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#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sysexits.h>
#ifdef WIN32
#define setuid(s)
#define getuid()
#define setgid(s)
#define getgid()
#define chroot(p) (-1)
#endif
/*
* This program chroots into a given directory,
* then executes the asn1c command with strict arguments checking.
*/
int
main(int ac, char **av) {
char cmdPath[32];
char *envp[] = { NULL }; /* Empty environment */
int ret;
int i;
if(ac < 4) {
setgid(getgid());
setuid(getuid());
fprintf(stderr,
"Usage: %s <chroot-to> <chdir-to> <command> [options]\n",
av[0]);
exit(EX_USAGE);
}
ret = chroot(av[1]);
/* Drop the privileges */
setgid(getgid());
setuid(getuid());
if(ret != 0) {
fprintf(stderr, "chroot(\"%s\") failed: %s\n",
av[1], strerror(errno));
exit(EX_OSERR);
}
if(chdir(av[2]) != 0) {
fprintf(stderr, "chdir(\"%s\") failed: %s\n",
av[2], strerror(errno));
exit(EX_OSERR);
}
if(ac > 64) {
fprintf(stderr, "Insecure number of arguments: %d\n", ac);
exit(EX_DATAERR);
}
/*
* Add an argument if this is an asn1c compiler.
*/
if(strcmp(av[3], "asn1c") == 0) {
ac -= 2;
av += 2;
av[0] = "asn1c";
av[1] = "-S/skeletons";
i = 2;
strcpy(cmdPath, "/bin/asn1c");
} else {
ac -= 3;
av += 3;
i = 0;
}
if(strlen(av[0]) > sizeof(cmdPath)/2) {
fprintf(stderr, "Insecure command name: %s\n", av[0]);
exit(EX_DATAERR);
}
memcpy(cmdPath, "/bin/", 5);
strcpy(cmdPath + 5, av[0]);
/*
* Check arguments for the permitted alphabet constraints.
*/
for(; i < ac; i++) {
char *p;
for(p = av[i];; p++) {
switch(*p) {
case '0' ... '9': case 'A' ... 'Z': case 'a' ... 'z':
case '.': case '_': case '-': case '=':
continue;
case '\0':
default:
break;
}
break;
}
if(*p || (p - av[i]) > 250) {
fprintf(stderr, "Insecure argument %d\n", i);
exit(EX_DATAERR);
}
}
execve(cmdPath, av, envp);
perror(cmdPath);
exit(EX_UNAVAILABLE);
}
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