ubase

suckless linux base utils
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commit c50f7a3a27d879867bc6d442f878616895da68c2
parent 96f15f1d049bcecee159196131d2296ed7d39584
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date:   Wed Jul  9 15:04:45 +0000

login: separate write utmp in a separate function

write utmp entry (as root) before setuid.

Diffstat:
login.c | 64++++++++++++++++++++++++++++++++++++----------------------------
1 file changed, 36 insertions(+), 28 deletions(-)
diff --git a/login.c b/login.c @@ -24,13 +24,36 @@ usage(void) eprintf("usage: %s [-p] username\n", 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; @@ -51,9 +74,10 @@ main(int argc, char *argv[]) eprintf("stdin is not a tty\n"); 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?\n"); @@ -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); }