Add two new system calls, setloginclass(2) and getloginclass(2). This makes

it possible for the kernel to track login class the process is assigned to,
which is required for RCTL.  This change also make setusercontext(3) call
setloginclass(2) and makes it possible to retrieve current login class using
id(1).

Reviewed by:	kib (as part of a larger patch)

1 files changed, 220 insertions, 0 deletions

diff --git a/sys/kern/kern_loginclass.c b/sys/kern/kern_loginclass.c
new file mode 100644
index 0000000..cf644d5
--- /dev/null
+++ b/sys/kern/kern_loginclass.c
@@ -0,0 +1,220 @@
+/*-
+ * Copyright (c) 2011 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * This software was developed by Edward Tomasz Napierala 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 AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * Processes may set login class name using setloginclass(2).  This
+ * is usually done through call to setusercontext(3), by programs
+ * such as login(1), based on information from master.passwd(5).  Kernel
+ * uses this information to enforce per-class resource limits.  Current
+ * login class can be determined using id(1).  Login class is inherited
+ * from the parent process during fork(2).  If not set, it defaults
+ * to "default".
+ *
+ * Code in this file implements setloginclass(2) and getloginclass(2)
+ * system calls, and maintains class name storage and retrieval.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/eventhandler.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/loginclass.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/types.h>
+#include <sys/priv.h>
+#include <sys/proc.h>
+#include <sys/queue.h>
+#include <sys/refcount.h>
+#include <sys/sysproto.h>
+#include <sys/systm.h>
+
+static MALLOC_DEFINE(M_LOGINCLASS, "loginclass", "loginclass structures");
+
+LIST_HEAD(, loginclass)	loginclasses;
+
+/*
+ * Lock protecting loginclasses list.
+ */
+static struct mtx loginclasses_lock;
+
+static void lc_init(void);
+SYSINIT(loginclass, SI_SUB_CPU, SI_ORDER_FIRST, lc_init, NULL);
+
+void
+loginclass_hold(struct loginclass *lc)
+{
+
+	refcount_acquire(&lc->lc_refcount);
+}
+
+void
+loginclass_free(struct loginclass *lc)
+{
+	int old;
+
+	old = lc->lc_refcount;
+	if (old > 1 && atomic_cmpset_int(&lc->lc_refcount, old, old - 1))
+		return;
+
+	mtx_lock(&loginclasses_lock);
+	if (refcount_release(&lc->lc_refcount)) {
+		LIST_REMOVE(lc, lc_next);
+		mtx_unlock(&loginclasses_lock);
+		free(lc, M_LOGINCLASS);
+
+		return;
+	}
+	mtx_unlock(&loginclasses_lock);
+}
+
+/*
+ * Return loginclass structure with a corresponding name.  Not
+ * performance critical, as it's used mainly by setloginclass(2),
+ * which happens once per login session.  Caller has to use
+ * loginclass_free() on the returned value when it's no longer
+ * needed.
+ */
+struct loginclass *
+loginclass_find(const char *name)
+{
+	struct loginclass *lc, *newlc;
+
+	if (name[0] == '\0' || strlen(name) >= MAXLOGNAME)
+		return (NULL);
+
+	newlc = malloc(sizeof(*newlc), M_LOGINCLASS, M_ZERO | M_WAITOK);
+
+	mtx_lock(&loginclasses_lock);
+	LIST_FOREACH(lc, &loginclasses, lc_next) {
+		if (strcmp(name, lc->lc_name) != 0)
+			continue;
+
+		/* Found loginclass with a matching name? */
+		loginclass_hold(lc);
+		mtx_unlock(&loginclasses_lock);
+		free(newlc, M_LOGINCLASS);
+		return (lc);
+	}
+
+	/* Add new loginclass. */
+	strcpy(newlc->lc_name, name);
+	refcount_init(&newlc->lc_refcount, 1);
+	LIST_INSERT_HEAD(&loginclasses, newlc, lc_next);
+	mtx_unlock(&loginclasses_lock);
+
+	return (newlc);
+}
+
+/*
+ * Get login class name.
+ */
+#ifndef _SYS_SYSPROTO_H_
+struct getloginclass_args {
+	char	*namebuf;
+	size_t	namelen;
+};
+#endif
+/* ARGSUSED */
+int
+getloginclass(struct thread *td, struct getloginclass_args *uap)
+{
+	int error = 0;
+	size_t lcnamelen;
+	struct proc *p;
+	struct loginclass *lc;
+
+	p = td->td_proc;
+	PROC_LOCK(p);
+	lc = p->p_ucred->cr_loginclass;
+	loginclass_hold(lc);
+	PROC_UNLOCK(p);
+
+	lcnamelen = strlen(lc->lc_name) + 1;
+	if (lcnamelen > uap->namelen)
+		error = ERANGE;
+	if (error == 0)
+		error = copyout(lc->lc_name, uap->namebuf, lcnamelen);
+	loginclass_free(lc);
+	return (error);
+}
+
+/*
+ * Set login class name.
+ */
+#ifndef _SYS_SYSPROTO_H_
+struct setloginclass_args {
+	const char	*namebuf;
+};
+#endif
+/* ARGSUSED */
+int
+setloginclass(struct thread *td, struct setloginclass_args *uap)
+{
+	struct proc *p = td->td_proc;
+	int error;
+	char lcname[MAXLOGNAME];
+	struct loginclass *newlc;
+	struct ucred *newcred, *oldcred;
+
+	error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
+	if (error != 0)
+		return (error);
+	error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
+	if (error != 0)
+		return (error);
+
+	newlc = loginclass_find(lcname);
+	if (newlc == NULL)
+		return (EINVAL);
+	newcred = crget();
+
+	PROC_LOCK(p);
+	oldcred = crcopysafe(p, newcred);
+	newcred->cr_loginclass = newlc;
+	p->p_ucred = newcred;
+	PROC_UNLOCK(p);
+
+	loginclass_free(oldcred->cr_loginclass);
+	crfree(oldcred);
+
+	return (0);
+}
+
+static void
+lc_init(void)
+{
+
+	mtx_init(&loginclasses_lock, "loginclasses lock", NULL, MTX_DEF);
+}