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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 3022d272 2019-11-14 stsp #include "got_path.h"

 36 ad242220 2018-09-08 stsp 

 37 ad242220 2018-09-08 stsp #include "got_lib_delta.h"

 38 ad242220 2018-09-08 stsp #include "got_lib_inflate.h"

 39 ad242220 2018-09-08 stsp #include "got_lib_object.h"

 40 ad242220 2018-09-08 stsp #include "got_lib_object_parse.h"

 41 ad242220 2018-09-08 stsp #include "got_lib_privsep.h"

 42 d5c81d44 2021-07-08 stsp #include "got_lib_sha1.h"

 43 ad242220 2018-09-08 stsp 

 44 99437157 2018-11-11 stsp static volatile sig_atomic_t sigint_received;

 45 99437157 2018-11-11 stsp 

 46 99437157 2018-11-11 stsp static void

 47 99437157 2018-11-11 stsp catch_sigint(int signo)

 48 99437157 2018-11-11 stsp {

 49 99437157 2018-11-11 stsp 	sigint_received = 1;

 50 99437157 2018-11-11 stsp }

 51 3022d272 2019-11-14 stsp 

 52 ad242220 2018-09-08 stsp int

 53 ad242220 2018-09-08 stsp main(int argc, char *argv[])

 54 ad242220 2018-09-08 stsp {

 55 ad242220 2018-09-08 stsp 	const struct got_error *err = NULL;

 56 ad242220 2018-09-08 stsp 	struct imsgbuf ibuf;

 57 d5c81d44 2021-07-08 stsp 	size_t datalen;

 58 d294b1dc 2022-10-18 stsp 	struct got_parsed_tree_entry *entries = NULL;

 59 d294b1dc 2022-10-18 stsp 	size_t nentries = 0, nentries_alloc = 0;

 60 ad242220 2018-09-08 stsp 

 61 99437157 2018-11-11 stsp 	signal(SIGINT, catch_sigint);

 62 99437157 2018-11-11 stsp 

 63 ad242220 2018-09-08 stsp 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);

 64 ad242220 2018-09-08 stsp 

 65 2ff12563 2018-09-15 stsp #ifndef PROFILE

 66 ad242220 2018-09-08 stsp 	/* revoke access to most system calls */

 67 ad242220 2018-09-08 stsp 	if (pledge("stdio recvfd", NULL) == -1) {

 68 638f9024 2019-05-13 stsp 		err = got_error_from_errno("pledge");

 69 ad242220 2018-09-08 stsp 		got_privsep_send_error(&ibuf, err);

 70 ad242220 2018-09-08 stsp 		return 1;

 71 ad242220 2018-09-08 stsp 	}

 72 2ff12563 2018-09-15 stsp #endif

 73 ad242220 2018-09-08 stsp 

 74 656b1f76 2019-05-11 jcs 	for (;;) {

 75 ad242220 2018-09-08 stsp 		struct imsg imsg;

 76 3022d272 2019-11-14 stsp 		uint8_t *buf = NULL;

 77 d5c81d44 2021-07-08 stsp 		struct got_object_id expected_id;

 78 99437157 2018-11-11 stsp 

 79 99437157 2018-11-11 stsp 		if (sigint_received) {

 80 99437157 2018-11-11 stsp 			err = got_error(GOT_ERR_CANCELLED);

 81 99437157 2018-11-11 stsp 			break;

 82 99437157 2018-11-11 stsp 		}

 83 230a42bd 2019-05-11 jcs 

 84 ad242220 2018-09-08 stsp 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);

 85 ad242220 2018-09-08 stsp 		if (err) {

 86 876c234b 2018-09-10 stsp 			if (err->code == GOT_ERR_PRIVSEP_PIPE)

 87 ad242220 2018-09-08 stsp 				err = NULL;

 88 ad242220 2018-09-08 stsp 			break;

 89 ad242220 2018-09-08 stsp 		}

 90 ad242220 2018-09-08 stsp 

 91 ad242220 2018-09-08 stsp 		if (imsg.hdr.type == GOT_IMSG_STOP)

 92 ad242220 2018-09-08 stsp 			break;

 93 ad242220 2018-09-08 stsp 

 94 ad242220 2018-09-08 stsp 		if (imsg.hdr.type != GOT_IMSG_TREE_REQUEST) {

 95 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_MSG);

 96 ad242220 2018-09-08 stsp 			goto done;

 97 ad242220 2018-09-08 stsp 		}

 98 ad242220 2018-09-08 stsp 

 99 d5c81d44 2021-07-08 stsp 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;

100 d5c81d44 2021-07-08 stsp 		if (datalen != sizeof(expected_id)) {

101 d5c81d44 2021-07-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_LEN);

102 d5c81d44 2021-07-08 stsp 			goto done;

103 d5c81d44 2021-07-08 stsp 		}

104 d5c81d44 2021-07-08 stsp 		memcpy(&expected_id, imsg.data, sizeof(expected_id));

105 d5c81d44 2021-07-08 stsp 

106 ad242220 2018-09-08 stsp 		if (imsg.fd == -1) {

107 ad242220 2018-09-08 stsp 			err = got_error(GOT_ERR_PRIVSEP_NO_FD);

108 ad242220 2018-09-08 stsp 			goto done;

109 ad242220 2018-09-08 stsp 		}

110 ad242220 2018-09-08 stsp 

111 ad242220 2018-09-08 stsp 		/* Always assume file offset zero. */

112 13b2bc37 2022-10-23 stsp 		err = got_object_read_tree(&entries, &nentries, &nentries_alloc,

113 13b2bc37 2022-10-23 stsp 		    &buf, imsg.fd, &expected_id);

114 ad242220 2018-09-08 stsp 		if (err)

115 ad242220 2018-09-08 stsp 			goto done;

116 ad242220 2018-09-08 stsp 

117 9985f404 2022-05-19 stsp 		err = got_privsep_send_tree(&ibuf, entries, nentries);

118 ad242220 2018-09-08 stsp done:

119 3022d272 2019-11-14 stsp 		free(buf);

120 13b2bc37 2022-10-23 stsp 		if (imsg.fd != -1 && close(imsg.fd) == -1 && err == NULL)

121 13b2bc37 2022-10-23 stsp 			err = got_error_from_errno("close");

122 ad242220 2018-09-08 stsp 		imsg_free(&imsg);

123 99437157 2018-11-11 stsp 		if (err)

124 ad242220 2018-09-08 stsp 			break;

125 ad242220 2018-09-08 stsp 	}

126 ad242220 2018-09-08 stsp 

127 d294b1dc 2022-10-18 stsp 	free(entries);

128 ad242220 2018-09-08 stsp 	imsg_clear(&ibuf);

129 99437157 2018-11-11 stsp 	if (err) {

130 80d5f134 2018-11-11 stsp 		if (!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {

131 80d5f134 2018-11-11 stsp 			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);

132 99437157 2018-11-11 stsp 			got_privsep_send_error(&ibuf, err);

133 80d5f134 2018-11-11 stsp 		}

134 99437157 2018-11-11 stsp 	}

135 08578a35 2021-01-22 stsp 	if (close(GOT_IMSG_FD_CHILD) == -1 && err == NULL)

136 638f9024 2019-05-13 stsp 		err = got_error_from_errno("close");

137 ad242220 2018-09-08 stsp 	return err ? 1 : 0;

138 ad242220 2018-09-08 stsp }