Revert "ANDROID: AVB error handler to invalidate vbmeta partition."

This driver is not used and can cause problems if used on modern
devices. Remove it.

This reverts commit 6115619831.

Bug: 185178770
Signed-off-by: Alistair Delva <adelva@google.com>
Change-Id: I1d5acb96dda765a1e3ea0cf62a3bf4b2a78892ea

arch/arm64/configs/gki_defconfig

@@ -283,7 +283,6 @@ CONFIG_DM_DEFAULT_KEY=y
 CONFIG_DM_SNAPSHOT=y
 CONFIG_DM_UEVENT=y
 CONFIG_DM_VERITY=y
-CONFIG_DM_VERITY_AVB=y
 CONFIG_DM_VERITY_FEC=y
 CONFIG_DM_BOW=y
 CONFIG_NETDEVICES=y

arch/x86/configs/gki_defconfig

@@ -260,7 +260,6 @@ CONFIG_DM_DEFAULT_KEY=y
 CONFIG_DM_SNAPSHOT=y
 CONFIG_DM_UEVENT=y
 CONFIG_DM_VERITY=y
-CONFIG_DM_VERITY_AVB=y
 CONFIG_DM_VERITY_FEC=y
 CONFIG_DM_BOW=y
 CONFIG_NETDEVICES=y

drivers/md/Kconfig

@@ -579,17 +579,6 @@ config DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING
 
 	  If unsure, say N.
 
-config DM_VERITY_AVB
-	tristate "Support AVB specific verity error behavior"
-	depends on DM_VERITY
-	help
-	  Enables Android Verified Boot platform-specific error
-	  behavior. In particular, it will modify the vbmeta partition
-	  specified on the kernel command-line when non-transient error
-	  occurs (followed by a panic).
-
-	  If unsure, say N.
-
 config DM_VERITY_FEC
 	bool "Verity forward error correction support"
 	depends on DM_VERITY

drivers/md/Makefile

@@ -95,10 +95,6 @@ ifeq ($(CONFIG_DM_UEVENT),y)
 dm-mod-objs			+= dm-uevent.o
 endif
 
-ifeq ($(CONFIG_DM_VERITY_AVB),y)
-dm-verity-objs			+= dm-verity-avb.o
-endif
-
 ifeq ($(CONFIG_DM_VERITY_FEC),y)
 dm-verity-objs			+= dm-verity-fec.o
 endif

drivers/md/dm-verity-avb.c

@@ -1,229 +0,0 @@
-/*
- * Copyright (C) 2017 Google.
- *
- * This file is released under the GPLv2.
- *
- * Based on drivers/md/dm-verity-chromeos.c
- */
-
-#include <linux/device-mapper.h>
-#include <linux/module.h>
-#include <linux/mount.h>
-
-#define DM_MSG_PREFIX "verity-avb"
-
-/* Set via module parameters. */
-static char avb_vbmeta_device[64];
-static char avb_invalidate_on_error[4];
-
-static void invalidate_vbmeta_endio(struct bio *bio)
-{
-	if (bio->bi_status)
-		DMERR("invalidate_vbmeta_endio: error %d", bio->bi_status);
-	complete(bio->bi_private);
-}
-
-static int invalidate_vbmeta_submit(struct bio *bio,
-				    struct block_device *bdev,
-				    int op, int access_last_sector,
-				    struct page *page)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-
-	bio->bi_private = &wait;
-	bio->bi_end_io = invalidate_vbmeta_endio;
-	bio_set_dev(bio, bdev);
-	bio_set_op_attrs(bio, op, REQ_SYNC);
-
-	bio->bi_iter.bi_sector = 0;
-	if (access_last_sector) {
-		sector_t last_sector;
-
-		last_sector = (i_size_read(bdev->bd_inode)>>SECTOR_SHIFT) - 1;
-		bio->bi_iter.bi_sector = last_sector;
-	}
-	if (!bio_add_page(bio, page, PAGE_SIZE, 0)) {
-		DMERR("invalidate_vbmeta_submit: bio_add_page error");
-		return -EIO;
-	}
-
-	submit_bio(bio);
-	/* Wait up to 2 seconds for completion or fail. */
-	if (!wait_for_completion_timeout(&wait, msecs_to_jiffies(2000)))
-		return -EIO;
-	return 0;
-}
-
-static int invalidate_vbmeta(dev_t vbmeta_devt)
-{
-	int ret = 0;
-	struct block_device *bdev;
-	struct bio *bio;
-	struct page *page;
-	fmode_t dev_mode;
-	/* Ensure we do synchronous unblocked I/O. We may also need
-	 * sync_bdev() on completion, but it really shouldn't.
-	 */
-	int access_last_sector = 0;
-
-	DMINFO("invalidate_vbmeta: acting on device %d:%d",
-	       MAJOR(vbmeta_devt), MINOR(vbmeta_devt));
-
-	/* First we open the device for reading. */
-	dev_mode = FMODE_READ | FMODE_EXCL;
-	bdev = blkdev_get_by_dev(vbmeta_devt, dev_mode,
-				 invalidate_vbmeta);
-	if (IS_ERR(bdev)) {
-		DMERR("invalidate_kernel: could not open device for reading");
-		dev_mode = 0;
-		ret = -ENOENT;
-		goto failed_to_read;
-	}
-
-	bio = bio_alloc(GFP_NOIO, 1);
-	if (!bio) {
-		ret = -ENOMEM;
-		goto failed_bio_alloc;
-	}
-
-	page = alloc_page(GFP_NOIO);
-	if (!page) {
-		ret = -ENOMEM;
-		goto failed_to_alloc_page;
-	}
-
-	access_last_sector = 0;
-	ret = invalidate_vbmeta_submit(bio, bdev, REQ_OP_READ,
-				       access_last_sector, page);
-	if (ret) {
-		DMERR("invalidate_vbmeta: error reading");
-		goto failed_to_submit_read;
-	}
-
-	/* We have a page. Let's make sure it looks right. */
-	if (memcmp("AVB0", page_address(page), 4) == 0) {
-		/* Stamp it. */
-		memcpy(page_address(page), "AVE0", 4);
-		DMINFO("invalidate_vbmeta: found vbmeta partition");
-	} else {
-		/* Could be this is on a AVB footer, check. Also, since the
-		 * AVB footer is in the last 64 bytes, adjust for the fact that
-		 * we're dealing with 512-byte sectors.
-		 */
-		size_t offset = (1<<SECTOR_SHIFT) - 64;
-
-		access_last_sector = 1;
-		ret = invalidate_vbmeta_submit(bio, bdev, REQ_OP_READ,
-					       access_last_sector, page);
-		if (ret) {
-			DMERR("invalidate_vbmeta: error reading");
-			goto failed_to_submit_read;
-		}
-		if (memcmp("AVBf", page_address(page) + offset, 4) != 0) {
-			DMERR("invalidate_vbmeta on non-vbmeta partition");
-			ret = -EINVAL;
-			goto invalid_header;
-		}
-		/* Stamp it. */
-		memcpy(page_address(page) + offset, "AVE0", 4);
-		DMINFO("invalidate_vbmeta: found vbmeta footer partition");
-	}
-
-	/* Now rewrite the changed page - the block dev was being
-	 * changed on read. Let's reopen here.
-	 */
-	blkdev_put(bdev, dev_mode);
-	dev_mode = FMODE_WRITE | FMODE_EXCL;
-	bdev = blkdev_get_by_dev(vbmeta_devt, dev_mode,
-				 invalidate_vbmeta);
-	if (IS_ERR(bdev)) {
-		DMERR("invalidate_vbmeta: could not open device for writing");
-		dev_mode = 0;
-		ret = -ENOENT;
-		goto failed_to_write;
-	}
-
-	/* We re-use the same bio to do the write after the read. Need to reset
-	 * it to initialize bio->bi_remaining.
-	 */
-	bio_reset(bio);
-
-	ret = invalidate_vbmeta_submit(bio, bdev, REQ_OP_WRITE,
-				       access_last_sector, page);
-	if (ret) {
-		DMERR("invalidate_vbmeta: error writing");
-		goto failed_to_submit_write;
-	}
-
-	DMERR("invalidate_vbmeta: completed.");
-	ret = 0;
-failed_to_submit_write:
-failed_to_write:
-invalid_header:
-	__free_page(page);
-failed_to_submit_read:
-	/* Technically, we'll leak a page with the pending bio, but
-	 * we're about to reboot anyway.
-	 */
-failed_to_alloc_page:
-	bio_put(bio);
-failed_bio_alloc:
-	if (dev_mode)
-		blkdev_put(bdev, dev_mode);
-failed_to_read:
-	return ret;
-}
-
-void dm_verity_avb_error_handler(void)
-{
-	dev_t dev;
-
-	DMINFO("AVB error handler called for %s", avb_vbmeta_device);
-
-	if (strcmp(avb_invalidate_on_error, "yes") != 0) {
-		DMINFO("Not configured to invalidate");
-		return;
-	}
-
-	if (avb_vbmeta_device[0] == '\0') {
-		DMERR("avb_vbmeta_device parameter not set");
-		goto fail_no_dev;
-	}
-
-	dev = name_to_dev_t(avb_vbmeta_device);
-	if (!dev) {
-		DMERR("No matching partition for device: %s",
-		      avb_vbmeta_device);
-		goto fail_no_dev;
-	}
-
-	invalidate_vbmeta(dev);
-
-fail_no_dev:
-	;
-}
-
-static int __init dm_verity_avb_init(void)
-{
-	DMINFO("AVB error handler initialized with vbmeta device: %s",
-	       avb_vbmeta_device);
-	return 0;
-}
-
-static void __exit dm_verity_avb_exit(void)
-{
-}
-
-module_init(dm_verity_avb_init);
-module_exit(dm_verity_avb_exit);
-
-MODULE_AUTHOR("David Zeuthen <zeuthen@google.com>");
-MODULE_DESCRIPTION("AVB-specific error handler for dm-verity");
-MODULE_LICENSE("GPL");
-
-/* Declare parameter with no module prefix */
-#undef MODULE_PARAM_PREFIX
-#define MODULE_PARAM_PREFIX	"androidboot.vbmeta."
-module_param_string(device, avb_vbmeta_device, sizeof(avb_vbmeta_device), 0);
-module_param_string(invalidate_on_error, avb_invalidate_on_error,
-		    sizeof(avb_invalidate_on_error), 0);

drivers/md/dm-verity-target.c

@@ -252,12 +252,8 @@ out:
 	if (v->mode == DM_VERITY_MODE_LOGGING)
 		return 0;
 
-	if (v->mode == DM_VERITY_MODE_RESTART) {
+	if (v->mode == DM_VERITY_MODE_RESTART)
-#ifdef CONFIG_DM_VERITY_AVB
-		dm_verity_avb_error_handler();
-#endif
 		kernel_restart("dm-verity device corrupted");
-	}
 
 	if (v->mode == DM_VERITY_MODE_PANIC)
 		panic("dm-verity device corrupted");

drivers/md/dm-verity.h

@@ -129,6 +129,4 @@ extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 				 sector_t block, u8 *digest, bool *is_zero);
 
-extern void dm_verity_avb_error_handler(void);
-
 #endif /* DM_VERITY_H */