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 descriptor passing is used in cases where this is
25  * impractical, such as when accessing pack files or when transferring
26  * large blobs.
27  *
28  * We currently do not exec(2) after a fork(2).
29  * To achieve fork+exec, relevant parts of our library functionality could
30  * be made accessible via separate executables in a libexec directory.
31  */
32 
33 enum got_imsg_type {
34 	/* An error occured while processing a request. */
35 	GOT_IMSG_ERROR,
36 
37 	/* Messages for transmitting deltas and associated delta streams. */
38 	GOT_IMSG_DELTA,
39 	GOT_IMSG_DELTA_STREAM,
40 
41 	/*
42 	 * Messages concerned with read access to objects in a repository.
43 	 * Object and pack files are opened by the main process, where
44 	 * data may be read as a byte string but without any interpretation.
45 	 * Decompression and parsing of object and pack files occurs in a
46 	 * separate process which runs under pledge("stdio").
47 	 * This sandboxes our own repository parsing code, as well as zlib.
48 	 */
49 	GOT_IMSG_OBJECT,
50 	GOT_IMSG_COMMIT,
51 	GOT_IMSG_TREE,
52 	GOT_IMSG_TREE_ENTRY,
53 	GOT_IMSG_BLOB,
54 };
55 
56 /* Structure for GOT_IMSG_ERROR. */
57 struct got_imsg_error {
58 	int code; /* an error code from got_error.h */
59 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
60 };
61 
62 /* Structure for GOT_IMSG_DELTA data. */
63 struct got_imsg_delta {
64 	/* These fields are the same as in struct got_delta. */
65 	off_t offset;
66 	size_t tslen;
67 	int type;
68 	size_t size;
69 	off_t data_offset;
70 	size_t delta_len;
71 
72 	/*
73 	 * Followed by delta stream in remaining bytes of imsg buffer.
74 	 * If delta_len exceeds imsg buffer length, followed by one or
75 	 * more DELTA_STREAM messages until delta_len bytes of delta
76 	 * stream have been transmitted.
77 	 */
78 };
79 
80 /* Structure for GOT_IMSG_DELTA_STREAM data. */
81 struct got_imsg_delta_stream {
82 	/*
83 	 * Empty since the following is implied:
84 	 * Read additional delta stream data from imsg buffer.
85 	 */
86 };
87 
88 /* Structure for GOT_IMSG_OBJECT data. */
89 struct got_imsg_object {
90 	/* These fields are the same as in struct got_object. */
91 	int type;
92 	int flags;
93 	size_t hdrlen;
94 	size_t size;
95 
96 	int ndeltas; /* this many GOT_IMSG_DELTA messages follow */
97 };
98 
99 /* Structure for GOT_IMSG_COMMIT data. */
100 struct got_imsg_commit_object {
101 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
102 	size_t author_len;
103 	size_t committer_len;
104 	size_t logmsg_len;
105 	int nparents;
106 
107 	/* Followed by author_len + committer_len + logmsg_len data bytes */
108 
109 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
110 
111 	/* XXX should use more messages to support very large log messages */
112 } __attribute__((__packed__));
113 
114 
115 /* Structure for GOT_IMSG_TREE_ENTRY. */
116 struct got_imsg_tree_entry {
117 	char id[SHA1_DIGEST_LENGTH];
118 	mode_t mode;
119 	/* Followed by entry's name in remaining data of imsg buffer. */
120 } __attribute__((__packed__));
121 
122 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
123 struct got_imsg_tree_object {
124 	int nentries; /* This many TREE_ENTRY messages follow. */
125 };
126 
127 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
128 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
129     struct got_object *, int);
130 const struct got_error *got_privsep_recv_obj(struct got_object **,
131     struct imsgbuf *);
132 const struct got_error *got_privsep_send_commit_obj(struct imsgbuf *,
133     struct got_commit_object *);
134 const struct got_error *got_privsep_recv_commit_obj(struct got_commit_object **,
135     struct imsgbuf *);
136 const struct got_error *got_privsep_recv_tree_obj(struct got_tree_object **,
137     struct imsgbuf *);
138 const struct got_error *got_privsep_send_tree_obj(struct imsgbuf *,
139     struct got_tree_object *);
140 
141 /* TODO: Implement the above, and then add more message data types here. */