From 25f7136d326753cb0bb7612a98db6542c9fdc3bd Mon Sep 17 00:00:00 2001

From: Karel Zak <kzak@redhat.com>

Date: Thu, 2 Feb 2023 15:22:52 +0100

Subject: last: sync utmp strings use with upstream code

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=2160321

Signed-off-by: Karel Zak <kzak@redhat.com>

---

 include/strutils.h  | 30 +++++++++++++++++++

 include/timeutils.h |  1 +

 login-utils/last.c  | 73 +++++++++++++++++++++++----------------------

 3 files changed, 69 insertions(+), 35 deletions(-)

diff --git a/include/strutils.h b/include/strutils.h

index 5d07fcc7c..193f1acbc 100644

--- a/include/strutils.h

+++ b/include/strutils.h

@@ -65,6 +65,36 @@ static inline void xstrncpy(char *dest, const char *src, size_t n)

 	dest[n-1] = 0;

 }

+/* This is like strncpy(), but based on memcpy(), so compilers and static

+ * analyzers do not complain when sizeof(destination) is the same as 'n' and

+ * result is not terminated by zero.

+ *

+ * Use this function to copy string to logs with fixed sizes (wtmp/utmp. ...)

+ * where string terminator is optional.

+ */

+static inline void * __attribute__((nonnull (1)))

+str2memcpy(void *dest, const char *src, size_t n)

+{

+	size_t bytes = strlen(src) + 1;

+

+	if (bytes > n)

+		bytes = n;

+

+	memcpy(dest, src, bytes);

+	return dest;

+}

+

+static inline char * __attribute__((nonnull (1)))

+mem2strcpy(char *dest, const void *src, size_t n, size_t nmax)

+{

+	if (n + 1 > nmax)

+		n = nmax - 1;

+

+	memset(dest, '\0', nmax);

+	memcpy(dest, src, n);

+	return dest;

+}

+

 static inline int strdup_to_offset(void *stru, size_t offset, const char *str)

 {

 	char *n = NULL;

diff --git a/include/timeutils.h b/include/timeutils.h

index 230e6db5f..f1540a183 100644

--- a/include/timeutils.h

+++ b/include/timeutils.h

@@ -74,6 +74,7 @@ enum {

 	ISO_TIMESTAMP_COMMA_GT  = ISO_TIMESTAMP_COMMA_G | ISO_T

 };

+#define CTIME_BUFSIZ    26

 #define ISO_BUFSIZ	42

 int strtimeval_iso(struct timeval *tv, int flags, char *buf, size_t bufsz);

diff --git a/login-utils/last.c b/login-utils/last.c

index 80d77d20b..8f7c36984 100644

--- a/login-utils/last.c

+++ b/login-utils/last.c

@@ -339,15 +339,22 @@ static int time_formatter(int fmt, char *dst, size_t dlen, time_t *when)

 		break;

 	case LAST_TIMEFTM_HHMM:

 	{

-		struct tm *tm = localtime(when);

-		if (!snprintf(dst, dlen, "%02d:%02d", tm->tm_hour, tm->tm_min))

+		struct tm tm;

+

+		localtime_r(when, &tm;;

+		if (!snprintf(dst, dlen, "%02d:%02d", tm.tm_hour, tm.tm_min))

 			ret = -1;

 		break;

 	}

 	case LAST_TIMEFTM_CTIME:

-		snprintf(dst, dlen, "%s", ctime(when));

+	{

+		char buf[CTIME_BUFSIZ];

+

+		ctime_r(when, buf);

+		snprintf(dst, dlen, "%s", buf);

 		ret = rtrim_whitespace((unsigned char *) dst);

 		break;

+	}

 	case LAST_TIMEFTM_ISO8601:

 		ret = strtime_iso(when, ISO_TIMESTAMP_T, dst, dlen);

 		break;

@@ -394,8 +401,7 @@ static int list(const struct last_control *ctl, struct utmpx *p, time_t logout_t

 	/*

 	 *	uucp and ftp have special-type entries

 	 */

-	utline[0] = 0;

-	strncat(utline, p->ut_line, sizeof(p->ut_line));

+	mem2strcpy(utline, p->ut_line, sizeof(p->ut_line), sizeof(utline));

 	if (strncmp(utline, "ftp", 3) == 0 && isdigit(utline[3]))

 		utline[3] = 0;

 	if (strncmp(utline, "uucp", 4) == 0 && isdigit(utline[4]))

@@ -447,48 +453,48 @@ static int list(const struct last_control *ctl, struct utmpx *p, time_t logout_t

 	if (logout_time == currentdate) {

 		if (ctl->time_fmt > LAST_TIMEFTM_SHORT) {

-			sprintf(logouttime, "  still running");

+			snprintf(logouttime, sizeof(logouttime), "  still running");

 			length[0] = 0;

 		} else {

-			sprintf(logouttime, "  still");

-			sprintf(length, "running");

+			snprintf(logouttime, sizeof(logouttime), "  still");

+			snprintf(length, sizeof(length), "running");

 		}

 	} else if (days) {

-		sprintf(length, "(%d+%02d:%02d)", days, abs(hours), abs(mins)); /* hours and mins always shown as positive (w/o minus sign!) even if secs < 0 */

+		snprintf(length, sizeof(length), "(%d+%02d:%02d)", days, abs(hours), abs(mins)); /* hours and mins always shown as positive (w/o minus sign!) even if secs < 0 */

 	} else if (hours) {

-		sprintf(length, " (%02d:%02d)", hours, abs(mins));  /* mins always shown as positive (w/o minus sign!) even if secs < 0 */

+		snprintf(length, sizeof(length), " (%02d:%02d)", hours, abs(mins));  /* mins always shown as positive (w/o minus sign!) even if secs < 0 */

 	} else if (secs >= 0) {

-		sprintf(length, " (%02d:%02d)", hours, mins); 

+		snprintf(length, sizeof(length), " (%02d:%02d)", hours, mins);

 	} else {

-		sprintf(length, " (-00:%02d)", abs(mins));  /* mins always shown as positive (w/o minus sign!) even if secs < 0 */

+		snprintf(length, sizeof(length), " (-00:%02d)", abs(mins));  /* mins always shown as positive (w/o minus sign!) even if secs < 0 */

 	}

 	switch(what) {

 		case R_CRASH:

-			sprintf(logouttime, "- crash");

+			snprintf(logouttime, sizeof(logouttime), "- crash");

 			break;

 		case R_DOWN:

-			sprintf(logouttime, "- down ");

+			snprintf(logouttime, sizeof(logouttime), "- down ");

 			break;

 		case R_NOW:

 			if (ctl->time_fmt > LAST_TIMEFTM_SHORT) {

-				sprintf(logouttime, "  still logged in");

+				snprintf(logouttime, sizeof(logouttime), "  still logged in");

 				length[0] = 0;

 			} else {

-				sprintf(logouttime, "  still");

-				sprintf(length, "logged in");

+				snprintf(logouttime, sizeof(logouttime), "  still");

+				snprintf(length, sizeof(length), "logged in");

 			}

 			break;

 		case R_PHANTOM:

 			if (ctl->time_fmt > LAST_TIMEFTM_SHORT) {

-				sprintf(logouttime, "  gone - no logout");

+				snprintf(logouttime, sizeof(logouttime), "  gone - no logout");

 				length[0] = 0;

 			} else if (ctl->time_fmt == LAST_TIMEFTM_SHORT) {

-				sprintf(logouttime, "   gone");

-				sprintf(length, "- no logout");

+				snprintf(logouttime, sizeof(logouttime), "   gone");

+				snprintf(length, sizeof(length), "- no logout");

 			} else {

 				logouttime[0] = 0;

-				sprintf(length, "no logout");

+				snprintf(length, sizeof(length), "no logout");

 			}

 			break;

 		case R_TIMECHANGE:

@@ -508,15 +514,8 @@ static int list(const struct last_control *ctl, struct utmpx *p, time_t logout_t

 	r = -1;

 	if (ctl->usedns || ctl->useip)

 		r = dns_lookup(domain, sizeof(domain), ctl->useip, (int32_t*)p->ut_addr_v6);

-	if (r < 0) {

-		size_t sz = sizeof(p->ut_host);

-

-		if (sz > sizeof(domain))

-			sz = sizeof(domain);

-

-		xstrncpy(domain, p->ut_host, sz);

-	}

-

+	if (r < 0)

+		mem2strcpy(domain, p->ut_host, sizeof(p->ut_host), sizeof(domain));

 	if (ctl->showhost) {

 		if (!ctl->altlist) {

@@ -607,10 +606,11 @@ static int is_phantom(const struct last_control *ctl, struct utmpx *ut)

 	if (ut->ut_tv.tv_sec < ctl->boot_time.tv_sec)

 		return 1;

+	ut->ut_user[sizeof(ut->ut_user) - 1] = '\0';

 	pw = getpwnam(ut->ut_user);

 	if (!pw)

 		return 1;

-	sprintf(path, "/proc/%u/loginuid", ut->ut_pid);

+	snprintf(path, sizeof(path), "/proc/%u/loginuid", ut->ut_pid);

 	if (access(path, R_OK) == 0) {

 		unsigned int loginuid;

 		FILE *f = NULL;

@@ -624,8 +624,11 @@ static int is_phantom(const struct last_control *ctl, struct utmpx *ut)

 			return 1;

 	} else {

 		struct stat st;

+		char utline[sizeof(ut->ut_line) + 1];

+

+		mem2strcpy(utline, ut->ut_line, sizeof(ut->ut_line), sizeof(utline));

-		sprintf(path, "/dev/%s", ut->ut_line);

+		snprintf(path, sizeof(path), "/dev/%s", utline);

 		if (stat(path, &st))

 			return 1;

 		if (pw->pw_uid != st.st_uid)

@@ -736,7 +739,7 @@ static void process_wtmp_file(const struct last_control *ctl,

 		else {

 			if (ut.ut_type != DEAD_PROCESS &&

 			    ut.ut_user[0] && ut.ut_line[0] &&

-			    strcmp(ut.ut_user, "LOGIN") != 0)

+			    strncmp(ut.ut_user, "LOGIN", 5) != 0)

 				ut.ut_type = USER_PROCESS;

 			/*

 			 * Even worse, applications that write ghost

@@ -749,7 +752,7 @@ static void process_wtmp_file(const struct last_control *ctl,

 			/*

 			 * Clock changes.

 			 */

-			if (strcmp(ut.ut_user, "date") == 0) {

+			if (strncmp(ut.ut_user, "date", 4) == 0) {

 				if (ut.ut_line[0] == '|')

 					ut.ut_type = OLD_TIME;

 				if (ut.ut_line[0] == '{')

@@ -784,7 +787,7 @@ static void process_wtmp_file(const struct last_control *ctl,

 		case RUN_LVL:

 			x = ut.ut_pid & 255;

 			if (ctl->extended) {

-				sprintf(ut.ut_line, "(to lvl %c)", x);

+				snprintf(ut.ut_line, sizeof(ut.ut_line), "(to lvl %c)", x);

 				quit = list(ctl, &ut, lastrch, R_NORMAL);

 			}

 			if (x == '0' || x == '6') {

-- 

2.39.1