07ab1af55c
We're not even zeroing the last byte after this call. This was a completely gratuitous truncation of one byte, and the resulting character array still wasn't guaranteed to be null terminated, because strncpy(3) can't do that. Just to clarify, none of these structures needed zeroing, as they are treated as null-padded fixed-size character arrays. Calling strncpy(3) was actually the correct call, and the only problem was unnecessarily truncating strings by one byte more than necessary. Cc: Matthew House <mattlloydhouse@gmail.com> Signed-off-by: Alejandro Colomar <alx@kernel.org>
97 lines
2.2 KiB
C
97 lines
2.2 KiB
C
/*
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* SPDX-FileCopyrightText: 1989 - 1994, Julianne Frances Haugh
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* SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
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* SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
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* SPDX-FileCopyrightText: 2008 , Nicolas François
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <config.h>
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#ident "$Id$"
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#include <sys/types.h>
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#include <pwd.h>
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#include <fcntl.h>
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#include <time.h>
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#include "defines.h"
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#include <lastlog.h>
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#include "memzero.h"
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#include "prototypes.h"
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#include "strtcpy.h"
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/*
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* dolastlog - create lastlog entry
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*
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* A "last login" entry is created for the user being logged in. The
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* UID is extracted from the global (struct passwd) entry and the
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* TTY information is gotten from the (struct utmp).
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*/
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void dolastlog (
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struct lastlog *ll,
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const struct passwd *pw,
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/*@unique@*/const char *line,
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/*@unique@*/const char *host)
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{
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int fd;
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off_t offset;
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struct lastlog newlog;
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time_t ll_time;
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/*
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* If the file does not exist, don't create it.
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*/
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fd = open (LASTLOG_FILE, O_RDWR);
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if (-1 == fd) {
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return;
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}
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/*
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* The file is indexed by UID number. Seek to the record
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* for this UID. Negative UID's will create problems, but ...
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*/
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offset = (off_t) pw->pw_uid * sizeof newlog;
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if (lseek (fd, offset, SEEK_SET) != offset) {
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SYSLOG ((LOG_WARN,
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"Can't read last lastlog entry for UID %lu in %s. Entry not updated.",
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(unsigned long) pw->pw_uid, LASTLOG_FILE));
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(void) close (fd);
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return;
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}
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/*
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* Read the old entry so we can tell the user when they last
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* logged in. Then construct the new entry and write it out
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* the way we read the old one in.
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*/
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if (read (fd, &newlog, sizeof newlog) != (ssize_t) sizeof newlog) {
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memzero (&newlog, sizeof newlog);
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}
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if (NULL != ll) {
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*ll = newlog;
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}
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ll_time = newlog.ll_time;
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(void) time (&ll_time);
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newlog.ll_time = ll_time;
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STRTCPY(newlog.ll_line, line);
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#if HAVE_LL_HOST
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strncpy(newlog.ll_host, host, sizeof(newlog.ll_host));
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#endif
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if ( (lseek (fd, offset, SEEK_SET) != offset)
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|| (write_full(fd, &newlog, sizeof newlog) == -1)
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|| (close (fd) != 0)) {
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SYSLOG ((LOG_WARN,
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"Can't write lastlog entry for UID %lu in %s.",
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(unsigned long) pw->pw_uid, LASTLOG_FILE));
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(void) close (fd);
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}
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}
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