From 2459de58989a2794fbf732ab713e8575644dd19c Mon Sep 17 00:00:00 2001
From: jamie <jamie@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Wed, 15 Aug 2018 21:38:44 +0000
Subject: [PATCH] MFC r331332:

  If a jail parameter isn't found, try loading a related kernel module.

PR:		192092


git-svn-id: svn://svn.freebsd.org/base/stable/10@337876 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 lib/libjail/jail.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/lib/libjail/jail.c b/lib/libjail/jail.c
index 207b9f293..c942328ed 100644
--- a/lib/libjail/jail.c
+++ b/lib/libjail/jail.c
@@ -30,6 +30,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/types.h>
 #include <sys/jail.h>
+#include <sys/linker.h>
 #include <sys/socket.h>
 #include <sys/sysctl.h>
 
@@ -57,6 +58,7 @@ __FBSDID("$FreeBSD$");
 static int jailparam_import_enum(const char **values, int nvalues,
     const char *valstr, size_t valsize, int *value);
 static int jailparam_type(struct jailparam *jp);
+static int kldload_param(const char *name);
 static char *noname(const char *name);
 static char *nononame(const char *name);
 
@@ -885,6 +887,9 @@ jailparam_type(struct jailparam *jp)
 			    "sysctl(0.3.%s): %s", name, strerror(errno));
 			return (-1);
 		}
+		if (kldload_param(name) >= 0 && sysctl(mib, 2, mib + 2, &miblen,
+		    desc.s, strlen(desc.s)) >= 0)
+			goto mib_desc;
 		/*
 		 * The parameter probably doesn't exist.  But it might be
 		 * the "no" counterpart to a boolean.
@@ -1023,6 +1028,33 @@ jailparam_type(struct jailparam *jp)
 	return (0);
 }
 
+/*
+ * Attempt to load a kernel module matching an otherwise nonexistent parameter.
+ */
+static int
+kldload_param(const char *name)
+{
+	int kl;
+
+	if (strcmp(name, "linux") == 0 || strncmp(name, "linux.", 6) == 0)
+		kl = kldload("linux");
+	else if (strcmp(name, "sysvmsg") == 0 || strcmp(name, "sysvsem") == 0 ||
+	    strcmp(name, "sysvshm") == 0)
+		kl = kldload(name);
+	else {
+		errno = ENOENT;
+		return (-1);
+	}
+	if (kl < 0 && errno == EEXIST) {
+		/*
+		 * In the module is already loaded, then it must not contain
+		 * the parameter.
+		 */
+		errno = ENOENT;
+	}
+	return kl;
+}
+
 /*
  * Change a boolean parameter name into its "no" counterpart or vice versa.
  */
-- 
2.42.0