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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 8b925c6c 2022-07-16 thomas #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 12ce7a6c 2019-08-12 stsp #include <limits.h>

 24 99437157 2018-11-11 stsp #include <signal.h>

 25 ad242220 2018-09-08 stsp #include <stdio.h>

 26 ad242220 2018-09-08 stsp #include <stdlib.h>

 27 ad242220 2018-09-08 stsp #include <string.h>

 28 81a12da5 2020-09-09 naddy #include <unistd.h>

 29 ad242220 2018-09-08 stsp #include <zlib.h>

 30 ad242220 2018-09-08 stsp 

 31 dd038bc6 2021-09-21 thomas.ad #include "got_compat.h"

 32 dd038bc6 2021-09-21 thomas.ad 

 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 97799ccd 2022-02-06 thomas 

 70 97799ccd 2022-02-06 thomas 	/* revoke fs access */

 71 97799ccd 2022-02-06 thomas 	if (landlock_no_fs() == -1) {

 72 97799ccd 2022-02-06 thomas 		err = got_error_from_errno("landlock_no_fs");

 73 97799ccd 2022-02-06 thomas 		got_privsep_send_error(&ibuf, err);

 74 97799ccd 2022-02-06 thomas 		return 1;

 75 97799ccd 2022-02-06 thomas 	}

 76 5d120ea8 2022-06-23 op 	if (cap_enter() == -1) {

 77 5d120ea8 2022-06-23 op 		err = got_error_from_errno("cap_enter");

 78 5d120ea8 2022-06-23 op 		got_privsep_send_error(&ibuf, err);

 79 5d120ea8 2022-06-23 op 		return 1;

 80 5d120ea8 2022-06-23 op 	}

 81 2ff12563 2018-09-15 stsp #endif

 82 ad242220 2018-09-08 stsp 

 83 656b1f76 2019-05-11 jcs 	for (;;) {

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

 85 1785f84a 2018-12-23 stsp 		struct got_commit_object *commit = NULL;

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

 87 99437157 2018-11-11 stsp 

 88 99437157 2018-11-11 stsp 		if (sigint_received) {

 89 99437157 2018-11-11 stsp 			err = got_error(GOT_ERR_CANCELLED);

 90 99437157 2018-11-11 stsp 			break;

 91 99437157 2018-11-11 stsp 		}

 92 230a42bd 2019-05-11 jcs 

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

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

 95 876c234b 2018-09-10 stsp 			if (err->code == GOT_ERR_PRIVSEP_PIPE)

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

 97 ad242220 2018-09-08 stsp 			break;

 98 ad242220 2018-09-08 stsp 		}

 99 ad242220 2018-09-08 stsp 

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

101 ad242220 2018-09-08 stsp 			break;

102 ad242220 2018-09-08 stsp 

103 41fa1437 2018-11-05 stsp 		if (imsg.hdr.type != GOT_IMSG_COMMIT_REQUEST) {

104 41fa1437 2018-11-05 stsp 			err = got_error(GOT_ERR_PRIVSEP_MSG);

105 41fa1437 2018-11-05 stsp 			goto done;

106 ad242220 2018-09-08 stsp 		}

107 ad242220 2018-09-08 stsp 

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

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

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

111 d5c81d44 2021-07-08 stsp 			goto done;

112 d5c81d44 2021-07-08 stsp 		}

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

114 d5c81d44 2021-07-08 stsp 

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

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

117 ad242220 2018-09-08 stsp 			goto done;

118 ad242220 2018-09-08 stsp 		}

119 ad242220 2018-09-08 stsp 

120 3efd8e31 2022-10-23 thomas 		err = got_object_read_commit(&commit, imsg.fd, &expected_id, 0);

121 41fa1437 2018-11-05 stsp 		if (err)

122 41fa1437 2018-11-05 stsp 			goto done;

123 41fa1437 2018-11-05 stsp 

124 41fa1437 2018-11-05 stsp 		err = got_privsep_send_commit(&ibuf, commit);

125 fe558a04 2020-01-06 stsp 		got_object_commit_close(commit);

126 ad242220 2018-09-08 stsp done:

127 3efd8e31 2022-10-23 thomas 		if (imsg.fd != -1 && close(imsg.fd) == -1 && err == NULL)

128 3efd8e31 2022-10-23 thomas 			err = got_error_from_errno("close");

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

130 99437157 2018-11-11 stsp 		if (err)

131 ad242220 2018-09-08 stsp 			break;

132 ad242220 2018-09-08 stsp 	}

133 ad242220 2018-09-08 stsp 

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

135 99437157 2018-11-11 stsp 	if (err) {

136 80d5f134 2018-11-11 stsp 		if (!sigint_received && err->code != GOT_ERR_PRIVSEP_PIPE) {

137 80d5f134 2018-11-11 stsp 			fprintf(stderr, "%s: %s\n", getprogname(), err->msg);

138 99437157 2018-11-11 stsp 			got_privsep_send_error(&ibuf, err);

139 80d5f134 2018-11-11 stsp 		}

140 99437157 2018-11-11 stsp 	}

141 08578a35 2021-01-22 stsp 	if (close(GOT_IMSG_FD_CHILD) == -1 && err == NULL)

142 638f9024 2019-05-13 stsp 		err = got_error_from_errno("close");

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

144 ad242220 2018-09-08 stsp }