Please welcome casperd daemon. It (and its services) will be responsible for

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

2 files changed, 271 insertions, 0 deletions

diff --git a/libexec/casper/sysctl/Makefile b/libexec/casper/sysctl/Makefile
new file mode 100644
index 0000000..dc15099
--- /dev/null
+++ b/libexec/casper/sysctl/Makefile
@@ -0,0 +1,22 @@
+# $FreeBSD$
+
+.PATH:	${.CURDIR} ${.CURDIR}/../../../sbin/casper
+
+PROG=	sysctl
+
+SRCS=	sysctl.c
+
+DPADD=	${LIBCAPSICUM} ${LIBCASPER} ${LIBNV} ${LIBPJDLOG} ${LIBUTIL}
+LDADD=	-lcapsicum -lcasper -lnv -lpjdlog -lutil
+
+BINDIR=	/libexec/casper
+
+CFLAGS+=-I${.CURDIR}
+CFLAGS+=-I${.CURDIR}/../../../lib/libcapsicum
+CFLAGS+=-I${.CURDIR}/../../../lib/libcasper
+CFLAGS+=-I${.CURDIR}/../../../lib/libpjdlog
+CFLAGS+=-I${.CURDIR}/../../../sbin/casper
+
+NO_MAN=
+
+.include <bsd.prog.mk>
diff --git a/libexec/casper/sysctl/sysctl.c b/libexec/casper/sysctl/sysctl.c
new file mode 100644
index 0000000..8bb43b6
--- /dev/null
+++ b/libexec/casper/sysctl/sysctl.c
@@ -0,0 +1,249 @@
+/*-
+ * Copyright (c) 2013 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * This software was developed by Pawel Jakub Dawidek under sponsorship from
+ * the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <libcapsicum.h>
+#include <libcapsicum_sysctl.h>
+#include <libcasper.h>
+#include <nv.h>
+#include <pjdlog.h>
+
+static int
+sysctl_check_one(const nvlist_t *nvl, bool islimit)
+{
+	const char *name;
+	void *cookie;
+	int type;
+	unsigned int fields;
+
+	/* NULL nvl is of course invalid. */
+	if (nvl == NULL)
+		return (EINVAL);
+	if (nvlist_error(nvl) != 0)
+		return (nvlist_error(nvl));
+
+#define	HAS_NAME	0x01
+#define	HAS_OPERATION	0x02
+
+	fields = 0;
+	cookie = NULL;
+	while ((name = nvlist_next(nvl, &type, &cookie)) != NULL) {
+		/* We accept only one 'name' and one 'operation' in nvl. */
+		if (strcmp(name, "name") == 0) {
+			if (type != NV_TYPE_STRING)
+				return (EINVAL);
+			/* Only one 'name' can be present. */
+			if ((fields & HAS_NAME) != 0)
+				return (EINVAL);
+			fields |= HAS_NAME;
+		} else if (strcmp(name, "operation") == 0) {
+			uint64_t operation;
+
+			if (type != NV_TYPE_NUMBER)
+				return (EINVAL);
+			/*
+			 * We accept only CAP_SYSCTL_READ and
+			 * CAP_SYSCTL_WRITE flags.
+			 */
+			operation = nvlist_get_number(nvl, name);
+			if ((operation & ~(CAP_SYSCTL_RDWR)) != 0)
+				return (EINVAL);
+			/* ...but there has to be at least one of them. */
+			if ((operation & (CAP_SYSCTL_RDWR)) == 0)
+				return (EINVAL);
+			/* Only one 'operation' can be present. */
+			if ((fields & HAS_OPERATION) != 0)
+				return (EINVAL);
+			fields |= HAS_OPERATION;
+		} else if (islimit) {
+			/* If this is limit, there can be no other fields. */
+			return (EINVAL);
+		}
+	}
+
+	/* Both fields has to be there. */
+	if (fields != (HAS_NAME | HAS_OPERATION))
+		return (EINVAL);
+
+#undef	HAS_OPERATION
+#undef	HAS_NAME
+
+	return (0);
+}
+
+static bool
+sysctl_allowed(const nvlist_t *limits, const char *chname, uint64_t choperation)
+{
+	uint64_t operation;
+	const char *name;
+	void *cookie;
+	int type;
+
+	if (limits == NULL)
+		return (true);
+
+	cookie = NULL;
+	while ((name = nvlist_next(limits, &type, &cookie)) != NULL) {
+		PJDLOG_ASSERT(type == NV_TYPE_NUMBER);
+
+		operation = nvlist_get_number(limits, name);
+		if ((operation & choperation) != choperation)
+			continue;
+
+		if ((operation & CAP_SYSCTL_RECURSIVE) == 0) {
+			if (strcmp(name, chname) != 0)
+				continue;
+		} else {
+			size_t namelen;
+
+			namelen = strlen(name);
+			if (strncmp(name, chname, namelen) != 0)
+				continue;
+			if (chname[namelen] != '.' && chname[namelen] != '\0')
+				continue;
+		}
+
+		return (true);
+	}
+
+	return (false);
+}
+
+static int
+sysctl_limit(const nvlist_t *oldlimits, const nvlist_t *newlimits)
+{
+	const nvlist_t *nvl;
+	const char *name;
+	void *cookie;
+	uint64_t operation;
+	int error, type;
+
+	cookie = NULL;
+	while ((name = nvlist_next(newlimits, &type, &cookie)) != NULL) {
+		if (type != NV_TYPE_NUMBER)
+			return (EINVAL);
+		operation = nvlist_get_number(newlimits, name);
+		if ((operation & ~(CAP_SYSCTL_RDWR | CAP_SYSCTL_RECURSIVE)) != 0)
+			return (EINVAL);
+		if ((operation & (CAP_SYSCTL_RDWR | CAP_SYSCTL_RECURSIVE)) == 0)
+			return (EINVAL);
+		if (!sysctl_allowed(oldlimits, name, operation))
+			return (ENOTCAPABLE);
+	}
+
+	return (0);
+}
+
+static int
+sysctl_command(const char *cmd, const nvlist_t *limits, nvlist_t *nvlin,
+    nvlist_t *nvlout)
+{
+	const char *name;
+	const void *newp;
+	void *oldp;
+	uint64_t operation;
+	size_t oldlen, newlen;
+	size_t *oldlenp;
+	int error;
+
+	if (strcmp(cmd, "sysctl") != 0)
+		return (EINVAL);
+	error = sysctl_check_one(nvlin, false);
+	if (error != 0)
+		return (error);
+
+	name = nvlist_get_string(nvlin, "name");
+	operation = nvlist_get_number(nvlin, "operation");
+	if (!sysctl_allowed(limits, name, operation))
+		return (ENOTCAPABLE);
+
+	if ((operation & CAP_SYSCTL_WRITE) != 0) {
+		if (!nvlist_exists_binary(nvlin, "newp"))
+			return (EINVAL);
+		newp = nvlist_get_binary(nvlin, "newp", &newlen);
+		PJDLOG_ASSERT(newp != NULL && newlen > 0);
+	} else {
+		newp = NULL;
+		newlen = 0;
+	}
+
+	if ((operation & CAP_SYSCTL_READ) != 0) {
+		if (nvlist_exists_null(nvlin, "justsize")) {
+			oldp = NULL;
+			oldlen = 0;
+			oldlenp = &oldlen;
+		} else {
+			if (!nvlist_exists_number(nvlin, "oldlen"))
+				return (EINVAL);
+			oldlen = (size_t)nvlist_get_number(nvlin, "oldlen");
+			if (oldlen == 0)
+				return (EINVAL);
+			oldp = calloc(1, oldlen);
+			if (oldp == NULL)
+				return (ENOMEM);
+			oldlenp = &oldlen;
+		}
+	} else {
+		oldp = NULL;
+		oldlen = 0;
+		oldlenp = NULL;
+	}
+
+	if (sysctlbyname(name, oldp, oldlenp, newp, newlen) == -1) {
+		error = errno;
+		free(oldp);
+		return (error);
+	}
+
+	if ((operation & CAP_SYSCTL_READ) != 0) {
+		if (nvlist_exists_null(nvlin, "justsize"))
+			nvlist_add_number(nvlout, "oldlen", (uint64_t)oldlen);
+		else
+			nvlist_move_binary(nvlout, "oldp", oldp, oldlen);
+	}
+
+	return (0);
+}
+
+int
+main(int argc, char *argv[])
+{
+
+	return (service_start("system.sysctl", PARENT_FILENO, sysctl_limit,
+	    sysctl_command, argc, argv));
+}