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kernel: unregister vfs_read hook to avoid read performance

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weishu
2023-01-02 21:43:02 +07:00
parent ae18ab2b5e
commit 2e8645b50e
1 changed files with 15 additions and 8 deletions
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23
kernel/sucompat.c
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@@ -1,4 +1,5 @@
#include "linux/workqueue.h"
#include <asm/current.h>
#include <linux/cred.h>
#include <linux/dcache.h>
@@ -161,7 +162,8 @@ static const char KERNEL_SU_RC[] =
"\n"
;
static void unregister_read_kp();
static void unregister_vfs_read_kp();
static struct work_struct unregister_vfs_read_work;
static int read_handler_pre(struct kprobe *p, struct pt_regs *regs)
{
@@ -185,7 +187,7 @@ static int read_handler_pre(struct kprobe *p, struct pt_regs *regs)
const char *short_name = file->f_path.dentry->d_name.name;
if (strcmp(short_name, "vold.rc")) {
// we are only interest `init.rc` file name file
// we are only interest `vold.rc` file name file
return 0;
}
char path[PATH_MAX];
@@ -202,12 +204,12 @@ static int read_handler_pre(struct kprobe *p, struct pt_regs *regs)
static bool rc_inserted = false;
if (rc_inserted) {
// we don't need this kprobe, unregister it!
unregister_read_kp();
unregister_vfs_read_kp();
return 0;
}
rc_inserted = true;
// now we can sure that the init process is reading `/system/etc/init/hw/init.rc`
// now we can sure that the init process is reading `/system/etc/init/vold.rc`
buf = PT_REGS_PARM2(regs);
count = PT_REGS_PARM3(regs);
size_t rc_count = strlen(KERNEL_SU_RC);
@@ -250,10 +252,13 @@ static struct kprobe vfs_read_kp = {
.pre_handler = read_handler_pre,
};
static void unregister_read_kp() {
// todo: add it to kernel worker
// unregister_kprobe(&vfs_read_kp);
pr_info("unregister vfs_read kprobe!\n");
static void do_unregister_vfs_read_kp(struct work_struct *work) {
unregister_kprobe(&vfs_read_kp);
}
static void unregister_vfs_read_kp() {
bool ret = schedule_work(&unregister_vfs_read_work);
pr_info("unregister vfs_read kprobe: %d!\n", ret);
}
// sucompat: permited process can execute 'su' to gain root access.
@@ -270,4 +275,6 @@ void enable_sucompat()
ret = register_kprobe(&vfs_read_kp);
pr_info("vfs_read_kp: %d\n", ret);
INIT_WORK(&unregister_vfs_read_work, do_unregister_vfs_read_kp);
}