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: 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>

diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
index faa25541ccb6878419b5a934fba89a51aabb166a..89bffa82ed74aafba54a78539016c2635b2bec2f 100644 (file)
--- a/fs/crypto/inline_crypt.c
+++ b/fs/crypto/inline_crypt.c
@@ -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);

diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 615916897214602e08700ec2d33cc482aa9adfd4..47f19061ba10e765ea9f7d1a046a07f8fd461371 100644 (file)
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -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;
 

diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c
index a3cb52572b05c402b6504c4166a70df02b11712c..2762c53504323fff6ed531c32dfffeae46f11eed 100644 (file)
--- a/fs/crypto/keysetup_v1.c
+++ b/fs/crypto/keysetup_v1.c
@@ -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;