linux/fs/pstore/blk.c
Kees Cook f8feafeaee pstore/blk: Introduce "best_effort" mode
In order to use arbitrary block devices as a pstore backend, provide a
new module param named "best_effort", which will allow using any block
device, even if it has not provided a panic_write callback.

Link: https://lore.kernel.org/lkml/20200511233229.27745-12-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@chromium.org>
2020-05-31 19:49:01 -07:00

518 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Implements pstore backend driver that write to block (or non-block) storage
* devices, using the pstore/zone API.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include "../../block/blk.h"
#include <linux/blkdev.h>
#include <linux/string.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pstore_blk.h>
#include <linux/mount.h>
#include <linux/uio.h>
static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE;
module_param(kmsg_size, long, 0400);
MODULE_PARM_DESC(kmsg_size, "kmsg dump record size in kbytes");
static int max_reason = CONFIG_PSTORE_BLK_MAX_REASON;
module_param(max_reason, int, 0400);
MODULE_PARM_DESC(max_reason,
"maximum reason for kmsg dump (default 2: Oops and Panic)");
#if IS_ENABLED(CONFIG_PSTORE_PMSG)
static long pmsg_size = CONFIG_PSTORE_BLK_PMSG_SIZE;
#else
static long pmsg_size = -1;
#endif
module_param(pmsg_size, long, 0400);
MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
#if IS_ENABLED(CONFIG_PSTORE_CONSOLE)
static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE;
#else
static long console_size = -1;
#endif
module_param(console_size, long, 0400);
MODULE_PARM_DESC(console_size, "console size in kbytes");
#if IS_ENABLED(CONFIG_PSTORE_FTRACE)
static long ftrace_size = CONFIG_PSTORE_BLK_FTRACE_SIZE;
#else
static long ftrace_size = -1;
#endif
module_param(ftrace_size, long, 0400);
MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes");
static bool best_effort;
module_param(best_effort, bool, 0400);
MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require storage driver pstore support, default: off)");
/*
* blkdev - the block device to use for pstore storage
*
* Usually, this will be a partition of a block device.
*
* blkdev accepts the following variants:
* 1) <hex_major><hex_minor> device number in hexadecimal representation,
* with no leading 0x, for example b302.
* 2) /dev/<disk_name> represents the device number of disk
* 3) /dev/<disk_name><decimal> represents the device number
* of partition - device number of disk plus the partition number
* 4) /dev/<disk_name>p<decimal> - same as the above, that form is
* used when disk name of partitioned disk ends on a digit.
* 5) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
* unique id of a partition if the partition table provides it.
* The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
* partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
* filled hex representation of the 32-bit "NT disk signature", and PP
* is a zero-filled hex representation of the 1-based partition number.
* 6) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
* a partition with a known unique id.
* 7) <major>:<minor> major and minor number of the device separated by
* a colon.
*/
static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV;
module_param_string(blkdev, blkdev, 80, 0400);
MODULE_PARM_DESC(blkdev, "block device for pstore storage");
/*
* All globals must only be accessed under the pstore_blk_lock
* during the register/unregister functions.
*/
static DEFINE_MUTEX(pstore_blk_lock);
static struct block_device *psblk_bdev;
static struct pstore_zone_info *pstore_zone_info;
static pstore_blk_panic_write_op blkdev_panic_write;
struct bdev_info {
dev_t devt;
sector_t nr_sects;
sector_t start_sect;
};
#define check_size(name, alignsize) ({ \
long _##name_ = (name); \
_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \
if (_##name_ & ((alignsize) - 1)) { \
pr_info(#name " must align to %d\n", \
(alignsize)); \
_##name_ = ALIGN(name, (alignsize)); \
} \
_##name_; \
})
static int __register_pstore_device(struct pstore_device_info *dev)
{
int ret;
lockdep_assert_held(&pstore_blk_lock);
if (!dev || !dev->total_size || !dev->read || !dev->write)
return -EINVAL;
/* someone already registered before */
if (pstore_zone_info)
return -EBUSY;
pstore_zone_info = kzalloc(sizeof(struct pstore_zone_info), GFP_KERNEL);
if (!pstore_zone_info)
return -ENOMEM;
/* zero means not limit on which backends to attempt to store. */
if (!dev->flags)
dev->flags = UINT_MAX;
#define verify_size(name, alignsize, enabled) { \
long _##name_; \
if (enabled) \
_##name_ = check_size(name, alignsize); \
else \
_##name_ = 0; \
name = _##name_ / 1024; \
pstore_zone_info->name = _##name_; \
}
verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG);
verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE);
verify_size(ftrace_size, 4096, dev->flags & PSTORE_FLAGS_FTRACE);
#undef verify_size
pstore_zone_info->total_size = dev->total_size;
pstore_zone_info->max_reason = max_reason;
pstore_zone_info->read = dev->read;
pstore_zone_info->write = dev->write;
pstore_zone_info->erase = dev->erase;
pstore_zone_info->panic_write = dev->panic_write;
pstore_zone_info->name = KBUILD_MODNAME;
pstore_zone_info->owner = THIS_MODULE;
ret = register_pstore_zone(pstore_zone_info);
if (ret) {
kfree(pstore_zone_info);
pstore_zone_info = NULL;
}
return ret;
}
/**
* register_pstore_device() - register non-block device to pstore/blk
*
* @dev: non-block device information
*
* Return:
* * 0 - OK
* * Others - something error.
*/
int register_pstore_device(struct pstore_device_info *dev)
{
int ret;
mutex_lock(&pstore_blk_lock);
ret = __register_pstore_device(dev);
mutex_unlock(&pstore_blk_lock);
return ret;
}
EXPORT_SYMBOL_GPL(register_pstore_device);
static void __unregister_pstore_device(struct pstore_device_info *dev)
{
lockdep_assert_held(&pstore_blk_lock);
if (pstore_zone_info && pstore_zone_info->read == dev->read) {
unregister_pstore_zone(pstore_zone_info);
kfree(pstore_zone_info);
pstore_zone_info = NULL;
}
}
/**
* unregister_pstore_device() - unregister non-block device from pstore/blk
*
* @dev: non-block device information
*/
void unregister_pstore_device(struct pstore_device_info *dev)
{
mutex_lock(&pstore_blk_lock);
__unregister_pstore_device(dev);
mutex_unlock(&pstore_blk_lock);
}
EXPORT_SYMBOL_GPL(unregister_pstore_device);
/**
* psblk_get_bdev() - open block device
*
* @holder: Exclusive holder identifier
* @info: Information about bdev to fill in
*
* Return: pointer to block device on success and others on error.
*
* On success, the returned block_device has reference count of one.
*/
static struct block_device *psblk_get_bdev(void *holder,
struct bdev_info *info)
{
struct block_device *bdev = ERR_PTR(-ENODEV);
fmode_t mode = FMODE_READ | FMODE_WRITE;
sector_t nr_sects;
lockdep_assert_held(&pstore_blk_lock);
if (pstore_zone_info)
return ERR_PTR(-EBUSY);
if (!blkdev[0])
return ERR_PTR(-ENODEV);
if (holder)
mode |= FMODE_EXCL;
bdev = blkdev_get_by_path(blkdev, mode, holder);
if (IS_ERR(bdev)) {
dev_t devt;
devt = name_to_dev_t(blkdev);
if (devt == 0)
return ERR_PTR(-ENODEV);
bdev = blkdev_get_by_dev(devt, mode, holder);
if (IS_ERR(bdev))
return bdev;
}
nr_sects = part_nr_sects_read(bdev->bd_part);
if (!nr_sects) {
pr_err("not enough space for '%s'\n", blkdev);
blkdev_put(bdev, mode);
return ERR_PTR(-ENOSPC);
}
if (info) {
info->devt = bdev->bd_dev;
info->nr_sects = nr_sects;
info->start_sect = get_start_sect(bdev);
}
return bdev;
}
static void psblk_put_bdev(struct block_device *bdev, void *holder)
{
fmode_t mode = FMODE_READ | FMODE_WRITE;
lockdep_assert_held(&pstore_blk_lock);
if (!bdev)
return;
if (holder)
mode |= FMODE_EXCL;
blkdev_put(bdev, mode);
}
static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos)
{
struct block_device *bdev = psblk_bdev;
struct file file;
struct kiocb kiocb;
struct iov_iter iter;
struct kvec iov = {.iov_base = buf, .iov_len = bytes};
if (!bdev)
return -ENODEV;
memset(&file, 0, sizeof(struct file));
file.f_mapping = bdev->bd_inode->i_mapping;
file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
file.f_inode = bdev->bd_inode;
file_ra_state_init(&file.f_ra, file.f_mapping);
init_sync_kiocb(&kiocb, &file);
kiocb.ki_pos = pos;
iov_iter_kvec(&iter, READ, &iov, 1, bytes);
return generic_file_read_iter(&kiocb, &iter);
}
static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes,
loff_t pos)
{
struct block_device *bdev = psblk_bdev;
struct iov_iter iter;
struct kiocb kiocb;
struct file file;
ssize_t ret;
struct kvec iov = {.iov_base = (void *)buf, .iov_len = bytes};
if (!bdev)
return -ENODEV;
/* Console/Ftrace backend may handle buffer until flush dirty zones */
if (in_interrupt() || irqs_disabled())
return -EBUSY;
memset(&file, 0, sizeof(struct file));
file.f_mapping = bdev->bd_inode->i_mapping;
file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
file.f_inode = bdev->bd_inode;
init_sync_kiocb(&kiocb, &file);
kiocb.ki_pos = pos;
iov_iter_kvec(&iter, WRITE, &iov, 1, bytes);
inode_lock(bdev->bd_inode);
ret = generic_write_checks(&kiocb, &iter);
if (ret > 0)
ret = generic_perform_write(&file, &iter, pos);
inode_unlock(bdev->bd_inode);
if (likely(ret > 0)) {
const struct file_operations f_op = {.fsync = blkdev_fsync};
file.f_op = &f_op;
kiocb.ki_pos += ret;
ret = generic_write_sync(&kiocb, ret);
}
return ret;
}
static ssize_t psblk_blk_panic_write(const char *buf, size_t size,
loff_t off)
{
int ret;
if (!blkdev_panic_write)
return -EOPNOTSUPP;
/* size and off must align to SECTOR_SIZE for block device */
ret = blkdev_panic_write(buf, off >> SECTOR_SHIFT,
size >> SECTOR_SHIFT);
/* try next zone */
if (ret == -ENOMSG)
return ret;
return ret ? -EIO : size;
}
static int __register_pstore_blk(struct pstore_blk_info *info)
{
char bdev_name[BDEVNAME_SIZE];
struct block_device *bdev;
struct pstore_device_info dev;
struct bdev_info binfo;
void *holder = blkdev;
int ret = -ENODEV;
lockdep_assert_held(&pstore_blk_lock);
/* hold bdev exclusively */
memset(&binfo, 0, sizeof(binfo));
bdev = psblk_get_bdev(holder, &binfo);
if (IS_ERR(bdev)) {
pr_err("failed to open '%s'!\n", blkdev);
return PTR_ERR(bdev);
}
/* only allow driver matching the @blkdev */
if (!binfo.devt || (!best_effort &&
MAJOR(binfo.devt) != info->major)) {
pr_debug("invalid major %u (expect %u)\n",
info->major, MAJOR(binfo.devt));
ret = -ENODEV;
goto err_put_bdev;
}
/* psblk_bdev must be assigned before register to pstore/blk */
psblk_bdev = bdev;
blkdev_panic_write = info->panic_write;
/* Copy back block device details. */
info->devt = binfo.devt;
info->nr_sects = binfo.nr_sects;
info->start_sect = binfo.start_sect;
memset(&dev, 0, sizeof(dev));
dev.total_size = info->nr_sects << SECTOR_SHIFT;
dev.flags = info->flags;
dev.read = psblk_generic_blk_read;
dev.write = psblk_generic_blk_write;
dev.erase = NULL;
dev.panic_write = info->panic_write ? psblk_blk_panic_write : NULL;
ret = __register_pstore_device(&dev);
if (ret)
goto err_put_bdev;
bdevname(bdev, bdev_name);
pr_info("attached %s%s\n", bdev_name,
info->panic_write ? "" : " (no dedicated panic_write!)");
return 0;
err_put_bdev:
psblk_bdev = NULL;
blkdev_panic_write = NULL;
psblk_put_bdev(bdev, holder);
return ret;
}
/**
* register_pstore_blk() - register block device to pstore/blk
*
* @info: details on the desired block device interface
*
* Return:
* * 0 - OK
* * Others - something error.
*/
int register_pstore_blk(struct pstore_blk_info *info)
{
int ret;
mutex_lock(&pstore_blk_lock);
ret = __register_pstore_blk(info);
mutex_unlock(&pstore_blk_lock);
return ret;
}
EXPORT_SYMBOL_GPL(register_pstore_blk);
static void __unregister_pstore_blk(unsigned int major)
{
struct pstore_device_info dev = { .read = psblk_generic_blk_read };
void *holder = blkdev;
lockdep_assert_held(&pstore_blk_lock);
if (psblk_bdev && MAJOR(psblk_bdev->bd_dev) == major) {
__unregister_pstore_device(&dev);
psblk_put_bdev(psblk_bdev, holder);
blkdev_panic_write = NULL;
psblk_bdev = NULL;
}
}
/**
* unregister_pstore_blk() - unregister block device from pstore/blk
*
* @major: the major device number of device
*/
void unregister_pstore_blk(unsigned int major)
{
mutex_lock(&pstore_blk_lock);
__unregister_pstore_blk(major);
mutex_unlock(&pstore_blk_lock);
}
EXPORT_SYMBOL_GPL(unregister_pstore_blk);
/* get information of pstore/blk */
int pstore_blk_get_config(struct pstore_blk_config *info)
{
strncpy(info->device, blkdev, 80);
info->max_reason = max_reason;
info->kmsg_size = check_size(kmsg_size, 4096);
info->pmsg_size = check_size(pmsg_size, 4096);
info->ftrace_size = check_size(ftrace_size, 4096);
info->console_size = check_size(console_size, 4096);
return 0;
}
EXPORT_SYMBOL_GPL(pstore_blk_get_config);
static int __init pstore_blk_init(void)
{
struct pstore_blk_info info = { };
int ret = 0;
mutex_lock(&pstore_blk_lock);
if (!pstore_zone_info && best_effort && blkdev[0])
ret = __register_pstore_blk(&info);
mutex_unlock(&pstore_blk_lock);
return ret;
}
late_initcall(pstore_blk_init);
static void __exit pstore_blk_exit(void)
{
mutex_lock(&pstore_blk_lock);
if (psblk_bdev)
__unregister_pstore_blk(MAJOR(psblk_bdev->bd_dev));
else {
struct pstore_device_info dev = { };
if (pstore_zone_info)
dev.read = pstore_zone_info->read;
__unregister_pstore_device(&dev);
}
mutex_unlock(&pstore_blk_lock);
}
module_exit(pstore_blk_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
MODULE_DESCRIPTION("pstore backend for block devices");