Add compatibility for ashmem for Linux 6.0+.

ashmem/Makefile

@@ -1,6 +1,6 @@
 ccflags-y += -I$(src)
 obj-m := ashmem_linux.o
-ashmem_linux-y := ashmem.o deps.o
+ashmem_linux-y := ashmem.o deps.o get_kln.o
 
 KDIR ?= /lib/modules/`uname -r`/build
 

ashmem/ashmem.c

@@ -402,7 +402,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
 		ret = -EPERM;
 		goto out;
 	}
-	vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
+	vm_flags_clear(vma, ~calc_vm_may_flags(~asma->prot_mask));
 
 	if (!asma->file) {
 		char *name = ASHMEM_NAME_DEF;
@@ -947,7 +947,7 @@ static int __init ashmem_init(void)
 		goto out_free2;
 	}
 
-	ret = register_shrinker(&ashmem_shrinker);
+	ret = register_shrinker(&ashmem_shrinker, "ashmem_shrinker");
 	if (ret) {
 		pr_err("failed to register shrinker!\n");
 		goto out_demisc;

ashmem/deps.c

@@ -1,12 +1,15 @@
 #include <linux/mm.h>
 #include <linux/kallsyms.h>
+#include "get_kln.h"
 
 typedef int (*shmem_zero_setup_ptr_t)(struct vm_area_struct *);
 static shmem_zero_setup_ptr_t shmem_zero_setup_ptr = NULL;
 int shmem_zero_setup(struct vm_area_struct *vma)
 {
+	kln_p kln = get_kln_p();
+	if (kln == NULL) return -1;
 	if (!shmem_zero_setup_ptr)
-		shmem_zero_setup_ptr = (shmem_zero_setup_ptr_t) kallsyms_lookup_name("shmem_zero_setup");
+		shmem_zero_setup_ptr = (shmem_zero_setup_ptr_t) kln("shmem_zero_setup");
 	return shmem_zero_setup_ptr(vma);
 }
 

ashmem/get_kln.c

@@ -0,0 +1,70 @@
+/* Reference: https://github.com/xcellerator/linux_kernel_hacking/issues/3 */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+
+#include "get_kln.h"
+
+#define KPROBE_PRE_HANDLER(fname) static int __kprobes fname(struct kprobe *p, struct pt_regs *regs)
+
+long unsigned int kln_addr = 0;
+unsigned long (*kln_pointer)(const char* name) = NULL;
+
+static struct kprobe kp0, kp1;
+
+KPROBE_PRE_HANDLER(handler_pre0) {
+    #if defined(__arm__) || defined(__aarch64__)
+    kln_addr = (--regs->pc);
+    #else
+    kln_addr = (--regs->ip);
+    #endif
+
+    return 0;
+}
+
+KPROBE_PRE_HANDLER(handler_pre1) {
+    return 0;
+}
+
+static int do_register_kprobe(struct kprobe* kp, char* symbol_name, void* handler) {
+    int ret;
+
+    kp->symbol_name = symbol_name;
+    kp->pre_handler = handler;
+
+    ret = register_kprobe(kp);
+    if (ret < 0) {
+        pr_err("do_register_kprobe: failed to register for symbol %s, returning %d\n", symbol_name, ret);
+        return ret;
+    }
+
+    pr_info("Planted krpobe for symbol %s at %p\n", symbol_name, kp->addr);
+
+    return ret;
+}
+
+// this is the function that I have modified, as the name suggests it returns a pointer to the extracted kallsyms_lookup_name function
+kln_p get_kln_p(void) {
+    int status;
+
+    status = do_register_kprobe(&kp0, "kallsyms_lookup_name", handler_pre0);
+
+    if (status < 0) return NULL;
+
+    status = do_register_kprobe(&kp1, "kallsyms_lookup_name", handler_pre1);
+
+    if (status < 0) {
+        // cleaning initial krpobe
+        unregister_kprobe(&kp0);
+        return NULL;
+    }
+
+    unregister_kprobe(&kp0);
+    unregister_kprobe(&kp1);
+
+    pr_info("kallsyms_lookup_name address = 0x%lx\n", kln_addr);
+
+    kln_pointer = (unsigned long (*)(const char* name)) kln_addr;
+
+    return kln_pointer;
+}

ashmem/get_kln.h

@@ -0,0 +1,8 @@
+#ifndef GET_KLN_H
+#define GET_KLN_H
+/* Reference https://github.com/xcellerator/linux_kernel_hacking/issues/3 */
+
+typedef unsigned long (*kln_p)(const char*);
+kln_p get_kln_p(void);
+
+#endif