examples: setsid is now built into htparser.
[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 setsid();
57 if(getuid() == 0) {
58 if(initgroups(pwd->pw_name, pwd->pw_gid)) {
59 flog(LOG_ERR, "could not init group list for %s: %s", pwd->pw_name, strerror(errno));
60 exit(1);
61 }
62 if(setgid(pwd->pw_gid)) {
63 flog(LOG_ERR, "could not switch group for %s: %s", pwd->pw_name, strerror(errno));
64 exit(1);
65 }
66 if(setuid(pwd->pw_uid)) {
67 flog(LOG_ERR, "could not switch user to %s: %s", pwd->pw_name, strerror(errno));
68 exit(1);
69 }
70 } else {
71 if(getuid() != pwd->pw_uid)
72 exit(1);
73 }
74 if(chdir(pwd->pw_dir)) {
75 flog(LOG_ERR, "could not change to home directory for %s: %s", pwd->pw_name, strerror(errno));
76 exit(1);
77 }
78 if(usesyslog)
79 putenv("ASHD_USESYSLOG=1");
80 else
81 unsetenv("ASHD_USESYSLOG");
82 putenv(sprintf2("HOME=%s", pwd->pw_dir));
83 putenv(sprintf2("SHELL=%s", pwd->pw_shell));
84 putenv(sprintf2("USER=%s", pwd->pw_name));
85 putenv(sprintf2("LOGNAME", pwd->pw_name));
86 /* There's whole load of other stuff one could want to do here --
87 * getting Kerberos credentials, running PAM session modules, and
88 * who knows what. I'll add them along as I find them useful. */
89 if(((fd = open(".ashd/output", O_WRONLY | O_APPEND)) >= 0) ||
90 ((fd = open("/dev/null", O_WRONLY)) >= 0)) {
91 dup2(fd, 1);
92 close(fd);
93 }
94 if(((fd = open(".ashd/error", O_WRONLY | O_APPEND)) >= 0) ||
95 ((fd = open("/dev/null", O_WRONLY)) >= 0)) {
96 dup2(fd, 2);
97 close(fd);
98 }
99}
100
101static void discardreq(int fromfd)
102{
103 struct hthead *req;
104 int fd;
105
106 if((fd = recvreq(fromfd, &req)) >= 0) {
107 freehthead(req);
108 close(fd);
109 }
110}
111
112static void execchild(struct passwd *pwd, struct hthead *forreq, int reqfd)
113{
114 if(!ignore)
115 execl(".ashd/handler", ".ashd/handler", NULL);
116 if(dirname != NULL) {
117 if(access(dirname, X_OK | R_OK)) {
118 discardreq(0);
119 simpleerror(reqfd, 404, "Not Found", "No such resource could be found.");
120 return;
121 }
122 }
123 execvp(childspec[0], childspec);
124 discardreq(0);
125 flog(LOG_ERR, "could not start request handler for user `%s': %s", pwd->pw_name, strerror(errno));
126 simpleerror(reqfd, 500, "User Error", "Could not start any request handler for that user.");
127}
128
129static int forkchild(char *usrnm, struct hthead *forreq, int reqfd)
130{
131 struct passwd *pwd;
132 pid_t pid;
133 int fd[2];
134
135 /* XXX: There should be a way for the child to report errors (like
136 * 404 when htpub doesn't exist), but for now I don't bother with
137 * that. I might return to it at some later time. */
138 if(socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fd))
139 return(-1);
140 if((pwd = getpwnam(usrnm)) == NULL) {
141 flog(LOG_ERR, "already discovered user `%s' has disappeared", usrnm);
142 return(-1);
143 }
144 if((pid = fork()) < 0)
145 return(-1);
146 if(pid == 0) {
147 dup2(fd[0], 0);
148 close(fd[0]);
149 close(fd[1]);
150 login(pwd);
151 execchild(pwd, forreq, reqfd);
152 exit(127);
153 }
154 close(fd[0]);
155 fcntl(fd[1], F_SETFD, FD_CLOEXEC);
156 return(fd[1]);
157}
158
159static void serve2(struct user *usr, struct hthead *req, int fd)
160{
161 if(usr->fd < 0)
162 usr->fd = forkchild(usr->name, req, fd);
163 if(sendreq(usr->fd, req, fd)) {
164 if((errno == EPIPE) || (errno == ECONNRESET)) {
165 /* Assume that the child has crashed and restart it. */
166 close(usr->fd);
167 usr->fd = forkchild(usr->name, req, fd);
168 if(!sendreq(usr->fd, req, fd))
169 return;
170 }
171 flog(LOG_ERR, "could not pass on request to user `%s': %s", usr->name, strerror(errno));
172 close(usr->fd);
173 usr->fd = -1;
174 }
175}
176
177static void initnew(struct hthead *req, int fd, char *usrnm)
178{
179 struct user *usr;
180 struct passwd *pwd;
181 struct group *grp;
182 int i, valid;
183
184 pwd = getpwnam(usrnm);
185 if(pwd == NULL) {
186 simpleerror(fd, 404, "Not Found", "No such resource could be found.");
187 return;
188 }
189 if(pwd->pw_uid < minuid) {
190 simpleerror(fd, 404, "Not Found", "No such resource could be found.");
191 return;
192 }
193 if(mgroup) {
194 if((grp = getgrnam(mgroup)) == NULL) {
195 flog(LOG_ERR, "unknown group %s specified to userplex", mgroup);
196 simpleerror(fd, 500, "Configuration Error", "The server has been erroneously configured.");
197 return;
198 }
199 valid = 0;
200 if(grp->gr_gid == pwd->pw_gid) {
201 valid = 1;
202 } else {
203 for(i = 0; grp->gr_mem[i] != NULL; i++) {
204 if(!strcmp(grp->gr_mem[i], usrnm)) {
205 valid = 1;
206 break;
207 }
208 }
209 }
210 if(!valid) {
211 simpleerror(fd, 404, "Not Found", "No such resource could be found.");
212 return;
213 }
214 }
215 omalloc(usr);
216 usr->name = sstrdup(usrnm);
217 usr->fd = -1;
218 usr->next = users;
219 usr->prev = NULL;
220 if(users != NULL)
221 users->prev = usr;
222 users = usr;
223 serve2(usr, req, fd);
224}
225
226static void serve(struct hthead *req, int fd)
227{
228 struct user *usr;
229 char *usrnm, *p;
230
231 if((p = strchr(req->rest, '/')) == NULL) {
232 if(*req->rest)
233 stdredir(req, fd, 301, sprintf3("%s/", req->url));
234 else
235 simpleerror(fd, 404, "Not Found", "No such resource could be found.");
236 return;
237 }
238 *(p++) = 0;
239 usrnm = sstrdup(req->rest);
240 replrest(req, p);
241 for(usr = users; usr != NULL; usr = usr->next) {
242 if(!strcmp(usr->name, usrnm)) {
243 serve2(usr, req, fd);
244 goto out;
245 }
246 }
247 initnew(req, fd, usrnm);
248
249out:
250 free(usrnm);
251}
252
253static void sighandler(int sig)
254{
255}
256
257static void usage(FILE *out)
258{
259 fprintf(out, "usage: userplex [-hIs] [-g GROUP] [-m MIN-UID] [-d PUB-DIR] [PROGRAM ARGS...]\n");
260}
261
262int main(int argc, char **argv)
263{
264 struct hthead *req;
265 int c;
266 int fd;
267 struct charvbuf csbuf;
268
269 while((c = getopt(argc, argv, "+hIsg:m:d:")) >= 0) {
270 switch(c) {
271 case 'I':
272 ignore = 1;
273 break;
274 case 's':
275 usesyslog = 1;
276 break;
277 case 'm':
278 if((minuid = atoi(optarg)) < 1) {
279 fprintf(stderr, "userplex: argument to -m must be greater than 0\n");
280 exit(1);
281 }
282 break;
283 case 'g':
284 mgroup = optarg;
285 break;
286 case 'd':
287 dirname = optarg;
288 break;
289 case 'h':
290 usage(stdout);
291 exit(0);
292 default:
293 usage(stderr);
294 exit(1);
295 }
296 }
297 if(optind < argc) {
298 childspec = argv + optind;
299 } else {
300 if(dirname == NULL)
301 dirname = "htpub";
302 bufinit(csbuf);
303 bufadd(csbuf, "dirplex");
304 bufadd(csbuf, dirname);
305 bufadd(csbuf, NULL);
306 childspec = csbuf.b;
307 }
308 signal(SIGCHLD, SIG_IGN);
309 signal(SIGPIPE, sighandler);
310 while(1) {
311 if((fd = recvreq(0, &req)) < 0) {
312 if(errno != 0)
313 flog(LOG_ERR, "recvreq: %s", strerror(errno));
314 break;
315 }
316 serve(req, fd);
317 freehthead(req);
318 close(fd);
319 }
320 return(0);
321}