From 6e1918cfb263acacd3fc9239127732b69de64695 Mon Sep 17 00:00:00 2001 From: Daniel Rosenberg Date: Mon, 20 Jan 2020 14:31:56 -0800 Subject: fscrypt: don't allow v1 policies with casefolding Casefolded encrypted directories will use a new dirhash method that requires a secret key. If the directory uses a v2 encryption policy, it's easy to derive this key from the master key using HKDF. However, v1 encryption policies don't provide a way to derive additional keys. Therefore, don't allow casefolding on directories that use a v1 policy. Specifically, make it so that trying to enable casefolding on a directory that has a v1 policy fails, trying to set a v1 policy on a casefolded directory fails, and trying to open a casefolded directory that has a v1 policy (if one somehow exists on-disk) fails. Signed-off-by: Daniel Rosenberg [EB: improved commit message, updated fscrypt.rst, and other cleanups] Link: https://lore.kernel.org/r/20200120223201.241390-2-ebiggers@kernel.org Signed-off-by: Eric Biggers --- include/linux/fscrypt.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux') diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 6fe8d0f96a4a..3984eadd7023 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -263,6 +263,8 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir, unsigned int flags); extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, struct fscrypt_name *fname); +extern int fscrypt_prepare_setflags(struct inode *inode, + unsigned int oldflags, unsigned int flags); extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, unsigned int max_len, struct fscrypt_str *disk_link); @@ -519,6 +521,13 @@ static inline int __fscrypt_prepare_lookup(struct inode *dir, return -EOPNOTSUPP; } +static inline int fscrypt_prepare_setflags(struct inode *inode, + unsigned int oldflags, + unsigned int flags) +{ + return 0; +} + static inline int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, unsigned int max_len, -- cgit v1.2.3-71-gd317