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