Version 0.2.1

* Added -u option (run command as other username)
* Updated manual page a bit

1 files changed, 58 insertions, 0 deletions

diff --git a/execute_program.c b/execute_program.c
index 02d6471..d451f7b 100644
--- a/execute_program.c
+++ b/execute_program.c
@@ -1,13 +1,19 @@
 #include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 #include <unistd.h>
 #include <errno.h>
 #include <string.h>
+#include <pwd.h>
+#include <grp.h>
 
 #include "ltrace.h"
 #include "options.h"
 #include "output.h"
 #include "sysdep.h"
 
+static void change_uid(struct process * proc);
+
 void execute_program(struct process * sp, char **argv)
 {
 	int pid;
@@ -21,6 +27,7 @@ void execute_program(struct process * sp, char **argv)
 		perror("fork");
 		exit(1);
 	} else if (!pid) {	/* child */
+		change_uid(sp);
 		trace_me();
 		execvp(sp->filename, argv);
 		fprintf(stderr, "Can't execute `%s': %s\n", sp->filename, strerror(errno));
@@ -35,3 +42,54 @@ void execute_program(struct process * sp, char **argv)
 
 	return;
 }
+
+static void change_uid(struct process * proc)
+{
+	uid_t run_uid, run_euid;
+	gid_t run_gid, run_egid;
+
+	if (opt_u) {
+		struct passwd *pent;
+
+		if (getuid() != 0 || geteuid() != 0) {
+			fprintf(stderr, "you must be root to use the -u option\n");
+			exit(1);
+		}
+		if ((pent = getpwnam(opt_u)) == NULL) {
+			fprintf(stderr, "cannot find user `%s'\n", opt_u);
+			exit(1);
+		}
+		run_uid = pent->pw_uid;
+		run_gid = pent->pw_gid;
+
+		if (initgroups(opt_u, run_gid) < 0) {
+			perror("initgroups");
+			exit(1);
+		}
+	} else {
+		run_uid = getuid();
+		run_gid = getgid();
+	}
+	if (opt_u || !geteuid()) {
+		struct stat statbuf;
+		run_euid = run_uid;
+		run_egid = run_gid;
+
+		if (!stat(proc->filename, &statbuf)) {
+			if (statbuf.st_mode & S_ISUID) {
+				run_euid = statbuf.st_uid;
+			}
+			if (statbuf.st_mode & S_ISGID) {
+				run_euid = statbuf.st_gid;
+			}
+		}
+		if (setregid(run_gid, run_egid) < 0) {
+			perror("setregid");
+			exit(1);
+		}
+		if (setreuid(run_uid, run_euid) < 0) {
+			perror("setreuid");
+			exit(1);
+		}
+	}
+}