1 files changed, 448 insertions, 0 deletions

diff --git a/libpam/pam_dispatch.c b/libpam/pam_dispatch.c
new file mode 100644
index 0000000..cf632e8
--- /dev/null
+++ b/libpam/pam_dispatch.c
@@ -0,0 +1,448 @@
+/* pam_dispatch.c - handles module function dispatch */
+
+/*
+ * Copyright (c) 1998, 2005 Andrew G. Morgan <morgan@kernel.org>
+ *
+ */
+
+#include "pam_private.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+
+/*
+ * this is the return code we return when a function pointer is NULL
+ * or, the handler structure indicates a broken module config line
+ */
+#define PAM_MUST_FAIL_CODE        PAM_PERM_DENIED
+
+/* impression codes - this gives some sense to the logical choices */
+#define _PAM_UNDEF     0
+#define _PAM_POSITIVE +1
+#define _PAM_NEGATIVE -1
+
+/* frozen chain required codes */
+#define _PAM_PLEASE_FREEZE  0
+#define _PAM_MAY_BE_FROZEN  1
+#define _PAM_MUST_BE_FROZEN 2
+
+/*
+ * walk a stack of modules.  Interpret the administrator's instructions
+ * when combining the return code of each module.
+ */
+
+static int _pam_dispatch_aux(pam_handle_t *pamh, int flags, struct handler *h,
+			     _pam_boolean resumed, int use_cached_chain)
+{
+    int depth, impression, status, skip_depth, prev_level, stack_level;
+    struct _pam_substack_state *substates = NULL;
+
+    IF_NO_PAMH("_pam_dispatch_aux", pamh, PAM_SYSTEM_ERR);
+
+    if (h == NULL) {
+        const void *service=NULL;
+
+	(void) pam_get_item(pamh, PAM_SERVICE, &service);
+	pam_syslog(pamh, LOG_ERR, "no modules loaded for `%s' service",
+		   service ? (const char *)service:"<unknown>" );
+	service = NULL;
+	return PAM_MUST_FAIL_CODE;
+    }
+
+    /* if we are recalling this module stack because a former call did
+       not complete, we restore the state of play from pamh. */
+    if (resumed) {
+	skip_depth = pamh->former.depth;
+	status = pamh->former.status;
+	impression = pamh->former.impression;
+	substates = pamh->former.substates;
+	/* forget all that */
+	pamh->former.impression = _PAM_UNDEF;
+	pamh->former.status = PAM_MUST_FAIL_CODE;
+	pamh->former.depth = 0;
+	pamh->former.substates = NULL;
+    } else {
+	skip_depth = 0;
+	substates = malloc(PAM_SUBSTACK_MAX_LEVEL * sizeof(*substates));
+	if (substates == NULL) {
+	    pam_syslog(pamh, LOG_CRIT,
+		       "_pam_dispatch_aux: no memory for substack states");
+	    return PAM_BUF_ERR;
+	}
+	substates[0].impression = impression = _PAM_UNDEF;
+	substates[0].status = status = PAM_MUST_FAIL_CODE;
+    }
+
+    prev_level = 0;
+
+    /* Loop through module logic stack */
+    for (depth=0 ; h != NULL ; prev_level = stack_level, h = h->next, ++depth) {
+	int retval, cached_retval, action;
+
+        stack_level = h->stack_level;
+
+	/* skip leading modules if they have already returned */
+	if (depth < skip_depth) {
+	    continue;
+	}
+
+	/* remember state if we are entering a substack */
+	if (prev_level < stack_level) {
+	    substates[stack_level].impression = impression;
+	    substates[stack_level].status = status;
+	}
+
+	/* attempt to call the module */
+	if (h->handler_type == PAM_HT_MUST_FAIL) {
+	    D(("module poorly listed in PAM config; forcing failure"));
+	    retval = PAM_MUST_FAIL_CODE;
+	} else if (h->handler_type == PAM_HT_SUBSTACK) {
+	    D(("skipping substack handler"));
+	    continue;
+	} else if (h->func == NULL) {
+	    D(("module function is not defined, indicating failure"));
+	    retval = PAM_MODULE_UNKNOWN;
+	} else {
+	    D(("passing control to module..."));
+	    pamh->mod_name=h->mod_name;
+	    pamh->mod_argc = h->argc;
+	    pamh->mod_argv = h->argv;
+	    retval = h->func(pamh, flags, h->argc, h->argv);
+	    pamh->mod_name=NULL;
+	    pamh->mod_argc = 0;
+	    pamh->mod_argv = NULL;
+	    D(("module returned: %s", pam_strerror(pamh, retval)));
+	}
+
+	/*
+	 * PAM_INCOMPLETE return is special.  It indicates that the
+	 * module wants to wait for the application before continuing.
+	 * In order to return this, the module will have saved its
+	 * state so it can resume from an equivalent position when it
+	 * is called next time.  (This was added as of 0.65)
+	 */
+	if (retval == PAM_INCOMPLETE) {
+	    pamh->former.impression = impression;
+	    pamh->former.status = status;
+	    pamh->former.depth = depth;
+	    pamh->former.substates = substates;
+
+	    D(("module %d returned PAM_INCOMPLETE", depth));
+	    return retval;
+	}
+
+	/*
+	 * use_cached_chain is how we ensure that the setcred and
+         * close_session modules are called in the same order as they did
+	 * when they were invoked as auth/open_session. This feature was
+	 * added in 0.75 to make the behavior of pam_setcred sane.
+	 */
+	if (use_cached_chain != _PAM_PLEASE_FREEZE) {
+
+	    /* a former stack execution should have frozen the chain */
+
+	    cached_retval = *(h->cached_retval_p);
+	    if (cached_retval == _PAM_INVALID_RETVAL) {
+
+		/* This may be a problem condition. It implies that
+		   the application is running setcred, close_session,
+		   chauthtok(2nd) without having first run
+		   authenticate, open_session, chauthtok(1st)
+		   [respectively]. */
+
+		D(("use_cached_chain is set to [%d],"
+		   " but cached_retval == _PAM_INVALID_RETVAL",
+		   use_cached_chain));
+
+		/* In the case of close_session and setcred there is a
+		   backward compatibility reason for allowing this, in
+		   the chauthtok case we have encountered a bug in
+		   libpam! */
+
+		if (use_cached_chain == _PAM_MAY_BE_FROZEN) {
+		    /* (not ideal) force non-frozen stack control. */
+		    cached_retval = retval;
+		} else {
+		    D(("BUG in libpam -"
+		       " chain is required to be frozen but isn't"));
+
+		    /* cached_retval is already _PAM_INVALID_RETVAL */
+		}
+	    }
+	} else {
+	    /* this stack execution is defining the frozen chain */
+	    cached_retval = h->cached_retval = retval;
+	}
+
+	/* verify that the return value is a valid one */
+	if ((cached_retval < PAM_SUCCESS)
+	    || (cached_retval >= _PAM_RETURN_VALUES)) {
+
+	    retval = PAM_MUST_FAIL_CODE;
+	    action = _PAM_ACTION_BAD;
+	} else {
+	    /* We treat the current retval with some respect. It may
+	       (for example, in the case of setcred) have a value that
+	       needs to be propagated to the user.  We want to use the
+	       cached_retval to determine the modules to be executed
+	       in the stacked chain, but we want to treat each
+	       non-ignored module in the cached chain as now being
+	       'required'. We only need to treat the,
+	       _PAM_ACTION_IGNORE, _PAM_ACTION_IS_JUMP and
+	       _PAM_ACTION_RESET actions specially. */
+
+	    action = h->actions[cached_retval];
+	}
+
+	D(("use_cached_chain=%d action=%d cached_retval=%d retval=%d",
+	   use_cached_chain, action, cached_retval, retval));
+
+	/* decide what to do */
+	switch (action) {
+	case _PAM_ACTION_RESET:
+
+	    impression = substates[stack_level].impression;
+	    status = substates[stack_level].status;
+	    break;
+
+	case _PAM_ACTION_OK:
+	case _PAM_ACTION_DONE:
+
+	    if ( impression == _PAM_UNDEF
+		 || (impression == _PAM_POSITIVE && status == PAM_SUCCESS) ) {
+                /* in case of using cached chain
+                   we could get here with PAM_IGNORE - don't return it */
+                if ( retval != PAM_IGNORE || cached_retval == retval ) {
+		    impression = _PAM_POSITIVE;
+                    status = retval;
+                }
+	    }
+	    if ( impression == _PAM_POSITIVE ) {
+		if ( retval == PAM_SUCCESS ) {
+		    h->grantor = 1;
+		}
+
+		if ( action == _PAM_ACTION_DONE ) {
+		    goto decision_made;
+		}
+	    }
+	    break;
+
+	case _PAM_ACTION_BAD:
+	case _PAM_ACTION_DIE:
+#ifdef PAM_FAIL_NOW_ON
+	    if ( cached_retval == PAM_ABORT ) {
+		impression = _PAM_NEGATIVE;
+		status = PAM_PERM_DENIED;
+		goto decision_made;
+	    }
+#endif /* PAM_FAIL_NOW_ON */
+	    if ( impression != _PAM_NEGATIVE ) {
+		impression = _PAM_NEGATIVE;
+	        /* Don't return with PAM_IGNORE as status */
+	        if ( retval == PAM_IGNORE )
+		    status = PAM_MUST_FAIL_CODE;
+		else
+		    status = retval;
+	    }
+	    if ( action == _PAM_ACTION_DIE ) {
+		goto decision_made;
+	    }
+	    break;
+
+	case _PAM_ACTION_IGNORE:
+	    break;
+
+        /* if we get here, we expect action is a positive number --
+           this is what the ...JUMP macro checks. */
+
+	default:
+	    if ( _PAM_ACTION_IS_JUMP(action) ) {
+
+		/* If we are evaluating a cached chain, we treat this
+		   module as required (aka _PAM_ACTION_OK) as well as
+		   executing the jump. */
+
+		if (use_cached_chain) {
+		    if (impression == _PAM_UNDEF
+			|| (impression == _PAM_POSITIVE
+			    && status == PAM_SUCCESS) ) {
+			if ( retval != PAM_IGNORE || cached_retval == retval ) {
+			    if ( impression == _PAM_UNDEF && retval == PAM_SUCCESS ) {
+				h->grantor = 1;
+			    }
+			    impression = _PAM_POSITIVE;
+			    status = retval;
+			}
+		    }
+		}
+
+		/* this means that we need to skip #action stacked modules */
+		while (h->next != NULL && h->next->stack_level >= stack_level && action > 0) {
+		    do {
+			h = h->next;
+			++depth;
+		    } while (h->next != NULL && h->next->stack_level > stack_level);
+		    --action;
+		}
+
+		/* note if we try to skip too many modules action is
+                   still non-zero and we snag the next if. */
+	    }
+
+	    /* this case is a syntax error: we can't succeed */
+	    if (action) {
+		pam_syslog(pamh, LOG_ERR, "bad jump in stack");
+		impression = _PAM_NEGATIVE;
+		status = PAM_MUST_FAIL_CODE;
+	    }
+	}
+	continue;
+
+decision_made:     /* by getting  here we have made a decision */
+	while (h->next != NULL && h->next->stack_level >= stack_level) {
+	    h = h->next;
+	    ++depth;
+	}
+    }
+
+    /* Sanity check */
+    if ( status == PAM_SUCCESS && impression != _PAM_POSITIVE ) {
+	D(("caught on sanity check -- this is probably a config error!"));
+	status = PAM_MUST_FAIL_CODE;
+    }
+
+    free(substates);
+    /* We have made a decision about the modules executed */
+    return status;
+}
+
+static void _pam_clear_grantors(struct handler *h)
+{
+    for (; h != NULL; h = h->next) {
+	h->grantor = 0;
+    }
+}
+
+/*
+ * This function translates the module dispatch request into a pointer
+ * to the stack of modules that will actually be run.  the
+ * _pam_dispatch_aux() function (above) is responsible for walking the
+ * module stack.
+ */
+
+int _pam_dispatch(pam_handle_t *pamh, int flags, int choice)
+{
+    struct handler *h = NULL;
+    int retval = PAM_SYSTEM_ERR, use_cached_chain;
+    _pam_boolean resumed;
+
+    IF_NO_PAMH("_pam_dispatch", pamh, PAM_SYSTEM_ERR);
+
+    if (__PAM_FROM_MODULE(pamh)) {
+	D(("called from a module!?"));
+	goto end;
+    }
+
+    /* Load all modules, resolve all symbols */
+
+    if ((retval = _pam_init_handlers(pamh)) != PAM_SUCCESS) {
+	pam_syslog(pamh, LOG_ERR, "unable to dispatch function");
+	goto end;
+    }
+
+    use_cached_chain = _PAM_PLEASE_FREEZE;
+
+    switch (choice) {
+    case PAM_AUTHENTICATE:
+	h = pamh->handlers.conf.authenticate;
+	break;
+    case PAM_SETCRED:
+	h = pamh->handlers.conf.setcred;
+	use_cached_chain = _PAM_MAY_BE_FROZEN;
+	break;
+    case PAM_ACCOUNT:
+	h = pamh->handlers.conf.acct_mgmt;
+	break;
+    case PAM_OPEN_SESSION:
+	h = pamh->handlers.conf.open_session;
+	break;
+    case PAM_CLOSE_SESSION:
+	h = pamh->handlers.conf.close_session;
+	use_cached_chain = _PAM_MAY_BE_FROZEN;
+	break;
+    case PAM_CHAUTHTOK:
+	h = pamh->handlers.conf.chauthtok;
+	break;
+    default:
+	pam_syslog(pamh, LOG_ERR, "undefined fn choice; %d", choice);
+	retval = PAM_ABORT;
+	goto end;
+    }
+
+    if (h == NULL) {     /* there was no handlers.conf... entry; will use
+			  * handlers.other... */
+	switch (choice) {
+	case PAM_AUTHENTICATE:
+	    h = pamh->handlers.other.authenticate;
+	    break;
+	case PAM_SETCRED:
+	    h = pamh->handlers.other.setcred;
+	    break;
+	case PAM_ACCOUNT:
+	    h = pamh->handlers.other.acct_mgmt;
+	    break;
+	case PAM_OPEN_SESSION:
+	    h = pamh->handlers.other.open_session;
+	    break;
+	case PAM_CLOSE_SESSION:
+	    h = pamh->handlers.other.close_session;
+	    break;
+	case PAM_CHAUTHTOK:
+	    h = pamh->handlers.other.chauthtok;
+	    break;
+	}
+    }
+
+    /* Did a module return an "incomplete state" last time? */
+    if (pamh->former.choice != PAM_NOT_STACKED) {
+	if (pamh->former.choice != choice) {
+	    pam_syslog(pamh, LOG_ERR,
+			    "application failed to re-exec stack [%d:%d]",
+			    pamh->former.choice, choice);
+	    retval = PAM_ABORT;
+	    goto end;
+	}
+	resumed = PAM_TRUE;
+    } else {
+	resumed = PAM_FALSE;
+	_pam_clear_grantors(h);
+    }
+
+    __PAM_TO_MODULE(pamh);
+
+    /* call the list of module functions */
+    pamh->choice = choice;
+    retval = _pam_dispatch_aux(pamh, flags, h, resumed, use_cached_chain);
+    resumed = PAM_FALSE;
+
+    __PAM_TO_APP(pamh);
+
+    /* Should we recall where to resume next time? */
+    if (retval == PAM_INCOMPLETE) {
+	D(("module [%d] returned PAM_INCOMPLETE"));
+	pamh->former.choice = choice;
+    } else {
+	pamh->former.choice = PAM_NOT_STACKED;
+    }
+
+end:
+
+#ifdef HAVE_LIBAUDIT
+    if (choice != PAM_CHAUTHTOK || flags & PAM_UPDATE_AUTHTOK || retval != PAM_SUCCESS) {
+	retval = _pam_auditlog(pamh, choice, retval, flags, h);
+    }
+#endif
+
+    return retval;
+}