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login: separate write utmp in a separate function

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write utmp entry (as root) before setuid.
This commit is contained in:
Hiltjo Posthuma 2014-07-09 15:04:45 +00:00 committed by sin
parent 96f15f1d04
commit c50f7a3a27
1 changed files with 36 additions and 28 deletions
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64
login.c
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@ -24,13 +24,36 @@ usage(void)
eprintf("usage: %s [-p] username\n", argv0); 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 int
main(int argc, char *argv[]) main(int argc, char *argv[])
{ {
struct passwd *pw; struct passwd *pw;
struct utmp usr; char *pass, *user;
FILE *fp;
char *pass;
char *tty; char *tty;
uid_t uid; uid_t uid;
gid_t gid; gid_t gid;
@ -51,9 +74,10 @@ main(int argc, char *argv[])
eprintf("stdin is not a tty\n"); eprintf("stdin is not a tty\n");
errno = 0; errno = 0;
pw = getpwnam(argv[0]); user = argv[0];
pw = getpwnam(user);
if (errno) if (errno)
eprintf("getpwnam: %s:", argv[0]); eprintf("getpwnam: %s:", user);
else if (!pw) else if (!pw)
eprintf("who are you?\n"); eprintf("who are you?\n");
@ -69,35 +93,19 @@ main(int argc, char *argv[])
if (pw_check(pw, pass) <= 0) if (pw_check(pw, pass) <= 0)
exit(EXIT_FAILURE); 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:"); eprintf("initgroups:");
if (setgid(gid) < 0) if (setgid(gid) < 0)
eprintf("setgid:"); eprintf("setgid:");
if (setuid(uid) < 0) if (setuid(uid) < 0)
eprintf("setuid:"); 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); return dologin(pw, pflag);
} }