tmpl.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: d40d72252acfe868ab25337d60776f25b995db8a $
 *
 * @file unlang/tmpl.c
 * @brief Defines functions for calling tmpl__t asynchronously
 *
 * @copyright 2021 Arran Cudbard-Bell <a.cudbardb@freeradius.org>
 * @copyright 2020 Network RADIUS SAS (legal@networkradius.com)
 */
RCSID("$Id: d40d72252acfe868ab25337d60776f25b995db8a $")
 
#include <freeradius-devel/unlang/tmpl.h>
#include <freeradius-devel/server/exec.h>
#include <freeradius-devel/util/syserror.h>
#include "tmpl_priv.h"
#include <signal.h>
 
#if defined(__linux__) || defined(__FreeBSD__)
#include <sys/wait.h>
#endif
 
/** Send a signal (usually stop) to a request
 *
 * This is typically called via an "async" action, i.e. an action
 * outside of the normal processing of the request.
 *
 * If there is no #fr_unlang_tmpl_signal_t callback defined, the action is ignored.
 *
 * @param[in] request           The current request.
 * @param[in] frame             being signalled.
 * @param[in] action            to signal.
 */
static void unlang_tmpl_signal(request_t *request, unlang_stack_frame_t *frame, fr_signal_t action)
{
        unlang_frame_state_tmpl_t       *state = talloc_get_type_abort(frame->state,
                                                                       unlang_frame_state_tmpl_t);
 
        /*
         *      If we're cancelled, then kill any child processes
         */
        if ((action == FR_SIGNAL_CANCEL) && state->exec.request) fr_exec_oneshot_cleanup(&state->exec, SIGKILL);
 
        if (!state->signal) return;
 
        state->signal(request, state->rctx, action);
 
        /*
         *      If we're cancelled then disable this signal handler.
         *      fr_exec_oneshot_cleanup should handle being called spuriously.
         */
        if (action == FR_SIGNAL_CANCEL) state->signal = NULL;
}
 
/** Wrapper to call a resumption function after a tmpl has been expanded
 *
 *  If the resumption function returns YIELD, then this function is
 *  called repeatedly until the resumption function returns a final
 *  value.
 */
static unlang_action_t unlang_tmpl_resume(unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_tmpl_t       *state = talloc_get_type_abort(frame->state, unlang_frame_state_tmpl_t);
        unlang_tmpl_t                   *ut = unlang_generic_to_tmpl(frame->instruction);
 
        if (tmpl_eval_cast_in_place(&state->list, request, ut->tmpl) < 0) {
                RPEDEBUG("Failed casting expansion");
                RETURN_UNLANG_OK;
        }
 
        if (state->out) fr_value_box_list_move(state->out, &state->list);
 
        if (state->resume) return state->resume(p_result, request, state->rctx);
 
        RETURN_UNLANG_OK;
}
 
/** Wrapper to call exec after the program has finished executing
 *
 */
static unlang_action_t unlang_tmpl_exec_wait_final(unlang_result_t *p_result, request_t *request,
                                                   unlang_stack_frame_t *frame)
{
        unlang_frame_state_tmpl_t       *state = talloc_get_type_abort(frame->state,
                                                                       unlang_frame_state_tmpl_t);
 
        /*
         *      The exec failed for some internal reason.  We don't
         *      care about output, and we don't care about the programs exit status.
         */
        if (state->exec.failed) {
                fr_value_box_list_talloc_free(&state->list);
                goto resume;
        }
 
        fr_assert(state->exec.pid < 0); /* Assert this has been cleaned up */
 
        if (!state->args.exec.stdout_on_error && (state->exec.status != 0)) {
                fr_assert(fr_value_box_list_empty(&state->list));
                goto resume;
        }
 
        /*
         *      We might want to just get the status of the program,
         *      and not care about the output.
         *
         *      If we do care about the output, it's unquoted, and tainted.
         *
         *      FIXME - It would be much more efficient to just reparent
         *      the string buffer into the context of the box... but we'd
         *      need to fix talloc first.
         */
        if (state->out) {
                fr_type_t type = FR_TYPE_STRING;
                fr_value_box_t *box;
 
                /*
                 *      Remove any trailing LF / CR
                 */
                fr_sbuff_trim(&state->exec.stdout_buff, sbuff_char_line_endings);
 
                fr_value_box_list_init(&state->list);
                MEM(box = fr_value_box_alloc(state->ctx, FR_TYPE_STRING, NULL));
                if (fr_value_box_from_str(state->ctx, box, type, NULL,
                                          fr_sbuff_start(&state->exec.stdout_buff),
                                          fr_sbuff_used(&state->exec.stdout_buff),
                                          NULL) < 0) {
                        talloc_free(box);
                        RETURN_UNLANG_FAIL;
                }
                fr_value_box_list_insert_head(&state->list, box);
        }
 
resume:
        /*
         *      Inform the caller of the status if it asked for it
         */
        if (state->args.exec.status_out) *state->args.exec.status_out = state->exec.status;
 
        /*
         *      Ensure that the callers resume function is called.
         */
        frame->process = unlang_tmpl_resume;
        return unlang_tmpl_resume(p_result, request, frame);
}
 
 
/** Wrapper to call exec after a tmpl has been expanded
 *
 */
static unlang_action_t unlang_tmpl_exec_wait_resume(unlang_result_t *p_result, request_t *request,
                                                    unlang_stack_frame_t *frame)
{
        unlang_frame_state_tmpl_t       *state = talloc_get_type_abort(frame->state, unlang_frame_state_tmpl_t);
 
        if (fr_exec_oneshot(state->ctx, &state->exec, request,
                          &state->list,
                          state->args.exec.env, false, false,
                          false,
                          (state->out != NULL), state,
                          state->args.exec.timeout) < 0) {
                RPEDEBUG("Failed executing program");
                RETURN_UNLANG_FAIL;
        }
 
        fr_value_box_list_talloc_free(&state->list); /* this is the xlat expansion, and not the output string we want */
        frame_repeat(frame, unlang_tmpl_exec_wait_final);
 
        return UNLANG_ACTION_YIELD;
}
 
 
static unlang_action_t unlang_tmpl(unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_tmpl_t       *state = talloc_get_type_abort(frame->state, unlang_frame_state_tmpl_t);
        unlang_tmpl_t                   *ut = unlang_generic_to_tmpl(frame->instruction);
 
        /*
         *      If we're not called from unlang_tmpl_push(), then
         *      ensure that we clean up the resulting value boxes
         *      and that the list to write the boxes in is initialised.
         */
        if (!state->ctx) {
                state->ctx = state;
                fr_value_box_list_init(&state->list);
        }
 
        /*
         *      Synchronous tmpls can just be resolved immediately, and directly to the output list.
         *
         *      However, xlat expansions (including fully synchronous function calls!) need to be expanded by
         *      the xlat framework.
         */
        if (!tmpl_async_required(ut->tmpl) && !tmpl_contains_xlat(ut->tmpl)) {
                if (tmpl_eval(state->ctx, state->out, request, ut->tmpl) < 0) {
                        RPEDEBUG("Failed evaluating expansion");
                        goto fail;
                }
 
                RETURN_UNLANG_OK;
        }
 
        /*
         *      XLAT structs are allowed.
         */
        if (tmpl_is_xlat(ut->tmpl)) {
                frame_repeat(frame, unlang_tmpl_resume);
                goto push;
        }
 
        fr_assert(tmpl_is_exec(ut->tmpl));
 
        /*
         *      Expand the arguments to the program we're executing.
         */
        frame_repeat(frame, unlang_tmpl_exec_wait_resume);
push:
        if (unlang_xlat_push(state->ctx, NULL, &state->list, request, tmpl_xlat(ut->tmpl), false) < 0) {
        fail:
                return UNLANG_ACTION_STOP_PROCESSING;
        }
 
        return UNLANG_ACTION_PUSHED_CHILD;
}
 
/** Push a tmpl onto the stack for evaluation
 *
 * @param[in] ctx               To allocate value boxes and values in.
 * @param[out] out              The value_box created from the tmpl.  May be NULL,
 *                              in which case the result is discarded.
 * @param[in] request           The current request.
 * @param[in] tmpl              the tmpl to expand
 * @param[in] args              additional controls for expanding #TMPL_TYPE_EXEC,
 *                              and where the status of exited programs will be stored.
 * @return
 *      - 0 on success
 *      - -1 on failure
 */
int unlang_tmpl_push(TALLOC_CTX *ctx, fr_value_box_list_t *out, request_t *request,
                     tmpl_t const *tmpl, unlang_tmpl_args_t *args)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame;
        unlang_frame_state_tmpl_t       *state;
 
        unlang_tmpl_t                   *ut;
 
        static unlang_t tmpl_instruction = {
                .type = UNLANG_TYPE_TMPL,
                .name = "tmpl",
                .debug_name = "tmpl",
                .actions = {
                        .actions = {
                                [RLM_MODULE_REJECT]     = 0,
                                [RLM_MODULE_FAIL]       = MOD_ACTION_RETURN,
                                [RLM_MODULE_OK]         = 0,
                                [RLM_MODULE_HANDLED]    = 0,
                                [RLM_MODULE_INVALID]    = 0,
                                [RLM_MODULE_DISALLOW]   = 0,
                                [RLM_MODULE_NOTFOUND]   = 0,
                                [RLM_MODULE_NOOP]       = 0,
                                [RLM_MODULE_UPDATED]    = 0
                        },
                        .retry = RETRY_INIT,
                },
        };
 
        if (tmpl_needs_resolving(tmpl)) {
                REDEBUG("Expansion \"%pV\" needs to be resolved before it is used", fr_box_strvalue_len(tmpl->name, tmpl->len));
                return -1;
        }
 
        fr_assert(!tmpl_contains_regex(tmpl));
 
        MEM(ut = talloc(stack, unlang_tmpl_t));
        *ut = (unlang_tmpl_t){
                .self = tmpl_instruction,
                .tmpl = tmpl
        };
 
        /*
         *      Push a new tmpl frame onto the stack
         */
        if (unlang_interpret_push(NULL, request, unlang_tmpl_to_generic(ut),
                                  FRAME_CONF(RLM_MODULE_NOT_SET, false), UNLANG_NEXT_STOP) < 0) return -1;
 
        frame = &stack->frame[stack->depth];
        state = talloc_get_type_abort(frame->state, unlang_frame_state_tmpl_t);
 
        /*
         *      Set the frame as repeatable so that multiple tmpls can
         *      be pushed on the stack before returning UNLANG_ACTION_PUSHED_CHILD
         */
        repeatable_set(frame);
 
        *state = (unlang_frame_state_tmpl_t) {
                .out = out,
                .ctx = ctx,
        };
        if (args) state->args = *args;  /* Copy these because they're usually ephemeral/initialised as compound literal */
 
        /*
         *      Default to something sensible
         *      instead of locking the same indefinitely.
         */
        if (!fr_time_delta_ispos(state->args.exec.timeout)) state->args.exec.timeout = fr_time_delta_from_sec(EXEC_TIMEOUT);
 
        fr_value_box_list_init(&state->list);
 
        return 0;
}
 
void unlang_tmpl_init(void)
{
        unlang_register(UNLANG_TYPE_TMPL,
                           &(unlang_op_t){
                                .name = "tmpl",
                                .interpret = unlang_tmpl,
                                .signal = unlang_tmpl_signal,
                                .frame_state_size = sizeof(unlang_frame_state_tmpl_t),
                                .frame_state_type = "unlang_frame_state_tmpl_t",
                           });
}