMSG_TAG data. */
172 struct got_imsg_tag_object {
173 	uint8_t id[SHA1_DIGEST_LENGTH];
174 	int obj_type;
175 	size_t tag_len;
176 	size_t tagger_len;
177 	time_t tagger_time;
178 	time_t tagger_gmtoff;
179 	size_t tagmsg_len;
180 
181 	/*
182 	 * Followed by tag_len + tagger_len data bytes
183 	 */
184 
185 	/*
186 	 * Followed by 'tagmsg_len' bytes of tag message data in
187 	 * one or more GOT_IMSG_TAG_TAGMSG messages.
188 	 */
189 } __attribute__((__packed__));
190 
191 /* Structure for GOT_IMSG_PACKIDX. */
192 struct got_imsg_packidx {
193 	size_t len;
194 	/* Additionally, a file desciptor is passed via imsg. */
195 };
196 
197 /* Structure for GOT_IMSG_PACK. */
198 struct got_imsg_pack {
199 	char path_packfile[PATH_MAX];
200 	size_t filesize;
201 	/* Additionally, a file desciptor is passed via imsg. */
202 } __attribute__((__packed__));
203 
204 /*
205  * Structure for GOT_IMSG_PACKED_OBJECT_REQUEST data.
206  */
207 struct got_imsg_packed_object {
208 	uint8_t id[SHA1_DIGEST_LENGTH];
209 	int idx;
210 } __attribute__((__packed__));
211 
212 struct got_pack;
213 struct got_packidx;
214 
215 const struct got_error *got_privsep_wait_for_child(pid_t);
216 const struct got_error *got_privsep_send_stop(int);
217 const struct got_error *got_privsep_recv_imsg(struct imsg *, struct imsgbuf *,
218     size_t);
219 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
220 const struct got_error *got_privsep_send_obj_req(struct imsgbuf *, int,
221     struct got_object *);
222 const struct got_error *got_privsep_send_blob_req(struct imsgbuf *, int);
223 const struct got_error *got_privsep_send_blob_outfd(struct imsgbuf *, int);
224 const struct got_error *got_privsep_send_tmpfd(struct imsgbuf *, int);
225 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
226     struct got_object *);
227 const struct got_error *got_privsep_get_imsg_obj(struct got_object **,
228     struct imsg *, struct imsgbuf *);
229 const struct got_error *got_privsep_recv_obj(struct got_object **,
230     struct imsgbuf *);
231 const struct got_error *got_privsep_send_commit(struct imsgbuf *,
232     struct got_commit_object *);
233 const struct got_error *got_privsep_recv_commit(struct got_commit_object **,
234     struct imsgbuf *);
235 const struct got_error *got_privsep_recv_tree(struct got_tree_object **,
236     struct imsgbuf *);
237 const struct got_error *got_privsep_send_tree(struct imsgbuf *,
238     struct got_tree_object *);
239 const struct got_error *got_privsep_send_blob(struct imsgbuf *, size_t);
240 const struct got_error *got_privsep_recv_blob(size_t *, struct imsgbuf *);
241 const struct got_error *got_privsep_send_tag(struct imsgbuf *,
242     struct got_tag_object *);
243 const struct got_error *got_privsep_recv_tag(struct got_tag_object **,
244     struct imsgbuf *);
245 const struct got_error *got_privsep_init_pack_child(struct imsgbuf *,
246     struct got_pack *, struct got_packidx *);
247 const struct got_error *got_privsep_send_packed_obj_req(struct imsgbuf *, int,
248     struct got_object_id *);
249 const struct got_error *got_privsep_send_pack_child_ready(struct imsgbuf *);