bughz
/
anbox-modules
mirror of https://github.com/choff/anbox-modules.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

drop ashmem

This commit is contained in:
Rahammetoela 2024-10-02 09:22:15 -03:00
parent 0a0f26e4a9
commit 966ca69a08
No known key found for this signature in database
GPG Key ID: ACD083CB585C9AA9
6 changed files with 0 additions and 1094 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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 */