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3b5e2f2d FT |
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; | |
23c627d2 | 46 | static char *dirname = NULL; |
3b5e2f2d FT |
47 | static char **childspec; |
48 | static uid_t minuid = 0; | |
49 | static struct user *users = NULL; | |
50 | ||
51 | static void login(struct passwd *pwd) | |
52 | { | |
53 | int fd; | |
54 | ||
55 | if(getuid() == 0) { | |
56 | if(initgroups(pwd->pw_name, pwd->pw_gid)) { | |
57 | flog(LOG_ERR, "could not init group list for %s: %s", pwd->pw_name, strerror(errno)); | |
58 | exit(1); | |
59 | } | |
60 | if(setgid(pwd->pw_gid)) { | |
61 | flog(LOG_ERR, "could not switch group for %s: %s", pwd->pw_name, strerror(errno)); | |
62 | exit(1); | |
63 | } | |
64 | if(setuid(pwd->pw_uid)) { | |
65 | flog(LOG_ERR, "could not switch user to %s: %s", pwd->pw_name, strerror(errno)); | |
66 | exit(1); | |
67 | } | |
68 | } else { | |
69 | if(getuid() != pwd->pw_uid) | |
70 | exit(1); | |
71 | } | |
72 | if(chdir(pwd->pw_dir)) { | |
73 | flog(LOG_ERR, "could not change to home directory for %s: %s", pwd->pw_name, strerror(errno)); | |
74 | exit(1); | |
75 | } | |
76 | putenv(sprintf2("HOME=%s", pwd->pw_dir)); | |
77 | putenv(sprintf2("SHELL=%s", pwd->pw_shell)); | |
78 | putenv(sprintf2("USER=%s", pwd->pw_name)); | |
79 | putenv(sprintf2("LOGNAME", pwd->pw_name)); | |
80 | /* There's whole load of other stuff one could want to do here -- | |
81 | * getting Kerberos credentials, running PAM session modules, and | |
82 | * who knows what. I'll add them along as I find them useful. */ | |
1755d287 | 83 | if(((fd = open(".ashd/output", O_WRONLY | O_APPEND)) >= 0) || |
3b5e2f2d FT |
84 | ((fd = open("/dev/null", 0)) >= 0)) { |
85 | dup2(fd, 1); | |
86 | close(fd); | |
87 | } | |
1755d287 | 88 | if(((fd = open(".ashd/error", O_WRONLY | O_APPEND)) >= 0) || |
3b5e2f2d FT |
89 | ((fd = open("/dev/null", 0)) >= 0)) { |
90 | dup2(fd, 2); | |
91 | close(fd); | |
92 | } | |
93 | } | |
94 | ||
95 | static void execchild(struct passwd *pwd) | |
96 | { | |
97 | if(!ignore) | |
98 | execl(".ashd/handler", ".ashd/handler", NULL); | |
99 | if(dirname != NULL) { | |
100 | if(access(dirname, X_OK | R_OK)) | |
101 | return; | |
102 | } | |
103 | execvp(childspec[0], childspec); | |
104 | } | |
105 | ||
106 | static int forkchild(char *usrnm) | |
107 | { | |
108 | struct passwd *pwd; | |
109 | pid_t pid; | |
110 | int i, fd[2]; | |
111 | ||
112 | /* XXX: There should be a way for the child to report errors (like | |
113 | * 404 when htpub doesn't exist), but for now I don't bother with | |
114 | * that. I might return to it at some later time. */ | |
115 | if(socketpair(PF_UNIX, SOCK_SEQPACKET, 0, fd)) | |
116 | return(-1); | |
117 | if((pwd = getpwnam(usrnm)) == NULL) { | |
118 | flog(LOG_ERR, "already discovered user `%s' has disappeared", usrnm); | |
119 | return(-1); | |
120 | } | |
121 | if((pid = fork()) < 0) | |
122 | return(-1); | |
123 | if(pid == 0) { | |
124 | for(i = 3; i < FD_SETSIZE; i++) { | |
125 | if(i != fd[0]) | |
126 | close(i); | |
127 | } | |
128 | dup2(fd[0], 0); | |
129 | close(fd[0]); | |
130 | login(pwd); | |
131 | execchild(pwd); | |
132 | exit(127); | |
133 | } | |
134 | close(fd[0]); | |
135 | return(fd[1]); | |
136 | } | |
137 | ||
138 | static void serve2(struct user *usr, struct hthead *req, int fd) | |
139 | { | |
140 | if(usr->fd < 0) | |
141 | usr->fd = forkchild(usr->name); | |
142 | if(sendreq(usr->fd, req, fd)) { | |
143 | if(errno == EPIPE) { | |
144 | /* Assume that the child has crashed and restart it. */ | |
145 | close(usr->fd); | |
146 | usr->fd = forkchild(usr->name); | |
147 | if(!sendreq(usr->fd, req, fd)) | |
148 | return; | |
149 | } | |
150 | flog(LOG_ERR, "could not pass on request to user `%s': %s", usr->name, strerror(errno)); | |
151 | close(usr->fd); | |
152 | usr->fd = -1; | |
153 | simpleerror(fd, 500, "User Error", "The request handler for that user keeps crashing."); | |
154 | } | |
155 | } | |
156 | ||
157 | static void initnew(struct hthead *req, int fd, char *usrnm) | |
158 | { | |
159 | struct user *usr; | |
160 | struct passwd *pwd; | |
161 | struct group *grp; | |
162 | int i, valid; | |
163 | ||
164 | pwd = getpwnam(usrnm); | |
165 | if(pwd == NULL) { | |
166 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); | |
167 | return; | |
168 | } | |
169 | if(pwd->pw_uid < minuid) { | |
170 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); | |
171 | return; | |
172 | } | |
173 | if(mgroup) { | |
174 | if((grp = getgrnam(mgroup)) == NULL) { | |
175 | flog(LOG_ERR, "unknown group %s specified to userplex", mgroup); | |
176 | simpleerror(fd, 500, "Configuration Error", "The server has been erroneously configured."); | |
177 | return; | |
178 | } | |
179 | valid = 0; | |
180 | if(grp->gr_gid == pwd->pw_gid) { | |
181 | valid = 1; | |
182 | } else { | |
183 | for(i = 0; grp->gr_mem[i] != NULL; i++) { | |
184 | if(!strcmp(grp->gr_mem[i], usrnm)) { | |
185 | valid = 1; | |
186 | break; | |
187 | } | |
188 | } | |
189 | } | |
190 | if(!valid) { | |
191 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); | |
192 | return; | |
193 | } | |
194 | } | |
195 | omalloc(usr); | |
196 | usr->name = sstrdup(usrnm); | |
197 | usr->fd = -1; | |
198 | usr->next = users; | |
199 | usr->prev = NULL; | |
200 | if(users != NULL) | |
201 | users->prev = usr; | |
202 | users = usr; | |
203 | serve2(usr, req, fd); | |
204 | } | |
205 | ||
206 | static void serve(struct hthead *req, int fd) | |
207 | { | |
208 | struct user *usr; | |
209 | char *usrnm, *p; | |
210 | ||
211 | if((p = strchr(req->rest, '/')) == NULL) { | |
212 | if(*req->rest) | |
213 | stdredir(req, fd, 301, sprintf3("%s/", req->url)); | |
214 | else | |
215 | simpleerror(fd, 404, "Not Found", "No such resource could be found."); | |
216 | return; | |
217 | } | |
218 | *(p++) = 0; | |
219 | usrnm = sstrdup(req->rest); | |
220 | replrest(req, p); | |
221 | for(usr = users; usr != NULL; usr = usr->next) { | |
222 | if(!strcmp(usr->name, usrnm)) { | |
223 | serve2(usr, req, fd); | |
224 | goto out; | |
225 | } | |
226 | } | |
227 | initnew(req, fd, usrnm); | |
228 | ||
229 | out: | |
230 | free(usrnm); | |
231 | } | |
232 | ||
fd735432 FT |
233 | static void sighandler(int sig) |
234 | { | |
235 | } | |
236 | ||
3b5e2f2d FT |
237 | static void usage(FILE *out) |
238 | { | |
b9e7ec7a | 239 | fprintf(out, "usage: userplex [-hI] [-g GROUP] [-m MIN-UID] [-d PUB-DIR] [PROGRAM ARGS...]\n"); |
3b5e2f2d FT |
240 | } |
241 | ||
242 | int main(int argc, char **argv) | |
243 | { | |
244 | struct hthead *req; | |
245 | int c; | |
246 | int fd; | |
247 | struct charvbuf csbuf; | |
248 | ||
42384d2a | 249 | while((c = getopt(argc, argv, "+hIg:m:d:")) >= 0) { |
3b5e2f2d FT |
250 | switch(c) { |
251 | case 'I': | |
252 | ignore = 1; | |
253 | break; | |
254 | case 'm': | |
255 | if((minuid = atoi(optarg)) < 1) { | |
256 | fprintf(stderr, "userplex: argument to -m must be greater than 0\n"); | |
257 | exit(1); | |
258 | } | |
259 | break; | |
260 | case 'g': | |
261 | mgroup = optarg; | |
262 | break; | |
263 | case 'd': | |
264 | dirname = optarg; | |
265 | break; | |
266 | case 'h': | |
267 | usage(stdout); | |
268 | exit(0); | |
269 | default: | |
270 | usage(stderr); | |
271 | exit(1); | |
272 | } | |
273 | } | |
274 | if(optind < argc) { | |
275 | childspec = argv + optind; | |
3b5e2f2d | 276 | } else { |
23c627d2 FT |
277 | if(dirname == NULL) |
278 | dirname = "htpub"; | |
3b5e2f2d FT |
279 | bufinit(csbuf); |
280 | bufadd(csbuf, "dirplex"); | |
281 | bufadd(csbuf, dirname); | |
282 | bufadd(csbuf, NULL); | |
283 | childspec = csbuf.b; | |
284 | } | |
285 | signal(SIGCHLD, SIG_IGN); | |
fd735432 | 286 | signal(SIGPIPE, sighandler); |
3b5e2f2d FT |
287 | while(1) { |
288 | if((fd = recvreq(0, &req)) < 0) { | |
289 | if(errno != 0) | |
290 | flog(LOG_ERR, "recvreq: %s", strerror(errno)); | |
291 | break; | |
292 | } | |
293 | serve(req, fd); | |
294 | freehthead(req); | |
295 | close(fd); | |
296 | } | |
297 | return(0); | |
298 | } |