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Date:: Sun Oct 23 00:37:19 2022 UTC
Message:: introduce gotd(8), a Git repository server reachable via ssh(1) This is an initial barebones implementation which provides the absolute minimum of functionality required to serve got(1) and git(1) clients. Basic fetch/send functionality has been tested and seems to work here, but this server is not yet expected to be stable. More testing is welcome. See the man pages for setup instructions. The current design uses one reader and one writer process per repository, which will have to be extended to N readers and N writers in the future. At startup, each process will chroot(2) into its assigned repository. This works because gotd(8) can only be started as root, and will then fork+exec, chroot, and privdrop. At present the parent process runs with the following pledge(2) promises: "stdio rpath wpath cpath proc getpw sendfd recvfd fattr flock unix unveil" The parent is the only process able to modify the repository in a way that becomes visible to Git clients. The parent uses unveil(2) to restrict its view of the filesystem to /tmp and the repositories listed in the configuration file gotd.conf(5). Per-repository chroot(2) processes use "stdio rpath sendfd recvfd". The writer defers to the parent for modifying references in the repository to point at newly uploaded commits. The reader is fine without such help, because Git repositories can be read without having to create any lock-files. gotd(8) requires a dedicated user ID, which should own repositories on the filesystem, and a separate secondary group, which should not have filesystem-level repository access, and must be allowed access to the gotd(8) socket. To obtain Git repository access, users must be members of this secondary group, and must have their login shell set to gotsh(1). gotsh(1) connects to the gotd(8) socket and speaks Git-protocol towards the client on the other end of the SSH connection. gotsh(1) is not an interactive command shell. At present, authenticated clients are granted read/write access to all repositories and all references (except for the "refs/got/" and the "refs/remotes/" namespaces, which are already being protected from modification). While complicated access control mechanism are not a design goal, making it possible to safely offer anonymous Git repository access over ssh(1) is on the road map.
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  1 ad242220 2018-09-08 stsp /*
  2 ad242220 2018-09-08 stsp  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
  3 ad242220 2018-09-08 stsp  *
  4 ad242220 2018-09-08 stsp  * Permission to use, copy, modify, and distribute this software for any
  5 ad242220 2018-09-08 stsp  * purpose with or without fee is hereby granted, provided that the above
  6 ad242220 2018-09-08 stsp  * copyright notice and this permission notice appear in all copies.
  7 ad242220 2018-09-08 stsp  *
  8 ad242220 2018-09-08 stsp  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  9 ad242220 2018-09-08 stsp  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 10 ad242220 2018-09-08 stsp  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 11 ad242220 2018-09-08 stsp  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 12 ad242220 2018-09-08 stsp  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 13 ad242220 2018-09-08 stsp  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 14 ad242220 2018-09-08 stsp  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 15 ad242220 2018-09-08 stsp  */
 16 ad242220 2018-09-08 stsp 
 17 ad242220 2018-09-08 stsp #include <sys/types.h>
 18 ad242220 2018-09-08 stsp #include <sys/queue.h>
 19 ad242220 2018-09-08 stsp #include <sys/uio.h>
 20 ad242220 2018-09-08 stsp #include <sys/time.h>
 21 ad242220 2018-09-08 stsp 
 22 ad242220 2018-09-08 stsp #include <stdint.h>
 23 ad242220 2018-09-08 stsp #include <imsg.h>
 24 12ce7a6c 2019-08-12 stsp #include <limits.h>
 25 99437157 2018-11-11 stsp #include <signal.h>
 26 ad242220 2018-09-08 stsp #include <stdio.h>
 27 ad242220 2018-09-08 stsp #include <stdlib.h>
 28 ad242220 2018-09-08 stsp #include <string.h>
 29 ad242220 2018-09-08 stsp #include <sha1.h>
 30 81a12da5 2020-09-09 naddy #include <unistd.h>
 31 ad242220 2018-09-08 stsp #include <zlib.h>
 32 ad242220 2018-09-08 stsp 
 33 ad242220 2018-09-08 stsp #include "got_error.h"
 34 ad242220 2018-09-08 stsp #include "got_object.h"
 35 ad242220 2018-09-08 stsp 
 36 ad242220 2018-09-08 stsp #include "got_lib_delta.h"
 37 ad242220 2018-09-08 stsp #include "got_lib_inflate.h"
 38 ad242220 2018-09-08 stsp #include "got_lib_object.h"
 39 1785f84a 2018-12-23 stsp #include "got_lib_object_parse.h"
 40 ad242220 2018-09-08 stsp #include "got_lib_privsep.h"
 41 d5c81d44 2021-07-08 stsp #include "got_lib_sha1.h"
 42 ad242220 2018-09-08 stsp 
 43 ad242220 2018-09-08 stsp #ifndef nitems
 44 ad242220 2018-09-08 stsp #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
 45 ad242220 2018-09-08 stsp #endif
 46 ad242220 2018-09-08 stsp 
 47 ad242220 2018-09-08 stsp #define GOT_OBJ_TAG_COMMIT	"commit"
 48 ad242220 2018-09-08 stsp #define GOT_OBJ_TAG_TREE	"tree"
 49 ad242220 2018-09-08 stsp #define GOT_OBJ_TAG_BLOB	"blob"
 50 f4a881ce 2018-11-17 stsp #define GOT_OBJ_TAG_TAG		"tag"
 51 ad242220 2018-09-08 stsp 
 52 99437157 2018-11-11 stsp static volatile sig_atomic_t sigint_received;
 53 99437157 2018-11-11 stsp 
 54 99437157 2018-11-11 stsp static void
 55 99437157 2018-11-11 stsp catch_sigint(int signo)
 56 99437157 2018-11-11 stsp {
 57 99437157 2018-11-11 stsp 	sigint_received = 1;
 58 99437157 2018-11-11 stsp }
 59 99437157 2018-11-11 stsp 
 60 59d1e4a0 2021-03-10 stsp static const struct got_error *
 61 d5c81d44 2021-07-08 stsp send_raw_obj(struct imsgbuf *ibuf, struct got_object *obj,
 62 d5c81d44 2021-07-08 stsp     struct got_object_id *expected_id,
 63 d5c81d44 2021-07-08 stsp     int fd, int outfd)
 64 59d1e4a0 2021-03-10 stsp {
 65 59d1e4a0 2021-03-10 stsp 	const struct got_error *err = NULL;
 66 59d1e4a0 2021-03-10 stsp 	uint8_t *data = NULL;
 67 13b2bc37 2022-10-23 stsp 	off_t size;
 68 13b2bc37 2022-10-23 stsp 	size_t hdrlen;
 69 59d1e4a0 2021-03-10 stsp 
 70 59d1e4a0 2021-03-10 stsp 	if (lseek(fd, SEEK_SET, 0) == -1) {
 71 59d1e4a0 2021-03-10 stsp 		err = got_error_from_errno("lseek");
 72 13b2bc37 2022-10-23 stsp 		goto done;
 73 59d1e4a0 2021-03-10 stsp 	}
 74 59d1e4a0 2021-03-10 stsp 
 75 13b2bc37 2022-10-23 stsp 	err = got_object_read_raw(&data, &size, &hdrlen,
 76 13b2bc37 2022-10-23 stsp 	    GOT_PRIVSEP_INLINE_BLOB_DATA_MAX, outfd, expected_id, fd);
 77 59d1e4a0 2021-03-10 stsp 	if (err)
 78 59d1e4a0 2021-03-10 stsp 		goto done;
 79 59d1e4a0 2021-03-10 stsp 
 80 13b2bc37 2022-10-23 stsp 	err = got_privsep_send_raw_obj(ibuf, size, hdrlen, data);
 81 59d1e4a0 2021-03-10 stsp done:
 82 59d1e4a0 2021-03-10 stsp 	free(data);
 83 13b2bc37 2022-10-23 stsp 	if (close(fd) == -1 && err == NULL)
 84 13b2bc37 2022-10-23 stsp 		err = got_error_from_errno("close");
 85 59d1e4a0 2021-03-10 stsp 	return err;
 86 59d1e4a0 2021-03-10 stsp }
 87 59d1e4a0 2021-03-10 stsp 
 88 ad242220 2018-09-08 stsp int
 89 ad242220 2018-09-08 stsp main(int argc, char *argv[])
 90 ad242220 2018-09-08 stsp {
 91 ad242220 2018-09-08 stsp 	const struct got_error *err = NULL;
 92 ad242220 2018-09-08 stsp 	struct got_object *obj = NULL;
 93 ad242220 2018-09-08 stsp 	struct imsg imsg;
 94 ad242220 2018-09-08 stsp 	struct imsgbuf ibuf;
 95 ad242220 2018-09-08 stsp 	size_t datalen;
 96 d5c81d44 2021-07-08 stsp 	struct got_object_id expected_id;
 97 ad242220 2018-09-08 stsp 
 98 99437157 2018-11-11 stsp 	signal(SIGINT, catch_sigint);
 99 99437157 2018-11-11 stsp 
100 ad242220 2018-09-08 stsp 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
101 ad242220 2018-09-08 stsp 
102 2ff12563 2018-09-15 stsp #ifndef PROFILE
103 ad242220 2018-09-08 stsp 	/* revoke access to most system calls */
104 ad242220 2018-09-08 stsp 	if (pledge("stdio recvfd", NULL) == -1) {
105 638f9024 2019-05-13 stsp 		err = got_error_from_errno("pledge");
106 ad242220 2018-09-08 stsp 		got_privsep_send_error(&ibuf, err);
107 ad242220 2018-09-08 stsp 		return 1;
108 ad242220 2018-09-08 stsp 	}
109 2ff12563 2018-09-15 stsp #endif
110 ad242220 2018-09-08 stsp 
111 656b1f76 2019-05-11 jcs 	for (;;) {
112 99437157 2018-11-11 stsp 		if (sigint_received) {
113 99437157 2018-11-11 stsp 			err = got_error(GOT_ERR_CANCELLED);
114 99437157 2018-11-11 stsp 			break;
115 99437157 2018-11-11 stsp 		}
116 99437157 2018-11-11 stsp 
117 ad242220 2018-09-08 stsp 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
118 ad242220 2018-09-08 stsp 		if (err) {
119 876c234b 2018-09-10 stsp 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
120 ad242220 2018-09-08 stsp 				err = NULL;
121 ad242220 2018-09-08 stsp 			break;
122 ad242220 2018-09-08 stsp 		}
123 ad242220 2018-09-08 stsp 
124 ad242220 2018-09-08 stsp 		if (imsg.hdr.type == GOT_IMSG_STOP)
125 ad242220 2018-09-08 stsp 			break;
126 ad242220 2018-09-08 stsp 
127 59d1e4a0 2021-03-10 stsp 		if (imsg.hdr.type != GOT_IMSG_OBJECT_REQUEST &&
128 59d1e4a0 2021-03-10 stsp 		    imsg.hdr.type != GOT_IMSG_RAW_OBJECT_REQUEST) {
129 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_MSG);
130 ad242220 2018-09-08 stsp 			goto done;
131 ad242220 2018-09-08 stsp 		}
132 ad242220 2018-09-08 stsp 
133 ad242220 2018-09-08 stsp 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
134 d5c81d44 2021-07-08 stsp 		if (datalen != sizeof(expected_id)) {
135 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_LEN);
136 ad242220 2018-09-08 stsp 			goto done;
137 ad242220 2018-09-08 stsp 		}
138 d5c81d44 2021-07-08 stsp 		memcpy(&expected_id, imsg.data, sizeof(expected_id));
139 ad242220 2018-09-08 stsp 
140 59d1e4a0 2021-03-10 stsp 		if (imsg.fd == -1) {
141 59d1e4a0 2021-03-10 stsp 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
142 59d1e4a0 2021-03-10 stsp 			goto done;
143 59d1e4a0 2021-03-10 stsp 		}
144 59d1e4a0 2021-03-10 stsp 
145 1785f84a 2018-12-23 stsp 		err = got_object_read_header(&obj, imsg.fd);
146 ad242220 2018-09-08 stsp 		if (err)
147 ad242220 2018-09-08 stsp 			goto done;
148 ad242220 2018-09-08 stsp 
149 59d1e4a0 2021-03-10 stsp 		if (imsg.hdr.type == GOT_IMSG_RAW_OBJECT_REQUEST) {
150 59d1e4a0 2021-03-10 stsp 			struct imsg imsg_outfd;
151 d5c81d44 2021-07-08 stsp 
152 59d1e4a0 2021-03-10 stsp 			err = got_privsep_recv_imsg(&imsg_outfd, &ibuf, 0);
153 59d1e4a0 2021-03-10 stsp 			if (err) {
154 59d1e4a0 2021-03-10 stsp 				if (imsg_outfd.hdr.len == 0)
155 59d1e4a0 2021-03-10 stsp 					err = NULL;
156 59d1e4a0 2021-03-10 stsp 				goto done;
157 59d1e4a0 2021-03-10 stsp 			}
158 59d1e4a0 2021-03-10 stsp 
159 59d1e4a0 2021-03-10 stsp 			if (imsg_outfd.hdr.type == GOT_IMSG_STOP) {
160 59d1e4a0 2021-03-10 stsp 				imsg_free(&imsg_outfd);
161 59d1e4a0 2021-03-10 stsp 				goto done;
162 59d1e4a0 2021-03-10 stsp 			}
163 59d1e4a0 2021-03-10 stsp 
164 59d1e4a0 2021-03-10 stsp 			if (imsg_outfd.hdr.type != GOT_IMSG_RAW_OBJECT_OUTFD) {
165 59d1e4a0 2021-03-10 stsp 				err = got_error(GOT_ERR_PRIVSEP_MSG);
166 59d1e4a0 2021-03-10 stsp 				imsg_free(&imsg_outfd);
167 59d1e4a0 2021-03-10 stsp 				goto done;
168 59d1e4a0 2021-03-10 stsp 			}
169 59d1e4a0 2021-03-10 stsp 
170 59d1e4a0 2021-03-10 stsp 			datalen = imsg_outfd.hdr.len - IMSG_HEADER_SIZE;
171 59d1e4a0 2021-03-10 stsp 			if (datalen != 0) {
172 59d1e4a0 2021-03-10 stsp 				err = got_error(GOT_ERR_PRIVSEP_LEN);
173 59d1e4a0 2021-03-10 stsp 				imsg_free(&imsg_outfd);
174 59d1e4a0 2021-03-10 stsp 				goto done;
175 59d1e4a0 2021-03-10 stsp 			}
176 59d1e4a0 2021-03-10 stsp 			if (imsg_outfd.fd == -1) {
177 59d1e4a0 2021-03-10 stsp 				err = got_error(GOT_ERR_PRIVSEP_NO_FD);
178 59d1e4a0 2021-03-10 stsp 				imsg_free(&imsg_outfd);
179 59d1e4a0 2021-03-10 stsp 				goto done;
180 59d1e4a0 2021-03-10 stsp 			}
181 d5c81d44 2021-07-08 stsp 			err = send_raw_obj(&ibuf, obj, &expected_id,
182 d5c81d44 2021-07-08 stsp 			    imsg.fd, imsg_outfd.fd);
183 59d1e4a0 2021-03-10 stsp 			imsg.fd = -1; /* imsg.fd is owned by send_raw_obj() */
184 e5ad7365 2021-05-20 stsp 			if (close(imsg_outfd.fd) == -1 && err == NULL)
185 e5ad7365 2021-05-20 stsp 				err = got_error_from_errno("close");
186 59d1e4a0 2021-03-10 stsp 			imsg_free(&imsg_outfd);
187 59d1e4a0 2021-03-10 stsp 			if (err)
188 59d1e4a0 2021-03-10 stsp 				goto done;
189 59d1e4a0 2021-03-10 stsp 		} else
190 59d1e4a0 2021-03-10 stsp 			err = got_privsep_send_obj(&ibuf, obj);
191 ad242220 2018-09-08 stsp done:
192 59d1e4a0 2021-03-10 stsp 		if (imsg.fd != -1 && close(imsg.fd) == -1 && err == NULL)
193 638f9024 2019-05-13 stsp 			err = got_error_from_errno("close");
194 ad242220 2018-09-08 stsp 		imsg_free(&imsg);
195 ad242220 2018-09-08 stsp 		if (obj)
196 ad242220 2018-09-08 stsp 			got_object_close(obj);
197 99437157 2018-11-11 stsp 		if (err)
198 ad242220 2018-09-08 stsp 			break;
199 ad242220 2018-09-08 stsp 	}
200 ad242220 2018-09-08 stsp 
201 ad242220 2018-09-08 stsp 	imsg_clear(&ibuf);
202 99437157 2018-11-11 stsp 	if (err) {
203 80d5f134 2018-11-11 stsp 		if(!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {
204 80d5f134 2018-11-11 stsp 			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
205 99437157 2018-11-11 stsp 			got_privsep_send_error(&ibuf, err);
206 80d5f134 2018-11-11 stsp 		}
207 99437157 2018-11-11 stsp 	}
208 08578a35 2021-01-22 stsp 	if (close(GOT_IMSG_FD_CHILD) == -1 && err == NULL)
209 638f9024 2019-05-13 stsp 		err = got_error_from_errno("close");
210 ad242220 2018-09-08 stsp 	return err ? 1 : 0;
211 ad242220 2018-09-08 stsp }