execute_program.c revision a8909f71e1421949c960f287217be6c42c286c0f 
1#if HAVE_CONFIG_H
2#include "config.h"
3#endif
4
5#include <stdio.h>
6#include <stdlib.h>
7#include <sys/types.h>
8#include <sys/stat.h>
9#include <unistd.h>
10#include <errno.h>
11#include <string.h>
12#include <pwd.h>
13#include <grp.h>
14
15#include "ltrace.h"
16#include "options.h"
17#include "debug.h"
18#include "sysdep.h"
19
20static void
21change_uid(Process *proc) {
22	uid_t run_uid, run_euid;
23	gid_t run_gid, run_egid;
24
25	if (options.user) {
26		struct passwd *pent;
27
28		if (getuid() != 0 || geteuid() != 0) {
29			fprintf(stderr,
30				"you must be root to use the -u option\n");
31			exit(1);
32		}
33		if ((pent = getpwnam(options.user)) == NULL) {
34			fprintf(stderr, "cannot find user `%s'\n", options.user);
35			exit(1);
36		}
37		run_uid = pent->pw_uid;
38		run_gid = pent->pw_gid;
39
40		if (initgroups(options.user, run_gid) < 0) {
41			perror("ltrace: initgroups");
42			exit(1);
43		}
44	} else {
45		run_uid = getuid();
46		run_gid = getgid();
47	}
48	if (options.user || !geteuid()) {
49		struct stat statbuf;
50		run_euid = run_uid;
51		run_egid = run_gid;
52
53		if (!stat(proc->filename, &statbuf)) {
54			if (statbuf.st_mode & S_ISUID) {
55				run_euid = statbuf.st_uid;
56			}
57			if (statbuf.st_mode & S_ISGID) {
58				run_egid = statbuf.st_gid;
59			}
60		}
61		if (setregid(run_gid, run_egid) < 0) {
62			perror("ltrace: setregid");
63			exit(1);
64		}
65		if (setreuid(run_uid, run_euid) < 0) {
66			perror("ltrace: setreuid");
67			exit(1);
68		}
69	}
70}
71
72void
73execute_program(Process *sp, char **argv) {
74	pid_t pid;
75
76	debug(1, "Executing `%s'...", sp->filename);
77
78	pid = fork();
79	if (pid < 0) {
80		perror("ltrace: fork");
81		exit(1);
82	} else if (!pid) {	/* child */
83		change_uid(sp);
84		trace_me();
85		execvp(sp->filename, argv);
86		fprintf(stderr, "Can't execute `%s': %s\n", sp->filename,
87			strerror(errno));
88		_exit(1);
89	}
90
91	debug(1, "PID=%d", pid);
92
93	sp->pid = pid;
94
95	return;
96}
97