Place hostnames and similar information fully under the prison system.

The system hostname is now stored in prison0, and the global variable
"hostname" has been removed, as has the hostname_mtx mutex.  Jails may
have their own host information, or they may inherit it from the
parent/system.  The proper way to read the hostname is via
getcredhostname(), which will copy either the hostname associated with
the passed cred, or the system hostname if you pass NULL.  The system
hostname can still be accessed directly (and without locking) at
prison0.pr_host, but that should be avoided where possible.

The "similar information" referred to is domainname, hostid, and
hostuuid, which have also become prison parameters and had their
associated global variables removed.

Approved by:	bz (mentor)

1 files changed, 79 insertions, 77 deletions

diff --git a/sys/kern/kern_mib.c b/sys/kern/kern_mib.c
index 38116d5..823df6b 100644
--- a/sys/kern/kern_mib.c
+++ b/sys/kern/kern_mib.c
@@ -54,7 +54,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/smp.h>
 #include <sys/sx.h>
 #include <sys/unistd.h>
-#include <sys/vimage.h>
 
 SYSCTL_NODE(, 0,	  sysctl, CTLFLAG_RW, 0,
 	"Sysctl internal magic");
@@ -209,71 +208,69 @@ static char	machine_arch[] = MACHINE_ARCH;
 SYSCTL_STRING(_hw, HW_MACHINE_ARCH, machine_arch, CTLFLAG_RD,
     machine_arch, 0, "System architecture");
 
-#ifdef VIMAGE_GLOBALS
-char hostname[MAXHOSTNAMELEN];
-#endif
-
-/*
- * This mutex is used to protect the hostname and domainname variables, and
- * perhaps in the future should also protect hostid, hostuid, and others.
- */
-struct mtx hostname_mtx;
-MTX_SYSINIT(hostname_mtx, &hostname_mtx, "hostname", MTX_DEF);
-
 static int
 sysctl_hostname(SYSCTL_HANDLER_ARGS)
 {
-	INIT_VPROCG(TD_TO_VPROCG(req->td));
-	struct prison *pr;
-	char tmphostname[MAXHOSTNAMELEN];
-	int error;
+	struct prison *pr, *cpr;
+	size_t pr_offset;
+	char tmpname[MAXHOSTNAMELEN];
+	int descend, error, len;
+
+	/*
+	 * This function can set: hostname domainname hostuuid.
+	 * Keep that in mind when comments say "hostname".
+	 */
+	pr_offset = (size_t)arg1;
+	len = arg2;
+	KASSERT(len <= sizeof(tmpname),
+	    ("length %d too long for %s", len, __func__));
 
 	pr = req->td->td_ucred->cr_prison;
-	if (pr != &prison0) {
-		if (!(pr->pr_allow & PR_ALLOW_SET_HOSTNAME) && req->newptr)
-			return (EPERM);
+	if (!(pr->pr_allow & PR_ALLOW_SET_HOSTNAME) && req->newptr)
+		return (EPERM);
+	/*
+	 * Make a local copy of hostname to get/set so we don't have to hold
+	 * the jail mutex during the sysctl copyin/copyout activities.
+	 */
+	mtx_lock(&pr->pr_mtx);
+	bcopy((char *)pr + pr_offset, tmpname, len);
+	mtx_unlock(&pr->pr_mtx);
+
+	error = sysctl_handle_string(oidp, tmpname, len, req);
+
+	if (req->newptr != NULL && error == 0) {
 		/*
-		 * Process is in jail, so make a local copy of jail
-		 * hostname to get/set so we don't have to hold the jail
-		 * mutex during the sysctl copyin/copyout activities.
+		 * Copy the locally set hostname to all jails that share
+		 * this host info.
 		 */
+		sx_slock(&allprison_lock);
+		while (!(pr->pr_flags & PR_HOST))
+			pr = pr->pr_parent;
 		mtx_lock(&pr->pr_mtx);
-		bcopy(pr->pr_host, tmphostname, MAXHOSTNAMELEN);
+		bcopy(tmpname, (char *)pr + pr_offset, len);
+		FOREACH_PRISON_DESCENDANT_LOCKED(pr, cpr, descend)
+			if (cpr->pr_flags & PR_HOST)
+				descend = 0;
+			else
+				bcopy(tmpname, (char *)cpr + pr_offset, len);
 		mtx_unlock(&pr->pr_mtx);
-
-		error = sysctl_handle_string(oidp, tmphostname,
-		    sizeof pr->pr_host, req);
-
-		if (req->newptr != NULL && error == 0) {
-			/*
-			 * Copy the locally set hostname to the jail, if
-			 * appropriate.
-			 */
-			mtx_lock(&pr->pr_mtx);
-			bcopy(tmphostname, pr->pr_host, MAXHOSTNAMELEN);
-			mtx_unlock(&pr->pr_mtx);
-		}
-	} else {
-		mtx_lock(&hostname_mtx);
-		bcopy(V_hostname, tmphostname, MAXHOSTNAMELEN);
-		mtx_unlock(&hostname_mtx);
-		error = sysctl_handle_string(oidp, tmphostname,
-		    sizeof tmphostname, req);
-		if (req->newptr != NULL && error == 0) {
-			mtx_lock(&prison0.pr_mtx);
-			mtx_lock(&hostname_mtx);
-			bcopy(tmphostname, prison0.pr_host, MAXHOSTNAMELEN);
-			bcopy(tmphostname, V_hostname, MAXHOSTNAMELEN);
-			mtx_unlock(&hostname_mtx);
-			mtx_unlock(&prison0.pr_mtx);
-		}
+		sx_sunlock(&allprison_lock);
 	}
 	return (error);
 }
 
 SYSCTL_PROC(_kern, KERN_HOSTNAME, hostname,
-       CTLTYPE_STRING|CTLFLAG_RW|CTLFLAG_PRISON|CTLFLAG_MPSAFE,
-       0, 0, sysctl_hostname, "A", "Hostname");
+    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
+    (void *)(offsetof(struct prison, pr_host)), MAXHOSTNAMELEN,
+    sysctl_hostname, "A", "Hostname");
+SYSCTL_PROC(_kern, KERN_NISDOMAINNAME, domainname,
+    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
+    (void *)(offsetof(struct prison, pr_domain)), MAXHOSTNAMELEN,
+    sysctl_hostname, "A", "Name of the current YP/NIS domain");
+SYSCTL_PROC(_kern, KERN_HOSTUUID, hostuuid,
+    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
+    (void *)(offsetof(struct prison, pr_uuid)), HOSTUUIDLEN,
+    sysctl_hostname, "A", "Host UUID");
 
 static int	regression_securelevel_nonmonotonic = 0;
 
@@ -341,38 +338,43 @@ SYSCTL_PROC(_kern, OID_AUTO, conftxt, CTLTYPE_STRING|CTLFLAG_RW,
     0, 0, sysctl_kern_config, "", "Kernel configuration file");
 #endif
 
-#ifdef VIMAGE_GLOBALS
-char domainname[MAXHOSTNAMELEN];	/* Protected by hostname_mtx. */
-#endif
-
 static int
-sysctl_domainname(SYSCTL_HANDLER_ARGS)
+sysctl_hostid(SYSCTL_HANDLER_ARGS)
 {
-	INIT_VPROCG(TD_TO_VPROCG(req->td));
-	char tmpdomainname[MAXHOSTNAMELEN];
-	int error;
-
-	mtx_lock(&hostname_mtx);
-	bcopy(V_domainname, tmpdomainname, MAXHOSTNAMELEN);
-	mtx_unlock(&hostname_mtx);
-	error = sysctl_handle_string(oidp, tmpdomainname,
-	    sizeof tmpdomainname, req);
+	struct prison *pr, *cpr;
+	u_long tmpid;
+	int descend, error;
+
+	/*
+	 * Like sysctl_hostname, except it operates on a u_long
+	 * instead of a string, and is used only for hostid.
+	 */
+	pr = req->td->td_ucred->cr_prison;
+	if (!(pr->pr_allow & PR_ALLOW_SET_HOSTNAME) && req->newptr)
+		return (EPERM);
+	tmpid = pr->pr_hostid;
+	error = sysctl_handle_long(oidp, &tmpid, 0, req);
+
 	if (req->newptr != NULL && error == 0) {
-		mtx_lock(&hostname_mtx);
-		bcopy(tmpdomainname, V_domainname, MAXHOSTNAMELEN);
-		mtx_unlock(&hostname_mtx);
+		sx_slock(&allprison_lock);
+		while (!(pr->pr_flags & PR_HOST))
+			pr = pr->pr_parent;
+		mtx_lock(&pr->pr_mtx);
+		pr->pr_hostid = tmpid;
+		FOREACH_PRISON_DESCENDANT_LOCKED(pr, cpr, descend)
+			if (cpr->pr_flags & PR_HOST)
+				descend = 0;
+			else
+				cpr->pr_hostid = tmpid;
+		mtx_unlock(&pr->pr_mtx);
+		sx_sunlock(&allprison_lock);
 	}
 	return (error);
 }
 
-SYSCTL_PROC(_kern, KERN_NISDOMAINNAME, domainname, CTLTYPE_STRING|CTLFLAG_RW,
-       0, 0, sysctl_domainname, "A", "Name of the current YP/NIS domain");
-
-u_long hostid;
-SYSCTL_ULONG(_kern, KERN_HOSTID, hostid, CTLFLAG_RW, &hostid, 0, "Host ID");
-char hostuuid[64] = "00000000-0000-0000-0000-000000000000";
-SYSCTL_STRING(_kern, KERN_HOSTUUID, hostuuid, CTLFLAG_RW, hostuuid,
-    sizeof(hostuuid), "Host UUID");
+SYSCTL_PROC(_kern, KERN_HOSTID, hostid,
+    CTLTYPE_ULONG | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE,
+    NULL, 0, sysctl_hostid, "LU", "Host ID");
 
 SYSCTL_NODE(_kern, OID_AUTO, features, CTLFLAG_RD, 0, "Kernel Features");