OSCL-LXR linux-6.0.1/​fs/​crypto/​inline_crypt.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Inline encryption support for fscrypt
  *
  * Copyright 2019 Google LLC
  */
 
 /*
  * With "inline encryption", the block layer handles the decryption/encryption
  * as part of the bio, instead of the filesystem doing the crypto itself via
  * crypto API.  See Documentation/block/inline-encryption.rst.  fscrypt still
  * provides the key and IV to use.
  */
 
 #include <linux/blk-crypto-profile.h>
 #include <linux/blkdev.h>
 #include <linux/buffer_head.h>
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
 #include <linux/uio.h>
 
 #include "fscrypt_private.h"
 
 struct fscrypt_blk_crypto_key {
     struct blk_crypto_key base;
     int num_devs;
     struct request_queue *devs[];
 };
 
 static int fscrypt_get_num_devices(struct super_block *sb)
 {
     if (sb->s_cop->get_num_devices)
         return sb->s_cop->get_num_devices(sb);
     return 1;
 }
 
 static void fscrypt_get_devices(struct super_block *sb, int num_devs,
                 struct request_queue **devs)
 {
     if (num_devs == 1)
         devs[0] = bdev_get_queue(sb->s_bdev);
     else
         sb->s_cop->get_devices(sb, devs);
 }
 
 static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci)
 {
     struct super_block *sb = ci->ci_inode->i_sb;
     unsigned int flags = fscrypt_policy_flags(&ci->ci_policy);
     int ino_bits = 64, lblk_bits = 64;
 
     if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
         return offsetofend(union fscrypt_iv, nonce);
 
     if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)
         return sizeof(__le64);
 
     if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)
         return sizeof(__le32);
 
     /* Default case: IVs are just the file logical block number */
     if (sb->s_cop->get_ino_and_lblk_bits)
         sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits);
     return DIV_ROUND_UP(lblk_bits, 8);
 }
 
 /*
  * Log a message when starting to use blk-crypto (native) or blk-crypto-fallback
  * for an encryption mode for the first time.  This is the blk-crypto
  * counterpart to the message logged when starting to use the crypto API for the
  * first time.  A limitation is that these messages don't convey which specific
  * filesystems or files are using each implementation.  However, *usually*
  * systems use just one implementation per mode, which makes these messages
  * helpful for debugging problems where the "wrong" implementation is used.
  */
 static void fscrypt_log_blk_crypto_impl(struct fscrypt_mode *mode,
                     struct request_queue **devs,
                     int num_devs,
                     const struct blk_crypto_config *cfg)
 {
     int i;
 
     for (i = 0; i < num_devs; i++) {
         if (!IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) ||
             __blk_crypto_cfg_supported(devs[i]->crypto_profile, cfg)) {
             if (!xchg(&mode->logged_blk_crypto_native, 1))
                 pr_info("fscrypt: %s using blk-crypto (native)\n",
                     mode->friendly_name);
         } else if (!xchg(&mode->logged_blk_crypto_fallback, 1)) {
             pr_info("fscrypt: %s using blk-crypto-fallback\n",
                 mode->friendly_name);
         }
     }
 }
 
 /* Enable inline encryption for this file if supported. */
 int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
 {
     const struct inode *inode = ci->ci_inode;
     struct super_block *sb = inode->i_sb;
     struct blk_crypto_config crypto_cfg;
     int num_devs;
     struct request_queue **devs;
     int i;
 
     /* The file must need contents encryption, not filenames encryption */
     if (!S_ISREG(inode->i_mode))
         return 0;
 
     /* The crypto mode must have a blk-crypto counterpart */
     if (ci->ci_mode->blk_crypto_mode == BLK_ENCRYPTION_MODE_INVALID)
         return 0;
 
     /* The filesystem must be mounted with -o inlinecrypt */
     if (!(sb->s_flags & SB_INLINECRYPT))
         return 0;
 
     /*
      * When a page contains multiple logically contiguous filesystem blocks,
      * some filesystem code only calls fscrypt_mergeable_bio() for the first
      * block in the page. This is fine for most of fscrypt's IV generation
      * strategies, where contiguous blocks imply contiguous IVs. But it
      * doesn't work with IV_INO_LBLK_32. For now, simply exclude
      * IV_INO_LBLK_32 with blocksize != PAGE_SIZE from inline encryption.
      */
     if ((fscrypt_policy_flags(&ci->ci_policy) &
          FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
         sb->s_blocksize != PAGE_SIZE)
         return 0;
 
     /*
      * On all the filesystem's devices, blk-crypto must support the crypto
      * configuration that the file would use.
      */
     crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode;
     crypto_cfg.data_unit_size = sb->s_blocksize;
     crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
     num_devs = fscrypt_get_num_devices(sb);
     devs = kmalloc_array(num_devs, sizeof(*devs), GFP_KERNEL);
     if (!devs)
         return -ENOMEM;
     fscrypt_get_devices(sb, num_devs, devs);
 
     for (i = 0; i < num_devs; i++) {
         if (!blk_crypto_config_supported(devs[i], &crypto_cfg))
             goto out_free_devs;
     }
 
     fscrypt_log_blk_crypto_impl(ci->ci_mode, devs, num_devs, &crypto_cfg);
 
     ci->ci_inlinecrypt = true;
 out_free_devs:
     kfree(devs);
 
     return 0;
 }
 
 int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
                      const u8 *raw_key,
                      const struct fscrypt_info *ci)
 {
     const struct inode *inode = ci->ci_inode;
     struct super_block *sb = inode->i_sb;
     enum blk_crypto_mode_num crypto_mode = ci->ci_mode->blk_crypto_mode;
     int num_devs = fscrypt_get_num_devices(sb);
     int queue_refs = 0;
     struct fscrypt_blk_crypto_key *blk_key;
     int err;
     int i;
 
     blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_KERNEL);
     if (!blk_key)
         return -ENOMEM;
 
     blk_key->num_devs = num_devs;
     fscrypt_get_devices(sb, num_devs, blk_key->devs);
 
     err = blk_crypto_init_key(&blk_key->base, raw_key, crypto_mode,
                   fscrypt_get_dun_bytes(ci), sb->s_blocksize);
     if (err) {
         fscrypt_err(inode, "error %d initializing blk-crypto key", err);
         goto fail;
     }
 
     /*
      * We have to start using blk-crypto on all the filesystem's devices.
      * We also have to save all the request_queue's for later so that the
      * key can be evicted from them.  This is needed because some keys
      * aren't destroyed until after the filesystem was already unmounted
      * (namely, the per-mode keys in struct fscrypt_master_key).
      */
     for (i = 0; i < num_devs; i++) {
         if (!blk_get_queue(blk_key->devs[i])) {
             fscrypt_err(inode, "couldn't get request_queue");
             err = -EAGAIN;
             goto fail;
         }
         queue_refs++;
 
         err = blk_crypto_start_using_key(&blk_key->base,
                          blk_key->devs[i]);
         if (err) {
             fscrypt_err(inode,
                     "error %d starting to use blk-crypto", err);
             goto fail;
         }
     }
     /*
      * Pairs with the smp_load_acquire() in fscrypt_is_key_prepared().
      * I.e., here we publish ->blk_key with a RELEASE barrier so that
      * concurrent tasks can ACQUIRE it.  Note that this concurrency is only
      * possible for per-mode keys, not for per-file keys.
      */
     smp_store_release(&prep_key->blk_key, blk_key);
     return 0;
 
 fail:
     for (i = 0; i < queue_refs; i++)
         blk_put_queue(blk_key->devs[i]);
     kfree_sensitive(blk_key);
     return err;
 }
 
 void fscrypt_destroy_inline_crypt_key(struct fscrypt_prepared_key *prep_key)
 {
     struct fscrypt_blk_crypto_key *blk_key = prep_key->blk_key;
     int i;
 
     if (blk_key) {
         for (i = 0; i < blk_key->num_devs; i++) {
             blk_crypto_evict_key(blk_key->devs[i], &blk_key->base);
             blk_put_queue(blk_key->devs[i]);
         }
         kfree_sensitive(blk_key);
     }
 }
 
 bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
 {
     return inode->i_crypt_info->ci_inlinecrypt;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto);
 
 static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num,
                  u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
 {
     union fscrypt_iv iv;
     int i;
 
     fscrypt_generate_iv(&iv, lblk_num, ci);
 
     BUILD_BUG_ON(FSCRYPT_MAX_IV_SIZE > BLK_CRYPTO_MAX_IV_SIZE);
     memset(dun, 0, BLK_CRYPTO_MAX_IV_SIZE);
     for (i = 0; i < ci->ci_mode->ivsize/sizeof(dun[0]); i++)
         dun[i] = le64_to_cpu(iv.dun[i]);
 }
 
 /**
  * fscrypt_set_bio_crypt_ctx() - prepare a file contents bio for inline crypto
  * @bio: a bio which will eventually be submitted to the file
  * @inode: the file's inode
  * @first_lblk: the first file logical block number in the I/O
  * @gfp_mask: memory allocation flags - these must be a waiting mask so that
  *                  bio_crypt_set_ctx can't fail.
  *
  * If the contents of the file should be encrypted (or decrypted) with inline
  * encryption, then assign the appropriate encryption context to the bio.
  *
  * Normally the bio should be newly allocated (i.e. no pages added yet), as
  * otherwise fscrypt_mergeable_bio() won't work as intended.
  *
  * The encryption context will be freed automatically when the bio is freed.
  */
 void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
                    u64 first_lblk, gfp_t gfp_mask)
 {
     const struct fscrypt_info *ci;
     u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
     if (!fscrypt_inode_uses_inline_crypto(inode))
         return;
     ci = inode->i_crypt_info;
 
     fscrypt_generate_dun(ci, first_lblk, dun);
     bio_crypt_set_ctx(bio, &ci->ci_enc_key.blk_key->base, dun, gfp_mask);
 }
 EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx);
 
 /* Extract the inode and logical block number from a buffer_head. */
 static bool bh_get_inode_and_lblk_num(const struct buffer_head *bh,
                       const struct inode **inode_ret,
                       u64 *lblk_num_ret)
 {
     struct page *page = bh->b_page;
     const struct address_space *mapping;
     const struct inode *inode;
 
     /*
      * The ext4 journal (jbd2) can submit a buffer_head it directly created
      * for a non-pagecache page.  fscrypt doesn't care about these.
      */
     mapping = page_mapping(page);
     if (!mapping)
         return false;
     inode = mapping->host;
 
     *inode_ret = inode;
     *lblk_num_ret = ((u64)page->index << (PAGE_SHIFT - inode->i_blkbits)) +
             (bh_offset(bh) >> inode->i_blkbits);
     return true;
 }
 
 /**
  * fscrypt_set_bio_crypt_ctx_bh() - prepare a file contents bio for inline
  *                  crypto
  * @bio: a bio which will eventually be submitted to the file
  * @first_bh: the first buffer_head for which I/O will be submitted
  * @gfp_mask: memory allocation flags
  *
  * Same as fscrypt_set_bio_crypt_ctx(), except this takes a buffer_head instead
  * of an inode and block number directly.
  */
 void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio,
                   const struct buffer_head *first_bh,
                   gfp_t gfp_mask)
 {
     const struct inode *inode;
     u64 first_lblk;
 
     if (bh_get_inode_and_lblk_num(first_bh, &inode, &first_lblk))
         fscrypt_set_bio_crypt_ctx(bio, inode, first_lblk, gfp_mask);
 }
 EXPORT_SYMBOL_GPL(fscrypt_set_bio_crypt_ctx_bh);
 
 /**
  * fscrypt_mergeable_bio() - test whether data can be added to a bio
  * @bio: the bio being built up
  * @inode: the inode for the next part of the I/O
  * @next_lblk: the next file logical block number in the I/O
  *
  * When building a bio which may contain data which should undergo inline
  * encryption (or decryption) via fscrypt, filesystems should call this function
  * to ensure that the resulting bio contains only contiguous data unit numbers.
  * This will return false if the next part of the I/O cannot be merged with the
  * bio because either the encryption key would be different or the encryption
  * data unit numbers would be discontiguous.
  *
  * fscrypt_set_bio_crypt_ctx() must have already been called on the bio.
  *
  * This function isn't required in cases where crypto-mergeability is ensured in
  * another way, such as I/O targeting only a single file (and thus a single key)
  * combined with fscrypt_limit_io_blocks() to ensure DUN contiguity.
  *
  * Return: true iff the I/O is mergeable
  */
 bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
                u64 next_lblk)
 {
     const struct bio_crypt_ctx *bc = bio->bi_crypt_context;
     u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
     if (!!bc != fscrypt_inode_uses_inline_crypto(inode))
         return false;
     if (!bc)
         return true;
 
     /*
      * Comparing the key pointers is good enough, as all I/O for each key
      * uses the same pointer.  I.e., there's currently no need to support
      * merging requests where the keys are the same but the pointers differ.
      */
     if (bc->bc_key != &inode->i_crypt_info->ci_enc_key.blk_key->base)
         return false;
 
     fscrypt_generate_dun(inode->i_crypt_info, next_lblk, next_dun);
     return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun);
 }
 EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio);
 
 /**
  * fscrypt_mergeable_bio_bh() - test whether data can be added to a bio
  * @bio: the bio being built up
  * @next_bh: the next buffer_head for which I/O will be submitted
  *
  * Same as fscrypt_mergeable_bio(), except this takes a buffer_head instead of
  * an inode and block number directly.
  *
  * Return: true iff the I/O is mergeable
  */
 bool fscrypt_mergeable_bio_bh(struct bio *bio,
                   const struct buffer_head *next_bh)
 {
     const struct inode *inode;
     u64 next_lblk;
 
     if (!bh_get_inode_and_lblk_num(next_bh, &inode, &next_lblk))
         return !bio->bi_crypt_context;
 
     return fscrypt_mergeable_bio(bio, inode, next_lblk);
 }
 EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh);
 
 /**
  * fscrypt_dio_supported() - check whether a DIO (direct I/O) request is
  *               supported as far as encryption is concerned
  * @iocb: the file and position the I/O is targeting
  * @iter: the I/O data segment(s)
  *
  * Return: %true if there are no encryption constraints that prevent DIO from
  *     being supported; %false if DIO is unsupported.  (Note that in the
  *     %true case, the filesystem might have other, non-encryption-related
  *     constraints that prevent DIO from actually being supported.)
  */
 bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
 {
     const struct inode *inode = file_inode(iocb->ki_filp);
     const unsigned int blocksize = i_blocksize(inode);
 
     /* If the file is unencrypted, no veto from us. */
     if (!fscrypt_needs_contents_encryption(inode))
         return true;
 
     /* We only support DIO with inline crypto, not fs-layer crypto. */
     if (!fscrypt_inode_uses_inline_crypto(inode))
         return false;
 
     /*
      * Since the granularity of encryption is filesystem blocks, the file
      * position and total I/O length must be aligned to the filesystem block
      * size -- not just to the block device's logical block size as is
      * traditionally the case for DIO on many filesystems.
      *
      * We require that the user-provided memory buffers be filesystem block
      * aligned too.  It is simpler to have a single alignment value required
      * for all properties of the I/O, as is normally the case for DIO.
      * Also, allowing less aligned buffers would imply that data units could
      * cross bvecs, which would greatly complicate the I/O stack, which
      * assumes that bios can be split at any bvec boundary.
      */
     if (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), blocksize))
         return false;
 
     return true;
 }
 EXPORT_SYMBOL_GPL(fscrypt_dio_supported);
 
 /**
  * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs
  * @inode: the file on which I/O is being done
  * @lblk: the block at which the I/O is being started from
  * @nr_blocks: the number of blocks we want to submit starting at @lblk
  *
  * Determine the limit to the number of blocks that can be submitted in a bio
  * targeting @lblk without causing a data unit number (DUN) discontiguity.
  *
  * This is normally just @nr_blocks, as normally the DUNs just increment along
  * with the logical blocks.  (Or the file is not encrypted.)
  *
  * In rare cases, fscrypt can be using an IV generation method that allows the
  * DUN to wrap around within logically contiguous blocks, and that wraparound
  * will occur.  If this happens, a value less than @nr_blocks will be returned
  * so that the wraparound doesn't occur in the middle of a bio, which would
  * cause encryption/decryption to produce wrong results.
  *
  * Return: the actual number of blocks that can be submitted
  */
 u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks)
 {
     const struct fscrypt_info *ci;
     u32 dun;
 
     if (!fscrypt_inode_uses_inline_crypto(inode))
         return nr_blocks;
 
     if (nr_blocks <= 1)
         return nr_blocks;
 
     ci = inode->i_crypt_info;
     if (!(fscrypt_policy_flags(&ci->ci_policy) &
           FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
         return nr_blocks;
 
     /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */
 
     dun = ci->ci_hashed_ino + lblk;
 
     return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun);
 }
 EXPORT_SYMBOL_GPL(fscrypt_limit_io_blocks);

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