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The following changes make ftpd able to remove its own entries. Ftpd 

calls pututxline() with ruid = 0, euid = current-ftp-user. This ends
up calling update_utmp:
- if the real uid is root, don't do password or tty ownership checks
- if we cannot open the tty line, assume that it is a daemon that does
  not use ttys and allow it to change a live entry to a dead one if
  indeed it is the same process that created the entry.
This commit is contained in:
christos 2003-02-26 18:16:50 +00:00
parent e651d04ed9
commit dc7c6aef2a
1 changed files with 39 additions and 21 deletions
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60
libexec/utmp_update/utmp_update.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: utmp_update.c,v 1.5 2002/12/18 15:20:47 christos Exp $ */
/* $NetBSD: utmp_update.c,v 1.6 2003/02/26 18:16:50 christos Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: utmp_update.c,v 1.5 2002/12/18 15:20:47 christos Exp $");
__RCSID("$NetBSD: utmp_update.c,v 1.6 2003/02/26 18:16:50 christos Exp $");
#include <sys/types.h>
#include <sys/param.h>
@ -64,11 +64,12 @@ main(int argc, char *argv[])
struct passwd *pwd;
struct stat st;
int fd;
uid_t euid;
uid_t euid, ruid;
char tty[MAXPATHLEN];
euid = geteuid();
if (seteuid(getuid()) == -1)
ruid = getuid();
if (seteuid(ruid) == -1)
err(1, "seteuid");
if (argc != 2) {
@ -96,27 +97,44 @@ main(int argc, char *argv[])
errx(1, "Invalid utmpx type %d", (int)utx->ut_type);
}
if ((pwd = getpwuid(getuid())) == NULL)
errx(1, "User %lu does not exist in password database",
(long)getuid());
if (ruid != 0) {
if ((pwd = getpwuid(ruid)) == NULL)
errx(1, "User %lu does not exist in password database",
(long)ruid);
if (strcmp(pwd->pw_name, utx->ut_name) != 0)
errx(1, "Current user `%s' does not match `%s' in utmpx entry",
pwd->pw_name, utx->ut_name);
if (strcmp(pwd->pw_name, utx->ut_name) != 0)
errx(1, "Current user `%s' does not match "
"`%s' in utmpx entry", pwd->pw_name, utx->ut_name);
}
(void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line);
fd = open(tty, O_RDONLY, 0);
if (fd == -1)
err(1, "Cannot open `%s'", tty);
if (fstat(fd, &st) == -1)
err(1, "Cannot stat `%s'", tty);
if (st.st_uid != getuid())
errx(1, "%s: Is not owned by you", tty);
if (!isatty(fd))
errx(1, "%s: Not a tty device", tty);
(void)close(fd);
if (access(tty, W_OK|R_OK) == -1)
err(1, "%s", tty);
if (fd != -1) {
if (fstat(fd, &st) == -1)
err(1, "Cannot stat `%s'", tty);
if (ruid != 0 && st.st_uid != ruid)
errx(1, "%s: Is not owned by you", tty);
if (!isatty(fd))
errx(1, "%s: Not a tty device", tty);
(void)close(fd);
if (access(tty, W_OK|R_OK) == -1)
err(1, "%s", tty);
} else {
struct utmpx utold, *utoldp;
/*
* A daemon like ftpd that does not use a tty line?
* We only allow it to kill its own existing entries
*/
if (utx->ut_type != DEAD_PROCESS)
err(1, "Cannot open `%s'", tty);
(void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line));
if ((utoldp = getutxline(&utold)) == NULL)
err(1, "Cannot find existing entry for `%s'",
utx->ut_line);
if (utoldp->ut_pid != getppid())
err(1, "Cannot modify entry for `%s'", tty);
}
(void)seteuid(euid);
if (pututxline(utx) == NULL)