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