gitwrapper/gitwrapper.c

   1 /*
   2  * Copyright (c) 2023 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  * Resolve path namespace conflicts for git-upload-pack and git-receive-pack.
  19  */
  20
  21 #include <sys/queue.h>
  22 #include <sys/types.h>
  23 #include <sys/uio.h>
  24
  25 #include <err.h>
  26 #include <errno.h>
  27 #include <event.h>
  28 #include <imsg.h>
  29 #include <limits.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <sha1.h>
  34 #include <sha2.h>
  35 #include <syslog.h>
  36 #include <util.h>
  37 #include <unistd.h>
  38
  39 #include "got_error.h"
  40 #include "got_path.h"
  41
  42 #include "got_lib_dial.h"
  43
  44 #include "gotd.h"
  45 #include "log.h"
  46
  47 #ifndef GITWRAPPER_GIT_LIBEXEC_DIR
  48 #define GITWRAPPER_GIT_LIBEXEC_DIR "/usr/local/libexec/git"
  49 #endif
  50
  51 #ifndef GITWRAPPER_MY_SERVER_PROG
  52 #define GITWRAPPER_MY_SERVER_PROG "gotsh"
  53 #endif
  54
  55
  56 __dead static void
  57 usage(void)
  58 {
  59         fprintf(stderr, "usage: %s -c '%s|%s repository-path'\n",
  60             getprogname(), GOT_DIAL_CMD_SEND, GOT_DIAL_CMD_FETCH);
  61         exit(1);
  62 }
  63
  64 /*
  65  * Unveil the specific programs we want to start and hide everything else.
  66  * This is important to limit the impact of our "exec" pledge.
  67  */
  68 static const struct got_error *
  69 apply_unveil(const char *myserver)
  70 {
  71         const char *fetchcmd = GITWRAPPER_GIT_LIBEXEC_DIR "/" \
  72                 GOT_DIAL_CMD_FETCH;
  73         const char *sendcmd = GITWRAPPER_GIT_LIBEXEC_DIR "/" \
  74                 GOT_DIAL_CMD_SEND;
  75
  76 #ifdef PROFILE
  77         if (unveil("gmon.out", "rwc") != 0)
  78                 return got_error_from_errno2("unveil", "gmon.out");
  79 #endif
  80         if (unveil(fetchcmd, "x") != 0 && errno != ENOENT)
  81                 return got_error_from_errno2("unveil", fetchcmd);
  82
  83         if (unveil(sendcmd, "x") != 0 && errno != ENOENT)
  84                 return got_error_from_errno2("unveil", sendcmd);
  85
  86         if (myserver && unveil(myserver, "x") != 0 && errno != ENOENT)
  87                 return got_error_from_errno2("unveil", myserver);
  88
  89         if (unveil(NULL, NULL) != 0)
  90                 return got_error_from_errno("unveil");
  91
  92         return NULL;
  93 }
  94
  95 int
  96 main(int argc, char *argv[])
  97 {
  98         const struct got_error *error;
  99         const char *confpath = NULL;
 100         char *command = NULL, *repo_name = NULL; /* for matching gotd.conf */
 101         char *myserver = NULL;
 102         const char *repo_path = NULL; /* as passed on the command line */
 103         const char *relpath;
 104         char *gitcommand = NULL;
 105         struct gotd gotd;
 106         struct gotd_repo *repo = NULL;
 107
 108         log_init(1, LOG_USER); /* Log to stderr. */
 109
 110 #ifndef PROFILE
 111         if (pledge("stdio rpath exec unveil", NULL) == -1)
 112                 err(1, "pledge");
 113 #endif
 114
 115         /*
 116          * Look up our own server program in PATH so we can unveil(2) it.
 117          * This call only errors out upon memory allocation failure.
 118          * If the program cannot be found then myserver will be set to NULL.
 119          */
 120         error = got_path_find_prog(&myserver, GITWRAPPER_MY_SERVER_PROG);
 121         if (error)
 122                 goto done;
 123
 124         /*
 125          * Run parse_config() before unveil(2) because parse_config()
 126          * checks whether repository paths exist on disk.
 127          * Parsing errors and warnings will be logged to stderr.
 128          * Upon failure we will run Git's native tooling so do not
 129          * bother checking for errors here.
 130          */
 131         confpath = getenv("GOTD_CONF_PATH");
 132         if (confpath == NULL)
 133                 confpath = GOTD_CONF_PATH;
 134         parse_config(confpath, PROC_GITWRAPPER, &gotd);
 135
 136         error = apply_unveil(myserver);
 137         if (error)
 138                 goto done;
 139
 140 #ifndef PROFILE
 141         if (pledge("stdio exec", NULL) == -1)
 142                 err(1, "pledge");
 143 #endif
 144
 145         if (strcmp(getprogname(), GOT_DIAL_CMD_SEND) == 0 ||
 146             strcmp(getprogname(), GOT_DIAL_CMD_FETCH) == 0) {
 147                 if (argc != 2)
 148                         usage();
 149                 command = strdup(getprogname());
 150                 if (command == NULL) {
 151                         error = got_error_from_errno("strdup");
 152                         goto done;
 153                 }
 154                 repo_path = argv[1];
 155                 relpath = argv[1];
 156                 while (relpath[0] == '/')
 157                         relpath++;
 158                 repo_name = strdup(relpath);
 159                 if (repo_name == NULL) {
 160                         error = got_error_from_errno("strdup");
 161                         goto done;
 162                 }
 163         } else {
 164                 if (argc != 3 || strcmp(argv[1], "-c") != 0)
 165                         usage();
 166                 repo_path = argv[2];
 167                 error = got_dial_parse_command(&command, &repo_name,
 168                     repo_path);
 169                 if (error && error->code == GOT_ERR_BAD_PACKET)
 170                         usage();
 171                 if (error)
 172                         goto done;
 173         }
 174
 175         repo = gotd_find_repo_by_name(repo_name, &gotd);
 176
 177         /*
 178          * Invoke our custom Git server if the repository was found
 179          * in gotd.conf. Otherwise invoke native git(1) tooling.
 180          */
 181         if (repo) {
 182                 if (myserver == NULL) {
 183                         error = got_error_fmt(GOT_ERR_NO_PROG,
 184                             "cannot run '%s'",
 185                             GITWRAPPER_MY_SERVER_PROG);
 186                         goto done;
 187                 }
 188                 execl(myserver, command, repo_name, (char *)NULL);
 189                 error = got_error_from_errno2("execl", myserver);
 190         } else {
 191                 if (asprintf(&gitcommand, "%s/%s",
 192                     GITWRAPPER_GIT_LIBEXEC_DIR, command) == -1) {
 193                         error = got_error_from_errno("asprintf");
 194                         goto done;
 195                 }
 196                 execl(gitcommand, gitcommand, repo_path, (char *)NULL);
 197                 error = got_error_from_errno2("execl", gitcommand);
 198         }
 199
 200 done:
 201         free(command);
 202         free(repo_name);
 203         free(myserver);
 204         free(gitcommand);
 205         if (error) {
 206                 fprintf(stderr, "%s: %s\n", getprogname(), error->msg);
 207                 return 1;
 208         }
 209
 210         return 0;
 211 }