login: use getpwnam_r() rather than manually copy passwd struct

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

diff --git a/login-utils/login.c b/login-utils/login.c
index c4f3d9cd0e74fbb76d6c5c4c81dbe27084972ba8..15c5feeb315cdaf09746dd8343b4286ec3b6a9bd 100644 (file)
--- a/login-utils/login.c
+++ b/login-utils/login.c
@@ -94,6 +94,8 @@ struct login_context {
 
        char            *username;      /* from command line or PAM */
 
+       struct passwd   *pwd;           /* user info */
+
 #ifdef LOGIN_CHOWN_VCS
        char            vcsn[VCS_PATH_MAX];     /* virtual console name */
        char            vcsan[VCS_PATH_MAX];
@@ -112,10 +114,6 @@ struct login_context {
  */
 int timeout = LOGIN_TIMEOUT;
 
-struct passwd *pwd;
-
-static struct passwd pwdcopy;
-
 static void timedout(int);
 static void sigint(int);
 static void motd(void);
@@ -315,9 +313,10 @@ static void sig_handler(int signal)
 }
 
 #ifdef HAVE_LIBAUDIT
-static void log_audit(struct login_context *cxt, struct passwd *pwd, int status)
+static void log_audit(struct login_context *cxt, int status)
 {
        int audit_fd;
+       struct passwd *pwd = cxt->pwd;
 
        audit_fd = audit_open();
        if (audit_fd == -1)
@@ -338,8 +337,8 @@ static void log_audit(struct login_context *cxt, struct passwd *pwd, int status)
 
        close(audit_fd);
 }
-#else                          /* ! HAVE_LIBAUDIT */
-#define log_audit(cxt, pwd, status)
+#else                          /* !HAVE_LIBAUDIT */
+# define log_audit(cxt, status)
 #endif                         /* HAVE_LIBAUDIT */
 
 static void log_lastlog(struct login_context *cxt)
@@ -348,11 +347,14 @@ static void log_lastlog(struct login_context *cxt)
        time_t t;
        int fd;
 
+       if (!cxt->pwd)
+               return;
+
        fd = open(_PATH_LASTLOG, O_RDWR, 0);
        if (fd < 0)
                return;
 
-       lseek(fd, (off_t) pwd->pw_uid * sizeof(ll), SEEK_SET);
+       lseek(fd, (off_t) cxt->pwd->pw_uid * sizeof(ll), SEEK_SET);
 
        /*
         * Print last log message
@@ -370,7 +372,7 @@ static void log_lastlog(struct login_context *cxt)
                                printf(_("on %.*s\n"),
                                       (int)sizeof(ll.ll_line), ll.ll_line);
                }
-               lseek(fd, (off_t) pwd->pw_uid * sizeof(ll), SEEK_SET);
+               lseek(fd, (off_t) cxt->pwd->pw_uid * sizeof(ll), SEEK_SET);
        }
 
        memset((char *)&ll, 0, sizeof(ll));
@@ -464,6 +466,40 @@ static void log_utmp(struct login_context *cxt)
        updwtmp(_PATH_WTMP, &ut);
 }
 
+static struct passwd *get_passwd_entry(const char *username,
+                                        char **pwdbuf,
+                                        struct passwd *pwd)
+{
+       struct passwd *res = NULL;
+       size_t sz;
+       char *tmp;
+       int x;
+
+       if (!pwdbuf || !username)
+               return NULL;
+
+#ifdef _SC_GETPW_R_SIZE_MAX
+       sz = sysconf(_SC_GETPW_R_SIZE_MAX);
+       if (sz <= 0)
+#endif
+               sz = 16384;
+
+       tmp = realloc(*pwdbuf, sz);
+       if (!tmp) {
+               free(*pwdbuf);
+               *pwdbuf = NULL;
+               return NULL;
+       }
+       *pwdbuf = tmp;
+
+       x = getpwnam_r(username, pwd, *pwdbuf, sz, &res);
+       if (!res) {
+               errno = x;
+               return NULL;
+       }
+       return res;
+}
+
 /* encapsulate stupid "void **" pam_get_item() API */
 static int loginpam_get_username(pam_handle_t * pamh, char **name)
 {
@@ -521,6 +557,9 @@ int main(int argc, char **argv)
        struct pam_conv conv = { misc_conv, NULL };
        struct sigaction sa, oldsa_hup, oldsa_term;
 
+       char *pwdbuf = NULL;
+       struct passwd *pwd = NULL, _pwd;
+
        struct login_context cxt = {
                .pid = getpid()
        };
@@ -700,7 +739,7 @@ int main(int argc, char **argv)
                               failcount, cxt.hostname, cxt.username, pam_strerror(pamh,
                                                                           retcode));
                        logbtmp(&cxt);
-                       log_audit(&cxt, NULL, 0);
+                       log_audit(&cxt, 0);
 
                        fprintf(stderr, _("Login incorrect\n\n"));
                        pam_set_item(pamh, PAM_USER, NULL);
@@ -723,7 +762,7 @@ int main(int argc, char **argv)
                                       cxt.hostname, cxt.username, pam_strerror(pamh,
                                                                        retcode));
                        logbtmp(&cxt);
-                       log_audit(&cxt, NULL, 0);
+                       log_audit(&cxt, 0);
 
                        fprintf(stderr, _("\nLogin incorrect\n"));
                        pam_end(pamh, retcode);
@@ -759,7 +798,7 @@ int main(int argc, char **argv)
                pam_end(pamh, PAM_SYSTEM_ERR);
                exit(EXIT_FAILURE);
        }
-       if (!(pwd = getpwnam(cxt.username))) {
+       if (!(cxt.pwd = get_passwd_entry(cxt.username, &pwdbuf, &_pwd))) {
                warnx(_("\nSession setup problem, abort."));
                syslog(LOG_ERR, _("Invalid user name \"%s\" in %s:%d. Abort."),
                       cxt.username, __FUNCTION__, __LINE__);
@@ -767,24 +806,7 @@ int main(int argc, char **argv)
                exit(EXIT_FAILURE);
        }
 
-       /*
-        * Create a copy of the pwd struct - otherwise it may get
-        * clobbered by PAM
-        */
-       memcpy(&pwdcopy, pwd, sizeof(*pwd));
-       pwd = &pwdcopy;
-       pwd->pw_name = strdup(pwd->pw_name);
-       pwd->pw_passwd = strdup(pwd->pw_passwd);
-       pwd->pw_gecos = strdup(pwd->pw_gecos);
-       pwd->pw_dir = strdup(pwd->pw_dir);
-       pwd->pw_shell = strdup(pwd->pw_shell);
-       if (!pwd->pw_name || !pwd->pw_passwd || !pwd->pw_gecos ||
-           !pwd->pw_dir || !pwd->pw_shell) {
-               warnx(_("out of memory"));
-               syslog(LOG_ERR, "Out of memory");
-               pam_end(pamh, PAM_SYSTEM_ERR);
-               exit(EXIT_FAILURE);
-       }
+       pwd = cxt.pwd;
        cxt.username = pwd->pw_name;
 
        /*
@@ -847,7 +869,7 @@ int main(int argc, char **argv)
        }
 
        log_utmp(&cxt);
-       log_audit(&cxt, pwd, 1);
+       log_audit(&cxt, 1);
        log_lastlog(&cxt);
 
        if (fchown(0, pwd->pw_uid,