Message ID | 20171008215530.hnty5a7v6dsip45e@thunk.org |
---|---|
State | Not Applicable, archived |
Headers | show |
Series | [FOR,STABLE,4.1,-v2] ext4 crypto: don't regenerate the per-inode encryption key unnecessarily | expand |
On Sun, Oct 08, 2017 at 05:55:30PM -0400, Theodore Ts'o wrote: > diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c > index 52170d0b7c40..4f9818719d61 100644 > --- a/fs/ext4/crypto_key.c > +++ b/fs/ext4/crypto_key.c > @@ -99,9 +99,17 @@ int ext4_generate_encryption_key(struct inode *inode) > struct ext4_encryption_context ctx; > struct user_key_payload *ukp; > struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); > - int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION, > - EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, > - &ctx, sizeof(ctx)); > + int res; > + > + mutex_lock(&ei->i_encryption_lock); > + if (ext4_has_encryption_key(inode)) { > + mutex_unlock(&ei->i_encryption_lock); > + return 0; > + } > + > + res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION, > + EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, > + &ctx, sizeof(ctx)); > > if (res != sizeof(ctx)) { > if (res > 0) > @@ -154,6 +162,7 @@ out: > key_put(keyring_key); > if (res < 0) > crypt_key->mode = EXT4_ENCRYPTION_MODE_INVALID; > + mutex_unlock(&ei->i_encryption_lock); > return res; This looks better, but maybe the call to ext4_has_encryption_key() should also be removed from ext4_get_fname_crypto_ctx() --- so it calls ext4_generate_encryption_key() unconditionally, like ext4_file_open() and ext4_file_mmap() do? Otherwise it will still be doing a racy check without the lock. Eric
diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c index 52170d0b7c40..4f9818719d61 100644 --- a/fs/ext4/crypto_key.c +++ b/fs/ext4/crypto_key.c @@ -99,9 +99,17 @@ int ext4_generate_encryption_key(struct inode *inode) struct ext4_encryption_context ctx; struct user_key_payload *ukp; struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); - int res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION, - EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, - &ctx, sizeof(ctx)); + int res; + + mutex_lock(&ei->i_encryption_lock); + if (ext4_has_encryption_key(inode)) { + mutex_unlock(&ei->i_encryption_lock); + return 0; + } + + res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION, + EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, + &ctx, sizeof(ctx)); if (res != sizeof(ctx)) { if (res > 0) @@ -154,6 +162,7 @@ out: key_put(keyring_key); if (res < 0) crypt_key->mode = EXT4_ENCRYPTION_MODE_INVALID; + mutex_unlock(&ei->i_encryption_lock); return res; } diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index df67a6f8582a..01771ed4529d 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -989,6 +989,7 @@ struct ext4_inode_info { #ifdef CONFIG_EXT4_FS_ENCRYPTION /* Encryption params */ struct ext4_encryption_key i_encryption_key; + struct mutex i_encryption_lock; #endif }; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 97aa8be40175..683eb88863dc 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -946,6 +946,9 @@ static void init_once(void *foo) init_rwsem(&ei->xattr_sem); init_rwsem(&ei->i_data_sem); init_rwsem(&ei->i_mmap_sem); +#ifdef CONFIG_EXT4_FS_ENCRYPTION + mutex_init(&ei->i_encryption_lock); +#endif inode_init_once(&ei->vfs_inode); }