verify_exec.c

/*
  Copyright 2021 Northern.tech AS

  This file is part of CFEngine 3 - written and maintained by Northern.tech AS.

  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; version 3.

  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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA

  To the extent this program is licensed as part of the Enterprise
  versions of CFEngine, the applicable Commercial Open Source License
  (COSL) may apply to this file if you as a licensee so wish it. See
  included file COSL.txt.
*/

#include <verify_exec.h>

#include <actuator.h>
#include <promises.h>
#include <files_lib.h>
#include <files_interfaces.h>
#include <vars.h>
#include <conversion.h>
#include <instrumentation.h>
#include <attributes.h>
#include <pipes.h>
#include <locks.h>
#include <evalfunction.h>
#include <exec_tools.h>
#include <misc_lib.h>
#include <writer.h>
#include <policy.h>
#include <string_lib.h>
#include <scope.h>
#include <ornaments.h>
#include <eval_context.h>
#include <retcode.h>
#include <timeout.h>

typedef enum
{
    ACTION_RESULT_OK,
    ACTION_RESULT_TIMEOUT,
    ACTION_RESULT_FAILED
} ActionResult;

static bool SyntaxCheckExec(const Attributes *attr, const Promise *pp);
static bool PromiseKeptExec(const Attributes *a, const Promise *pp);
static char *GetLockNameExec(const Attributes *a, const Promise *pp);
static ActionResult RepairExec(EvalContext *ctx, const Attributes *a, const Promise *pp, PromiseResult *result);

static void PreviewProtocolLine(char *line, char *comm);

char* BuildCommandLine(const Attributes *a, const Promise *pp)
{
    assert(a != NULL);
    Writer *w = StringWriter();
    WriterWriteF(w, "%s", pp->promiser);

    if (a->args)
    {
        WriterWrite(w, " ");
        WriterWrite(w, a->args);
    }

    if (a->arglist)
    {
        for (const Rlist *rp = a->arglist; rp != NULL; rp = rp->next)
        {
            if (rp->val.type == RVAL_TYPE_SCALAR)
            {
                WriterWrite(w, " ");
                WriterWrite(w, RlistScalarValue(rp));
            }
            else
            {
                Log(LOG_LEVEL_INFO, "GetLockNameExec: invalid rval (not a scalar) in arglist of commands promise '%s'", pp->promiser);
            }
        }
    }

    return StringWriterClose(w);
}

PromiseResult VerifyExecPromise(EvalContext *ctx, const Promise *pp)
{
    Attributes a = GetExecAttributes(ctx, pp);

    if (!SyntaxCheckExec(&a, pp))
    {
        return PROMISE_RESULT_FAIL;
    }

    if (PromiseKeptExec(&a, pp))
    {
        return PROMISE_RESULT_NOOP;
    }

    char *lock_name = GetLockNameExec(&a, pp);
    CfLock thislock = AcquireLock(ctx, lock_name, VUQNAME, CFSTARTTIME, a.transaction.ifelapsed, a.transaction.expireafter, pp, false);
    free(lock_name);
    if (thislock.lock == NULL)
    {
        return PROMISE_RESULT_SKIPPED;
    }

    PromiseBanner(ctx,pp);

    PromiseResult result = PROMISE_RESULT_NOOP;
    /* See VerifyCommandRetcode for interpretation of return codes.
     * Unless overridden by attributes in body classes, an exit code 0 means
     * reparied (PROMISE_RESULT_CHANGE), an exit code != 0 means failure.
     */
    switch (RepairExec(ctx, &a, pp, &result))
    {
    case ACTION_RESULT_OK:
        result = PromiseResultUpdate(result, PROMISE_RESULT_NOOP);
        break;

    case ACTION_RESULT_TIMEOUT:
        result = PromiseResultUpdate(result, PROMISE_RESULT_TIMEOUT);
        break;

    case ACTION_RESULT_FAILED:
        result = PromiseResultUpdate(result, PROMISE_RESULT_FAIL);
        break;

    default:
        ProgrammingError("Unexpected ActionResult value");
    }

    YieldCurrentLock(thislock);

    return result;
}

/*****************************************************************************/
/* Level                                                                     */
/*****************************************************************************/

static bool SyntaxCheckExec(const Attributes *attr, const Promise *pp)
{
    assert(attr != NULL);
    Attributes a = *attr; // TODO get rid of this, this function was probably
                          // intended to have side effects on the attr struct
    if ((a.contain.nooutput) && (a.contain.preview))
    {
        Log(LOG_LEVEL_ERR, "no_output and preview are mutually exclusive (broken promise)");
        PromiseRef(LOG_LEVEL_ERR, pp);
        return false;
    }

#ifdef __MINGW32__
    if (a.contain.umask != (mode_t)CF_UNDEFINED)
    {
        Log(LOG_LEVEL_VERBOSE, "contain.umask is ignored on Windows");
    }

    if (a.contain.owner != CF_UNDEFINED)
    {
        Log(LOG_LEVEL_VERBOSE, "contain.exec_owner is ignored on Windows");
    }

    if (a.contain.group != CF_UNDEFINED)
    {
        Log(LOG_LEVEL_VERBOSE, "contain.exec_group is ignored on Windows");
    }

    if (a.contain.chroot != NULL)
    {
        Log(LOG_LEVEL_VERBOSE, "contain.chroot is ignored on Windows");
    }

#else /* !__MINGW32__ */
    if (a.contain.umask == (mode_t)CF_UNDEFINED)
    {
        a.contain.umask = 077; // FIXME: This has no effect!
    }
#endif /* !__MINGW32__ */

    return true;
}

static bool PromiseKeptExec(ARG_UNUSED const Attributes *a, ARG_UNUSED const Promise *pp)
{
    return false;
}

static char *GetLockNameExec(const Attributes *a, const Promise *pp)
{
    return BuildCommandLine(a, pp);
}

/*****************************************************************************/

static ActionResult RepairExec(EvalContext *ctx, const Attributes *a,
                               const Promise *pp, PromiseResult *result)
{
    assert(a != NULL);
    assert(pp != NULL);
    char cmdline[CF_BUFSIZE];
    char comm[20];
    int count = 0;
#if !defined(__MINGW32__)
    mode_t maskval = 0;
#endif
    FILE *pfp;
    char cmdOutBuf[CF_BUFSIZE];
    size_t cmdOutBufPos = 0;
    size_t lineOutLen;
    char module_context[CF_BUFSIZE];

    module_context[0] = '\0';

    if (IsAbsoluteFileName(CommandArg0(pp->promiser)) || a->contain.shelltype == SHELL_TYPE_NONE)
    {
        if (!IsExecutable(CommandArg0(pp->promiser)))
        {
            cfPS(ctx, LOG_LEVEL_ERR, PROMISE_RESULT_FAIL, pp, a, "'%s' promises to be executable but isn't", pp->promiser);
            *result = PromiseResultUpdate(*result, PROMISE_RESULT_FAIL);

            if (strchr(pp->promiser, ' '))
            {
                Log(LOG_LEVEL_VERBOSE, "Paths with spaces must be inside escaped quoutes (e.g. \\\"%s\\\")", pp->promiser);
            }

            return ACTION_RESULT_FAILED;
        }
        else
        {
            Log(LOG_LEVEL_VERBOSE, "Promiser string contains a valid executable '%s' - ok", CommandArg0(pp->promiser));
        }
    }

    char timeout_str[CF_BUFSIZE];
    if (a->contain.timeout == CF_NOINT)
    {
        snprintf(timeout_str, CF_BUFSIZE, "no timeout");
    }
    else
    {
        snprintf(timeout_str, CF_BUFSIZE, "timeout=%ds", a->contain.timeout);
    }

    char owner_str[CF_BUFSIZE] = "";
    if (a->contain.owner != (uid_t) -1)
    {
        snprintf(owner_str, CF_BUFSIZE, ",uid=%ju", (uintmax_t)a->contain.owner);
    }

    char group_str[CF_BUFSIZE] = "";
    if (a->contain.group != (gid_t) -1)
    {
        snprintf(group_str, CF_BUFSIZE, ",gid=%ju", (uintmax_t)a->contain.group);
    }

    char* temp = BuildCommandLine(a, pp);
    snprintf(cmdline, CF_BUFSIZE, "%s", temp); // TODO: remove CF_BUFSIZE limitation
    free(temp);

    const LogLevel info_or_verbose = a->inform ? LOG_LEVEL_INFO : LOG_LEVEL_VERBOSE;
    Log(info_or_verbose, "Executing '%s%s%s' ... '%s'", timeout_str, owner_str, group_str, cmdline);

    BeginMeasure();

    if (DONTDO && (!a->contain.preview))
    {
        cfPS(ctx, LOG_LEVEL_WARNING, PROMISE_RESULT_WARN, pp, a, "Would execute script '%s'", cmdline);
        *result = PromiseResultUpdate(*result, PROMISE_RESULT_WARN);
        return ACTION_RESULT_OK;
    }

    if (a->transaction.action != cfa_fix)
    {
        cfPS(ctx, LOG_LEVEL_WARNING, PROMISE_RESULT_WARN, pp, a, "Command '%s' needs to be executed, but only warning was promised", cmdline);
        *result = PromiseResultUpdate(*result, PROMISE_RESULT_WARN);
        return ACTION_RESULT_OK;
    }

    CommandPrefix(cmdline, comm);

    bool do_work_here = true;

#ifndef __MINGW32__
    if (a->transaction.background)
    {
        Log(LOG_LEVEL_VERBOSE, "Backgrounding job '%s'", cmdline);
        do_work_here = (fork() == 0); // true for child, false for parent
    }
#endif

    if (do_work_here)    // work done here: either by child or non-background parent
    {
        if (a->contain.timeout != CF_NOINT)
        {
            SetTimeOut(a->contain.timeout);
        }

#ifndef __MINGW32__
        Log(LOG_LEVEL_VERBOSE, "Setting umask to %jo", (uintmax_t)a->contain.umask);
        maskval = umask(a->contain.umask);

        if (a->contain.umask == 0)
        {
            Log(LOG_LEVEL_VERBOSE, "Programming '%s' running with umask 0! Use umask= to set", cmdline);
        }
#endif /* !__MINGW32__ */

        const char *open_mode = a->module ? "rt" : "r";
        if (a->contain.shelltype == SHELL_TYPE_POWERSHELL)
        {
#ifdef __MINGW32__
            pfp =
                cf_popen_powershell_setuid(cmdline, open_mode, a->contain.owner, a->contain.group, a->contain.chdir, a->contain.chroot,
                                           a->transaction.background);
#else // !__MINGW32__
            Log(LOG_LEVEL_ERR, "Powershell is only supported on Windows");
            return ACTION_RESULT_FAILED;
#endif // !__MINGW32__
        }
        else if (a->contain.shelltype == SHELL_TYPE_USE)
        {
            pfp =
                cf_popen_shsetuid(cmdline, open_mode, a->contain.owner, a->contain.group, a->contain.chdir, a->contain.chroot,
                                  a->transaction.background);
        }
        else
        {
            pfp =
                cf_popensetuid(cmdline, open_mode, a->contain.owner, a->contain.group, a->contain.chdir, a->contain.chroot,
                               a->transaction.background);
        }

        if (pfp == NULL)
        {
            Log(LOG_LEVEL_ERR, "Couldn't open pipe to command '%s'. (cf_popen: %s)", cmdline, GetErrorStr());
            return ACTION_RESULT_FAILED;
        }

        StringSet *module_tags = StringSetNew();
        long persistence = 0;

        size_t line_size = CF_BUFSIZE;
        char *line = xmalloc(line_size);

        for (;;)
        {
            ssize_t res = CfReadLine(&line, &line_size, pfp);
            if (res == -1)
            {
                if (!feof(pfp))
                {
                    Log(LOG_LEVEL_ERR, "Unable to read output from command '%s'. (fread: %s)", cmdline, GetErrorStr());
                    cf_pclose(pfp);
                    free(line);
                    return ACTION_RESULT_FAILED;
                }
                else
                {
                    break;
                }
            }

            if (strstr(line, "cfengine-die"))
            {
                break;
            }

            if (a->contain.preview)
            {
                PreviewProtocolLine(line, cmdline);
            }

            if (a->module)
            {
                ModuleProtocol(ctx, cmdline, line, !a->contain.nooutput, module_context, sizeof(module_context), module_tags, &persistence);
            }

            if (!a->contain.nooutput && !EmptyString(line))
            {
                lineOutLen = strlen(comm) + strlen(line) + 12;

                // if buffer is to small for this line, output it directly
                if (lineOutLen > sizeof(cmdOutBuf))
                {
                    Log(LOG_LEVEL_NOTICE, "Q: '%s': %s", comm, line);
                }
                else
                {
                    if (cmdOutBufPos + lineOutLen > sizeof(cmdOutBuf))
                    {
                        Log(LOG_LEVEL_NOTICE, "%s", cmdOutBuf);
                        cmdOutBufPos = 0;
                    }
                    snprintf(cmdOutBuf + cmdOutBufPos,
                             sizeof(cmdOutBuf) - cmdOutBufPos,
                             "Q: \"...%s\": %s\n", comm, line);
                    cmdOutBufPos += (lineOutLen - 1);
                }
                count++;
            }
        }

        StringSetDestroy(module_tags);
        free(line);

#ifdef __MINGW32__
        if (a->transaction.background) // only get return value if we waited for command execution
        {
            cf_pclose_nowait(pfp);
        }
        else
#endif /* __MINGW32__ */
        {
            int ret = cf_pclose(pfp);

            if (ret == -1)
            {
                cfPS(ctx, LOG_LEVEL_ERR, PROMISE_RESULT_FAIL, pp, a, "Finished script '%s' - failed (abnormal termination)", pp->promiser);
                *result = PromiseResultUpdate(*result, PROMISE_RESULT_FAIL);
            }
            else
            {
                VerifyCommandRetcode(ctx, ret, a, pp, result);
            }
        }
    }

    if (count)
    {
        if (cmdOutBufPos)
        {
            Log(LOG_LEVEL_NOTICE, "%s", cmdOutBuf);
        }

        Log(LOG_LEVEL_INFO, "Last %d quoted lines were generated by promiser '%s'", count, cmdline);
    }

    if (a->contain.timeout != CF_NOINT)
    {
        alarm(0);
        signal(SIGALRM, SIG_DFL);
    }

    Log(info_or_verbose, "Completed execution of '%s'", cmdline);

#ifndef __MINGW32__
    umask(maskval);
#endif

#ifndef __MINGW32__
    if ((a->transaction.background) && do_work_here) // Child process
    {
        Log(LOG_LEVEL_VERBOSE, "Backgrounded command '%s' is done - exiting", cmdline);

        // _exit() since this is the child and we don't want to run cleanup
        _exit(EXIT_SUCCESS);
    }
#endif /* !__MINGW32__ */

    return ACTION_RESULT_OK;
}

/*************************************************************/
/* Level                                                     */
/*************************************************************/

void PreviewProtocolLine(char *line, char *comm)
{
    int i;
    char *message = line;

    /*
     * Table matching cfoutputlevel enums to log prefixes.
     */

    char *prefixes[] =
        {
            ":silent:",
            ":inform:",
            ":verbose:",
            ":editverbose:",
            ":error:",
            ":logonly:",
        };

    int precount = sizeof(prefixes) / sizeof(char *);

    if (line[0] == ':')
    {
        /*
         * Line begins with colon - see if it matches a log prefix.
         */

        for (i = 0; i < precount; i++)
        {
            int prelen = 0;

            prelen = strlen(prefixes[i]);

            if (strncmp(line, prefixes[i], prelen) == 0)
            {
                /*
                 * Found log prefix - set logging level, and remove the
                 * prefix from the log message.
                 */

                message += prelen;
                break;
            }
        }
    }

    Log(LOG_LEVEL_VERBOSE, "'%s', preview of '%s'", message, comm);
}