Install the library headers.
[ashd.git] / src / userplex.c
... / ...
CommitLineData
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
38struct user {
39 struct user *next, *prev;
40 char *name;
41 int fd;
42};
43
44static int ignore = 0;
45static char *mgroup = NULL;
46static char *dirname = NULL;
47static char **childspec;
48static uid_t minuid = 0;
49static int usesyslog = 0;
50static struct user *users = NULL;
51
52static 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
100static 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
111static 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
143static 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
162static 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
211static 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
234out:
235 free(usrnm);
236}
237
238static void sighandler(int sig)
239{
240}
241
242static void usage(FILE *out)
243{
244 fprintf(out, "usage: userplex [-hIs] [-g GROUP] [-m MIN-UID] [-d PUB-DIR] [PROGRAM ARGS...]\n");
245}
246
247int 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}