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fscrypt: stop pretending that key setup is nofs-safe

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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: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20200917041136.178600-10-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers 2020-09-16 21:11:32 -07:00
parent 4cc1a3e7e8
commit 9dad5feb49
3 changed files with 7 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
fs/crypto/inline_crypt.c
View File

@ -106,7 +106,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
crypto_cfg.data_unit_size = sb->s_blocksize; crypto_cfg.data_unit_size = sb->s_blocksize;
crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci); crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
num_devs = fscrypt_get_num_devices(sb); 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) if (!devs)
return -ENOMEM; return -ENOMEM;
fscrypt_get_devices(sb, num_devs, devs); 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; struct fscrypt_blk_crypto_key *blk_key;
int err; int err;
int i; 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) if (!blk_key)
return -ENOMEM; return -ENOMEM;
@ -166,10 +165,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
} }
queue_refs++; queue_refs++;
flags = memalloc_nofs_save();
err = blk_crypto_start_using_key(&blk_key->base, err = blk_crypto_start_using_key(&blk_key->base,
blk_key->devs[i]); blk_key->devs[i]);
memalloc_nofs_restore(flags);
if (err) { if (err) {
fscrypt_err(inode, fscrypt_err(inode,
"error %d starting to use blk-crypto", err); "error %d starting to use blk-crypto", err);

2
fs/crypto/keysetup.c
View File

@ -488,7 +488,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
if (res) if (res)
return 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) if (!crypt_info)
return -ENOMEM; return -ENOMEM;

8
fs/crypto/keysetup_v1.c
View File

@ -60,7 +60,7 @@ static int derive_key_aes(const u8 *master_key,
goto out; goto out;
} }
crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); 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) { if (!req) {
res = -ENOMEM; res = -ENOMEM;
goto out; goto out;
@ -99,7 +99,7 @@ find_and_lock_process_key(const char *prefix,
const struct user_key_payload *ukp; const struct user_key_payload *ukp;
const struct fscrypt_key *payload; const struct fscrypt_key *payload;
description = kasprintf(GFP_NOFS, "%s%*phN", prefix, description = kasprintf(GFP_KERNEL, "%s%*phN", prefix,
FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor); FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
if (!description) if (!description)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
@ -228,7 +228,7 @@ fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
return dk; return dk;
/* Nope, allocate one. */ /* Nope, allocate one. */
dk = kzalloc(sizeof(*dk), GFP_NOFS); dk = kzalloc(sizeof(*dk), GFP_KERNEL);
if (!dk) if (!dk)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
refcount_set(&dk->dk_refcount, 1); 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 * This cannot be a stack buffer because it will be passed to the
* scatterlist crypto API during derive_key_aes(). * 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) if (!derived_key)
return -ENOMEM; return -ENOMEM;