Commit 9dad5feb authored by Eric Biggers's avatar Eric Biggers
Browse files

fscrypt: stop pretending that key setup is nofs-safe 



fscrypt_get_encryption_info() has never actually been safe to call in a
context that needs GFP_NOFS, since it calls crypto_alloc_skcipher().

crypto_alloc_skcipher() isn't GFP_NOFS-safe, even if called under
memalloc_nofs_save().  This is because it may load kernel modules, and
also because it internally takes crypto_alg_sem.  Other tasks can do
GFP_KERNEL allocations while holding crypto_alg_sem for write.

The use of fscrypt_init_mutex isn't GFP_NOFS-safe either.

So, stop pretending that fscrypt_get_encryption_info() is nofs-safe.
I.e., when it allocates memory, just use GFP_KERNEL instead of GFP_NOFS.

Note, another reason to do this is that GFP_NOFS is deprecated in favor
of using memalloc_nofs_save() in the proper places.

Acked-by: default avatarJeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-10-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent 4cc1a3e7

fs/crypto/inline_crypt.c

+2 −5
Original line number Diff line number Diff line
@@ -106,7 +106,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci) 
	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_NOFS);

	devs = kmalloc_array(num_devs, sizeof(*devs), GFP_KERNEL);

	if (!devs)

		return -ENOMEM;

	fscrypt_get_devices(sb, num_devs, devs);
@@ -135,9 +135,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, 
	struct fscrypt_blk_crypto_key *blk_key;

	int err;

	int i;

	unsigned int flags;



	blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_NOFS);

	blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_KERNEL);

	if (!blk_key)

		return -ENOMEM;
@@ -166,10 +165,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, 
		}

		queue_refs++;



		flags = memalloc_nofs_save();

		err = blk_crypto_start_using_key(&blk_key->base,

						 blk_key->devs[i]);

		memalloc_nofs_restore(flags);

		if (err) {

			fscrypt_err(inode,

				    "error %d starting to use blk-crypto", err);

fs/crypto/keysetup.c

+1 −1
Original line number Diff line number Diff line
@@ -488,7 +488,7 @@ fscrypt_setup_encryption_info(struct inode *inode, 
	if (res)

		return res;



	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);

	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_KERNEL);

	if (!crypt_info)

		return -ENOMEM;

fs/crypto/keysetup_v1.c

+4 −4
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ static int derive_key_aes(const u8 *master_key, 
		goto out;

	}

	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);

	req = skcipher_request_alloc(tfm, GFP_NOFS);

	req = skcipher_request_alloc(tfm, GFP_KERNEL);

	if (!req) {

		res = -ENOMEM;

		goto out;
@@ -99,7 +99,7 @@ find_and_lock_process_key(const char *prefix, 
	const struct user_key_payload *ukp;

	const struct fscrypt_key *payload;



	description = kasprintf(GFP_NOFS, "%s%*phN", prefix,

	description = kasprintf(GFP_KERNEL, "%s%*phN", prefix,

				FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);

	if (!description)

		return ERR_PTR(-ENOMEM);
@@ -228,7 +228,7 @@ fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key) 
		return dk;



	/* Nope, allocate one. */

	dk = kzalloc(sizeof(*dk), GFP_NOFS);

	dk = kzalloc(sizeof(*dk), GFP_KERNEL);

	if (!dk)

		return ERR_PTR(-ENOMEM);

	refcount_set(&dk->dk_refcount, 1);
@@ -272,7 +272,7 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci, 
	 * This cannot be a stack buffer because it will be passed to the

	 * scatterlist crypto API during derive_key_aes().

	 */

	derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS);

	derived_key = kmalloc(ci->ci_mode->keysize, GFP_KERNEL);

	if (!derived_key)

		return -ENOMEM;

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