security: Add task_exit LSM hook
Add an early callback when a task exits for the LSM to check the state
before its gone.
BUG=b:148390640
TEST=Built and tested with KTD LSM.
SOURCE=KTD
Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
Tested-by: Thomas Garnier <thgarnie@chromium.org>
Change-Id: Ib7b003137c437a3db8495593f10428370bebb76d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/lakitu-kernel/+/2062187
Commit-Queue: Vaibhav Rustagi <vaibhavrustagi@google.com>
Reviewed-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Reviewed-by: Peter Martincic <martincic@google.com>
Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 3833c87..c7a692d 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -683,6 +683,9 @@
* @cred contains the cred of the process where the signal originated, or
* NULL if the current task is the originator.
* Return 0 if permission is granted.
+ * @task_exit:
+ * Called early when a task is exiting before all state is lost.
+ * @p contains the task_struct for process.
* @task_prctl:
* Check permission before performing a process control operation on the
* current process.
@@ -1610,6 +1613,7 @@
int (*task_movememory)(struct task_struct *p);
int (*task_kill)(struct task_struct *p, struct siginfo *info,
int sig, const struct cred *cred);
+ void (*task_exit)(struct task_struct *p);
int (*task_prctl)(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
void (*task_to_inode)(struct task_struct *p, struct inode *inode);
@@ -1897,6 +1901,7 @@
struct hlist_head task_getscheduler;
struct hlist_head task_movememory;
struct hlist_head task_kill;
+ struct hlist_head task_exit;
struct hlist_head task_prctl;
struct hlist_head task_to_inode;
struct hlist_head ipc_permission;
diff --git a/include/linux/security.h b/include/linux/security.h
index d2240605..2ffff66 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -366,6 +366,7 @@
int security_task_movememory(struct task_struct *p);
int security_task_kill(struct task_struct *p, struct siginfo *info,
int sig, const struct cred *cred);
+void security_task_exit(struct task_struct *p);
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
void security_task_to_inode(struct task_struct *p, struct inode *inode);
@@ -1026,6 +1027,9 @@
return 0;
}
+static inline void security_task_exit(struct task_struct *p)
+{ }
+
static inline int security_task_prctl(int option, unsigned long arg2,
unsigned long arg3,
unsigned long arg4,
diff --git a/kernel/exit.c b/kernel/exit.c
index 54c3269..34bb2b0 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -62,6 +62,7 @@
#include <linux/random.h>
#include <linux/rcuwait.h>
#include <linux/compat.h>
+#include <linux/security.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
@@ -855,6 +856,8 @@
#endif
if (tsk->mm)
setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
+
+ security_task_exit(tsk);
}
acct_collect(code, group_dead);
if (group_dead)
diff --git a/security/security.c b/security/security.c
index 9478444..08eb1e9 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1156,6 +1156,11 @@
return call_int_hook(task_kill, 0, p, info, sig, cred);
}
+void security_task_exit(struct task_struct *p)
+{
+ call_void_hook(task_exit, p);
+}
+
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
