@@ -27,10 +27,11 @@ struct fsverity_hash_alg {
/*
* The HASH_ALGO_* constant for this algorithm. This is different from
* FS_VERITY_HASH_ALG_*, which uses a different numbering scheme.
*/
enum hash_algo algo_id;
+ bool supports_multibuffer; /* crypto_shash_mb_max_msgs(tfm) >= 2 */
};
/* Merkle tree parameters: hash algorithm, initial hash state, and topology */
struct merkle_tree_params {
const struct fsverity_hash_alg *hash_alg; /* the hash algorithm */
@@ -65,10 +66,11 @@ struct merkle_tree_params {
*/
struct fsverity_info {
struct merkle_tree_params tree_params;
u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE];
u8 file_digest[FS_VERITY_MAX_DIGEST_SIZE];
+ u8 zero_block_hash[FS_VERITY_MAX_DIGEST_SIZE];
const struct inode *inode;
unsigned long *hash_block_verified;
};
#define FS_VERITY_MAX_SIGNATURE_SIZE (FS_VERITY_MAX_DESCRIPTOR_SIZE - \
@@ -82,10 +84,13 @@ const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,
unsigned int num);
const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg,
const u8 *salt, size_t salt_size);
int fsverity_hash_block(const struct merkle_tree_params *params,
const struct inode *inode, const void *data, u8 *out);
+int fsverity_hash_2_blocks(const struct merkle_tree_params *params,
+ const struct inode *inode, const void *data1,
+ const void *data2, u8 *out1, u8 *out2);
int fsverity_hash_buffer(const struct fsverity_hash_alg *alg,
const void *data, size_t size, u8 *out);
void __init fsverity_check_hash_algs(void);
/* init.c */
@@ -82,12 +82,15 @@ const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode,
if (WARN_ON_ONCE(alg->digest_size != crypto_shash_digestsize(tfm)))
goto err_free_tfm;
if (WARN_ON_ONCE(alg->block_size != crypto_shash_blocksize(tfm)))
goto err_free_tfm;
- pr_info("%s using implementation \"%s\"\n",
- alg->name, crypto_shash_driver_name(tfm));
+ alg->supports_multibuffer = (crypto_shash_mb_max_msgs(tfm) >= 2);
+
+ pr_info("%s using implementation \"%s\"%s\n",
+ alg->name, crypto_shash_driver_name(tfm),
+ alg->supports_multibuffer ? " (multibuffer)" : "");
/* pairs with smp_load_acquire() above */
smp_store_release(&alg->tfm, tfm);
goto out_unlock;
@@ -195,10 +198,35 @@ int fsverity_hash_block(const struct merkle_tree_params *params,
if (err)
fsverity_err(inode, "Error %d computing block hash", err);
return err;
}
+int fsverity_hash_2_blocks(const struct merkle_tree_params *params,
+ const struct inode *inode, const void *data1,
+ const void *data2, u8 *out1, u8 *out2)
+{
+ const u8 *data[2] = { data1, data2 };
+ u8 *outs[2] = { out1, out2 };
+ SHASH_DESC_ON_STACK(desc, params->hash_alg->tfm);
+ int err;
+
+ desc->tfm = params->hash_alg->tfm;
+
+ if (params->hashstate)
+ err = crypto_shash_import(desc, params->hashstate);
+ else
+ err = crypto_shash_init(desc);
+ if (err) {
+ fsverity_err(inode, "Error %d importing hash state", err);
+ return err;
+ }
+ err = crypto_shash_finup_mb(desc, data, params->block_size, outs, 2);
+ if (err)
+ fsverity_err(inode, "Error %d computing block hashes", err);
+ return err;
+}
+
/**
* fsverity_hash_buffer() - hash some data
* @alg: the hash algorithm to use
* @data: the data to hash
* @size: size of data to hash, in bytes
@@ -206,10 +206,16 @@ struct fsverity_info *fsverity_create_info(const struct inode *inode,
if (err) {
fsverity_err(inode, "Error %d computing file digest", err);
goto fail;
}
+ err = fsverity_hash_block(&vi->tree_params, inode,
+ page_address(ZERO_PAGE(0)),
+ vi->zero_block_hash);
+ if (err)
+ goto fail;
+
err = fsverity_verify_signature(vi, desc->signature,
le32_to_cpu(desc->sig_size));
if (err)
goto fail;
@@ -77,29 +77,33 @@ static bool is_hash_block_verified(struct fsverity_info *vi, struct page *hpage,
SetPageChecked(hpage);
return false;
}
/*
- * Verify a single data block against the file's Merkle tree.
+ * Verify the hash of a single data block against the file's Merkle tree.
+ *
+ * @real_dblock_hash specifies the hash of the data block, and @data_pos
+ * specifies the byte position of the data block within the file.
*
* In principle, we need to verify the entire path to the root node. However,
* for efficiency the filesystem may cache the hash blocks. Therefore we need
* only ascend the tree until an already-verified hash block is seen, and then
* verify the path to that block.
*
* Return: %true if the data block is valid, else %false.
*/
static bool
verify_data_block(struct inode *inode, struct fsverity_info *vi,
- const void *data, u64 data_pos, unsigned long max_ra_pages)
+ const u8 *real_dblock_hash, u64 data_pos,
+ unsigned long max_ra_pages)
{
const struct merkle_tree_params *params = &vi->tree_params;
const unsigned int hsize = params->digest_size;
int level;
u8 _want_hash[FS_VERITY_MAX_DIGEST_SIZE];
const u8 *want_hash;
- u8 real_hash[FS_VERITY_MAX_DIGEST_SIZE];
+ u8 real_hblock_hash[FS_VERITY_MAX_DIGEST_SIZE];
/* The hash blocks that are traversed, indexed by level */
struct {
/* Page containing the hash block */
struct page *page;
/* Mapped address of the hash block (will be within @page) */
@@ -125,11 +129,12 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi,
* doesn't cover data blocks fully past EOF. But the entire
* page spanning EOF can be visible to userspace via a mmap, and
* any part past EOF should be all zeroes. Therefore, we need
* to verify that any data blocks fully past EOF are all zeroes.
*/
- if (memchr_inv(data, 0, params->block_size)) {
+ if (memcmp(vi->zero_block_hash, real_dblock_hash,
+ params->block_size) != 0) {
fsverity_err(inode,
"FILE CORRUPTED! Data past EOF is not zeroed");
return false;
}
return true;
@@ -200,13 +205,14 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi,
struct page *hpage = hblocks[level - 1].page;
const void *haddr = hblocks[level - 1].addr;
unsigned long hblock_idx = hblocks[level - 1].index;
unsigned int hoffset = hblocks[level - 1].hoffset;
- if (fsverity_hash_block(params, inode, haddr, real_hash) != 0)
+ if (fsverity_hash_block(params, inode, haddr,
+ real_hblock_hash) != 0)
goto error;
- if (memcmp(want_hash, real_hash, hsize) != 0)
+ if (memcmp(want_hash, real_hblock_hash, hsize) != 0)
goto corrupted;
/*
* Mark the hash block as verified. This must be atomic and
* idempotent, as the same hash block might be verified by
* multiple threads concurrently.
@@ -219,55 +225,145 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi,
want_hash = _want_hash;
kunmap_local(haddr);
put_page(hpage);
}
- /* Finally, verify the data block. */
- if (fsverity_hash_block(params, inode, data, real_hash) != 0)
- goto error;
- if (memcmp(want_hash, real_hash, hsize) != 0)
+ /* Finally, verify the hash of the data block. */
+ if (memcmp(want_hash, real_dblock_hash, hsize) != 0)
goto corrupted;
return true;
corrupted:
fsverity_err(inode,
"FILE CORRUPTED! pos=%llu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN",
data_pos, level - 1,
params->hash_alg->name, hsize, want_hash,
- params->hash_alg->name, hsize, real_hash);
+ params->hash_alg->name, hsize,
+ level == 0 ? real_dblock_hash : real_hblock_hash);
error:
for (; level > 0; level--) {
kunmap_local(hblocks[level - 1].addr);
put_page(hblocks[level - 1].page);
}
return false;
}
+struct fsverity_verification_context {
+ struct inode *inode;
+ struct fsverity_info *vi;
+ unsigned long max_ra_pages;
+
+ /*
+ * pending_data and pending_pos are used when the selected hash
+ * algorithm supports multibuffer hashing. They're used to temporarily
+ * store the virtual address and position of a mapped data block that
+ * needs to be verified. If we then see another data block, we hash the
+ * two blocks simultaneously using the fast multibuffer hashing method.
+ */
+ const void *pending_data;
+ u64 pending_pos;
+
+ /* Buffers to temporarily store the calculated data block hashes */
+ u8 hash1[FS_VERITY_MAX_DIGEST_SIZE];
+ u8 hash2[FS_VERITY_MAX_DIGEST_SIZE];
+};
+
+static inline void
+fsverity_init_verification_context(struct fsverity_verification_context *ctx,
+ struct inode *inode,
+ unsigned long max_ra_pages)
+{
+ ctx->inode = inode;
+ ctx->vi = inode->i_verity_info;
+ ctx->max_ra_pages = max_ra_pages;
+ ctx->pending_data = NULL;
+}
+
+static bool
+fsverity_finish_verification(struct fsverity_verification_context *ctx)
+{
+ int err;
+
+ if (ctx->pending_data == NULL)
+ return true;
+ /*
+ * Multibuffer hashing is enabled but there was an odd number of data
+ * blocks. Hash and verify the last block by itself.
+ */
+ err = fsverity_hash_block(&ctx->vi->tree_params, ctx->inode,
+ ctx->pending_data, ctx->hash1);
+ kunmap_local(ctx->pending_data);
+ ctx->pending_data = NULL;
+ return err == 0 &&
+ verify_data_block(ctx->inode, ctx->vi, ctx->hash1,
+ ctx->pending_pos, ctx->max_ra_pages);
+}
+
+static inline void
+fsverity_abort_verification(struct fsverity_verification_context *ctx)
+{
+ if (ctx->pending_data) {
+ kunmap_local(ctx->pending_data);
+ ctx->pending_data = NULL;
+ }
+}
+
static bool
-verify_data_blocks(struct folio *data_folio, size_t len, size_t offset,
- unsigned long max_ra_pages)
+fsverity_add_data_blocks(struct fsverity_verification_context *ctx,
+ struct folio *data_folio, size_t len, size_t offset)
{
- struct inode *inode = data_folio->mapping->host;
- struct fsverity_info *vi = inode->i_verity_info;
- const unsigned int block_size = vi->tree_params.block_size;
- u64 pos = (u64)data_folio->index << PAGE_SHIFT;
+ struct inode *inode = ctx->inode;
+ struct fsverity_info *vi = ctx->vi;
+ const struct merkle_tree_params *params = &vi->tree_params;
+ const unsigned int block_size = params->block_size;
+ const bool multibuffer = params->hash_alg->supports_multibuffer;
+ u64 pos = ((u64)data_folio->index << PAGE_SHIFT) + offset;
if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offset, block_size)))
return false;
if (WARN_ON_ONCE(!folio_test_locked(data_folio) ||
folio_test_uptodate(data_folio)))
return false;
do {
- void *data;
- bool valid;
-
- data = kmap_local_folio(data_folio, offset);
- valid = verify_data_block(inode, vi, data, pos + offset,
- max_ra_pages);
- kunmap_local(data);
- if (!valid)
- return false;
+ const void *data = kmap_local_folio(data_folio, offset);
+ int err;
+
+ if (multibuffer) {
+ if (ctx->pending_data) {
+ /* Hash and verify two data blocks. */
+ err = fsverity_hash_2_blocks(params,
+ inode,
+ ctx->pending_data,
+ data,
+ ctx->hash1,
+ ctx->hash2);
+ kunmap_local(data);
+ kunmap_local(ctx->pending_data);
+ ctx->pending_data = NULL;
+ if (err != 0 ||
+ !verify_data_block(inode, vi, ctx->hash1,
+ ctx->pending_pos,
+ ctx->max_ra_pages) ||
+ !verify_data_block(inode, vi, ctx->hash2,
+ pos, ctx->max_ra_pages))
+ return false;
+ } else {
+ /* Wait and see if there's another block. */
+ ctx->pending_data = data;
+ ctx->pending_pos = pos;
+ }
+ } else {
+ /* Hash and verify one data block. */
+ err = fsverity_hash_block(params, inode, data,
+ ctx->hash1);
+ kunmap_local(data);
+ if (err != 0 ||
+ !verify_data_block(inode, vi, ctx->hash1,
+ pos, ctx->max_ra_pages))
+ return false;
+ }
+ pos += block_size;
offset += block_size;
len -= block_size;
} while (len);
return true;
}
@@ -284,11 +380,19 @@ verify_data_blocks(struct folio *data_folio, size_t len, size_t offset,
*
* Return: %true if the data is valid, else %false.
*/
bool fsverity_verify_blocks(struct folio *folio, size_t len, size_t offset)
{
- return verify_data_blocks(folio, len, offset, 0);
+ struct fsverity_verification_context ctx;
+
+ fsverity_init_verification_context(&ctx, folio->mapping->host, 0);
+
+ if (!fsverity_add_data_blocks(&ctx, folio, len, offset)) {
+ fsverity_abort_verification(&ctx);
+ return false;
+ }
+ return fsverity_finish_verification(&ctx);
}
EXPORT_SYMBOL_GPL(fsverity_verify_blocks);
#ifdef CONFIG_BLOCK
/**
@@ -305,10 +409,12 @@ EXPORT_SYMBOL_GPL(fsverity_verify_blocks);
* filesystems) must instead call fsverity_verify_page() directly on each page.
* All filesystems must also call fsverity_verify_page() on holes.
*/
void fsverity_verify_bio(struct bio *bio)
{
+ struct inode *inode = bio_first_folio_all(bio)->mapping->host;
+ struct fsverity_verification_context ctx;
struct folio_iter fi;
unsigned long max_ra_pages = 0;
if (bio->bi_opf & REQ_RAHEAD) {
/*
@@ -321,17 +427,26 @@ void fsverity_verify_bio(struct bio *bio)
* reduces the number of I/O requests made to the Merkle tree.
*/
max_ra_pages = bio->bi_iter.bi_size >> (PAGE_SHIFT + 2);
}
+ fsverity_init_verification_context(&ctx, inode, max_ra_pages);
+
bio_for_each_folio_all(fi, bio) {
- if (!verify_data_blocks(fi.folio, fi.length, fi.offset,
- max_ra_pages)) {
- bio->bi_status = BLK_STS_IOERR;
- break;
+ if (!fsverity_add_data_blocks(&ctx, fi.folio, fi.length,
+ fi.offset)) {
+ fsverity_abort_verification(&ctx);
+ goto ioerr;
}
}
+
+ if (!fsverity_finish_verification(&ctx))
+ goto ioerr;
+ return;
+
+ioerr:
+ bio->bi_status = BLK_STS_IOERR;
}
EXPORT_SYMBOL_GPL(fsverity_verify_bio);
#endif /* CONFIG_BLOCK */
/**