6:54 p.m.
Adapt audit to use task watchers.
Signed-off-by: Matt Helsley <matthltc(a)us.ibm.com>
Cc: David Woodhouse <dwmw2(a)infradead.org>
Cc: linux-audit(a)redhat.com
--
kernel/audit.c | 25 ++++++++++++++++++++++++-
kernel/exit.c | 3 ---
kernel/fork.c | 7 +------
3 files changed, 25 insertions(+), 10 deletions(-)
Index: linux-2.6.17-rc5-mm2/kernel/exit.c
===================================================================
--- linux-2.6.17-rc5-mm2.orig/kernel/exit.c
+++ linux-2.6.17-rc5-mm2/kernel/exit.c
@@ -35,11 +35,10 @@
#include <linux/posix-timers.h>
#include <linux/mutex.h>
#include <linux/futex.h>
#include <linux/compat.h>
#include <linux/pipe_fs_i.h>
-#include <linux/audit.h> /* for audit_free() */
#include <linux/resource.h>
#include <linux/notifier.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -914,12 +913,10 @@ fastcall NORET_TYPE void do_exit(long co
exit_robust_list(tsk);
#ifdef CONFIG_COMPAT
if (unlikely(tsk->compat_robust_list))
compat_exit_robust_list(tsk);
#endif
- if (unlikely(tsk->audit_context))
- audit_free(tsk);
tsk->exit_code = code;
taskstats_exit_send(tsk, tidstats, tgidstats);
taskstats_exit_free(tidstats, tgidstats);
delayacct_tsk_exit(tsk);
notify_result = notify_watchers(WATCH_TASK_FREE, tsk);
Index: linux-2.6.17-rc5-mm2/kernel/audit.c
===================================================================
--- linux-2.6.17-rc5-mm2.orig/kernel/audit.c
+++ linux-2.6.17-rc5-mm2/kernel/audit.c
@@ -46,10 +46,11 @@
#include <asm/atomic.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/kthread.h>
+#include <linux/notifier.h>
#include <linux/audit.h>
#include <net/sock.h>
#include <net/netlink.h>
@@ -64,10 +65,30 @@
static int audit_initialized;
/* No syscall auditing will take place unless audit_enabled != 0. */
int audit_enabled;
+static int audit_task(struct notifier_block *nb, unsigned long val, void *t)
+{
+ struct task_struct *tsk = t;
+
+ switch(get_watch_event(val)) {
+ case WATCH_TASK_INIT:
+ /* Hack: -EFOO sets NOTIFY_STOP_MASK */
+ return audit_alloc(tsk);
+ case WATCH_TASK_FREE:
+ if (unlikely(tsk->audit_context))
+ audit_free(tsk);
+ default:
+ return NOTIFY_DONE;
+ }
+}
+
+static struct notifier_block __read_mostly audit_watch_tasks_nb = {
+ .notifier_call = audit_task,
+};
+
/* Default state when kernel boots without any parameters. */
static int audit_default;
/* If auditing cannot proceed, audit_failure selects what happens. */
static int audit_failure = AUDIT_FAIL_PRINTK;
@@ -707,12 +728,14 @@ static int __init audit_enable(char *str
{
audit_default = !!simple_strtol(str, NULL, 0);
printk(KERN_INFO "audit: %s%s\n",
audit_default ? "enabled" : "disabled",
audit_initialized ? "" : " (after initialization)");
- if (audit_initialized)
+ if (audit_initialized) {
audit_enabled = audit_default;
+ register_task_watcher(&audit_watch_tasks_nb);
+ }
return 1;
}
__setup("audit=", audit_enable);
Index: linux-2.6.17-rc5-mm2/kernel/fork.c
===================================================================
--- linux-2.6.17-rc5-mm2.orig/kernel/fork.c
+++ linux-2.6.17-rc5-mm2/kernel/fork.c
@@ -38,11 +38,10 @@
#include <linux/jiffies.h>
#include <linux/futex.h>
#include <linux/rcupdate.h>
#include <linux/ptrace.h>
#include <linux/mount.h>
-#include <linux/audit.h>
#include <linux/profile.h>
#include <linux/rmap.h>
#include <linux/acct.h>
#include <linux/delayacct.h>
#include <linux/notifier.h>
@@ -1088,15 +1087,13 @@ static task_t *copy_process(unsigned lon
p->softirq_context = 0;
#endif
if ((retval = security_task_alloc(p)))
goto bad_fork_cleanup_policy;
- if ((retval = audit_alloc(p)))
- goto bad_fork_cleanup_security;
/* copy all the process information */
if ((retval = copy_semundo(clone_flags, p)))
- goto bad_fork_cleanup_audit;
+ goto bad_fork_cleanup_security;
if ((retval = copy_files(clone_flags, p)))
goto bad_fork_cleanup_semundo;
if ((retval = copy_fs(clone_flags, p)))
goto bad_fork_cleanup_files;
if ((retval = copy_sighand(clone_flags, p)))
@@ -1270,12 +1267,10 @@ bad_fork_cleanup_fs:
exit_fs(p); /* blocking */
bad_fork_cleanup_files:
exit_files(p); /* blocking */
bad_fork_cleanup_semundo:
exit_sem(p);
-bad_fork_cleanup_audit:
- audit_free(p);
bad_fork_cleanup_security:
security_task_free(p);
notify_result = notify_watchers(WATCH_TASK_FREE, p);
WARN_ON(notify_result & NOTIFY_STOP_MASK);
bad_fork_cleanup_policy:
--
6:28 p.m.
On Wed, 2006-06-14 at 10:46 -0400, Alexander Viro wrote:
On Tue, Jun 13, 2006 at 04:54:46PM -0700, Matt Helsley wrote:
> Adapt audit to use task watchers.
audit_free(p) really expects that either p is a stillborn (never ran)
*or* that p == current.
Makes sense. I think the task watcher patches are consistent with this.
I think the first patch of this series helps explain how this patch
remains consistent with the above. I should have cc'd linux-audit when
posting that patch -- here's a link for now:
http://www.ussg.iu.edu/hypermail/linux/kernel/0606.1/1800.html
In copy_process() and do_exit() notify_watchers() passes the same
pointers as audit_alloc() and audit_free() used before. The patches also
do not introduce or remove calls to audit_alloc() or audit_free(). The
patches trigger these calls with notify_watchers() while passing
WATCH_TASK_INIT and WATCH_TASK_FREE for audit_alloc() and audit_free()
respectively. WATCH_TASK_INIT (and hence audit_alloc()) only happens in
copy_process(). WATCH_TASK_FREE (and hence audit_free()) happens in
copy_process()'s error recovery path and in do_exit().
This results in the same calls to audit_alloc() and audit_free() except
with an additional function call preceding them on the stack.
Are you concerned that future modifications of task watchers would pass
in task structs that violate these expectations? I can alter the patches
to incorporate these restrictions:
copy_process()
{
...
notify_watchers(WATCH_TASK_INIT, p);
...
if (<succeeding>)
notify_watchers(WATCH_TASK_CLONE, p);
...
bad_foo:
...
- notify_watchers(WATCH_TASK_FREE, p);
+ notify_watchers(WATCH_TASK_ABORT, p);
...
}
<change all other notify_watchers() invocations to pass NULL as
the second parameter, e.g.>
do_exit()
{
...
notify_watchers(WATCH_TSK_FREE, NULL); /* callees must use current */
}
However this requires that I modify each user of task watchers with
something like:
int foo (struct notifier_block *nb, unsigned long val, void *v)
{
- struct task_struct *tsk = v;
+ struct task_struct *tsk = current;
...
switch(get_watch_event(val)) {
case WATCH_TASK_INIT:
+ tsk = v; /* INIT and ABORT use v, the rest use current */
...
+ case WATCH_TASK_ABORT:
+ tsk = v; /* fall through */
case WATCH_TASK_FREE:
...
}
...
}
Which seems a bit more complicated. Is this worth it?
Cheers,
-Matt Helsley
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6767
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linux-audit@lists.linux-audit.osci.io
2 comments
2 participants
participants (2)
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Alexander Viro -
Matt Helsley