| Message ID | 9a4890026719e5d6dc16ee9338f309f3fa452d16.1688927487.git.sweettea-kernel@dorminy.me (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fscrypt: add extent encryption | expand |
On Sun, Jul 09, 2023 at 02:53:38PM -0400, Sweet Tea Dorminy wrote: > For extent-based encryption, leaf/regular file inodes are special: it's > useful to set their i_crypt_info field so that it's easy to inherit > their encryption policy for a new extent, but they never need to do any > encyption themselves. Additionally, since encryption can only be set up > on a directory, not a single file, their encryption policy can always > duplicate their parent inode's policy. > > Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> > --- > fs/crypto/fscrypt_private.h | 17 +++++++++++++ > fs/crypto/keysetup.c | 49 ++++++++++++++++++++++++++----------- > 2 files changed, 52 insertions(+), 14 deletions(-) > > diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h > index c04454c289fd..260635e8b558 100644 > --- a/fs/crypto/fscrypt_private.h > +++ b/fs/crypto/fscrypt_private.h > @@ -308,6 +308,23 @@ fscrypt_get_lblk_info(const struct inode *inode, u64 lblk, u64 *offset, > return inode->i_crypt_info; > } > > +/** > + * fscrypt_uses_extent_encryption() -- whether an inode uses per-extent > + * encryption > + * > + * @inode: the inode in question > + * > + * Return: true if the inode uses per-extent fscrypt_infos, false otherwise > + */ > +static inline bool fscrypt_uses_extent_encryption(const struct inode *inode) > +{ > + // Non-regular files don't have extents > + if (!S_ISREG(inode->i_mode)) > + return false; > + > + // No filesystems currently use per-extent infos > + return false; Wrong comment format. > +} > > /* crypto.c */ > extern struct kmem_cache *fscrypt_info_cachep; > diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c > index c5f68cf65a6f..7469b2d8ac87 100644 > --- a/fs/crypto/keysetup.c > +++ b/fs/crypto/keysetup.c > @@ -747,27 +747,48 @@ fscrypt_setup_encryption_info(struct inode *inode, > int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) > { > int res; > - union fscrypt_context ctx; > + union fscrypt_context ctx = { 0 }; > union fscrypt_policy policy; > > if (fscrypt_has_encryption_key(inode)) > return 0; > > - res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); > - if (res < 0) { > - if (res == -ERANGE && allow_unsupported) > - return 0; > - fscrypt_warn(inode, "Error %d getting encryption context", res); > - return res; > - } > + if (fscrypt_uses_extent_encryption(inode)) { > + /* > + * Nothing will be encrypted with this info, so we can borrow > + * the parent (dir) inode's policy and use a zero nonce. > + */ > + struct dentry *dentry = d_find_any_alias(inode); > + struct dentry *parent_dentry = dget_parent(dentry); > + struct inode *dir = parent_dentry->d_inode; > + bool found = false; > Can this be extracted to a helper to keep this function cleaner? Thanks, Josef
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index c04454c289fd..260635e8b558 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -308,6 +308,23 @@ fscrypt_get_lblk_info(const struct inode *inode, u64 lblk, u64 *offset, return inode->i_crypt_info; } +/** + * fscrypt_uses_extent_encryption() -- whether an inode uses per-extent + * encryption + * + * @inode: the inode in question + * + * Return: true if the inode uses per-extent fscrypt_infos, false otherwise + */ +static inline bool fscrypt_uses_extent_encryption(const struct inode *inode) +{ + // Non-regular files don't have extents + if (!S_ISREG(inode->i_mode)) + return false; + + // No filesystems currently use per-extent infos + return false; +} /* crypto.c */ extern struct kmem_cache *fscrypt_info_cachep; diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index c5f68cf65a6f..7469b2d8ac87 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -747,27 +747,48 @@ fscrypt_setup_encryption_info(struct inode *inode, int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) { int res; - union fscrypt_context ctx; + union fscrypt_context ctx = { 0 }; union fscrypt_policy policy; if (fscrypt_has_encryption_key(inode)) return 0; - res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); - if (res < 0) { - if (res == -ERANGE && allow_unsupported) - return 0; - fscrypt_warn(inode, "Error %d getting encryption context", res); - return res; - } + if (fscrypt_uses_extent_encryption(inode)) { + /* + * Nothing will be encrypted with this info, so we can borrow + * the parent (dir) inode's policy and use a zero nonce. + */ + struct dentry *dentry = d_find_any_alias(inode); + struct dentry *parent_dentry = dget_parent(dentry); + struct inode *dir = parent_dentry->d_inode; + bool found = false; - res = fscrypt_policy_from_context(&policy, &ctx, res); - if (res) { - if (allow_unsupported) + if (dir->i_crypt_info) { + found = true; + policy = dir->i_crypt_info->ci_policy; + nonce = dir->i_crypt_info->ci_nonce; + } + dput(parent_dentry); + dput(dentry); + if (!found) return 0; - fscrypt_warn(inode, - "Unrecognized or corrupt encryption context"); - return res; + } else { + res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (res < 0) { + if (res == -ERANGE && allow_unsupported) + return 0; + fscrypt_warn(inode, "Error %d getting encryption context", res); + return res; + } + + res = fscrypt_policy_from_context(&policy, &ctx, res); + if (res) { + if (allow_unsupported) + return 0; + fscrypt_warn(inode, + "Unrecognized or corrupt encryption context"); + return res; + } } if (!fscrypt_supported_policy(&policy, inode)) {
For extent-based encryption, leaf/regular file inodes are special: it's useful to set their i_crypt_info field so that it's easy to inherit their encryption policy for a new extent, but they never need to do any encyption themselves. Additionally, since encryption can only be set up on a directory, not a single file, their encryption policy can always duplicate their parent inode's policy. Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> --- fs/crypto/fscrypt_private.h | 17 +++++++++++++ fs/crypto/keysetup.c | 49 ++++++++++++++++++++++++++----------- 2 files changed, 52 insertions(+), 14 deletions(-)