Module Name: src
Committed By: hannken
Date: Wed Jan 17 10:18:41 UTC 2024
Modified Files:
src/sys/kern: init_main.c kern_hook.c
Log Message:
Protect kernel hooks exechook, exithook and forkhook with rwlock.
Lock as writer on establish/disestablish and as reader on list traverse.
For exechook ride "exec_lock" as it is already take as reader when
traversing the list. Add local locks for exithook and forkhook.
Move exec_init before signal_init as signal_init calls exechook_establish()
that needs "exec_lock".
PR kern/39913 "exec, fork, exit hooks need locking"
To generate a diff of this commit:
cvs rdiff -u -r1.546 -r1.547 src/sys/kern/init_main.c
cvs rdiff -u -r1.14 -r1.15 src/sys/kern/kern_hook.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/init_main.c
diff -u src/sys/kern/init_main.c:1.546 src/sys/kern/init_main.c:1.547
--- src/sys/kern/init_main.c:1.546 Sat Sep 23 18:21:11 2023
+++ src/sys/kern/init_main.c Wed Jan 17 10:18:41 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: init_main.c,v 1.546 2023/09/23 18:21:11 ad Exp $ */
+/* $NetBSD: init_main.c,v 1.547 2024/01/17 10:18:41 hannken Exp $ */
/*-
* Copyright (c) 2008, 2009, 2019, 2023 The NetBSD Foundation, Inc.
@@ -97,7 +97,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.546 2023/09/23 18:21:11 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.547 2024/01/17 10:18:41 hannken Exp $");
#include "opt_cnmagic.h"
#include "opt_ddb.h"
@@ -407,6 +407,9 @@ main(void)
/* Must be called after lwpinit (lwpinit_specificdata) */
psref_init();
+ /* Initialize exec structures */
+ exec_init(1); /* signal_init calls exechook_establish() */
+
/* Initialize signal-related data structures. */
signal_init();
@@ -579,9 +582,6 @@ main(void)
vmem_rehash_start(); /* must be before exec_init */
- /* Initialize exec structures */
- exec_init(1); /* seminit calls exithook_establish() */
-
#if NVERIEXEC > 0
/*
* Initialise the Veriexec subsystem.
Index: src/sys/kern/kern_hook.c
diff -u src/sys/kern/kern_hook.c:1.14 src/sys/kern/kern_hook.c:1.15
--- src/sys/kern/kern_hook.c:1.14 Wed Oct 26 23:21:06 2022
+++ src/sys/kern/kern_hook.c Wed Jan 17 10:18:41 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_hook.c,v 1.14 2022/10/26 23:21:06 riastradh Exp $ */
+/* $NetBSD: kern_hook.c,v 1.15 2024/01/17 10:18:41 hannken Exp $ */
/*-
* Copyright (c) 1997, 1998, 1999, 2002, 2007, 2008 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_hook.c,v 1.14 2022/10/26 23:21:06 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_hook.c,v 1.15 2024/01/17 10:18:41 hannken Exp $");
#include <sys/param.h>
@@ -42,6 +42,7 @@ __KERNEL_RCSID(0, "$NetBSD: kern_hook.c,
#include <sys/hook.h>
#include <sys/kmem.h>
#include <sys/malloc.h>
+#include <sys/once.h>
#include <sys/rwlock.h>
#include <sys/systm.h>
@@ -74,25 +75,48 @@ struct khook_list {
int powerhook_debug = 0;
+static ONCE_DECL(hook_control);
+static krwlock_t exithook_lock;
+static krwlock_t forkhook_lock;
+
+static int
+hook_init(void)
+{
+
+ rw_init(&exithook_lock);
+ rw_init(&forkhook_lock);
+
+ return 0;
+}
+
static void *
-hook_establish(hook_list_t *list, void (*fn)(void *), void *arg)
+hook_establish(hook_list_t *list, krwlock_t *lock,
+ void (*fn)(void *), void *arg)
{
struct hook_desc *hd;
- hd = malloc(sizeof(*hd), M_DEVBUF, M_NOWAIT);
- if (hd == NULL)
- return (NULL);
+ RUN_ONCE(&hook_control, hook_init);
- hd->hk_fn = fn;
- hd->hk_arg = arg;
- LIST_INSERT_HEAD(list, hd, hk_list);
+ hd = malloc(sizeof(*hd), M_DEVBUF, M_NOWAIT);
+ if (hd != NULL) {
+ if (lock)
+ rw_enter(lock, RW_WRITER);
+ hd->hk_fn = fn;
+ hd->hk_arg = arg;
+ LIST_INSERT_HEAD(list, hd, hk_list);
+ if (lock)
+ rw_exit(lock);
+ }
return (hd);
}
static void
-hook_disestablish(hook_list_t *list, void *vhook)
+hook_disestablish(hook_list_t *list, krwlock_t *lock, void *vhook)
{
+
+ if (lock)
+ rw_enter(lock, RW_WRITER);
#ifdef DIAGNOSTIC
struct hook_desc *hd;
@@ -106,6 +130,8 @@ hook_disestablish(hook_list_t *list, voi
#endif
LIST_REMOVE((struct hook_desc *)vhook, hk_list);
free(vhook, M_DEVBUF);
+ if (lock)
+ rw_exit(lock);
}
static void
@@ -120,14 +146,20 @@ hook_destroy(hook_list_t *list)
}
static void
-hook_proc_run(hook_list_t *list, struct proc *p)
+hook_proc_run(hook_list_t *list, krwlock_t *lock, struct proc *p)
{
struct hook_desc *hd;
+ RUN_ONCE(&hook_control, hook_init);
+
+ if (lock)
+ rw_enter(lock, RW_READER);
LIST_FOREACH(hd, list, hk_list) {
__FPTRCAST(void (*)(struct proc *, void *), *hd->hk_fn)(p,
hd->hk_arg);
}
+ if (lock)
+ rw_exit(lock);
}
/*
@@ -146,13 +178,13 @@ static hook_list_t shutdownhook_list = L
void *
shutdownhook_establish(void (*fn)(void *), void *arg)
{
- return hook_establish(&shutdownhook_list, fn, arg);
+ return hook_establish(&shutdownhook_list, NULL, fn, arg);
}
void
shutdownhook_disestablish(void *vhook)
{
- hook_disestablish(&shutdownhook_list, vhook);
+ hook_disestablish(&shutdownhook_list, NULL, vhook);
}
/*
@@ -193,14 +225,14 @@ static hook_list_t mountroothook_list=LI
void *
mountroothook_establish(void (*fn)(device_t), device_t dev)
{
- return hook_establish(&mountroothook_list, __FPTRCAST(void (*), fn),
- dev);
+ return hook_establish(&mountroothook_list, NULL,
+ __FPTRCAST(void (*), fn), dev);
}
void
mountroothook_disestablish(void *vhook)
{
- hook_disestablish(&mountroothook_list, vhook);
+ hook_disestablish(&mountroothook_list, NULL, vhook);
}
void
@@ -227,14 +259,14 @@ static hook_list_t exechook_list = LIST_
void *
exechook_establish(void (*fn)(struct proc *, void *), void *arg)
{
- return hook_establish(&exechook_list, __FPTRCAST(void (*)(void *), fn),
- arg);
+ return hook_establish(&exechook_list, &exec_lock,
+ __FPTRCAST(void (*)(void *), fn), arg);
}
void
exechook_disestablish(void *vhook)
{
- hook_disestablish(&exechook_list, vhook);
+ hook_disestablish(&exechook_list, &exec_lock, vhook);
}
/*
@@ -243,7 +275,9 @@ exechook_disestablish(void *vhook)
void
doexechooks(struct proc *p)
{
- hook_proc_run(&exechook_list, p);
+ KASSERT(rw_lock_held(&exec_lock));
+
+ hook_proc_run(&exechook_list, NULL, p);
}
static hook_list_t exithook_list = LIST_HEAD_INITIALIZER(exithook_list);
@@ -251,22 +285,16 @@ static hook_list_t exithook_list = LIST_
void *
exithook_establish(void (*fn)(struct proc *, void *), void *arg)
{
- void *rv;
- rw_enter(&exec_lock, RW_WRITER);
- rv = hook_establish(&exithook_list, __FPTRCAST(void (*)(void *), fn),
- arg);
- rw_exit(&exec_lock);
- return rv;
+ return hook_establish(&exithook_list, &exithook_lock,
+ __FPTRCAST(void (*)(void *), fn), arg);
}
void
exithook_disestablish(void *vhook)
{
- rw_enter(&exec_lock, RW_WRITER);
- hook_disestablish(&exithook_list, vhook);
- rw_exit(&exec_lock);
+ hook_disestablish(&exithook_list, &exithook_lock, vhook);
}
/*
@@ -275,7 +303,7 @@ exithook_disestablish(void *vhook)
void
doexithooks(struct proc *p)
{
- hook_proc_run(&exithook_list, p);
+ hook_proc_run(&exithook_list, &exithook_lock, p);
}
static hook_list_t forkhook_list = LIST_HEAD_INITIALIZER(forkhook_list);
@@ -283,14 +311,14 @@ static hook_list_t forkhook_list = LIST_
void *
forkhook_establish(void (*fn)(struct proc *, struct proc *))
{
- return hook_establish(&forkhook_list, __FPTRCAST(void (*)(void *), fn),
- NULL);
+ return hook_establish(&forkhook_list, &forkhook_lock,
+ __FPTRCAST(void (*)(void *), fn), NULL);
}
void
forkhook_disestablish(void *vhook)
{
- hook_disestablish(&forkhook_list, vhook);
+ hook_disestablish(&forkhook_list, &forkhook_lock, vhook);
}
/*
@@ -301,10 +329,14 @@ doforkhooks(struct proc *p2, struct proc
{
struct hook_desc *hd;
+ RUN_ONCE(&hook_control, hook_init);
+
+ rw_enter(&forkhook_lock, RW_READER);
LIST_FOREACH(hd, &forkhook_list, hk_list) {
__FPTRCAST(void (*)(struct proc *, struct proc *), *hd->hk_fn)
(p2, p1);
}
+ rw_exit(&forkhook_lock);
}
static hook_list_t critpollhook_list = LIST_HEAD_INITIALIZER(critpollhook_list);
@@ -312,13 +344,13 @@ static hook_list_t critpollhook_list = L
void *
critpollhook_establish(void (*fn)(void *), void *arg)
{
- return hook_establish(&critpollhook_list, fn, arg);
+ return hook_establish(&critpollhook_list, NULL, fn, arg);
}
void
critpollhook_disestablish(void *vhook)
{
- hook_disestablish(&critpollhook_list, vhook);
+ hook_disestablish(&critpollhook_list, NULL, vhook);
}
/*
