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_LOOSE_OBJECT_HEADER_REQUEST,
50 	GOT_IMSG_LOOSE_OBJECT_HEADER_REPLY,
51 	GOT_IMSG_LOOSE_BLOB_OBJECT_REQUEST,
52 	GOT_IMSG_LOOSE_BLOB_OBJECT_REQUEST_OUTPUT,
53 	GOT_IMSG_LOOSE_BLOB_OBJECT_REPLY,
54 	GOT_IMSG_LOOSE_TREE_OBJECT_REQUEST,
55 	GOT_IMSG_LOOSE_TREE_OBJECT_REPLY,
56 	GOT_IMSG_TREE_ENTRY,
57 	GOT_IMSG_LOOSE_COMMIT_OBJECT_REQUEST,
58 	GOT_IMSG_LOOSE_COMMIT_OBJECT_REPLY,
59 	GOT_IMSG_PACKED_BLOB_OBJECT_REQUEST,
60 	GOT_IMSG_PACKED_BLOB_OBJECT_REQUEST_OUTPUT,
61 	GOT_IMSG_PACKED_BLOB_OBJECT_REPLY,
62 	GOT_IMSG_PACKED_TREE_OBJECT_REQUEST,
63 	GOT_IMSG_PACKED_TREE_OBJECT_REPLY,
64 	GOT_IMSG_PACKED_COMMIT_OBJECT_REQUEST,
65 	GOT_IMSG_PACKED_COMMIT_OBJECT_REPLY
66 };
67 
68 /* Structure for GOT_IMSG_ERROR. */
69 struct got_imsg_error {
70 	int code; /* an error code from got_error.h */
71 };
72 
73 /* Structure for GOT_IMSG_DELTA data. */
74 struct got_imsg_delta {
75 	/* These fields are the same as in struct got_delta. */
76 	off_t offset;
77 	size_t tslen;
78 	int type;
79 	size_t size;
80 	off_t data_offset;
81 	size_t delta_len;
82 
83 	/*
84 	 * Followed by delta stream in remaining bytes of imsg buffer.
85 	 * If delta_len exceeds imsg buffer length, followed by one or
86 	 * more DELTA_STREAM messages until delta_len bytes of delta
87 	 * stream have been transmitted.
88 	 */
89 };
90 
91 /* Structure for GOT_IMSG_DELTA_STREAM data. */
92 struct got_imsg_delta_stream {
93 	/*
94 	 * Empty since the following is implied:
95 	 * Read additional delta stream data from imsg buffer.
96 	 */
97 };
98 
99 /* Structure for GOT_IMSG_LOOSE_OBJECT_HEADER_REQUEST data. */
100 struct got_imsg_loose_object_header_request {
101 	/*
102 	 * Empty since the following is implied: If imsg fd == -1 then
103 	 * read raw object data from imsg buffer, else read from fd.
104 	 */
105 };
106 
107 /* Structure for transmitting struct got_object data in an imsg. */
108 struct got_imsg_object {
109 	/* These fields are the same as in struct got_object. */
110 	int type;
111 	int flags;
112 	size_t hdrlen;
113 	size_t size;
114 	struct got_object_id id;
115 
116 	int ndeltas; /* this many GOT_IMSG_DELTA messages follow */
117 } __attribute__((__packed__));
118 
119 /* Structure for GOT_IMSG_LOOSE_OBJECT_HEADER_REPLY data. */
120 struct got_imsg_loose_object_header_reply {
121 	struct got_imsg_object iobj;
122 };
123 
124 /* Structure for GOT_IMSG_LOOSE_BLOB_OBJECT_REQUEST data. */
125 struct got_imsg_loose_blob_object_request {
126 	struct got_imsg_object iobj;
127 
128 	/*
129 	 * The following is implied: If imsg fd == -1 then read raw
130 	 * blob data from imsg buffer, else read from fd.
131 	 */
132 };
133 
134 /* Structure for GOT_IMSG_LOOSE_BLOB_OBJECT_REQUEST_OUTPUT data. */
135 struct got_imsg_loose_blob_object_request_output {
136 	/*
137 	 * Empty since the following is implied: If imsg fd == -1 then
138 	 * respond with blob data in imsg buffer, else write to fd.
139 	 */
140 };
141 
142 /* Structure for GOT_IMSG_LOOSE_TREE_OBJECT_REQUEST data. */
143 struct got_imsg_loose_tree_object_request {
144 	struct got_imsg_object iobj;
145 
146 	/*
147 	 * The following is implied: If imsg fd == -1 then read raw tree
148 	 * data from imsg buffer, else read from fd.
149 	 */
150 };
151 
152 /* Structure for GOT_IMSG_TREE_ENTRY. */
153 struct got_imsg_tree_entry {
154 	struct got_object_id id;
155 	mode_t mode;
156 	/* Followed by entry's name in remaining data of imsg buffer. */
157 } __attribute__((__packed__));
158 
159 /* Structure for transmitting struct got_tree_object data in an imsg. */
160 struct got_imsg_tree_object {
161 	int nentries; /* This many TREE_ENTRY messages follow. */
162 };
163 
164 /* TODO: Implement the above, and then add more message data types here. */