Stop poking into block layer internals and just open the block device file an use kernel_read and kernel_write on it. Note that this means the transformation from name_to_dev_t can't be used anymore when pstore_blk is loaded as a module: a full filesystem device path name must be used instead. Co-developed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- This reworks hch's proposal from https://lore.kernel.org/lkml/20201016132047.3068029-9-hch@xxxxxx/ --- fs/pstore/blk.c | 262 ++++++++++++++++-------------------------------- 1 file changed, 84 insertions(+), 178 deletions(-) diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c index 4bb8a344957a..35458445cbd4 100644 --- a/fs/pstore/blk.c +++ b/fs/pstore/blk.c @@ -8,15 +8,16 @@ #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/fs.h> +#include <linux/file.h> +#include <linux/init_syscalls.h> #include <linux/mount.h> -#include <linux/uio.h> static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE; module_param(kmsg_size, long, 0400); @@ -60,23 +61,25 @@ MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require sto * * 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 + * blkdev accepts the following variants, when built as a module: + * 1) /dev/<disk_name> represents the device number of disk + * 2) /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 + * 3) /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 + * + * blkdev accepts the following variants when built into the kernel: + * 1) <hex_major><hex_minor> device number in hexadecimal representation, + * with no leading 0x, for example b302. + * 2) 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 + * 3) 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 + * 4) <major>:<minor> major and minor number of the device separated by * a colon. */ static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV; @@ -88,15 +91,9 @@ MODULE_PARM_DESC(blkdev, "block device for pstore storage"); * during the register/unregister functions. */ static DEFINE_MUTEX(pstore_blk_lock); -static struct block_device *psblk_bdev; +static struct file *psblk_file; static struct pstore_zone_info *pstore_zone_info; -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); \ @@ -114,8 +111,19 @@ static int __register_pstore_device(struct pstore_device_info *dev) lockdep_assert_held(&pstore_blk_lock); - if (!dev || !dev->total_size || !dev->read || !dev->write) + if (!dev || !dev->total_size || !dev->read || !dev->write) { + if (!dev) + pr_err("NULL device info\n"); + else { + if (!dev->total_size) + pr_err("zero sized device\n"); + if (!dev->read) + pr_err("no read handler for device\n"); + if (!dev->write) + pr_err("no write handler for device\n"); + } return -EINVAL; + } /* someone already registered before */ if (pstore_zone_info) @@ -205,203 +213,101 @@ void unregister_pstore_device(struct pstore_device_info *dev) } 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 = bdev_nr_sectors(bdev); - 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); + return kernel_read(psblk_file, buf, bytes, &pos); } 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; + return kernel_write(psblk_file, buf, bytes, &pos); } /* * This takes its configuration only from the module parameters now. - * See psblk_get_bdev() and blkdev. */ static int __register_pstore_blk(void) { - char bdev_name[BDEVNAME_SIZE]; - struct block_device *bdev; - struct pstore_device_info dev; - struct bdev_info binfo; - void *holder = blkdev; + struct pstore_device_info dev = { + .read = psblk_generic_blk_read, + .write = psblk_generic_blk_write, + }; 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); + if (!__is_defined(MODULE)) { + /* + * During early boot the real root file system hasn't been + * mounted yet, and no device nodes are present yet. Use the + * same scheme to find the device that we use for mounting + * the root file system. + */ + static const char devname[] = "/dev/pstore-blk"; + dev_t dev = name_to_dev_t(blkdev); + + if (!dev) { + pr_err("failed to resolve '%s'!\n", blkdev); + goto err; + } + + init_unlink(devname); + init_mknod(devname, S_IFBLK | 0600, new_encode_dev(dev)); + strscpy(blkdev, devname, sizeof(blkdev)); } - /* only allow driver matching the @blkdev */ - if (!binfo.devt) { - pr_debug("no major\n"); - ret = -ENODEV; - goto err_put_bdev; + psblk_file = filp_open(blkdev, O_RDWR | O_DSYNC | O_NOATIME | O_EXCL, 0); + if (IS_ERR(psblk_file)) { + ret = PTR_ERR(psblk_file); + pr_err("failed to open '%s': %d!\n", blkdev, ret); + goto err; } - /* psblk_bdev must be assigned before register to pstore/blk */ - psblk_bdev = bdev; + if (!S_ISBLK(file_inode(psblk_file)->i_mode)) { + pr_err("'%s' is not block device!\n", blkdev); + goto err_fput; + } - memset(&dev, 0, sizeof(dev)); - dev.total_size = binfo.nr_sects << SECTOR_SHIFT; - dev.read = psblk_generic_blk_read; - dev.write = psblk_generic_blk_write; + if (!psblk_file->f_mapping) + pr_err("missing f_mapping\n"); + else if (!psblk_file->f_mapping->host) + pr_err("missing host\n"); + else if (!I_BDEV(psblk_file->f_mapping->host)) + pr_err("missing I_BDEV\n"); + else if (!I_BDEV(psblk_file->f_mapping->host)->bd_inode) + pr_err("missing bd_inode\n"); + else + dev.total_size = i_size_read(I_BDEV(psblk_file->f_mapping->host)->bd_inode); ret = __register_pstore_device(&dev); if (ret) - goto err_put_bdev; + goto err_fput; - bdevname(bdev, bdev_name); - pr_info("attached %s (no dedicated panic_write!)\n", bdev_name); + pr_info("attached %s (%zu) (no dedicated panic_write!)\n", + blkdev, dev.total_size); return 0; -err_put_bdev: - psblk_bdev = NULL; - psblk_put_bdev(bdev, holder); +err_fput: + fput(psblk_file); +err: + psblk_file = NULL; + return ret; } -static void __unregister_pstore_blk(unsigned int major) +static void __unregister_pstore_blk(struct file *device) { 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) { + if (psblk_file && psblk_file == device) { __unregister_pstore_device(&dev); - psblk_put_bdev(psblk_bdev, holder); - psblk_bdev = NULL; + fput(psblk_file); + psblk_file = NULL; } } @@ -435,8 +341,8 @@ 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)); + if (psblk_file) + __unregister_pstore_blk(psblk_file); else { struct pstore_device_info dev = { }; -- 2.25.1
