Re: [PATCH v5 2/2] mm, treewide: Rename kzfree() to kfree_sensitive()
On 6/16/20 2:09 PM, Andrew Morton wrote: On Tue, 16 Jun 2020 11:43:11 -0400 Waiman Long wrote: As said by Linus: A symmetric naming is only helpful if it implies symmetries in use. Otherwise it's actively misleading. In "kzalloc()", the z is meaningful and an important part of what the caller wants. In "kzfree()", the z is actively detrimental, because maybe in the future we really _might_ want to use that "memfill(0xdeadbeef)" or something. The "zero" part of the interface isn't even _relevant_. The main reason that kzfree() exists is to clear sensitive information that should not be leaked to other future users of the same memory objects. Rename kzfree() to kfree_sensitive() to follow the example of the recently added kvfree_sensitive() and make the intention of the API more explicit. In addition, memzero_explicit() is used to clear the memory to make sure that it won't get optimized away by the compiler. The renaming is done by using the command sequence: git grep -w --name-only kzfree |\ xargs sed -i 's/\bkzfree\b/kfree_sensitive/' followed by some editing of the kfree_sensitive() kerneldoc and adding a kzfree backward compatibility macro in slab.h. ... --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -186,10 +186,12 @@ void memcg_deactivate_kmem_caches(struct mem_cgroup *, struct mem_cgroup *); */ void * __must_check krealloc(const void *, size_t, gfp_t); void kfree(const void *); -void kzfree(const void *); +void kfree_sensitive(const void *); size_t __ksize(const void *); size_t ksize(const void *); +#define kzfree(x) kfree_sensitive(x) /* For backward compatibility */ + What was the thinking here? Is this really necessary? I suppose we could keep this around for a while to ease migration. But not for too long, please. It should be there just for 1 release cycle. I have broken out the btrfs patch to the btrfs list and I didn't make the kzfree to kfree_sensitive conversion there as that patch was in front in my patch list. So depending on which one lands first, there can be a window where the compilation may fail without this workaround. I am going to send out another patch in the next release cycle to remove it. Cheers, Longman ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v5 2/2] mm, treewide: Rename kzfree() to kfree_sensitive()
On Tue, 16 Jun 2020 11:43:11 -0400 Waiman Long wrote: > As said by Linus: > > A symmetric naming is only helpful if it implies symmetries in use. > Otherwise it's actively misleading. > > In "kzalloc()", the z is meaningful and an important part of what the > caller wants. > > In "kzfree()", the z is actively detrimental, because maybe in the > future we really _might_ want to use that "memfill(0xdeadbeef)" or > something. The "zero" part of the interface isn't even _relevant_. > > The main reason that kzfree() exists is to clear sensitive information > that should not be leaked to other future users of the same memory > objects. > > Rename kzfree() to kfree_sensitive() to follow the example of the > recently added kvfree_sensitive() and make the intention of the API > more explicit. In addition, memzero_explicit() is used to clear the > memory to make sure that it won't get optimized away by the compiler. > > The renaming is done by using the command sequence: > > git grep -w --name-only kzfree |\ > xargs sed -i 's/\bkzfree\b/kfree_sensitive/' > > followed by some editing of the kfree_sensitive() kerneldoc and adding > a kzfree backward compatibility macro in slab.h. > > ... > > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -186,10 +186,12 @@ void memcg_deactivate_kmem_caches(struct mem_cgroup *, > struct mem_cgroup *); > */ > void * __must_check krealloc(const void *, size_t, gfp_t); > void kfree(const void *); > -void kzfree(const void *); > +void kfree_sensitive(const void *); > size_t __ksize(const void *); > size_t ksize(const void *); > > +#define kzfree(x)kfree_sensitive(x) /* For backward compatibility */ > + What was the thinking here? Is this really necessary? I suppose we could keep this around for a while to ease migration. But not for too long, please. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH v5 2/2] mm, treewide: Rename kzfree() to kfree_sensitive()
As said by Linus: A symmetric naming is only helpful if it implies symmetries in use. Otherwise it's actively misleading. In "kzalloc()", the z is meaningful and an important part of what the caller wants. In "kzfree()", the z is actively detrimental, because maybe in the future we really _might_ want to use that "memfill(0xdeadbeef)" or something. The "zero" part of the interface isn't even _relevant_. The main reason that kzfree() exists is to clear sensitive information that should not be leaked to other future users of the same memory objects. Rename kzfree() to kfree_sensitive() to follow the example of the recently added kvfree_sensitive() and make the intention of the API more explicit. In addition, memzero_explicit() is used to clear the memory to make sure that it won't get optimized away by the compiler. The renaming is done by using the command sequence: git grep -w --name-only kzfree |\ xargs sed -i 's/\bkzfree\b/kfree_sensitive/' followed by some editing of the kfree_sensitive() kerneldoc and adding a kzfree backward compatibility macro in slab.h. Suggested-by: Joe Perches Acked-by: David Howells Acked-by: Michal Hocko Acked-by: Johannes Weiner Signed-off-by: Waiman Long --- arch/s390/crypto/prng.c | 4 +-- arch/x86/power/hibernate.c| 2 +- crypto/adiantum.c | 2 +- crypto/ahash.c| 4 +-- crypto/api.c | 2 +- crypto/asymmetric_keys/verify_pefile.c| 4 +-- crypto/deflate.c | 2 +- crypto/drbg.c | 10 +++--- crypto/ecc.c | 8 ++--- crypto/ecdh.c | 2 +- crypto/gcm.c | 2 +- crypto/gf128mul.c | 4 +-- crypto/jitterentropy-kcapi.c | 2 +- crypto/rng.c | 2 +- crypto/rsa-pkcs1pad.c | 6 ++-- crypto/seqiv.c| 2 +- crypto/shash.c| 2 +- crypto/skcipher.c | 2 +- crypto/testmgr.c | 6 ++-- crypto/zstd.c | 2 +- .../allwinner/sun8i-ce/sun8i-ce-cipher.c | 2 +- .../allwinner/sun8i-ss/sun8i-ss-cipher.c | 2 +- drivers/crypto/amlogic/amlogic-gxl-cipher.c | 4 +-- drivers/crypto/atmel-ecc.c| 2 +- drivers/crypto/caam/caampkc.c | 28 +++ drivers/crypto/cavium/cpt/cptvf_main.c| 6 ++-- drivers/crypto/cavium/cpt/cptvf_reqmanager.c | 12 +++ drivers/crypto/cavium/nitrox/nitrox_lib.c | 4 +-- drivers/crypto/cavium/zip/zip_crypto.c| 6 ++-- drivers/crypto/ccp/ccp-crypto-rsa.c | 6 ++-- drivers/crypto/ccree/cc_aead.c| 4 +-- drivers/crypto/ccree/cc_buffer_mgr.c | 4 +-- drivers/crypto/ccree/cc_cipher.c | 6 ++-- drivers/crypto/ccree/cc_hash.c| 8 ++--- drivers/crypto/ccree/cc_request_mgr.c | 2 +- drivers/crypto/marvell/cesa/hash.c| 2 +- .../crypto/marvell/octeontx/otx_cptvf_main.c | 6 ++-- .../marvell/octeontx/otx_cptvf_reqmgr.h | 2 +- drivers/crypto/mediatek/mtk-aes.c | 2 +- drivers/crypto/nx/nx.c| 4 +-- drivers/crypto/virtio/virtio_crypto_algs.c| 12 +++ drivers/crypto/virtio/virtio_crypto_core.c| 2 +- drivers/md/dm-crypt.c | 32 - drivers/md/dm-integrity.c | 6 ++-- drivers/misc/ibmvmc.c | 6 ++-- .../hisilicon/hns3/hns3pf/hclge_mbx.c | 2 +- .../net/ethernet/intel/ixgbe/ixgbe_ipsec.c| 6 ++-- drivers/net/ppp/ppp_mppe.c| 6 ++-- drivers/net/wireguard/noise.c | 4 +-- drivers/net/wireguard/peer.c | 2 +- drivers/net/wireless/intel/iwlwifi/pcie/rx.c | 2 +- .../net/wireless/intel/iwlwifi/pcie/tx-gen2.c | 6 ++-- drivers/net/wireless/intel/iwlwifi/pcie/tx.c | 6 ++-- drivers/net/wireless/intersil/orinoco/wext.c | 4 +-- drivers/s390/crypto/ap_bus.h | 4 +-- drivers/staging/ks7010/ks_hostif.c| 2 +- drivers/staging/rtl8723bs/core/rtw_security.c | 2 +- drivers/staging/wlan-ng/p80211netdev.c| 2 +- drivers/target/iscsi/iscsi_target_auth.c | 2 +- fs/cifs/cifsencrypt.c | 2 +- fs/cifs/connect.c | 10 +++--- fs/cifs/dfs_cache.c | 2 +- fs/cifs/misc.c| 8 ++--- fs/crypto/keyring.c | 6 ++-- fs/crypto/keysetup_v1.c | 4 +-- fs/ecryptfs/keystore.c| 4 +-- fs/ecryptfs/messaging.c
