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Remove ashmem

Browse Source 
Use memfd
This commit is contained in:
llyyr 2025-03-05 06:03:00 +05:30
parent 10c115cdde
commit 18f37babc3
15 changed files with 21 additions and 1148 deletions
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1
99-anbox.rules
View File

@ -1,2 +1 @@
KERNEL=="ashmem", MODE="0666"
KERNEL=="*binder", MODE="0666", SYMLINK+="anbox-%k"

11
INSTALL.sh
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@ -4,16 +4,13 @@
sudo cp anbox.conf /etc/modules-load.d/
sudo cp 99-anbox.rules /lib/udev/rules.d/
# Then copy the module sources to /usr/src/:
sudo cp -rT ashmem /usr/src/anbox-ashmem-1
# Then copy the module source to /usr/src/:
sudo cp -rT binder /usr/src/anbox-binder-1
# Finally use dkms to build and install:
sudo dkms install anbox-ashmem/1
sudo dkms install anbox-binder/1
# Verify by loading these modules and checking the created devices:
sudo modprobe ashmem_linux
# Verify by loading the module and checking the created device:
sudo modprobe binder_linux
lsmod | grep -e ashmem_linux -e binder_linux
ls -alh /dev/binder /dev/ashmem
lsmod | grep -e binder_linux
ls -alh /dev/binder

30
README.md
View File

@ -1,8 +1,6 @@
[![Build Status](https://travis-ci.org/anbox/anbox-modules.svg?branch=master)](https://travis-ci.org/anbox/anbox-modules)
# Anbox Kernel Module
# Anbox Kernel Modules
This repository contains the kernel modules necessary to run the Anbox
This repository contains the kernel module necessary to run the Anbox
Android container runtime. They're split out of the original Anbox
repository to make packaging in various Linux distributions easier.
@ -29,32 +27,27 @@ You can either run `./INSTALL.sh` script to automate the installation steps or f
* Then copy the module sources to `/usr/src/`:
```
sudo cp -rT ashmem /usr/src/anbox-ashmem-1
sudo cp -rT binder /usr/src/anbox-binder-1
```
* Finally use `dkms` to build and install:
```
sudo dkms install anbox-ashmem/1
sudo dkms install anbox-binder/1
```
You can verify by loading these modules and checking the created devices:
You can verify by loading these module and checking the created device:
```
sudo modprobe ashmem_linux
sudo modprobe binder_linux
lsmod | grep -e ashmem_linux -e binder_linux
ls -alh /dev/binder /dev/ashmem
lsmod | grep -e binder_linux
ls -alh /dev/binder
```
You are expected to see output like:
```
binder_linux 114688 0
ashmem_linux 16384 0
crw-rw-rw- 1 root root 10, 55 Jun 19 16:30 /dev/ashmem
crw-rw-rw- 1 root root 511, 0 Jun 19 16:30 /dev/binder
```
@ -62,17 +55,15 @@ crw-rw-rw- 1 root root 511, 0 Jun 19 16:30 /dev/binder
ou can either run `./UNINSTALL.sh` script to automate the installation steps or follow them manually below:
* First use dkms to remove the modules:
* First use dkms to remove the module:
```
sudo dkms remove anbox-ashmem/1
sudo dkms remove anbox-binder/1
```
* Then remove the module sources from /usr/src/:
```
sudo rm -rf /usr/src/anbox-ashmem-1
sudo rm -rf /usr/src/anbox-binder-1
```
@ -83,22 +74,19 @@ ou can either run `./UNINSTALL.sh` script to automate the installation steps or
sudo rm -f /lib/udev/rules.d/99-anbox.rules
```
You must then restart your device. You can then verify modules were removed by trying to load the modules and checking the created devices:
You must then restart your device. You can then verify module was removed by trying to load the module and checking the created device:
```
sudo modprobe ashmem_linux
sudo modprobe binder_linux
lsmod | grep -e ashmem_linux -e binder_linux
ls -alh /dev/binder /dev/ashmem
lsmod | grep -e binder_linux
ls -alh /dev/binder
```
You are expected to see output like:
```
modprobe: FATAL: Module ashmem_linux not found in directory /lib/modules/6.0.2-76060002-generic
modprobe: FATAL: Module binder_linux not found in directory /lib/modules/6.0.2-76060002-generic
ls: cannot access '/dev/binder': No such file or directory
ls: cannot access '/dev/ashmem': No such file or directory
```
# Packaging:

16
UNINSTALL.sh
View File

@ -1,11 +1,9 @@
#!/usr/bin/env bash
# First use dkms to remove the modules:
sudo dkms remove anbox-ashmem/1
# First use dkms to remove the module:
sudo dkms remove anbox-binder/1
# Then remove the module sources from /usr/src/:
sudo rm -rf /usr/src/anbox-ashmem-1
sudo rm -rf /usr/src/anbox-binder-1
# Finally remove the configuration files:
@ -14,25 +12,19 @@ sudo rm -f /lib/udev/rules.d/99-anbox.rules
# Verify remove by trying to load the modules and checking the created devices:
failed_checks=0
if sudo modprobe ashmem_linux > /dev/null 2>&1; then
failed_checks=1
else
failed_checks=0
fi
if sudo modprobe binder_linux > /dev/null 2>&1; then
failed_checks=1
else
failed_checks=0
fi
if lsmod | grep -e ashmem_linux -e binder_linux > /dev/null 2>&1; then
if lsmod | grep -e binder_linux > /dev/null 2>&1; then
failed_checks=1
else
failed_checks=0
fi
if ls -alh /dev/binder /dev/ashmem > /dev/null 2>&1; then
if ls -alh /dev/binder > /dev/null 2>&1; then
failed_checks=1
else
failed_checks=0
@ -42,4 +34,4 @@ if [ $failed_checks == 1 ]; then
echo "Please restart your device and rerun this script to verify changes"
else
echo "Modules not installed"
fi
fi

1
anbox.conf
View File

@ -1,2 +1 @@
ashmem_linux
binder_linux

18
ashmem/Makefile
View File

@ -1,18 +0,0 @@
ccflags-y += -I$(src) -Wno-error=implicit-int -Wno-int-conversion
obj-m := ashmem_linux.o
ashmem_linux-y := deps.o ashmem.o
KERNEL_SRC ?= /lib/modules/$(shell uname -r)/build
VZ= $(shell uname -r | grep vz)
ifneq ($(VZ),)
ccflags-y += -DVZKERNEL
endif
all:
$(MAKE) -C $(KERNEL_SRC) V=0 M=$$PWD
install:
cp ashmem_linux.ko $(DESTDIR)/
clean:
rm -rf deps.h *.o *.ko *.mod.c *.symvers *.order .*.cmd .tmp_versions

926
ashmem/ashmem.c
View File

@ -1,926 +0,0 @@
/* mm/ashmem.c
*
* Anonymous Shared Memory Subsystem, ashmem
*
* Copyright (C) 2008 Google, Inc.
*
* Robert Love <rlove@google.com>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) "ashmem: " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/falloc.h>
#include <linux/miscdevice.h>
#include <linux/security.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
#include <linux/personality.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/shmem_fs.h>
#include <linux/version.h>
#include "ashmem.h"
#define ASHMEM_NAME_PREFIX "dev/ashmem/"
#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
/**
* struct ashmem_area - The anonymous shared memory area
* @name: The optional name in /proc/pid/maps
* @unpinned_list: The list of all ashmem areas
* @file: The shmem-based backing file
* @size: The size of the mapping, in bytes
* @prot_mask: The allowed protection bits, as vm_flags
*
* The lifecycle of this structure is from our parent file's open() until
* its release(). It is also protected by 'ashmem_mutex'
*
* Warning: Mappings do NOT pin this structure; It dies on close()
*/
struct ashmem_area {
char name[ASHMEM_FULL_NAME_LEN];
struct list_head unpinned_list;
struct file *file;
size_t size;
unsigned long prot_mask;
};
/**
* struct ashmem_range - A range of unpinned/evictable pages
* @lru: The entry in the LRU list
* @unpinned: The entry in its area's unpinned list
* @asma: The associated anonymous shared memory area.
* @pgstart: The starting page (inclusive)
* @pgend: The ending page (inclusive)
* @purged: The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED)
*
* The lifecycle of this structure is from unpin to pin.
* It is protected by 'ashmem_mutex'
*/
struct ashmem_range {
struct list_head lru;
struct list_head unpinned;
struct ashmem_area *asma;
size_t pgstart;
size_t pgend;
unsigned int purged;
};
/* LRU list of unpinned pages, protected by ashmem_mutex */
static LIST_HEAD(ashmem_lru_list);
/*
* long lru_count - The count of pages on our LRU list.
*
* This is protected by ashmem_mutex.
*/
static unsigned long lru_count;
/*
* ashmem_mutex - protects the list of and each individual ashmem_area
*
* Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
*/
static DEFINE_MUTEX(ashmem_mutex);
static struct kmem_cache *ashmem_area_cachep __read_mostly;
static struct kmem_cache *ashmem_range_cachep __read_mostly;
#define range_size(range) \
((range)->pgend - (range)->pgstart + 1)
#define range_on_lru(range) \
((range)->purged == ASHMEM_NOT_PURGED)
#define page_range_subsumes_range(range, start, end) \
(((range)->pgstart >= (start)) && ((range)->pgend <= (end)))
#define page_range_subsumed_by_range(range, start, end) \
(((range)->pgstart <= (start)) && ((range)->pgend >= (end)))
#define page_in_range(range, page) \
(((range)->pgstart <= (page)) && ((range)->pgend >= (page)))
#define page_range_in_range(range, start, end) \
(page_in_range(range, start) || page_in_range(range, end) || \
page_range_subsumes_range(range, start, end))
#define range_before_page(range, page) \
((range)->pgend < (page))
#define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE)
/**
* lru_add() - Adds a range of memory to the LRU list
* @range: The memory range being added.
*
* The range is first added to the end (tail) of the LRU list.
* After this, the size of the range is added to @lru_count
*/
static inline void lru_add(struct ashmem_range *range)
{
list_add_tail(&range->lru, &ashmem_lru_list);
lru_count += range_size(range);
}
/**
* lru_del() - Removes a range of memory from the LRU list
* @range: The memory range being removed
*
* The range is first deleted from the LRU list.
* After this, the size of the range is removed from @lru_count
*/
static inline void lru_del(struct ashmem_range *range)
{
list_del(&range->lru);
lru_count -= range_size(range);
}
/**
* range_alloc() - Allocates and initializes a new ashmem_range structure
* @asma: The associated ashmem_area
* @prev_range: The previous ashmem_range in the sorted asma->unpinned list
* @purged: Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
* @start: The starting page (inclusive)
* @end: The ending page (inclusive)
*
* This function is protected by ashmem_mutex.
*
* Return: 0 if successful, or -ENOMEM if there is an error
*/
static int range_alloc(struct ashmem_area *asma,
struct ashmem_range *prev_range, unsigned int purged,
size_t start, size_t end)
{
struct ashmem_range *range;
range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
if (unlikely(!range))
return -ENOMEM;
range->asma = asma;
range->pgstart = start;
range->pgend = end;
range->purged = purged;
list_add_tail(&range->unpinned, &prev_range->unpinned);
if (range_on_lru(range))
lru_add(range);
return 0;
}
/**
* range_del() - Deletes and dealloctes an ashmem_range structure
* @range: The associated ashmem_range that has previously been allocated
*/
static void range_del(struct ashmem_range *range)
{
list_del(&range->unpinned);
if (range_on_lru(range))
lru_del(range);
kmem_cache_free(ashmem_range_cachep, range);
}
/**
* range_shrink() - Shrinks an ashmem_range
* @range: The associated ashmem_range being shrunk
* @start: The starting byte of the new range
* @end: The ending byte of the new range
*
* This does not modify the data inside the existing range in any way - It
* simply shrinks the boundaries of the range.
*
* Theoretically, with a little tweaking, this could eventually be changed
* to range_resize, and expand the lru_count if the new range is larger.
*/
static inline void range_shrink(struct ashmem_range *range,
size_t start, size_t end)
{
size_t pre = range_size(range);
range->pgstart = start;
range->pgend = end;
if (range_on_lru(range))
lru_count -= pre - range_size(range);
}
/**
* ashmem_open() - Opens an Anonymous Shared Memory structure
* @inode: The backing file's index node(?)
* @file: The backing file
*
* Please note that the ashmem_area is not returned by this function - It is
* instead written to "file->private_data".
*
* Return: 0 if successful, or another code if unsuccessful.
*/
static int ashmem_open(struct inode *inode, struct file *file)
{
struct ashmem_area *asma;
int ret;
ret = generic_file_open(inode, file);
if (unlikely(ret))
return ret;
asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
if (unlikely(!asma))
return -ENOMEM;
INIT_LIST_HEAD(&asma->unpinned_list);
memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
asma->prot_mask = PROT_MASK;
file->private_data = asma;
return 0;
}
/**
* ashmem_release() - Releases an Anonymous Shared Memory structure
* @ignored: The backing file's Index Node(?) - It is ignored here.
* @file: The backing file
*
* Return: 0 if successful. If it is anything else, go have a coffee and
* try again.
*/
static int ashmem_release(struct inode *ignored, struct file *file)
{
struct ashmem_area *asma = file->private_data;
struct ashmem_range *range, *next;
mutex_lock(&ashmem_mutex);
list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
range_del(range);
mutex_unlock(&ashmem_mutex);
if (asma->file)
fput(asma->file);
kmem_cache_free(ashmem_area_cachep, asma);
return 0;
}
/**
* ashmem_read() - Reads a set of bytes from an Ashmem-enabled file
* @file: The associated backing file.
* @buf: The buffer of data being written to
* @len: The number of bytes being read
* @pos: The position of the first byte to read.
*
* Return: 0 if successful, or another return code if not.
*/
static ssize_t ashmem_read(struct file *file, char __user *buf,
size_t len, loff_t *pos)
{
struct ashmem_area *asma = file->private_data;
int ret = 0;
mutex_lock(&ashmem_mutex);
/* If size is not set, or set to 0, always return EOF. */
if (asma->size == 0)
goto out_unlock;
if (!asma->file) {
ret = -EBADF;
goto out_unlock;
}
mutex_unlock(&ashmem_mutex);
/*
* asma and asma->file are used outside the lock here. We assume
* once asma->file is set it will never be changed, and will not
* be destroyed until all references to the file are dropped and
* ashmem_release is called.
*
* kernel_read supersedes vfs_read from kernel version 3.9
*/
#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 9, 0)
ret = __vfs_read(asma->file, buf, len, pos);
#else
ret = kernel_read(asma->file, buf, len, pos);
#endif
if (ret >= 0)
/** Update backing file pos, since f_ops->read() doesn't */
asma->file->f_pos = *pos;
return ret;
out_unlock:
mutex_unlock(&ashmem_mutex);
return ret;
}
static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
{
struct ashmem_area *asma = file->private_data;
int ret;
mutex_lock(&ashmem_mutex);
if (asma->size == 0) {
ret = -EINVAL;
goto out;
}
if (!asma->file) {
ret = -EBADF;
goto out;
}
ret = vfs_llseek(asma->file, offset, origin);
if (ret < 0)
goto out;
/** Copy f_pos from backing file, since f_ops->llseek() sets it */
file->f_pos = asma->file->f_pos;
out:
mutex_unlock(&ashmem_mutex);
return ret;
}
static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
{
return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) |
_calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
_calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC);
}
static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
{
struct ashmem_area *asma = file->private_data;
int ret = 0;
mutex_lock(&ashmem_mutex);
/* user needs to SET_SIZE before mapping */
if (unlikely(!asma->size)) {
ret = -EINVAL;
goto out;
}
/* requested protection bits must match our allowed protection mask */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0) || defined(VZKERNEL)
if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
calc_vm_prot_bits(PROT_MASK, 0))) {
#else
if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) &
calc_vm_prot_bits(PROT_MASK))) {
#endif
ret = -EPERM;
goto out;
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 3, 0)
vm_flags_clear(vma, calc_vm_may_flags(~asma->prot_mask));
#else
vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
#endif
if (!asma->file) {
char *name = ASHMEM_NAME_DEF;
struct file *vmfile;
if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
name = asma->name;
/* ... and allocate the backing shmem file */
vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
if (IS_ERR(vmfile)) {
ret = PTR_ERR(vmfile);
goto out;
}
asma->file = vmfile;
}
get_file(asma->file);
/*
* XXX - Reworked to use shmem_zero_setup() instead of
* shmem_set_file while we're in staging. -jstultz
*/
if (vma->vm_flags & VM_SHARED) {
ret = shmem_zero_setup(vma);
if (ret) {
fput(asma->file);
goto out;
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 18, 0)
} else {
vma_set_anonymous(vma);
}
#else
}
#endif
if (vma->vm_file)
fput(vma->vm_file);
vma->vm_file = asma->file;
out:
mutex_unlock(&ashmem_mutex);
return ret;
}
/*
* ashmem_shrink - our cache shrinker, called from mm/vmscan.c
*
* 'nr_to_scan' is the number of objects to scan for freeing.
*
* 'gfp_mask' is the mask of the allocation that got us into this mess.
*
* Return value is the number of objects freed or -1 if we cannot
* proceed without risk of deadlock (due to gfp_mask).
*
* We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
* chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
* pages freed.
*/
static unsigned long
ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
{
struct ashmem_range *range, *next;
unsigned long freed = 0;
/* We might recurse into filesystem code, so bail out if necessary */
if (!(sc->gfp_mask & __GFP_FS))
return SHRINK_STOP;
mutex_lock(&ashmem_mutex);
list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
loff_t start = range->pgstart * PAGE_SIZE;
loff_t end = (range->pgend + 1) * PAGE_SIZE;
vfs_fallocate(range->asma->file,
FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
start, end - start);
range->purged = ASHMEM_WAS_PURGED;
lru_del(range);
freed += range_size(range);
if (--sc->nr_to_scan <= 0)
break;
}
mutex_unlock(&ashmem_mutex);
return freed;
}
static unsigned long
ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
{
/*
* note that lru_count is count of pages on the lru, not a count of
* objects on the list. This means the scan function needs to return the
* number of pages freed, not the number of objects scanned.
*/
return lru_count;
}
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(6,7,0))
static struct shrinker *ashmem_shrinker;
#else
static struct shrinker ashmem_shrinker = {
.count_objects = ashmem_shrink_count,
.scan_objects = ashmem_shrink_scan,
/*
* XXX (dchinner): I wish people would comment on why they need on
* significant changes to the default value here
*/
.seeks = DEFAULT_SEEKS * 4,
};
#endif
static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
{
int ret = 0;
mutex_lock(&ashmem_mutex);
/* the user can only remove, not add, protection bits */
if (unlikely((asma->prot_mask & prot) != prot)) {
ret = -EINVAL;
goto out;
}
/* does the application expect PROT_READ to imply PROT_EXEC? */
if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
prot |= PROT_EXEC;
asma->prot_mask = prot;
out:
mutex_unlock(&ashmem_mutex);
return ret;
}
static int set_name(struct ashmem_area *asma, void __user *name)
{
int len;
int ret = 0;
char local_name[ASHMEM_NAME_LEN];
/*
* Holding the ashmem_mutex while doing a copy_from_user might cause
* an data abort which would try to access mmap_sem. If another
* thread has invoked ashmem_mmap then it will be holding the
* semaphore and will be waiting for ashmem_mutex, there by leading to
* deadlock. We'll release the mutex and take the name to a local
* variable that does not need protection and later copy the local
* variable to the structure member with lock held.
*/
len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN);
if (len < 0)
return len;
if (len == ASHMEM_NAME_LEN)
local_name[ASHMEM_NAME_LEN - 1] = '\0';
mutex_lock(&ashmem_mutex);
/* cannot change an existing mapping's name */
if (unlikely(asma->file))
ret = -EINVAL;
else
strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
mutex_unlock(&ashmem_mutex);
return ret;
}
static int get_name(struct ashmem_area *asma, void __user *name)
{
int ret = 0;
size_t len;
/*
* Have a local variable to which we'll copy the content
* from asma with the lock held. Later we can copy this to the user
* space safely without holding any locks. So even if we proceed to
* wait for mmap_sem, it won't lead to deadlock.
*/
char local_name[ASHMEM_NAME_LEN];
mutex_lock(&ashmem_mutex);
if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
/*
* Copying only `len', instead of ASHMEM_NAME_LEN, bytes
* prevents us from revealing one user's stack to another.
*/
len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len);
} else {
len = sizeof(ASHMEM_NAME_DEF);
memcpy(local_name, ASHMEM_NAME_DEF, len);
}
mutex_unlock(&ashmem_mutex);
/*
* Now we are just copying from the stack variable to userland
* No lock held
*/
if (unlikely(copy_to_user(name, local_name, len)))
ret = -EFAULT;
return ret;
}
/*
* ashmem_pin - pin the given ashmem region, returning whether it was
* previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
*
* Caller must hold ashmem_mutex.
*/
static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
{
struct ashmem_range *range, *next;
int ret = ASHMEM_NOT_PURGED;
list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
/* moved past last applicable page; we can short circuit */
if (range_before_page(range, pgstart))
break;
/*
* The user can ask us to pin pages that span multiple ranges,
* or to pin pages that aren't even unpinned, so this is messy.
*
* Four cases:
* 1. The requested range subsumes an existing range, so we
* just remove the entire matching range.
* 2. The requested range overlaps the start of an existing
* range, so we just update that range.
* 3. The requested range overlaps the end of an existing
* range, so we just update that range.
* 4. The requested range punches a hole in an existing range,
* so we have to update one side of the range and then
* create a new range for the other side.
*/
if (page_range_in_range(range, pgstart, pgend)) {
ret |= range->purged;
/* Case #1: Easy. Just nuke the whole thing. */
if (page_range_subsumes_range(range, pgstart, pgend)) {
range_del(range);
continue;
}
/* Case #2: We overlap from the start, so adjust it */
if (range->pgstart >= pgstart) {
range_shrink(range, pgend + 1, range->pgend);
continue;
}
/* Case #3: We overlap from the rear, so adjust it */
if (range->pgend <= pgend) {
range_shrink(range, range->pgstart,
pgstart - 1);
continue;
}
/*
* Case #4: We eat a chunk out of the middle. A bit
* more complicated, we allocate a new range for the
* second half and adjust the first chunk's endpoint.
*/
range_alloc(asma, range, range->purged,
pgend + 1, range->pgend);
range_shrink(range, range->pgstart, pgstart - 1);
break;
}
}
return ret;
}
/*
* ashmem_unpin - unpin the given range of pages. Returns zero on success.
*
* Caller must hold ashmem_mutex.
*/
static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
{
struct ashmem_range *range, *next;
unsigned int purged = ASHMEM_NOT_PURGED;
restart:
list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
/* short circuit: this is our insertion point */
if (range_before_page(range, pgstart))
break;
/*
* The user can ask us to unpin pages that are already entirely
* or partially pinned. We handle those two cases here.
*/
if (page_range_subsumed_by_range(range, pgstart, pgend))
return 0;
if (page_range_in_range(range, pgstart, pgend)) {
pgstart = min_t(size_t, range->pgstart, pgstart);
pgend = max_t(size_t, range->pgend, pgend);
purged |= range->purged;
range_del(range);
goto restart;
}
}
return range_alloc(asma, range, purged, pgstart, pgend);
}
/*
* ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
* given interval are unpinned and ASHMEM_IS_PINNED otherwise.
*
* Caller must hold ashmem_mutex.
*/
static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
size_t pgend)
{
struct ashmem_range *range;
int ret = ASHMEM_IS_PINNED;
list_for_each_entry(range, &asma->unpinned_list, unpinned) {
if (range_before_page(range, pgstart))
break;
if (page_range_in_range(range, pgstart, pgend)) {
ret = ASHMEM_IS_UNPINNED;
break;
}
}
return ret;
}
static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
void __user *p)
{
struct ashmem_pin pin;
size_t pgstart, pgend;
int ret = -EINVAL;
if (unlikely(!asma->file))
return -EINVAL;
if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
return -EFAULT;
/* per custom, you can pass zero for len to mean "everything onward" */
if (!pin.len)
pin.len = PAGE_ALIGN(asma->size) - pin.offset;
if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
return -EINVAL;
if (unlikely(((__u32)-1) - pin.offset < pin.len))
return -EINVAL;
if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
return -EINVAL;
pgstart = pin.offset / PAGE_SIZE;
pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
mutex_lock(&ashmem_mutex);
switch (cmd) {
case ASHMEM_PIN:
ret = ashmem_pin(asma, pgstart, pgend);
break;
case ASHMEM_UNPIN:
ret = ashmem_unpin(asma, pgstart, pgend);
break;
case ASHMEM_GET_PIN_STATUS:
ret = ashmem_get_pin_status(asma, pgstart, pgend);
break;
}
mutex_unlock(&ashmem_mutex);
return ret;
}
static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct ashmem_area *asma = file->private_data;
long ret = -ENOTTY;
switch (cmd) {
case ASHMEM_SET_NAME:
ret = set_name(asma, (void __user *)arg);
break;
case ASHMEM_GET_NAME:
ret = get_name(asma, (void __user *)arg);
break;
case ASHMEM_SET_SIZE:
ret = -EINVAL;
if (!asma->file) {
ret = 0;
asma->size = (size_t)arg;
}
break;
case ASHMEM_GET_SIZE:
ret = asma->size;
break;
case ASHMEM_SET_PROT_MASK:
ret = set_prot_mask(asma, arg);
break;
case ASHMEM_GET_PROT_MASK:
ret = asma->prot_mask;
break;
case ASHMEM_PIN:
case ASHMEM_UNPIN:
case ASHMEM_GET_PIN_STATUS:
ret = ashmem_pin_unpin(asma, cmd, (void __user *)arg);
break;
case ASHMEM_PURGE_ALL_CACHES:
ret = -EPERM;
if (capable(CAP_SYS_ADMIN)) {
struct shrink_control sc = {
.gfp_mask = GFP_KERNEL,
.nr_to_scan = LONG_MAX,
};
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(6,7,0))
ret = ashmem_shrink_count(ashmem_shrinker, &sc);
ashmem_shrink_scan(ashmem_shrinker, &sc);
#else
ret = ashmem_shrink_count(&ashmem_shrinker, &sc);
ashmem_shrink_scan(&ashmem_shrinker, &sc);
#endif
}
break;
}
return ret;
}
/* support of 32bit userspace on 64bit platforms */
#ifdef CONFIG_COMPAT
static long compat_ashmem_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
switch (cmd) {
case COMPAT_ASHMEM_SET_SIZE:
cmd = ASHMEM_SET_SIZE;
break;
case COMPAT_ASHMEM_SET_PROT_MASK:
cmd = ASHMEM_SET_PROT_MASK;
break;
}
return ashmem_ioctl(file, cmd, arg);
}
#endif
static const struct file_operations ashmem_fops = {
.owner = THIS_MODULE,
.open = ashmem_open,
.release = ashmem_release,
.read = ashmem_read,
.llseek = ashmem_llseek,
.mmap = ashmem_mmap,
.unlocked_ioctl = ashmem_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = compat_ashmem_ioctl,
#endif
};
static struct miscdevice ashmem_misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = "ashmem",
.fops = &ashmem_fops,
};
static int __init ashmem_init(void)
{
int ret;
ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
sizeof(struct ashmem_area),
0, 0, NULL);
if (unlikely(!ashmem_area_cachep)) {
pr_err("failed to create slab cache\n");
return -ENOMEM;
}
ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
sizeof(struct ashmem_range),
0, 0, NULL);
if (unlikely(!ashmem_range_cachep)) {
pr_err("failed to create slab cache\n");
return -ENOMEM;
}
ret = misc_register(&ashmem_misc);
if (unlikely(ret)) {
pr_err("failed to register misc device!\n");
return ret;
}
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(6,7,0))
ashmem_shrinker = shrinker_alloc(0, "android-ashmem");
if (ashmem_shrinker) {
ashmem_shrinker->count_objects = ashmem_shrink_count;
ashmem_shrinker->scan_objects = ashmem_shrink_scan;
ashmem_shrinker->seeks = DEFAULT_SEEKS * 4;
shrinker_register(ashmem_shrinker);
} else {
return -ENOMEM;
}
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(6,0,0))
register_shrinker(&ashmem_shrinker, "android-ashmem");
#else
register_shrinker(&ashmem_shrinker);
#endif
return 0;
}
static void __exit ashmem_exit(void)
{
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(6,7,0))
shrinker_free(ashmem_shrinker);
#else
unregister_shrinker(&ashmem_shrinker);
#endif
misc_deregister(&ashmem_misc);
kmem_cache_destroy(ashmem_range_cachep);
kmem_cache_destroy(ashmem_area_cachep);
}
module_init(ashmem_init);
module_exit(ashmem_exit);
MODULE_LICENSE("GPL");

27
ashmem/ashmem.h
View File

@ -1,27 +0,0 @@
/*
* include/linux/ashmem.h
*
* Copyright 2008 Google Inc.
* Author: Robert Love
*
* This file is dual licensed. It may be redistributed and/or modified
* under the terms of the Apache 2.0 License OR version 2 of the GNU
* General Public License.
*/
#ifndef _LINUX_ASHMEM_H
#define _LINUX_ASHMEM_H
#include <linux/limits.h>
#include <linux/ioctl.h>
#include <linux/compat.h>
#include "uapi/ashmem.h"
/* support of 32bit userspace on 64bit platforms */
#ifdef CONFIG_COMPAT
#define COMPAT_ASHMEM_SET_SIZE _IOW(__ASHMEMIOC, 3, compat_size_t)
#define COMPAT_ASHMEM_SET_PROT_MASK _IOW(__ASHMEMIOC, 5, unsigned int)
#endif
#endif /* _LINUX_ASHMEM_H */

69
ashmem/deps.c
View File

@ -1,69 +0,0 @@
#include <linux/mm.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/version.h>
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
#ifndef CONFIG_KPROBES
# error "Your kernel does not support KProbes, but this is required to compile ashmem as a kernel module on kernel 5.7 and later"
#endif
typedef unsigned long (*kallsyms_lookup_name_t)(const char *name);
static int dummy_kprobe_handler(struct kprobe *p, struct pt_regs *regs)
{
return 0;
}
static kallsyms_lookup_name_t get_kallsyms_lookup_name_ptr(void)
{
struct kprobe probe;
int ret;
kallsyms_lookup_name_t addr;
memset(&probe, 0, sizeof(probe));
probe.pre_handler = dummy_kprobe_handler;
probe.symbol_name = "kallsyms_lookup_name";
ret = register_kprobe(&probe);
if (ret)
return NULL;
addr = (kallsyms_lookup_name_t) probe.addr;
unregister_kprobe(&probe);
return addr;
}
#endif
/*
* On kernel 5.7 and later, kallsyms_lookup_name() can no longer be called from a kernel
* module for reasons described here: https://lwn.net/Articles/813350/
* As ashmem really needs to use kallsysms_lookup_name() to access some kernel
* functions that otherwise wouldn't be accessible, KProbes are used on later
* kernels to get the address of kallsysms_lookup_name(). The function is
* afterwards used just as before. This is a very dirty hack though and the much
* better solution would be if all the functions that are currently resolved
* with kallsysms_lookup_name() would get an EXPORT_SYMBOL() annotation to
* make them directly accessible to kernel modules.
*/
static unsigned long kallsyms_lookup_name_wrapper(const char *name)
{
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
static kallsyms_lookup_name_t func_ptr = NULL;
if (!func_ptr)
func_ptr = get_kallsyms_lookup_name_ptr();
return func_ptr(name);
#else
return kallsyms_lookup_name(name);
#endif
}
static int (*shmem_zero_setup_ptr)(struct vm_area_struct *) = NULL;
int shmem_zero_setup(struct vm_area_struct *vma)
{
if (!shmem_zero_setup_ptr)
shmem_zero_setup_ptr = kallsyms_lookup_name_wrapper("shmem_zero_setup");
return shmem_zero_setup_ptr(vma);
}

7
ashmem/dkms.conf
View File

@ -1,7 +0,0 @@
PACKAGE_NAME="anbox-ashmem"
PACKAGE_VERSION="1"
CLEAN="make clean"
MAKE[0]="make all KERNEL_SRC=/lib/modules/$kernelver/build"
BUILT_MODULE_NAME[0]="ashmem_linux"
DEST_MODULE_LOCATION[0]="/updates"
AUTOINSTALL="yes"

47
ashmem/uapi/ashmem.h
View File

@ -1,47 +0,0 @@
/*
* drivers/staging/android/uapi/ashmem.h
*
* Copyright 2008 Google Inc.
* Author: Robert Love
*
* This file is dual licensed. It may be redistributed and/or modified
* under the terms of the Apache 2.0 License OR version 2 of the GNU
* General Public License.
*/
#ifndef _UAPI_LINUX_ASHMEM_H
#define _UAPI_LINUX_ASHMEM_H
#include <linux/ioctl.h>
#define ASHMEM_NAME_LEN 256
#define ASHMEM_NAME_DEF "dev/ashmem"
/* Return values from ASHMEM_PIN: Was the mapping purged while unpinned? */
#define ASHMEM_NOT_PURGED 0
#define ASHMEM_WAS_PURGED 1
/* Return values from ASHMEM_GET_PIN_STATUS: Is the mapping pinned? */
#define ASHMEM_IS_UNPINNED 0
#define ASHMEM_IS_PINNED 1
struct ashmem_pin {
__u32 offset; /* offset into region, in bytes, page-aligned */
__u32 len; /* length forward from offset, in bytes, page-aligned */
};
#define __ASHMEMIOC 0x77
#define ASHMEM_SET_NAME _IOW(__ASHMEMIOC, 1, char[ASHMEM_NAME_LEN])
#define ASHMEM_GET_NAME _IOR(__ASHMEMIOC, 2, char[ASHMEM_NAME_LEN])
#define ASHMEM_SET_SIZE _IOW(__ASHMEMIOC, 3, size_t)
#define ASHMEM_GET_SIZE _IO(__ASHMEMIOC, 4)
#define ASHMEM_SET_PROT_MASK _IOW(__ASHMEMIOC, 5, unsigned long)
#define ASHMEM_GET_PROT_MASK _IO(__ASHMEMIOC, 6)
#define ASHMEM_PIN _IOW(__ASHMEMIOC, 7, struct ashmem_pin)
#define ASHMEM_UNPIN _IOW(__ASHMEMIOC, 8, struct ashmem_pin)
#define ASHMEM_GET_PIN_STATUS _IO(__ASHMEMIOC, 9)
#define ASHMEM_PURGE_ALL_CACHES _IO(__ASHMEMIOC, 10)
#endif /* _UAPI_LINUX_ASHMEM_H */

4
debian/control vendored
View File

@ -16,7 +16,7 @@ Package: anbox-modules-dkms
Architecture: all
Depends:
${misc:Depends},
Description: Android kernel driver (binder, ashmem) in DKMS format.
Description: Android kernel driver (binder) in DKMS format.
.
This package contains a out-of-tree version of the core Android
kernel functionalities binder and ashmem.
kernel functionality binder.

6
debian/dkms vendored
View File

@ -1,9 +1,7 @@
PACKAGE_NAME="anbox"
PACKAGE_VERSION="1"
CLEAN="make -C ashmem clean && make -C binder clean"
MAKE[0]="'make' -j$parallel_jobs -C ashmem KERNEL_SRC=$kernel_source_dir && make -j$parallel_jobs -C binder KERNEL_SRC=$kernel_source_dir"
BUILT_MODULE_NAME[0]="ashmem_linux"
BUILT_MODULE_LOCATION[0]="ashmem"
CLEAN="make -C binder clean"
MAKE[0]="'make -j$parallel_jobs -C binder KERNEL_SRC=$kernel_source_dir"
DEST_MODULE_LOCATION[0]="/updates"
BUILT_MODULE_NAME[1]="binder_linux"
BUILT_MODULE_LOCATION[1]="binder"

1
debian/install vendored
View File

@ -1,3 +1,2 @@
ashmem usr/src/anbox-1
binder usr/src/anbox-1
anbox.conf /etc/modules-load.d/

5
scripts/build-against-kernel.sh
View File

@ -24,11 +24,6 @@ make prepare CC=${CC} HOSTCC=${CC}
make scripts CC=${CC} HOSTCC=${CC}
)
(
cd ashmem || exit 1
make KERNEL_SRC="../${src_dir}" CC=${CC} HOSTCC=${CC}
)
(
cd binder || exit 1
make KERNEL_SRC="../${src_dir}" CC=${CC} HOSTCC=${CC}