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 currently do not exec(2) after a fork(2).
28  * To achieve fork+exec, relevant parts of our library functionality could
29  * be made accessible via separate executables in a libexec directory.
30  */
31 
32 enum got_imsg_type {
33 	/* An error occured while processing a request. */
34 	GOT_IMSG_ERROR,
35 
36 	/* Messages for transmitting deltas and associated delta streams. */
37 	GOT_IMSG_DELTA,
38 	GOT_IMSG_DELTA_STREAM,
39 
40 	/*
41 	 * Messages concerned with read access to objects in a repository.
42 	 * Object and pack files are opened by the main process, where
43 	 * data may be read as a byte string but without any interpretation.
44 	 * Decompression and parsing of object and pack files occurs in a
45 	 * separate process which runs under pledge("stdio").
46 	 * This sandboxes our own repository parsing code, as well as zlib.
47 	 */
48 	GOT_IMSG_OBJECT,
49 	GOT_IMSG_COMMIT,
50 	GOT_IMSG_TREE,
51 	GOT_IMSG_TREE_ENTRY,
52 	GOT_IMSG_BLOB,
53 };
54 
55 /* Structure for GOT_IMSG_ERROR. */
56 struct got_imsg_error {
57 	int code; /* an error code from got_error.h */
58 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
59 };
60 
61 /* Structure for GOT_IMSG_DELTA data. */
62 struct got_imsg_delta {
63 	/* These fields are the same as in struct got_delta. */
64 	off_t offset;
65 	size_t tslen;
66 	int type;
67 	size_t size;
68 	off_t data_offset;
69 	size_t delta_len;
70 
71 	/*
72 	 * Followed by delta stream in remaining bytes of imsg buffer.
73 	 * If delta_len exceeds imsg buffer length, followed by one or
74 	 * more DELTA_STREAM messages until delta_len bytes of delta
75 	 * stream have been transmitted.
76 	 */
77 };
78 
79 /* Structure for GOT_IMSG_DELTA_STREAM data. */
80 struct got_imsg_delta_stream {
81 	/*
82 	 * Empty since the following is implied:
83 	 * Read additional delta stream data from imsg buffer.
84 	 */
85 };
86 
87 /* Structure for GOT_IMSG_OBJECT data. */
88 struct got_imsg_object {
89 	/* These fields are the same as in struct got_object. */
90 	int type;
91 	int flags;
92 	size_t hdrlen;
93 	size_t size;
94 
95 	int ndeltas; /* this many GOT_IMSG_DELTA messages follow */
96 };
97 
98 /* Structure for GOT_IMSG_COMMIT data. */
99 struct got_imsg_commit_object {
100 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
101 	size_t author_len;
102 	struct tm tm_author;
103 	size_t committer_len;
104 	struct tm tm_committer;
105 	size_t logmsg_len;
106 	int nparents;
107 
108 	/*
109 	 * Followed by author_len + committer_len + logmsg_len data bytes
110 	 */
111 
112 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
113 
114 	/* XXX should use more messages to support very large log messages */
115 } __attribute__((__packed__));
116 
117 
118 /* Structure for GOT_IMSG_TREE_ENTRY. */
119 struct got_imsg_tree_entry {
120 	char id[SHA1_DIGEST_LENGTH];
121 	mode_t mode;
122 	/* Followed by entry's name in remaining data of imsg buffer. */
123 } __attribute__((__packed__));
124 
125 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
126 struct got_imsg_tree_object {
127 	int nentries; /* This many TREE_ENTRY messages follow. */
128 };
129 
130 /* Structure for GOT_IMSG_BLOB. */
131 struct got_imsg_blob {
132 	size_t size;
133 };
134 
135 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
136 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
137     struct got_object *, int);
138 const struct got_error *got_privsep_recv_obj(struct got_object **,
139     struct imsgbuf *);
140 const struct got_error *got_privsep_send_commit(struct imsgbuf *,
141     struct got_commit_object *);
142 const struct got_error *got_privsep_recv_commit(struct got_commit_object **,
143     struct imsgbuf *);
144 const struct got_error *got_privsep_recv_tree(struct got_tree_object **,
145     struct imsgbuf *);
146 const struct got_error *got_privsep_send_tree(struct imsgbuf *,
147     struct got_tree_object *);
148 const struct got_error *got_privsep_send_blob(struct imsgbuf *, size_t);
149 const struct got_error *got_privsep_recv_blob(size_t *, struct imsgbuf *);
150 
151 /* TODO: Implement the above, and then add more message data types here. */