login: optional support for PAM

diff --git a/Makefile.flags b/Makefile.flags
index d8817be..c64a5c8 100644 (file)
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -60,18 +60,20 @@ LDFLAGS += -static
 endif
 
 BBOX_LIB_LIST = m crypt
+
+ifeq ($(CONFIG_PAM),y)
+BBOX_LIB_LIST += pam pam_misc
+endif
+
 ifeq ($(CONFIG_SELINUX),y)
-#LDLIBS += -lselinux -lsepol
 BBOX_LIB_LIST += selinux sepol
 endif
 
 ifeq ($(CONFIG_EFENCE),y)
-#LDLIBS += -lefence
 BBOX_LIB_LIST += efence
 endif
 
 ifeq ($(CONFIG_DMALLOC),y)
-#LDLIBS += -ldmalloc
 BBOX_LIB_LIST += dmalloc
 endif
 

diff --git a/loginutils/Config.in b/loginutils/Config.in
index 63ae9b4..6f2702e 100644 (file)
--- a/loginutils/Config.in
+++ b/loginutils/Config.in
@@ -128,6 +128,13 @@ config LOGIN
          Note that Busybox binary must be setuid root for this applet to
          work properly.
 
+config PAM
+       bool "Support for PAM (Pluggable Authentication Modules)"
+       default n
+       depends on LOGIN
+       help
+         Use PAM in login(1) instead of direct access to password database.
+
 config LOGIN_SCRIPTS
        bool "Support for login scripts"
        depends on LOGIN

diff --git a/loginutils/login.c b/loginutils/login.c
index 7b60fd0..b633a7f 100644 (file)
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -14,6 +14,15 @@
 #include <selinux/flask.h> /* for security class definitions  */
 #endif
 
+#if ENABLE_PAM
+#include <pam/pam_appl.h>
+#include <pam/pam_misc.h>
+static const struct pam_conv conv = {
+       misc_conv,
+       NULL
+};
+#endif
+
 enum {
        TIMEOUT = 60,
        EMPTY_USERNAME_COUNT = 10,
@@ -125,7 +134,7 @@ static void die_if_nologin_and_non_root(int amroot)
 static ALWAYS_INLINE void die_if_nologin_and_non_root(int amroot) {}
 #endif
 
-#if ENABLE_FEATURE_SECURETTY
+#if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM
 static int check_securetty(void)
 {
        FILE *fp;
@@ -214,7 +223,7 @@ int login_main(int argc, char **argv)
                LOGIN_OPT_h = (1<<1),
                LOGIN_OPT_p = (1<<2),
        };
-       char fromhost[512];
+       char *fromhost;
        char username[USERNAME_SIZE];
        const char *tmp;
        int amroot;
@@ -226,6 +235,9 @@ int login_main(int argc, char **argv)
        char full_tty[TTYNAME_SIZE];
        USE_SELINUX(security_context_t user_sid = NULL;)
        USE_FEATURE_UTMP(struct utmp utent;)
+       USE_PAM(pam_handle_t *pamh;)
+       USE_PAM(int pamret;)
+       USE_PAM(const char *failed_msg;)
 
        short_tty = full_tty;
        username[0] = '\0';
@@ -265,13 +277,12 @@ int login_main(int argc, char **argv)
                USE_FEATURE_UTMP(
                        safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
                )
-               snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s' from "
-                                       "'%.200s'", short_tty, opt_host);
+               fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host);
        } else
-               snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s'", short_tty);
+               fromhost = xasprintf(" on '%s'", short_tty);
 
-       // Was breaking "login <username>" from shell command line:
-       // bb_setpgrp();
+       /* Was breaking "login <username>" from shell command line: */
+       /*bb_setpgrp();*/
 
        openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
 
@@ -279,6 +290,46 @@ int login_main(int argc, char **argv)
                if (!username[0])
                        get_username_or_die(username, sizeof(username));
 
+#if ENABLE_PAM
+               pamret = pam_start("login", username, &conv, &pamh);
+               if (pamret != PAM_SUCCESS) {
+                       failed_msg = "pam_start";
+                       goto pam_auth_failed;
+               }
+               /* set TTY (so things like securetty work) */
+               pamret = pam_set_item(pamh, PAM_TTY, short_tty);
+               if (pamret != PAM_SUCCESS) {
+                       failed_msg = "pam_set_item(TTY)";
+                       goto pam_auth_failed;
+               }
+               pamret = pam_authenticate(pamh, 0);
+               if (pamret == PAM_SUCCESS) {
+                       char *pamuser;
+                       /* check that the account is healthy. */
+                       pamret = pam_acct_mgmt(pamh, 0);
+                       if (pamret != PAM_SUCCESS) {
+                               failed_msg = "account setup";
+                               goto pam_auth_failed;
+                       }
+                       /* read user back */
+                       /* gcc: "dereferencing type-punned pointer breaks aliasing rules..."
+                        * thus we use double cast */
+                       if (pam_get_item(pamh, PAM_USER, (const void **)(void*)&pamuser) != PAM_SUCCESS) {
+                               failed_msg = "pam_get_item(USER)";
+                               goto pam_auth_failed;
+                       }
+                       safe_strncpy(username, pamuser, sizeof(username));
+               }
+               /* If we get here, the user was authenticated, and is
+                * granted access. */
+               pw = getpwnam(username);
+               if (pw)
+                       break;
+               goto auth_failed;
+ pam_auth_failed:
+               bb_error_msg("%s failed: %s", failed_msg, pam_strerror(pamh, pamret));
+               safe_strncpy(username, "UNKNOWN", sizeof(username));
+#else /* not PAM */
                pw = getpwnam(username);
                if (!pw) {
                        strcpy(username, "UNKNOWN");
@@ -301,6 +352,7 @@ int login_main(int argc, char **argv)
                /* authorization takes place here */
                if (correct_password(pw))
                        break;
+#endif /* ENABLE_PAM */
  auth_failed:
                opt &= ~LOGIN_OPT_f;
                bb_do_delay(FAIL_DELAY);