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 #define GOT_PROG_READ_PACK	got-read-pack
43 
44 #define GOT_STRINGIFY(x) #x
45 #define GOT_STRINGVAL(x) GOT_STRINGIFY(x)
46 
47 /* Paths to helper programs in libexec directory */
48 #define GOT_PATH_PROG_READ_OBJECT \
49 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_OBJECT)
50 #define GOT_PATH_PROG_READ_TREE \
51 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_TREE)
52 #define GOT_PATH_PROG_READ_COMMIT \
53 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_COMMIT)
54 #define GOT_PATH_PROG_READ_BLOB \
55 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_BLOB)
56 #define GOT_PATH_PROG_READ_PACK \
57 	GOT_STRINGVAL(GOT_LIBEXECDIR) "/" GOT_STRINGVAL(GOT_PROG_READ_PACK)
58 
59 struct got_privsep_child {
60 	int imsg_fd;
61 	pid_t pid;
62 	struct imsgbuf *ibuf;
63 };
64 
65 enum got_imsg_type {
66 	/* An error occured while processing a request. */
67 	GOT_IMSG_ERROR,
68 
69 	/* Stop the child process. */
70 	GOT_IMSG_STOP,
71 
72 	/*
73 	 * Messages concerned with read access to objects in a repository.
74 	 * Object and pack files are opened by the main process, where
75 	 * data may be read as a byte string but without any interpretation.
76 	 * Decompression and parsing of object and pack files occurs in a
77 	 * separate process which runs under pledge("stdio recvfd").
78 	 * This sandboxes our own repository parsing code, as well as zlib.
79 	 */
80 	GOT_IMSG_OBJECT_REQUEST,
81 	GOT_IMSG_OBJECT,
82 	GOT_IMSG_COMMIT_REQUEST,
83 	GOT_IMSG_COMMIT,
84 	GOT_IMSG_COMMIT_LOGMSG,
85 	GOT_IMSG_TREE_REQUEST,
86 	GOT_IMSG_TREE,
87 	GOT_IMSG_TREE_ENTRY,
88 	GOT_IMSG_BLOB_REQUEST,
89 	GOT_IMSG_BLOB_OUTFD,
90 	GOT_IMSG_BLOB,
91 
92 	/* Messages related to pack files. */
93 	GOT_IMSG_PACKIDX,
94 	GOT_IMSG_PACK,
95 	GOT_IMSG_PACKED_OBJECT_REQUEST,
96 
97 	/* Message sending file desciprtor to a temporary file. */
98 	GOT_IMSG_TMPFD,
99 };
100 
101 /* Structure for GOT_IMSG_ERROR. */
102 struct got_imsg_error {
103 	int code; /* an error code from got_error.h */
104 	int errno_code; /* in case code equals GOT_ERR_ERRNO */
105 };
106 
107 /*
108  * Structure for GOT_IMSG_TREE_REQUEST, GOT_IMSG_COMMIT_REQUEST,
109  * and GOT_IMSG_OBJECT data.
110  */
111 struct got_imsg_object {
112 	uint8_t id[SHA1_DIGEST_LENGTH];
113 
114 	/* These fields are the same as in struct got_object. */
115 	int type;
116 	int flags;
117 	size_t hdrlen;
118 	size_t size;
119 	off_t pack_offset;
120 	int pack_idx;
121 };
122 
123 /* Structure for GOT_IMSG_COMMIT data. */
124 struct got_imsg_commit_object {
125 	uint8_t tree_id[SHA1_DIGEST_LENGTH];
126 	size_t author_len;
127 	struct tm tm_author;
128 	size_t committer_len;
129 	struct tm tm_committer;
130 	size_t logmsg_len;
131 	int nparents;
132 
133 	/*
134 	 * Followed by author_len + committer_len data bytes
135 	 */
136 
137 	/* Followed by 'nparents' SHA1_DIGEST_LENGTH length strings */
138 
139 	/*
140 	 * Followed by 'logmsg_len' bytes of commit log message data in
141 	 * one or more GOT_IMSG_COMMIT_LOGMSG messages.
142 	 */
143 } __attribute__((__packed__));
144 
145 
146 /* Structure for GOT_IMSG_TREE_ENTRY. */
147 struct got_imsg_tree_entry {
148 	char id[SHA1_DIGEST_LENGTH];
149 	mode_t mode;
150 	/* Followed by entry's name in remaining data of imsg buffer. */
151 } __attribute__((__packed__));
152 
153 /* Structure for GOT_IMSG_TREE_OBJECT_REPLY data. */
154 struct got_imsg_tree_object {
155 	int nentries; /* This many TREE_ENTRY messages follow. */
156 };
157 
158 /* Structure for GOT_IMSG_BLOB. */
159 struct got_imsg_blob {
160 	size_t size;
161 };
162 
163 /* Structure for GOT_IMSG_PACKIDX. */
164 struct got_imsg_packidx {
165 	size_t len;
166 	/* Additionally, a file desciptor is passed via imsg. */
167 };
168 
169 /* Structure for GOT_IMSG_PACK. */
170 struct got_imsg_pack {
171 	char path_packfile[PATH_MAX];
172 	size_t filesize;
173 	/* Additionally, a file desciptor is passed via imsg. */
174 };
175 
176 /*
177  * Structure for GOT_IMSG_PACKED_OBJECT_REQUEST data.
178  */
179 struct got_imsg_packed_object {
180 	int idx;
181 };
182 
183 struct got_pack;
184 struct got_packidx;
185 
186 const struct got_error *got_privsep_wait_for_child(pid_t);
187 const struct got_error *got_privsep_send_stop(int);
188 const struct got_error *got_privsep_recv_imsg(struct imsg *, struct imsgbuf *,
189     size_t);
190 void got_privsep_send_error(struct imsgbuf *, const struct got_error *);
191 const struct got_error *got_privsep_send_obj_req(struct imsgbuf *, int,
192     struct got_object *);
193 const struct got_error *got_privsep_send_blob_req(struct imsgbuf *, int);
194 const struct got_error *got_privsep_send_blob_outfd(struct imsgbuf *, int);
195 const struct got_error *got_privsep_send_tmpfd(struct imsgbuf *, int);
196 const struct got_error *got_privsep_send_obj(struct imsgbuf *,
197     struct got_object *);
198 const struct got_error *got_privsep_get_imsg_obj(struct got_object **,
199     struct imsg *, struct imsgbuf *);
200 const struct got_error *got_privsep_recv_obj(struct got_object **,
201     struct imsgbuf *);
202 const struct got_error *got_privsep_send_commit(struct imsgbuf *,
203     struct got_commit_object *);
204 const struct got_error *got_privsep_recv_commit(struct got_commit_object **,
205     struct imsgbuf *);
206 const struct got_error *got_privsep_recv_tree(struct got_tree_object **,
207     struct imsgbuf *);
208 const struct got_error *got_privsep_send_tree(struct imsgbuf *,
209     struct got_tree_object *);
210 const struct got_error *got_privsep_send_blob(struct imsgbuf *, size_t);
211 const struct got_error *got_privsep_recv_blob(size_t *, struct imsgbuf *);
212 const struct got_error *got_privsep_init_pack_child(struct imsgbuf *,
213     struct got_pack *, struct got_packidx *);
214 const struct got_error *got_privsep_send_packed_obj_req(struct imsgbuf *, int);
215 const struct got_error *got_privsep_send_pack_child_ready(struct imsgbuf *);