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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 5aa81393 2020-01-06 stsp  * Copyright (c) 2018, 2019, 2020 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 ad242220 2018-09-08 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 99437157 2018-11-11 stsp static volatile sig_atomic_t sigint_received;
 44 99437157 2018-11-11 stsp 
 45 99437157 2018-11-11 stsp static void
 46 99437157 2018-11-11 stsp catch_sigint(int signo)
 47 99437157 2018-11-11 stsp {
 48 99437157 2018-11-11 stsp 	sigint_received = 1;
 49 99437157 2018-11-11 stsp }
 50 99437157 2018-11-11 stsp 
 51 ad242220 2018-09-08 stsp int
 52 ad242220 2018-09-08 stsp main(int argc, char *argv[])
 53 ad242220 2018-09-08 stsp {
 54 ad242220 2018-09-08 stsp 	const struct got_error *err = NULL;
 55 ad242220 2018-09-08 stsp 	struct imsgbuf ibuf;
 56 d5c81d44 2021-07-08 stsp 	size_t datalen;
 57 ad242220 2018-09-08 stsp 
 58 99437157 2018-11-11 stsp 	signal(SIGINT, catch_sigint);
 59 99437157 2018-11-11 stsp 
 60 ad242220 2018-09-08 stsp 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
 61 ad242220 2018-09-08 stsp 
 62 2ff12563 2018-09-15 stsp #ifndef PROFILE
 63 ad242220 2018-09-08 stsp 	/* revoke access to most system calls */
 64 ad242220 2018-09-08 stsp 	if (pledge("stdio recvfd", NULL) == -1) {
 65 638f9024 2019-05-13 stsp 		err = got_error_from_errno("pledge");
 66 ad242220 2018-09-08 stsp 		got_privsep_send_error(&ibuf, err);
 67 ad242220 2018-09-08 stsp 		return 1;
 68 ad242220 2018-09-08 stsp 	}
 69 2ff12563 2018-09-15 stsp #endif
 70 ad242220 2018-09-08 stsp 
 71 656b1f76 2019-05-11 jcs 	for (;;) {
 72 ad242220 2018-09-08 stsp 		struct imsg imsg;
 73 1785f84a 2018-12-23 stsp 		struct got_commit_object *commit = NULL;
 74 d5c81d44 2021-07-08 stsp 		struct got_object_id expected_id;
 75 99437157 2018-11-11 stsp 
 76 99437157 2018-11-11 stsp 		if (sigint_received) {
 77 99437157 2018-11-11 stsp 			err = got_error(GOT_ERR_CANCELLED);
 78 99437157 2018-11-11 stsp 			break;
 79 99437157 2018-11-11 stsp 		}
 80 230a42bd 2019-05-11 jcs 
 81 ad242220 2018-09-08 stsp 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
 82 ad242220 2018-09-08 stsp 		if (err) {
 83 876c234b 2018-09-10 stsp 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
 84 ad242220 2018-09-08 stsp 				err = NULL;
 85 ad242220 2018-09-08 stsp 			break;
 86 ad242220 2018-09-08 stsp 		}
 87 ad242220 2018-09-08 stsp 
 88 ad242220 2018-09-08 stsp 		if (imsg.hdr.type == GOT_IMSG_STOP)
 89 ad242220 2018-09-08 stsp 			break;
 90 ad242220 2018-09-08 stsp 
 91 41fa1437 2018-11-05 stsp 		if (imsg.hdr.type != GOT_IMSG_COMMIT_REQUEST) {
 92 41fa1437 2018-11-05 stsp 			err = got_error(GOT_ERR_PRIVSEP_MSG);
 93 41fa1437 2018-11-05 stsp 			goto done;
 94 ad242220 2018-09-08 stsp 		}
 95 ad242220 2018-09-08 stsp 
 96 d5c81d44 2021-07-08 stsp 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
 97 d5c81d44 2021-07-08 stsp 		if (datalen != sizeof(expected_id)) {
 98 d5c81d44 2021-07-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_LEN);
 99 d5c81d44 2021-07-08 stsp 			goto done;
100 d5c81d44 2021-07-08 stsp 		}
101 d5c81d44 2021-07-08 stsp 		memcpy(&expected_id, imsg.data, sizeof(expected_id));
102 d5c81d44 2021-07-08 stsp 
103 ad242220 2018-09-08 stsp 		if (imsg.fd == -1) {
104 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);
105 ad242220 2018-09-08 stsp 			goto done;
106 ad242220 2018-09-08 stsp 		}
107 ad242220 2018-09-08 stsp 
108 13b2bc37 2022-10-23 stsp 		err = got_object_read_commit(&commit, imsg.fd, &expected_id, 0);
109 41fa1437 2018-11-05 stsp 		if (err)
110 41fa1437 2018-11-05 stsp 			goto done;
111 41fa1437 2018-11-05 stsp 
112 41fa1437 2018-11-05 stsp 		err = got_privsep_send_commit(&ibuf, commit);
113 fe558a04 2020-01-06 stsp 		got_object_commit_close(commit);
114 ad242220 2018-09-08 stsp done:
115 13b2bc37 2022-10-23 stsp 		if (imsg.fd != -1 && close(imsg.fd) == -1 && err == NULL)
116 13b2bc37 2022-10-23 stsp 			err = got_error_from_errno("close");
117 ad242220 2018-09-08 stsp 		imsg_free(&imsg);
118 99437157 2018-11-11 stsp 		if (err)
119 ad242220 2018-09-08 stsp 			break;
120 ad242220 2018-09-08 stsp 	}
121 ad242220 2018-09-08 stsp 
122 ad242220 2018-09-08 stsp 	imsg_clear(&ibuf);
123 99437157 2018-11-11 stsp 	if (err) {
124 80d5f134 2018-11-11 stsp 		if (!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {
125 80d5f134 2018-11-11 stsp 			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
126 99437157 2018-11-11 stsp 			got_privsep_send_error(&ibuf, err);
127 80d5f134 2018-11-11 stsp 		}
128 99437157 2018-11-11 stsp 	}
129 08578a35 2021-01-22 stsp 	if (close(GOT_IMSG_FD_CHILD) == -1 && err == NULL)
130 638f9024 2019-05-13 stsp 		err = got_error_from_errno("close");
131 ad242220 2018-09-08 stsp 	return err ? 1 : 0;
132 ad242220 2018-09-08 stsp }