1073fb03ac
giving access to functionality that is not available in capability mode sandbox. The functionality can be precisely restricted. Start with the following services: - system.dns - provides API compatible to: - gethostbyname(3), - gethostbyname2(3), - gethostbyaddr(3), - getaddrinfo(3), - getnameinfo(3), - system.grp - provides getgrent(3)-compatible API, - system.pwd - provides getpwent(3)-compatible API, - system.random - allows to obtain entropy from /dev/random, - system.sysctl - provides sysctlbyname(3-compatible API. Sponsored by: The FreeBSD Foundation
250 lines
6.2 KiB
C
250 lines
6.2 KiB
C
/*-
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* Copyright (c) 2013 The FreeBSD Foundation
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* All rights reserved.
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*
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* This software was developed by Pawel Jakub Dawidek under sponsorship from
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* the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/sysctl.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <libcapsicum.h>
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#include <libcapsicum_sysctl.h>
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#include <libcasper.h>
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#include <nv.h>
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#include <pjdlog.h>
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static int
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sysctl_check_one(const nvlist_t *nvl, bool islimit)
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{
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const char *name;
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void *cookie;
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int type;
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unsigned int fields;
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/* NULL nvl is of course invalid. */
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if (nvl == NULL)
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return (EINVAL);
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if (nvlist_error(nvl) != 0)
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return (nvlist_error(nvl));
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#define HAS_NAME 0x01
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#define HAS_OPERATION 0x02
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fields = 0;
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cookie = NULL;
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while ((name = nvlist_next(nvl, &type, &cookie)) != NULL) {
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/* We accept only one 'name' and one 'operation' in nvl. */
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if (strcmp(name, "name") == 0) {
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if (type != NV_TYPE_STRING)
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return (EINVAL);
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/* Only one 'name' can be present. */
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if ((fields & HAS_NAME) != 0)
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return (EINVAL);
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fields |= HAS_NAME;
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} else if (strcmp(name, "operation") == 0) {
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uint64_t operation;
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if (type != NV_TYPE_NUMBER)
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return (EINVAL);
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/*
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* We accept only CAP_SYSCTL_READ and
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* CAP_SYSCTL_WRITE flags.
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*/
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operation = nvlist_get_number(nvl, name);
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if ((operation & ~(CAP_SYSCTL_RDWR)) != 0)
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return (EINVAL);
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/* ...but there has to be at least one of them. */
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if ((operation & (CAP_SYSCTL_RDWR)) == 0)
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return (EINVAL);
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/* Only one 'operation' can be present. */
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if ((fields & HAS_OPERATION) != 0)
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return (EINVAL);
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fields |= HAS_OPERATION;
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} else if (islimit) {
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/* If this is limit, there can be no other fields. */
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return (EINVAL);
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}
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}
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/* Both fields has to be there. */
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if (fields != (HAS_NAME | HAS_OPERATION))
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return (EINVAL);
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#undef HAS_OPERATION
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#undef HAS_NAME
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return (0);
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}
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static bool
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sysctl_allowed(const nvlist_t *limits, const char *chname, uint64_t choperation)
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{
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uint64_t operation;
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const char *name;
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void *cookie;
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int type;
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if (limits == NULL)
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return (true);
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cookie = NULL;
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while ((name = nvlist_next(limits, &type, &cookie)) != NULL) {
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PJDLOG_ASSERT(type == NV_TYPE_NUMBER);
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operation = nvlist_get_number(limits, name);
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if ((operation & choperation) != choperation)
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continue;
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if ((operation & CAP_SYSCTL_RECURSIVE) == 0) {
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if (strcmp(name, chname) != 0)
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continue;
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} else {
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size_t namelen;
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namelen = strlen(name);
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if (strncmp(name, chname, namelen) != 0)
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continue;
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if (chname[namelen] != '.' && chname[namelen] != '\0')
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continue;
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}
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return (true);
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}
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return (false);
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}
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static int
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sysctl_limit(const nvlist_t *oldlimits, const nvlist_t *newlimits)
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{
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const nvlist_t *nvl;
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const char *name;
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void *cookie;
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uint64_t operation;
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int error, type;
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cookie = NULL;
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while ((name = nvlist_next(newlimits, &type, &cookie)) != NULL) {
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if (type != NV_TYPE_NUMBER)
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return (EINVAL);
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operation = nvlist_get_number(newlimits, name);
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if ((operation & ~(CAP_SYSCTL_RDWR | CAP_SYSCTL_RECURSIVE)) != 0)
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return (EINVAL);
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if ((operation & (CAP_SYSCTL_RDWR | CAP_SYSCTL_RECURSIVE)) == 0)
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return (EINVAL);
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if (!sysctl_allowed(oldlimits, name, operation))
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return (ENOTCAPABLE);
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}
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return (0);
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}
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static int
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sysctl_command(const char *cmd, const nvlist_t *limits, nvlist_t *nvlin,
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nvlist_t *nvlout)
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{
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const char *name;
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const void *newp;
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void *oldp;
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uint64_t operation;
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size_t oldlen, newlen;
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size_t *oldlenp;
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int error;
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if (strcmp(cmd, "sysctl") != 0)
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return (EINVAL);
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error = sysctl_check_one(nvlin, false);
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if (error != 0)
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return (error);
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name = nvlist_get_string(nvlin, "name");
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operation = nvlist_get_number(nvlin, "operation");
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if (!sysctl_allowed(limits, name, operation))
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return (ENOTCAPABLE);
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if ((operation & CAP_SYSCTL_WRITE) != 0) {
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if (!nvlist_exists_binary(nvlin, "newp"))
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return (EINVAL);
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newp = nvlist_get_binary(nvlin, "newp", &newlen);
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PJDLOG_ASSERT(newp != NULL && newlen > 0);
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} else {
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newp = NULL;
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newlen = 0;
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}
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if ((operation & CAP_SYSCTL_READ) != 0) {
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if (nvlist_exists_null(nvlin, "justsize")) {
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oldp = NULL;
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oldlen = 0;
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oldlenp = &oldlen;
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} else {
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if (!nvlist_exists_number(nvlin, "oldlen"))
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return (EINVAL);
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oldlen = (size_t)nvlist_get_number(nvlin, "oldlen");
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if (oldlen == 0)
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return (EINVAL);
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oldp = calloc(1, oldlen);
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if (oldp == NULL)
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return (ENOMEM);
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oldlenp = &oldlen;
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}
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} else {
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oldp = NULL;
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oldlen = 0;
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oldlenp = NULL;
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}
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if (sysctlbyname(name, oldp, oldlenp, newp, newlen) == -1) {
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error = errno;
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free(oldp);
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return (error);
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}
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if ((operation & CAP_SYSCTL_READ) != 0) {
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if (nvlist_exists_null(nvlin, "justsize"))
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nvlist_add_number(nvlout, "oldlen", (uint64_t)oldlen);
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else
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nvlist_move_binary(nvlout, "oldp", oldp, oldlen);
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}
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return (0);
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}
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int
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main(int argc, char *argv[])
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{
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return (service_start("system.sysctl", PARENT_FILENO, sysctl_limit,
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sysctl_command, argc, argv));
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}
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