In order to notify extents when their info is part of a master key which is going away, the fscrypt_info must have a backpointer to the extent somehow. Similarly, if a fscrypt_info is owned by an extent, the info must not have a pointer to an inode -- multiple inodes may reference a extent, and the first inode to cause an extent's creation may have a lifetime much shorter than the extent, so there is no inode pointer safe to track in an extent-owned info. Therefore, this adds a new pointer for extent-owned infos to track their extent and updates fscrypt_setup_encryption_info() accordingly. Since it's simple to track the piece of extent memory pointing to the info, and for the extent to then go from such a pointer to the whole extent via container_of(), we store that. Although some sort of generic void * or some artificial fscrypt_extent embedded structure would also work, those would require additional plumbing which doesn't seem strictly required or clarifying. Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx> --- fs/crypto/fscrypt_private.h | 6 +++++ fs/crypto/keysetup.c | 49 ++++++++++++++++++++++++++++--------- 2 files changed, 43 insertions(+), 12 deletions(-) diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 260635e8b558..1674e66e72e3 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -241,6 +241,12 @@ struct fscrypt_info { /* Back-pointer to the inode */ struct inode *ci_inode; + /* + * Back-pointer to the info pointer in the extent, for infos owned by + * an extent. + */ + struct fscrypt_info **ci_info_ptr; + /* The superblock of the filesystem to which this info pertains */ struct super_block *ci_sb; diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index d79a42a54906..1aa5b2a0096e 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -625,12 +625,17 @@ static int fscrypt_setup_encryption_info(struct inode *inode, const union fscrypt_policy *policy, const u8 nonce[FSCRYPT_FILE_NONCE_SIZE], - bool need_dirhash_key) + bool need_dirhash_key, + struct fscrypt_info **info_ptr) { struct fscrypt_info *crypt_info; struct fscrypt_mode *mode; struct fscrypt_master_key *mk = NULL; int res; + bool info_for_extent = !!info_ptr; + + if (!info_ptr) + info_ptr = &inode->i_crypt_info; res = fscrypt_initialize(inode->i_sb); if (res) @@ -640,7 +645,11 @@ fscrypt_setup_encryption_info(struct inode *inode, if (!crypt_info) return -ENOMEM; - crypt_info->ci_inode = inode; + if (fscrypt_uses_extent_encryption(inode) && info_for_extent) + crypt_info->ci_info_ptr = info_ptr; + else + crypt_info->ci_inode = inode; + crypt_info->ci_sb = inode->i_sb; crypt_info->ci_policy = *policy; memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); @@ -656,6 +665,12 @@ fscrypt_setup_encryption_info(struct inode *inode, res = fscrypt_select_encryption_impl(crypt_info); if (res) goto out; + if (info_for_extent && !fscrypt_using_inline_encryption(crypt_info)) { + fscrypt_warn(inode, + "extent encryption requires inlinecrypt mount option"); + res = -EINVAL; + goto out; + } res = find_and_lock_master_key(crypt_info, &mk); if (res) @@ -701,7 +716,7 @@ fscrypt_setup_encryption_info(struct inode *inode, * fscrypt_get_info(). I.e., here we publish ->i_crypt_info with a * RELEASE barrier so that other tasks can ACQUIRE it. */ - if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) { + if (cmpxchg_release(info_ptr, NULL, crypt_info) == NULL) { /* * We won the race and set ->i_crypt_info to our crypt_info. * Now link it into the master key's inode list. @@ -735,7 +750,7 @@ fscrypt_setup_encryption_info(struct inode *inode, * %false unless the operation being performed is needed in * order for files (or directories) to be deleted. * - * Set up ->i_crypt_info, if it hasn't already been done. + * Set up inode->i_crypt_info, if it hasn't already been done. * * Note: unless ->i_crypt_info is already set, this isn't %GFP_NOFS-safe. So * generally this shouldn't be called from within a filesystem transaction. @@ -747,8 +762,9 @@ fscrypt_setup_encryption_info(struct inode *inode, int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) { int res; - union fscrypt_context ctx = { 0 }; + union fscrypt_context ctx; union fscrypt_policy policy; + const u8 *nonce; if (fscrypt_has_encryption_key(inode)) return 0; @@ -756,7 +772,7 @@ int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) 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. + * the parent (dir) inode's policy and nonce. */ struct dentry *dentry = d_find_any_alias(inode); struct dentry *parent_dentry = dget_parent(dentry); @@ -789,6 +805,7 @@ int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) "Unrecognized or corrupt encryption context"); return res; } + nonce = fscrypt_context_nonce(&ctx); } if (!fscrypt_supported_policy(&policy, inode)) { @@ -797,10 +814,10 @@ int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) return -EINVAL; } - res = fscrypt_setup_encryption_info(inode, &policy, - fscrypt_context_nonce(&ctx), + res = fscrypt_setup_encryption_info(inode, &policy, nonce, IS_CASEFOLDED(inode) && - S_ISDIR(inode->i_mode)); + S_ISDIR(inode->i_mode), + NULL); if (res == -ENOPKG && allow_unsupported) /* Algorithm unavailable? */ res = 0; @@ -834,7 +851,8 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode, bool *encrypt_ret) { const union fscrypt_policy *policy; - u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; + u8 nonce_bytes[FSCRYPT_FILE_NONCE_SIZE]; + const u8 *nonce; policy = fscrypt_policy_to_inherit(dir); if (policy == NULL) @@ -856,10 +874,17 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode, *encrypt_ret = true; - get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE); + if (fscrypt_uses_extent_encryption(inode)) { + nonce = dir->i_crypt_info->ci_nonce; + } else { + get_random_bytes(nonce_bytes, FSCRYPT_FILE_NONCE_SIZE); + nonce = nonce_bytes; + } + return fscrypt_setup_encryption_info(inode, policy, nonce, IS_CASEFOLDED(dir) && - S_ISDIR(inode->i_mode)); + S_ISDIR(inode->i_mode), + NULL); } EXPORT_SYMBOL_GPL(fscrypt_prepare_new_inode); -- 2.40.1
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