From d3e94fdc4ef476ca1edd468cc11badf2dbbb3c00 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 8 Jan 2021 15:34:38 -0500 Subject: fscrypt: export fscrypt_fname_encrypt and fscrypt_fname_encrypted_size For ceph, we want to use our own scheme for handling filenames that are are longer than NAME_MAX after encryption and Base64 encoding. This allows us to have a consistent view of the encrypted filenames for clients that don't support fscrypt and clients that do but that don't have the key. Currently, fs/crypto only supports encrypting filenames using fscrypt_setup_filename, but that also handles encoding nokey names. Ceph can't use that because it handles nokey names in a different way. Export fscrypt_fname_encrypt. Rename fscrypt_fname_encrypted_size to __fscrypt_fname_encrypted_size and add a new wrapper called fscrypt_fname_encrypted_size that takes an inode argument rather than a pointer to a fscrypt_policy union. Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li Acked-by: Eric Biggers Signed-off-by: Ilya Dryomov --- fs/crypto/fname.c | 36 ++++++++++++++++++++++++++++++------ fs/crypto/fscrypt_private.h | 9 +++------ fs/crypto/hooks.c | 6 +++--- 3 files changed, 36 insertions(+), 15 deletions(-) (limited to 'fs/crypto') diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 14e0ef5e9a20..12bd61d20f69 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -86,7 +86,8 @@ static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) /** * fscrypt_fname_encrypt() - encrypt a filename * @inode: inode of the parent directory (for regular filenames) - * or of the symlink (for symlink targets) + * or of the symlink (for symlink targets). Key must already be + * set up. * @iname: the filename to encrypt * @out: (output) the encrypted filename * @olen: size of the encrypted filename. It must be at least @iname->len. @@ -137,6 +138,7 @@ int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname, return 0; } +EXPORT_SYMBOL_GPL(fscrypt_fname_encrypt); /** * fname_decrypt() - decrypt a filename @@ -264,9 +266,9 @@ static int fscrypt_base64url_decode(const char *src, int srclen, u8 *dst) return bp - dst; } -bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, - u32 orig_len, u32 max_len, - u32 *encrypted_len_ret) +bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, + u32 orig_len, u32 max_len, + u32 *encrypted_len_ret) { int padding = 4 << (fscrypt_policy_flags(policy) & FSCRYPT_POLICY_FLAGS_PAD_MASK); @@ -280,6 +282,29 @@ bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, return true; } +/** + * fscrypt_fname_encrypted_size() - calculate length of encrypted filename + * @inode: parent inode of dentry name being encrypted. Key must + * already be set up. + * @orig_len: length of the original filename + * @max_len: maximum length to return + * @encrypted_len_ret: where calculated length should be returned (on success) + * + * Filenames that are shorter than the maximum length may have their lengths + * increased slightly by encryption, due to padding that is applied. + * + * Return: false if the orig_len is greater than max_len. Otherwise, true and + * fill out encrypted_len_ret with the length (up to max_len). + */ +bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len, + u32 max_len, u32 *encrypted_len_ret) +{ + return __fscrypt_fname_encrypted_size(&inode->i_crypt_info->ci_policy, + orig_len, max_len, + encrypted_len_ret); +} +EXPORT_SYMBOL_GPL(fscrypt_fname_encrypted_size); + /** * fscrypt_fname_alloc_buffer() - allocate a buffer for presented filenames * @max_encrypted_len: maximum length of encrypted filenames the buffer will be @@ -435,8 +460,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, return ret; if (fscrypt_has_encryption_key(dir)) { - if (!fscrypt_fname_encrypted_size(&dir->i_crypt_info->ci_policy, - iname->len, NAME_MAX, + if (!fscrypt_fname_encrypted_size(dir, iname->len, NAME_MAX, &fname->crypto_buf.len)) return -ENAMETOOLONG; fname->crypto_buf.name = kmalloc(fname->crypto_buf.len, diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 6b4c8094cc7b..11fe9d213ae1 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -297,14 +297,11 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, const struct fscrypt_info *ci); /* fname.c */ -int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname, - u8 *out, unsigned int olen); -bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, - u32 orig_len, u32 max_len, - u32 *encrypted_len_ret); +bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, + u32 orig_len, u32 max_len, + u32 *encrypted_len_ret); /* hkdf.c */ - struct fscrypt_hkdf { struct crypto_shash *hmac_tfm; }; diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index af74599ae1cf..7c01025879b3 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -228,9 +228,9 @@ int fscrypt_prepare_symlink(struct inode *dir, const char *target, * counting it (even though it is meaningless for ciphertext) is simpler * for now since filesystems will assume it is there and subtract it. */ - if (!fscrypt_fname_encrypted_size(policy, len, - max_len - sizeof(struct fscrypt_symlink_data), - &disk_link->len)) + if (!__fscrypt_fname_encrypted_size(policy, len, + max_len - sizeof(struct fscrypt_symlink_data), + &disk_link->len)) return -ENAMETOOLONG; disk_link->len += sizeof(struct fscrypt_symlink_data); -- cgit v1.2.3 From 637fa738b590ec0e3414931d1e07c4f195eb5215 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 1 Sep 2020 12:56:42 -0400 Subject: fscrypt: add fscrypt_context_for_new_inode Most filesystems just call fscrypt_set_context on new inodes, which usually causes a setxattr. That's a bit late for ceph, which can send along a full set of attributes with the create request. Doing so allows it to avoid race windows that where the new inode could be seen by other clients without the crypto context attached. It also avoids the separate round trip to the server. Refactor the fscrypt code a bit to allow us to create a new crypto context, attach it to the inode, and write it to the buffer, but without calling set_context on it. ceph can later use this to marshal the context into the attributes we send along with the create request. Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li Acked-by: Eric Biggers Signed-off-by: Ilya Dryomov --- fs/crypto/policy.c | 35 +++++++++++++++++++++++++++++------ include/linux/fscrypt.h | 1 + 2 files changed, 30 insertions(+), 6 deletions(-) (limited to 'fs/crypto') diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 5f858cee1e3b..a450189565e3 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -685,6 +685,32 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir) return fscrypt_get_dummy_policy(dir->i_sb); } +/** + * fscrypt_context_for_new_inode() - create an encryption context for a new inode + * @ctx: where context should be written + * @inode: inode from which to fetch policy and nonce + * + * Given an in-core "prepared" (via fscrypt_prepare_new_inode) inode, + * generate a new context and write it to ctx. ctx _must_ be at least + * FSCRYPT_SET_CONTEXT_MAX_SIZE bytes. + * + * Return: size of the resulting context or a negative error code. + */ +int fscrypt_context_for_new_inode(void *ctx, struct inode *inode) +{ + struct fscrypt_info *ci = inode->i_crypt_info; + + BUILD_BUG_ON(sizeof(union fscrypt_context) != + FSCRYPT_SET_CONTEXT_MAX_SIZE); + + /* fscrypt_prepare_new_inode() should have set up the key already. */ + if (WARN_ON_ONCE(!ci)) + return -ENOKEY; + + return fscrypt_new_context(ctx, &ci->ci_policy, ci->ci_nonce); +} +EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode); + /** * fscrypt_set_context() - Set the fscrypt context of a new inode * @inode: a new inode @@ -701,12 +727,9 @@ int fscrypt_set_context(struct inode *inode, void *fs_data) union fscrypt_context ctx; int ctxsize; - /* fscrypt_prepare_new_inode() should have set up the key already. */ - if (WARN_ON_ONCE(!ci)) - return -ENOKEY; - - BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE); - ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, ci->ci_nonce); + ctxsize = fscrypt_context_for_new_inode(&ctx, inode); + if (ctxsize < 0) + return ctxsize; /* * This may be the first time the inode number is available, so do any diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 5926a4081c6d..7d2f1e0f23b1 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -284,6 +284,7 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg); int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg); int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg); int fscrypt_has_permitted_context(struct inode *parent, struct inode *child); +int fscrypt_context_for_new_inode(void *ctx, struct inode *inode); int fscrypt_set_context(struct inode *inode, void *fs_data); struct fscrypt_dummy_policy { -- cgit v1.2.3