| 1 | /* |
| 2 | ashd - A Sane HTTP Daemon |
| 3 | Copyright (C) 2008 Fredrik Tolf <fredrik@dolda2000.com> |
| 4 | |
| 5 | This program is free software: you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation, either version 3 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 17 | */ |
| 18 | |
| 19 | #include <stdlib.h> |
| 20 | #include <stdio.h> |
| 21 | #include <unistd.h> |
| 22 | #include <fcntl.h> |
| 23 | #include <string.h> |
| 24 | #include <signal.h> |
| 25 | #include <sys/socket.h> |
| 26 | #include <errno.h> |
| 27 | #include <pwd.h> |
| 28 | #include <grp.h> |
| 29 | |
| 30 | #ifdef HAVE_CONFIG_H |
| 31 | #include <config.h> |
| 32 | #endif |
| 33 | #include <utils.h> |
| 34 | #include <log.h> |
| 35 | #include <req.h> |
| 36 | #include <resp.h> |
| 37 | |
| 38 | struct user { |
| 39 | struct user *next, *prev; |
| 40 | char *name; |
| 41 | int fd; |
| 42 | }; |
| 43 | |
| 44 | static int ignore = 0; |
| 45 | static char *mgroup = NULL; |
| 46 | static char *dirname = NULL; |
| 47 | static char **childspec; |
| 48 | static uid_t minuid = 0; |
| 49 | static int usesyslog = 0; |
| 50 | static struct user *users = NULL; |
| 51 | |
| 52 | static void login(struct passwd *pwd) |
| 53 | { |
| 54 | int fd; |
| 55 | |
| 56 | if(getuid() == 0) { |
| 57 | if(initgroups(pwd->pw_name, pwd->pw_gid)) { |
| 58 | flog(LOG_ERR, "could not init group list for %s: %s", pwd->pw_name, strerror(errno)); |
| 59 | exit(1); |
| 60 | } |
| 61 | if(setgid(pwd->pw_gid)) { |
| 62 | flog(LOG_ERR, "could not switch group for %s: %s", pwd->pw_name, strerror(errno)); |
| 63 | exit(1); |
| 64 | } |
| 65 | if(setuid(pwd->pw_uid)) { |
| 66 | flog(LOG_ERR, "could not switch user to %s: %s", pwd->pw_name, strerror(errno)); |
| 67 | exit(1); |
| 68 | } |
| 69 | } else { |
| 70 | if(getuid() != pwd->pw_uid) |
| 71 | exit(1); |
| 72 | } |
| 73 | if(chdir(pwd->pw_dir)) { |
| 74 | flog(LOG_ERR, "could not change to home directory for %s: %s", pwd->pw_name, strerror(errno)); |
| 75 | exit(1); |
| 76 | } |
| 77 | if(usesyslog) |
| 78 | putenv("ASHD_USESYSLOG=1"); |
| 79 | else |
| 80 | unsetenv("ASHD_USESYSLOG"); |
| 81 | putenv(sprintf2("HOME=%s", pwd->pw_dir)); |
| 82 | putenv(sprintf2("SHELL=%s", pwd->pw_shell)); |
| 83 | putenv(sprintf2("USER=%s", pwd->pw_name)); |
| 84 | putenv(sprintf2("LOGNAME", pwd->pw_name)); |
| 85 | /* There's whole load of other stuff one could want to do here -- |
| 86 | * getting Kerberos credentials, running PAM session modules, and |
| 87 | * who knows what. I'll add them along as I find them useful. */ |
| 88 | if(((fd = open(".ashd/output", O_WRONLY | O_APPEND)) >= 0) || |
| 89 | ((fd = open("/dev/null", 0)) >= 0)) { |
| 90 | dup2(fd, 1); |
| 91 | close(fd); |
| 92 | } |
| 93 | if(((fd = open(".ashd/error", O_WRONLY | O_APPEND)) >= 0) || |
| 94 | ((fd = open("/dev/null", 0)) >= 0)) { |
| 95 | dup2(fd, 2); |
| 96 | close(fd); |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | static void execchild(struct passwd *pwd) |
| 101 | { |
| 102 | if(!ignore) |
| 103 | execl(".ashd/handler", ".ashd/handler", NULL); |
| 104 | if(dirname != NULL) { |
| 105 | if(access(dirname, X_OK | R_OK)) |
| 106 | return; |
| 107 | } |
| 108 | execvp(childspec[0], childspec); |
| 109 | } |
| 110 | |
| 111 | static int forkchild(char *usrnm) |
| 112 | { |
| 113 | struct passwd *pwd; |
| 114 | pid_t pid; |
| 115 | int i, fd[2]; |
| 116 | |
| 117 | /* XXX: There should be a way for the child to report errors (like |
| 118 | * 404 when htpub doesn't exist), but for now I don't bother with |
| 119 | * that. I might return to it at some later time. */ |
| 120 | if(socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fd)) |
| 121 | return(-1); |
| 122 | if((pwd = getpwnam(usrnm)) == NULL) { |
| 123 | flog(LOG_ERR, "already discovered user `%s' has disappeared", usrnm); |
| 124 | return(-1); |
| 125 | } |
| 126 | if((pid = fork()) < 0) |
| 127 | return(-1); |
| 128 | if(pid == 0) { |
| 129 | for(i = 3; i < FD_SETSIZE; i++) { |
| 130 | if(i != fd[0]) |
| 131 | close(i); |
| 132 | } |
| 133 | dup2(fd[0], 0); |
| 134 | close(fd[0]); |
| 135 | login(pwd); |
| 136 | execchild(pwd); |
| 137 | exit(127); |
| 138 | } |
| 139 | close(fd[0]); |
| 140 | return(fd[1]); |
| 141 | } |
| 142 | |
| 143 | static void serve2(struct user *usr, struct hthead *req, int fd) |
| 144 | { |
| 145 | if(usr->fd < 0) |
| 146 | usr->fd = forkchild(usr->name); |
| 147 | if(sendreq(usr->fd, req, fd)) { |
| 148 | if((errno == EPIPE) || (errno == ECONNRESET)) { |
| 149 | /* Assume that the child has crashed and restart it. */ |
| 150 | close(usr->fd); |
| 151 | usr->fd = forkchild(usr->name); |
| 152 | if(!sendreq(usr->fd, req, fd)) |
| 153 | return; |
| 154 | } |
| 155 | flog(LOG_ERR, "could not pass on request to user `%s': %s", usr->name, strerror(errno)); |
| 156 | close(usr->fd); |
| 157 | usr->fd = -1; |
| 158 | simpleerror(fd, 500, "User Error", "The request handler for that user keeps crashing."); |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | static void initnew(struct hthead *req, int fd, char *usrnm) |
| 163 | { |
| 164 | struct user *usr; |
| 165 | struct passwd *pwd; |
| 166 | struct group *grp; |
| 167 | int i, valid; |
| 168 | |
| 169 | pwd = getpwnam(usrnm); |
| 170 | if(pwd == NULL) { |
| 171 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); |
| 172 | return; |
| 173 | } |
| 174 | if(pwd->pw_uid < minuid) { |
| 175 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); |
| 176 | return; |
| 177 | } |
| 178 | if(mgroup) { |
| 179 | if((grp = getgrnam(mgroup)) == NULL) { |
| 180 | flog(LOG_ERR, "unknown group %s specified to userplex", mgroup); |
| 181 | simpleerror(fd, 500, "Configuration Error", "The server has been erroneously configured."); |
| 182 | return; |
| 183 | } |
| 184 | valid = 0; |
| 185 | if(grp->gr_gid == pwd->pw_gid) { |
| 186 | valid = 1; |
| 187 | } else { |
| 188 | for(i = 0; grp->gr_mem[i] != NULL; i++) { |
| 189 | if(!strcmp(grp->gr_mem[i], usrnm)) { |
| 190 | valid = 1; |
| 191 | break; |
| 192 | } |
| 193 | } |
| 194 | } |
| 195 | if(!valid) { |
| 196 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); |
| 197 | return; |
| 198 | } |
| 199 | } |
| 200 | omalloc(usr); |
| 201 | usr->name = sstrdup(usrnm); |
| 202 | usr->fd = -1; |
| 203 | usr->next = users; |
| 204 | usr->prev = NULL; |
| 205 | if(users != NULL) |
| 206 | users->prev = usr; |
| 207 | users = usr; |
| 208 | serve2(usr, req, fd); |
| 209 | } |
| 210 | |
| 211 | static void serve(struct hthead *req, int fd) |
| 212 | { |
| 213 | struct user *usr; |
| 214 | char *usrnm, *p; |
| 215 | |
| 216 | if((p = strchr(req->rest, '/')) == NULL) { |
| 217 | if(*req->rest) |
| 218 | stdredir(req, fd, 301, sprintf3("%s/", req->url)); |
| 219 | else |
| 220 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); |
| 221 | return; |
| 222 | } |
| 223 | *(p++) = 0; |
| 224 | usrnm = sstrdup(req->rest); |
| 225 | replrest(req, p); |
| 226 | for(usr = users; usr != NULL; usr = usr->next) { |
| 227 | if(!strcmp(usr->name, usrnm)) { |
| 228 | serve2(usr, req, fd); |
| 229 | goto out; |
| 230 | } |
| 231 | } |
| 232 | initnew(req, fd, usrnm); |
| 233 | |
| 234 | out: |
| 235 | free(usrnm); |
| 236 | } |
| 237 | |
| 238 | static void sighandler(int sig) |
| 239 | { |
| 240 | } |
| 241 | |
| 242 | static void usage(FILE *out) |
| 243 | { |
| 244 | fprintf(out, "usage: userplex [-hIs] [-g GROUP] [-m MIN-UID] [-d PUB-DIR] [PROGRAM ARGS...]\n"); |
| 245 | } |
| 246 | |
| 247 | int main(int argc, char **argv) |
| 248 | { |
| 249 | struct hthead *req; |
| 250 | int c; |
| 251 | int fd; |
| 252 | struct charvbuf csbuf; |
| 253 | |
| 254 | while((c = getopt(argc, argv, "+hIsg:m:d:")) >= 0) { |
| 255 | switch(c) { |
| 256 | case 'I': |
| 257 | ignore = 1; |
| 258 | break; |
| 259 | case 's': |
| 260 | usesyslog = 1; |
| 261 | break; |
| 262 | case 'm': |
| 263 | if((minuid = atoi(optarg)) < 1) { |
| 264 | fprintf(stderr, "userplex: argument to -m must be greater than 0\n"); |
| 265 | exit(1); |
| 266 | } |
| 267 | break; |
| 268 | case 'g': |
| 269 | mgroup = optarg; |
| 270 | break; |
| 271 | case 'd': |
| 272 | dirname = optarg; |
| 273 | break; |
| 274 | case 'h': |
| 275 | usage(stdout); |
| 276 | exit(0); |
| 277 | default: |
| 278 | usage(stderr); |
| 279 | exit(1); |
| 280 | } |
| 281 | } |
| 282 | if(optind < argc) { |
| 283 | childspec = argv + optind; |
| 284 | } else { |
| 285 | if(dirname == NULL) |
| 286 | dirname = "htpub"; |
| 287 | bufinit(csbuf); |
| 288 | bufadd(csbuf, "dirplex"); |
| 289 | bufadd(csbuf, dirname); |
| 290 | bufadd(csbuf, NULL); |
| 291 | childspec = csbuf.b; |
| 292 | } |
| 293 | signal(SIGCHLD, SIG_IGN); |
| 294 | signal(SIGPIPE, sighandler); |
| 295 | while(1) { |
| 296 | if((fd = recvreq(0, &req)) < 0) { |
| 297 | if(errno != 0) |
| 298 | flog(LOG_ERR, "recvreq: %s", strerror(errno)); |
| 299 | break; |
| 300 | } |
| 301 | serve(req, fd); |
| 302 | freehthead(req); |
| 303 | close(fd); |
| 304 | } |
| 305 | return(0); |
| 306 | } |