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 
43 #define GOT_STRINGIFY(x) #x
44 #define GOT_STRINGVAL(x) GOT_STRINGIFY(x)
45 
46 /* Paths to helper programs in libexec directory */
47 #define GOT_PATH_PROG_READ_OBJECT \
48 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_OBJECT)
49 #define GOT_PATH_PROG_READ_TREE \
50 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_TREE)
51 #define GOT_PATH_PROG_READ_COMMIT \
52 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_COMMIT)
53 #define GOT_PATH_PROG_READ_BLOB \
54 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_BLOB)
55 
56 enum got_imsg_type {
57 	/* An error occured while processing a request. */
58 	GOT_IMSG_ERROR,
59 
60 	/* Stop the child process. */
61 	GOT_IMSG_STOP,
62 
63 	/*
64 	 * Messages concerned with read access to objects in a repository.
65 	 * Object and pack files are opened by the main process, where
66 	 * data may be read as a byte string but without any interpretation.
67 	 * Decompression and parsing of object and pack files occurs in a
68 	 * separate process which runs under pledge("stdio").
69 	 * This sandboxes our own repository parsing code, as well as zlib.
70 	 */
71 	GOT_IMSG_OBJECT_REQUEST,
72 	GOT_IMSG_OBJECT,
73 	GOT_IMSG_COMMIT_REQUEST,
74 	GOT_IMSG_COMMIT,
75 	GOT_IMSG_TREE_REQUEST,
76 	GOT_IMSG_TREE,
77 	GOT_IMSG_TREE_ENTRY,
78 	GOT_IMSG_BLOB_REQUEST,
79 	GOT_IMSG_BLOB_OUTFD,
80 	GOT_IMSG_BLOB,
81 	/* Messages for transmitting deltas and associated delta streams: */
82 	GOT_IMSG_DELTA,
83 	GOT_IMSG_DELTA_STREAM,
84 };
85 
86 /* Structure for GOT_IMSG_ERROR. */
87 struct got_imsg_error {
88 	int code; /* an error code from got_error.h */
89 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
90 };
91 
92 /* Structure for GOT_IMSG_DELTA data. */
93 struct got_imsg_delta {
94 	/* These fields are the same as in struct got_delta. */
95 	off_t offset;
96 	size_t tslen;
97 	int type;
98 	size_t size;
99 	off_t data_offset;
100 	size_t delta_len;
101 
102 	/*
103 	 * Followed by delta stream in remaining bytes of imsg buffer.
104 	 * If delta_len exceeds imsg buffer length, followed by one or
105 	 * more DELTA_STREAM messages until delta_len bytes of delta
106 	 * stream have been transmitted.
107 	 */
108 };
109 
110 /* Structure for GOT_IMSG_DELTA_STREAM data. */
111 struct got_imsg_delta_stream {
112 	/*
113 	 * Empty since the following is implied:
114 	 * Read additional delta stream data from imsg buffer.
115 	 */
116 };
117 
118 /*
119  * Structure for GOT_IMSG_TREE_REQUEST, GOT_IMSG_COMMIT_REQUEST,
120  * and GOT_IMSG_OBJECT data.
121  */
122 struct got_imsg_object {
123 	/* These fields are the same as in struct got_object. */
124 	int type;
125 	int flags;
126 	size_t hdrlen;
127 	size_t size;
128 
129 	int ndeltas; /* this many GOT_IMSG_DELTA messages follow */
130 };
131 
132 /* Structure for GOT_IMSG_COMMIT data. */
133 struct got_imsg_commit_object {
134 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
135 	size_t author_len;
136 	struct tm tm_author;
137 	size_t committer_len;
138 	struct tm tm_committer;
139 	size_t logmsg_len;
140 	int nparents;
141 
142 	/*
143 	 * Followed by author_len + committer_len + logmsg_len data bytes
144 	 */
145 
146 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
147 
148 	/* XXX should use more messages to support very large log messages */
149 } __attribute__((__packed__));
150 
151 
152 /* Structure for GOT_IMSG_TREE_ENTRY. */
153 struct got_imsg_tree_entry {
154 	char id[SHA1_DIGEST_LENGTH];
155 	mode_t mode;
156 	/* Followed by entry's name in remaining data of imsg buffer. */
157 } __attribute__((__packed__));
158 
159 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
160 struct got_imsg_tree_object {
161 	int nentries; /* This many TREE_ENTRY messages follow. */
162 };
163 
164 /* Structure for GOT_IMSG_BLOB. */
165 struct got_imsg_blob {
166 	size_t size;
167 };
168 
169 const struct got_error *got_privsep_send_stop(int);
170 const struct got_error *got_privsep_recv_imsg(struct imsg *, struct imsgbuf *,
171     size_t);
172 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
173 const struct got_error *got_privsep_send_obj_req(struct imsgbuf *, int,
174     struct got_object *);
175 const struct got_error *got_privsep_send_blob_req(struct imsgbuf *, int, int);
176 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
177     struct got_object *, int);
178 const struct got_error *got_privsep_recv_obj(struct got_object **,
179     struct imsgbuf *);
180 const struct got_error *got_privsep_send_commit(struct imsgbuf *,
181     struct got_commit_object *);
182 const struct got_error *got_privsep_recv_commit(struct got_commit_object **,
183     struct imsgbuf *);
184 const struct got_error *got_privsep_recv_tree(struct got_tree_object **,
185     struct imsgbuf *);
186 const struct got_error *got_privsep_send_tree(struct imsgbuf *,
187     struct got_tree_object *);
188 const struct got_error *got_privsep_send_blob(struct imsgbuf *, size_t);
189 const struct got_error *got_privsep_recv_blob(size_t *, struct imsgbuf *);
190 
191 /* TODO: Implement the above, and then add more message data types here. */