74 lines
1.4 KiB
C
74 lines
1.4 KiB
C
#define _BSD_SOURCE
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#include <errno.h>
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#include <grp.h>
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#include <pwd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <unistd.h>
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int main(int argc, char **argv) {
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if(argc < 3) {
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fprintf(stderr, "Usage: %s username[:group] command [arguments]\n", argv[0]);
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return 1;
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}
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char *username_group = strdup(argv[1]);
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if(username_group == NULL) {
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perror("strdup");
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return 1;
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}
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char *colon_position, *username, *group;
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if((colon_position = strchr(username_group, ':')) != NULL) {
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*colon_position = 0;
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username = username_group;
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group = colon_position + 1;
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} else {
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username = username_group;
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group = NULL;
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}
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errno = 0;
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struct passwd *passwd_entry = getpwnam(username);
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if(passwd_entry == NULL) {
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perror("getpwnam");
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return 1;
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}
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uid_t ruid = passwd_entry->pw_uid;
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uid_t rgid;
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if(group != NULL) {
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errno = 0;
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struct group *group_entry = getgrnam(group);
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if(group_entry == NULL) {
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perror("getgrnam");
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return 1;
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}
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rgid = group_entry->gr_gid;
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} else {
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rgid = passwd_entry->pw_gid;
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}
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free(username_group);
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if(setreuid(ruid, -1) != 0) {
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perror("setreuid");
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return 1;
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}
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if(setregid(rgid, -1) != 0) {
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perror("setregid");
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return 1;
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}
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char **daemon_argv = &argv[2];
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const char *daemon_command = daemon_argv[0];
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execvp(daemon_command, daemon_argv);
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perror("execvp");
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return 1;
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}
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