Big loginrec.c update
- MIN_SIZEOF macro to pick smallest buffer for str[ln]cpy()
- fixes lastlog clobber spotted by P.S.S.Camp <P.S.S.Camp@ukc.ac.uk>
- Added some top-level api documentation
- Re-ordered construct_utmp(x)() to build well-formed structures for
both login and logout, based on li->type.
- change wtmp(x)_logout() to match new construct_*() form
- Improved error responses throughout
- Add ut_type cross-check for 'lastlog-from-wtmp(x)' where available
- utmp_write_direct() has had some testing. Oh yes!
- Re-ordered loginrec.h slightly
diff --git a/loginrec.c b/loginrec.c
index 59ce180..e51d686 100644
--- a/loginrec.c
+++ b/loginrec.c
@@ -141,10 +141,10 @@
** Known good:
** Linux (Redhat 6.2, need more variants)
** HP-UX 10.20 (gcc only)
+ ** IRIX
**
** Testing required: Please send reports!
** Solaris
- ** IRIX
** NetBSD
** HP-UX 11
** AIX
@@ -170,7 +170,7 @@
#include "xmalloc.h"
#include "loginrec.h"
-RCSID("$Id: loginrec.c,v 1.6 2000/06/13 11:23:17 djm Exp $");
+RCSID("$Id: loginrec.c,v 1.7 2000/06/19 08:20:03 andre Exp $");
/**
** prototypes for helper functions in this file
@@ -199,11 +199,28 @@
int wtmpx_get_entry(struct logininfo *li);
+#ifdef MIN
+# undef MIN
+# define MIN(a,b) ( (a)<(b) ? (a) : (b) )
+#endif
+
+/* pick the shortest string */
+#define MIN_SIZEOF(s1,s2) ( sizeof(s1) < sizeof(s2) ? sizeof(s1) : sizeof(s2) )
+
+
/**
** platform-independent login functions
**/
-/* Record a login */
+/* login_login(struct logininfo *) -Record a login
+ *
+ * Call with a pointer to a struct logininfo initialised with
+ * login_init_entry() or login_alloc_entry()
+ *
+ * Returns:
+ * >0 if successful
+ * 0 on failure (will use OpenSSH's logging facilities for diagnostics)
+ */
int
login_login (struct logininfo *li)
{
@@ -212,7 +229,14 @@
}
-/* Record a logout */
+/* login_logout(struct logininfo *) - Record a logout
+ *
+ * Call as with login_login()
+ *
+ * Returns:
+ * >0 if successful
+ * 0 on failure (will use OpenSSH's logging facilities for diagnostics)
+ */
int
login_logout(struct logininfo *li)
{
@@ -221,22 +245,65 @@
}
-/* Retrieve the last login time for a user (or fake on from wtmp/wtmpx) */
+/* login_get_lastlog_time(int) - Retrieve the last login time
+ *
+ * Retrieve the last login time for the given uid. Will try to use the
+ * system lastlog facilities if they are available, but will fall back
+ * to looking in wtmp/wtmpx if necessary
+ *
+ * Returns:
+ * 0 on failure, or if user has never logged in
+ * Time in seconds from the epoch if successful
+ *
+ * Useful preprocessor symbols:
+ * DISABLE_LASTLOG: If set, *never* even try to retrieve lastlog
+ * info
+ * USE_LASTLOG: If set, indicates the presence of system lastlog
+ * facilities. If this and DISABLE_LASTLOG are not set,
+ * try to retrieve lastlog information from wtmp/wtmpx.
+ */
unsigned int
login_get_lastlog_time(const int uid)
{
struct logininfo li;
- login_get_lastlog(&li, uid);
- return li.tv_sec;
+ if (login_get_lastlog(&li, uid))
+ return li.tv_sec;
+ else
+ return 0;
}
-/* Retrieve a lastlog entry (or fake one from wtmp/wtmpx) */
+/* login_get_lastlog(struct logininfo *, int) - Retrieve a lastlog entry
+ *
+ * Retrieve a logininfo structure populated (only partially) with
+ * information from the system lastlog data, or from wtmp/wtmpx if no
+ * system lastlog information exists.
+ *
+ * Note this routine must be given a pre-allocated logininfo.
+ *
+ * Returns:
+ * >0: A pointer to your struct logininfo if successful
+ * 0 on failure (will use OpenSSH's logging facilities for diagnostics)
+ *
+ */
struct logininfo *
login_get_lastlog(struct logininfo *li, const int uid)
{
+#ifndef USE_LASTLOG
+ struct passwd *pw;
+#endif
+
memset(li, '\0', sizeof(struct logininfo));
li->uid = uid;
+
+#ifndef USE_LASTLOG
+ /* If we don't have a 'real' lastlog, we need the username to
+ * reliably search wtmp(x) for the last login (see
+ * wtmp_get_entry().) */
+ pw = getpwuid(uid);
+ strlcpy(li->username, pw->pw_name,
+ MIN_SIZEOF(li->username, pw->pw_name));
+#endif
if (getlast_entry(li))
return li;
else
@@ -244,7 +311,15 @@
}
-/* login_alloc_entry() - allocate and initialise a logininfo */
+/* login_alloc_entry(int, char*, char*, char*) - Allocate and initialise
+ * a logininfo structure
+ *
+ * This function creates a new struct logininfo, a data structure
+ * meant to carry the information required to portably record login info.
+ *
+ * Returns a pointer to a newly created struct logininfo. If memory
+ * allocation fails, the program halts.
+ */
struct
logininfo *login_alloc_entry(int pid, const char *username,
const char *hostname, const char *line)
@@ -257,7 +332,7 @@
}
-/* login_free_entry() - free struct memory (trivial) */
+/* login_free_entry(struct logininfo *) - free struct memory */
void
login_free_entry(struct logininfo *li)
{
@@ -265,7 +340,14 @@
}
-/* login_init_entry() - initialise a struct logininfo */
+/* login_init_entry(struct logininfo *, int, char*, char*, char*)
+ * - initialise a struct logininfo
+ *
+ * Populates a new struct logininfo, a data structure meant to carry
+ * the information required to portably record login info.
+ *
+ * Returns: 1
+ */
int
login_init_entry(struct logininfo *li, int pid, const char *username,
const char *hostname, const char *line)
@@ -285,7 +367,12 @@
return 1;
}
-
+/* login_set_current_time(struct logininfo *) - set the current time
+ *
+ * Set the current time in a logininfo structure. This function is
+ * meant to eliminate the need to deal with system dependencies for
+ * time handling.
+ */
void
login_set_current_time(struct logininfo *li)
{
@@ -502,12 +589,15 @@
struct utmp *ut)
{
memset(ut, '\0', sizeof(struct utmp));
+
+ /* First fill out fields used for both logins and logouts */
+
#ifdef HAVE_ID_IN_UTMP
line_abbrevname(ut->ut_id, li->line, sizeof(ut->ut_id));
#endif
#ifdef HAVE_TYPE_IN_UTMP
- /* This is done here to keep utmp constants out of login.h */
+ /* This is done here to keep utmp constants out of struct logininfo */
switch (li->type) {
case LTYPE_LOGIN:
ut->ut_type = USER_PROCESS;
@@ -517,15 +607,24 @@
break;
}
#endif
+ set_utmp_time(li, ut);
+ line_stripname(ut->ut_line, li->line, sizeof(ut->ut_line));
#ifdef HAVE_PID_IN_UTMP
ut->ut_pid = li->pid;
#endif
- line_stripname(ut->ut_line, li->line, sizeof(ut->ut_line));
- strlcpy(ut->ut_name, li->username, sizeof(ut->ut_name));
- set_utmp_time(li, ut);
+
+ /* If we're logging out, leave all other fields blank */
+ if (li->type == LTYPE_LOGOUT)
+ return;
+
+ /* These fields are only used when logging in, and are blank
+ * for logouts. */
+
+ /* Use strncpy because we don't necessarily want null termination */
+ strncpy(ut->ut_user, li->username, MIN_SIZEOF(ut->ut_user, li->username));
#ifdef HAVE_HOST_IN_UTMP
- strlcpy(ut->ut_host, li->hostname, sizeof(ut->ut_host));
+ strncpy(ut->ut_host, li->hostname, MIN_SIZEOF(ut->ut_host, li->hostname));
#endif
#ifdef HAVE_ADDR_IN_UTMP
/* this is just a 32-bit IP address */
@@ -578,19 +677,27 @@
utx->ut_type = DEAD_PROCESS;
break;
}
- utx->ut_pid = li->pid;
line_stripname(utx->ut_line, li->line, sizeof(utx->ut_line));
- strlcpy(utx->ut_name, li->username, sizeof(utx->ut_name));
set_utmpx_time(li, utx);
+ utx->ut_pid = li->pid;
+
+ if (li->type == LTYPE_LOGOUT)
+ return;
+
+ /* These fields are only used when logging in, and are blank
+ * for logouts. */
+
+ /* strncpy(): Don't necessarily want null termination */
+ strncpy(utx->ut_name, li->username, MIN_SIZEOF(utx->ut_name, li->username));
#ifdef HAVE_HOST_IN_UTMPX
- strlcpy(utx->ut_host, li->hostname, sizeof(utx->ut_host));
+ strncpy(utx->ut_host, li->hostname, MIN_SIZEOF(utx->ut_host, li->hostname));
#endif
#ifdef HAVE_ADDR_IN_UTMPX
/* FIXME: (ATL) not supported yet */
#endif
-#ifdef HAVE_SYSLEN_IN_UTMPX
- /* this is safe because of the extra nulls in logininfo */
- utx->ut_syslen = strlen(li->hostname);
+#ifdef HAVE_SYSLEN_IN_UTMPX
+ /* ut_syslen is the length of the utx_host string */
+ utx->ut_syslen = MIN(strlen(li->hostname), sizeof(utx->ut_host));
#endif
}
@@ -639,6 +746,7 @@
register int fd;
int tty;
+ /* FIXME: (ATL) ttyslot() needs local implementation */
tty = ttyslot(); /* seems only to work for /dev/ttyp? style names */
if (tty > 0 && (fd = open(UTMP_FILE, O_RDWR|O_CREAT, 0644)) >= 0) {
@@ -658,7 +766,7 @@
(void)lseek(fd, (off_t)(tty * sizeof(struct utmp)), SEEK_SET);
if (write(fd, ut, sizeof(struct utmp))==-1)
log("utmp_write_direct: error writing %s: %s",
- UTMP_FILE, strerror(errno));
+ UTMP_FILE, strerror(errno));
(void)close(fd);
return 1;
@@ -676,7 +784,7 @@
construct_utmp(li, &ut);
#ifdef UTMP_USE_LIBRARY
if (!utmp_write_library(li, &ut)) {
- log("utmp_perform_login: utmp_write_library() failed");
+ log("utmp_perform_login: utmp_write_library() failed");
return 0;
}
#else
@@ -694,23 +802,18 @@
{
struct utmp ut;
- memset(&ut, '\0', sizeof(ut));
- set_utmp_time(li, &ut);
- line_stripname(ut.ut_line, li->line, sizeof(ut.ut_line));
-#ifdef HAVE_ID_IN_UTMP
- line_abbrevname(ut.ut_id, li->line, sizeof(ut.ut_id));
-#endif
-#ifdef HAVE_TYPE_IN_UTMP
- ut.ut_type = DEAD_PROCESS;
-#endif
-
-#if !defined(DISABLE_PUTUTLINE) \
- && defined(HAVE_SETUTENT) && defined(HAVE_PUTUTLINE)
- utmp_write_library(li, &ut);
+ construct_utmp(li, &ut);
+#ifdef UTMP_USE_LIBRARY
+ if (!utmp_write_library(li, &ut)) {
+ log("utmp_perform_logout: utmp_write_library() failed");
+ return 0;
+ }
#else
- utmp_write_direct(li, &ut);
+ if (!utmp_write_direct(li, &ut)) {
+ log("utmp_perform_logout: utmp_write_direct() failed");
+ return 0;
+ }
#endif
-
return 1;
}
@@ -890,17 +993,6 @@
struct utmp ut;
construct_utmp(li, &ut);
- /* blank out unnecessary fields */
- memset(&(ut.ut_name), '\0', sizeof(ut.ut_name));
-#ifdef HAVE_ID_IN_UTMP
- memset(&(ut.ut_id), '\0', sizeof(ut.ut_id));
-#endif
-#ifdef HAVE_HOST_IN_UTMP
- memset(&(ut.ut_host), '\0', sizeof(ut.ut_host));
-#endif
-#ifdef HAVE_ADDR_IN_UTMP
- memset(&(ut.ut_addr), '\0', sizeof(ut.ut_addr));
-#endif
return wtmp_write(li, &ut);
}
@@ -920,12 +1012,49 @@
}
+/* Notes on fetching login data from wtmp/wtmpx
+ *
+ * Logouts are usually recorded with (amongst other things) a blank
+ * username on a given tty line. However, some systems (HP-UX is one)
+ * leave all fields set, but change the ut_type field to DEAD_PROCESS.
+ *
+ * Since we're only looking for logins here, we know that the username
+ * must be set correctly. On systems that leave it in, we check for
+ * ut_type==USER_PROCESS (indicating a login.)
+ *
+ * Portability: Some systems may set something other than USER_PROCESS
+ * to indicate a login process. I don't know of any as I write. Also,
+ * it's possible that some systems may both leave the username in
+ * place and not have ut_type.
+ */
+
+
+/* return true if this wtmp entry indicates a login */
+static int
+wtmp_islogin(struct logininfo *li, struct utmp *ut)
+{
+ if ( strncmp(li->username, ut->ut_user,
+ MIN_SIZEOF(li->username, ut->ut_user)) == 0 ) {
+#ifdef HAVE_TYPE_IN_UTMP
+ if (ut->ut_type & USER_PROCESS)
+ return 1;
+#else
+ return 1;
+#endif
+ }
+ return 0;
+}
+
+
int
wtmp_get_entry(struct logininfo *li)
{
struct stat st;
struct utmp ut;
- int fd;
+ int fd, found=0;
+
+ /* Clear the time entries in our logininfo */
+ li->tv_sec = li->tv_usec = 0;
if ((fd = open(WTMP_FILE, O_RDONLY)) < 0) {
log("wtmp_get_entry: problem opening %s: %s",
@@ -938,19 +1067,25 @@
close(fd);
return 0;
}
- (void)lseek(fd, (off_t)(0-sizeof(struct utmp)), SEEK_END);
- do {
+ /* Seek to the start of the last struct utmp */
+ if (lseek(fd, (off_t)(0-sizeof(struct utmp)), SEEK_END) == -1) {
+ /* Looks like we've got a fresh wtmp file */
+ close(fd);
+ return 0;
+ }
+
+ while (!found) {
if (read(fd, &ut, sizeof(ut)) != sizeof(ut)) {
log("wtmp_get_entry: read of %s failed: %s",
WTMP_FILE, strerror(errno));
close (fd);
return 0;
}
- /* Logouts are recorded as a blank username on a particular line.
- * So, we just need to find the username in struct utmp */
- if ( strncmp(li->username, ut.ut_user, 8) == 0 ) {
- /* note we've already made sure there's a time in struct utmp */
+ if ( wtmp_islogin(li, &ut) ) {
+ found = 1;
+ /* We've already checked for a time in struct
+ * utmp, in login_getlast(). */
#ifdef HAVE_TIME_IN_UTMP
li->tv_sec = ut.ut_time;
#else
@@ -958,17 +1093,24 @@
li->tv_sec = ut.ut_tv.tv_sec;
# endif
#endif
- line_fullname(li->line, ut.ut_line, sizeof(li->line));
+ line_fullname(li->line, ut.ut_line,
+ MIN_SIZEOF(li->line, ut.ut_line));
#ifdef HAVE_HOST_IN_UTMP
- strlcpy(li->hostname, ut.ut_host, sizeof(li->hostname));
+ strlcpy(li->hostname, ut.ut_host,
+ MIN_SIZEOF(li->hostname, ut.ut_host));
#endif
+ continue;
}
+ /* Seek back 2 x struct utmp */
if (lseek(fd, (off_t)(0-2*sizeof(struct utmp)), SEEK_CUR) == -1) {
+ /* We've found the start of the file, so quit */
close (fd);
return 0;
}
- } while (li->tv_sec == 0);
-
+ }
+
+ /* We found an entry. Tidy up and return */
+ close(fd);
return 1;
}
@@ -1027,19 +1169,7 @@
struct utmpx utx;
construct_utmpx(li, &utx);
- /* blank out unnecessary fields */
- memset(&(utx.ut_name), '\0', sizeof(utx.ut_name));
-#ifdef HAVE_ID_IN_UTMPX
- memset(&(utx.ut_id), '\0', sizeof(utx.ut_id));
-#endif
-#ifdef HAVE_HOST_IN_UTMPX
- memset(&(utx.ut_host), '\0', sizeof(utx.ut_host));
-#endif
-#ifdef HAVE_ADDR_IN_UTMPX
- memset(&(utx.ut_addr), '\0', sizeof(utx.ut_addr));
-#endif
return wtmpx_write(li, &utx);
-
}
@@ -1057,13 +1187,35 @@
}
}
+/* Please see the notes above wtmp_islogin() for information about the
+ next two functions */
+
+/* Return true if this wtmpx entry indicates a login */
+static int
+wtmpx_islogin(struct logininfo *li, struct utmpx *utx)
+{
+ if ( strncmp(li->username, utx->ut_user,
+ MIN_SIZEOF(li->username, utx->us_user)) == 0 ) {
+#ifdef HAVE_TYPE_IN_UTMPX
+ if (utx->ut_type == USER_PROCESS)
+ return 1;
+#else
+ return 1;
+#endif
+ }
+ return 0;
+}
+
int
wtmpx_get_entry(struct logininfo *li)
{
struct stat st;
struct utmpx utx;
- int fd;
+ int fd, found=0;
+
+ /* Clear the time entries */
+ li->tv_sec = li->tv_usec = 0;
if ((fd = open(WTMPX_FILE, O_RDONLY)) < 0) {
log("wtmpx_get_entry: problem opening %s: %s",
@@ -1076,9 +1228,15 @@
close(fd);
return 0;
}
- (void)lseek(fd, (off_t)(0-sizeof(struct utmpx)), SEEK_END);
+
+ /* Seek to the start of the last struct utmpx */
+ if (lseek(fd, (off_t)(0-sizeof(struct utmpx)), SEEK_END) == -1 ) {
+ /* probably a newly rotated wtmpx file */
+ close(fd);
+ return 0;
+ }
- do {
+ while (!found) {
if (read(fd, &utx, sizeof(utx)) != sizeof(utx)) {
log("wtmpx_get_entry: read of %s failed: %s",
WTMPX_FILE, strerror(errno));
@@ -1087,8 +1245,7 @@
}
/* Logouts are recorded as a blank username on a particular line.
* So, we just need to find the username in struct utmpx */
- if ( strncmp(li->username, utx.ut_user, 8) == 0 ) {
- /* note we've already made sure there's a time in struct utmp */
+ if ( wtmpx_islogin(li, &utx) ) {
#ifdef HAVE_TV_IN_UTMPX
li->tv_sec = utx.ut_tv.tv_sec;
#else
@@ -1098,14 +1255,18 @@
#endif
line_fullname(li->line, utx.ut_line, sizeof(li->line));
#ifdef HAVE_HOST_IN_UTMPX
- strlcpy(li->hostname, utx.ut_host, sizeof(li->hostname));
+ strlcpy(li->hostname, utx.ut_host,
+ MIN_SIZEOF(li->hostname, utx.ut_host));
#endif
+ continue;
}
if (lseek(fd, (off_t)(0-2*sizeof(struct utmpx)), SEEK_CUR) == -1) {
close (fd);
return 0;
}
- } while (li->tv_sec == 0);
+ }
+
+ close(fd);
return 1;
}
@@ -1150,9 +1311,10 @@
logwtmp(line, "", "");
}
# endif
- /* TODO: what to do if we have login, but no logout?
- * what if logout but no logwtmp? All routines are in libutil
- * so they should all be there, but... */
+ /* FIXME: (ATL - if the need arises) What to do if we have
+ * login, but no logout? what if logout but no logwtmp? All
+ * routines are in libutil so they should all be there,
+ * but... */
#endif
return 1;
}
@@ -1192,7 +1354,8 @@
(void)line_stripname(last->ll_line, li->line,
sizeof(last->ll_line));
- strlcpy(last->ll_host, li->hostname, sizeof(last->ll_host));
+ strlcpy(last->ll_host, li->hostname,
+ MIN_SIZEOF(last->ll_host, li->hostname));
last->ll_time = li->tv_sec;
}
@@ -1300,7 +1463,8 @@
lastlog_populate_entry(struct logininfo *li, struct lastlog *last)
{
line_fullname(li->line, last->ll_line, sizeof(li->line));
- strlcpy(li->hostname, last->ll_host, sizeof(li->hostname));
+ strlcpy(li->hostname, last->ll_host,
+ MIN_SIZEOF(li->hostname, last->ll_host));
li->tv_sec = last->ll_time;
}