[hackers] [ubase] login: separate write utmp in a separate function || Hiltjo Posthuma

From: <git_AT_suckless.org>
Date: Wed, 09 Jul 2014 16:07:57 +0200

commit c50f7a3a27d879867bc6d442f878616895da68c2
Author: Hiltjo Posthuma <hiltjo_AT_codemadness.org>
Date: Wed Jul 9 15:04:45 2014 +0000

    login: separate write utmp in a separate function
    
    write utmp entry (as root) before setuid.

diff --git a/login.c b/login.c
index aec561f..1c2954f 100644
--- a/login.c
+++ b/login.c
_AT_@ -24,13 +24,36 @@ usage(void)
         eprintf("usage: %s [-p] username
", argv0);
 }
 
+/* Write utmp entry */
+static void
+writeutmp(const char *user, const char *tty) {
+ struct utmp usr;
+ FILE *fp;
+
+ memset(&usr, 0, sizeof(usr));
+
+ usr.ut_type = USER_PROCESS;
+ usr.ut_pid = getpid();
+ strlcpy(usr.ut_user, user, sizeof(usr.ut_user));
+ strlcpy(usr.ut_line, tty, sizeof(usr.ut_line));
+ usr.ut_tv.tv_sec = time(NULL);
+
+ fp = fopen(UTMP_PATH, "a");
+ if (fp) {
+ if (fwrite(&usr, sizeof(usr), 1, fp) != 1)
+ if (ferror(fp))
+ weprintf("%s: write error:", UTMP_PATH);
+ fclose(fp);
+ } else {
+ weprintf("fopen %s:", UTMP_PATH);
+ }
+}
+
 int
 main(int argc, char *argv[])
 {
         struct passwd *pw;
- struct utmp usr;
- FILE *fp;
- char *pass;
+ char *pass, *user;
         char *tty;
         uid_t uid;
         gid_t gid;
_AT_@ -51,9 +74,10 @@ main(int argc, char *argv[])
                 eprintf("stdin is not a tty
");
 
         errno = 0;
- pw = getpwnam(argv[0]);
+ user = argv[0];
+ pw = getpwnam(user);
         if (errno)
- eprintf("getpwnam: %s:", argv[0]);
+ eprintf("getpwnam: %s:", user);
         else if (!pw)
                 eprintf("who are you?
");
 
_AT_@ -69,35 +93,19 @@ main(int argc, char *argv[])
         if (pw_check(pw, pass) <= 0)
                 exit(EXIT_FAILURE);
 
- if (initgroups(argv[0], gid) < 0)
+ tty = ttyname(STDIN_FILENO);
+ if (!tty)
+ eprintf("ttyname:");
+
+ writeutmp(user, tty);
+
+ if (initgroups(user, gid) < 0)
                 eprintf("initgroups:");
         if (setgid(gid) < 0)
                 eprintf("setgid:");
         if (setuid(uid) < 0)
                 eprintf("setuid:");
 
- /* Write utmp entry */
- memset(&usr, 0, sizeof(usr));
-
- tty = ttyname(STDIN_FILENO);
- if (!tty)
- eprintf("ttyname:");
- usr.ut_type = USER_PROCESS;
- usr.ut_pid = getpid();
- strlcpy(usr.ut_user, argv[0], sizeof(usr.ut_user));
- strlcpy(usr.ut_line, tty, sizeof(usr.ut_line));
- usr.ut_tv.tv_sec = time(NULL);
-
- fp = fopen(UTMP_PATH, "a");
- if (fp) {
- if (fwrite(&usr, sizeof(usr), 1, fp) != 1)
- if (ferror(fp))
- weprintf("%s: write error:", UTMP_PATH);
- fclose(fp);
- } else {
- weprintf("fopen %s:", UTMP_PATH);
- }
-
         return dologin(pw, pflag);
 }
 
Received on Wed Jul 09 2014 - 16:07:57 CEST