summaryrefslogtreecommitdiffstats
path: root/fs/crypto/fname.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /fs/crypto/fname.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'fs/crypto/fname.c')
-rw-r--r--fs/crypto/fname.c514
1 files changed, 514 insertions, 0 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
new file mode 100644
index 000000000..629eb0d72
--- /dev/null
+++ b/fs/crypto/fname.c
@@ -0,0 +1,514 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This contains functions for filename crypto management
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility
+ *
+ * Written by Uday Savagaonkar, 2014.
+ * Modified by Jaegeuk Kim, 2015.
+ *
+ * This has not yet undergone a rigorous security audit.
+ */
+
+#include <crypto/sha2.h>
+#include <crypto/skcipher.h>
+#include <linux/export.h>
+#include <linux/namei.h>
+#include <linux/scatterlist.h>
+#include <linux/base64.h>
+
+#include "fscrypt_private.h"
+
+/*
+ * The minimum message length (input and output length), in bytes, for all
+ * filenames encryption modes. Filenames shorter than this will be zero-padded
+ * before being encrypted.
+ */
+#define FSCRYPT_FNAME_MIN_MSG_LEN 16
+
+/*
+ * struct fscrypt_nokey_name - identifier for directory entry when key is absent
+ *
+ * When userspace lists an encrypted directory without access to the key, the
+ * filesystem must present a unique "no-key name" for each filename that allows
+ * it to find the directory entry again if requested. Naively, that would just
+ * mean using the ciphertext filenames. However, since the ciphertext filenames
+ * can contain illegal characters ('\0' and '/'), they must be encoded in some
+ * way. We use base64url. But that can cause names to exceed NAME_MAX (255
+ * bytes), so we also need to use a strong hash to abbreviate long names.
+ *
+ * The filesystem may also need another kind of hash, the "dirhash", to quickly
+ * find the directory entry. Since filesystems normally compute the dirhash
+ * over the on-disk filename (i.e. the ciphertext), it's not computable from
+ * no-key names that abbreviate the ciphertext using the strong hash to fit in
+ * NAME_MAX. It's also not computable if it's a keyed hash taken over the
+ * plaintext (but it may still be available in the on-disk directory entry);
+ * casefolded directories use this type of dirhash. At least in these cases,
+ * each no-key name must include the name's dirhash too.
+ *
+ * To meet all these requirements, we base64url-encode the following
+ * variable-length structure. It contains the dirhash, or 0's if the filesystem
+ * didn't provide one; up to 149 bytes of the ciphertext name; and for
+ * ciphertexts longer than 149 bytes, also the SHA-256 of the remaining bytes.
+ *
+ * This ensures that each no-key name contains everything needed to find the
+ * directory entry again, contains only legal characters, doesn't exceed
+ * NAME_MAX, is unambiguous unless there's a SHA-256 collision, and that we only
+ * take the performance hit of SHA-256 on very long filenames (which are rare).
+ */
+struct fscrypt_nokey_name {
+ u32 dirhash[2];
+ u8 bytes[149];
+ u8 sha256[SHA256_DIGEST_SIZE];
+}; /* 189 bytes => 252 bytes base64url-encoded, which is <= NAME_MAX (255) */
+
+/*
+ * Decoded size of max-size no-key name, i.e. a name that was abbreviated using
+ * the strong hash and thus includes the 'sha256' field. This isn't simply
+ * sizeof(struct fscrypt_nokey_name), as the padding at the end isn't included.
+ */
+#define FSCRYPT_NOKEY_NAME_MAX offsetofend(struct fscrypt_nokey_name, sha256)
+
+/* Encoded size of max-size no-key name */
+#define FSCRYPT_NOKEY_NAME_MAX_ENCODED \
+ BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX)
+
+static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
+{
+ return name_is_dot_dotdot(str->name, str->len);
+}
+
+/**
+ * fscrypt_fname_encrypt() - encrypt a filename
+ * @inode: inode of the parent directory (for regular filenames)
+ * 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.
+ * Any extra space is filled with NUL padding before encryption.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
+ u8 *out, unsigned int olen)
+{
+ const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
+ struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm;
+ SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
+ union fscrypt_iv iv;
+ struct scatterlist sg;
+ int err;
+
+ /*
+ * Copy the filename to the output buffer for encrypting in-place and
+ * pad it with the needed number of NUL bytes.
+ */
+ if (WARN_ON_ONCE(olen < iname->len))
+ return -ENOBUFS;
+ memcpy(out, iname->name, iname->len);
+ memset(out + iname->len, 0, olen - iname->len);
+
+ fscrypt_generate_iv(&iv, 0, ci);
+
+ skcipher_request_set_callback(
+ req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ NULL, NULL);
+ sg_init_one(&sg, out, olen);
+ skcipher_request_set_crypt(req, &sg, &sg, olen, &iv);
+ err = crypto_skcipher_encrypt(req);
+ if (err)
+ fscrypt_err(inode, "Filename encryption failed: %d", err);
+ return err;
+}
+EXPORT_SYMBOL_GPL(fscrypt_fname_encrypt);
+
+/**
+ * fname_decrypt() - decrypt a filename
+ * @inode: inode of the parent directory (for regular filenames)
+ * or of the symlink (for symlink targets)
+ * @iname: the encrypted filename to decrypt
+ * @oname: (output) the decrypted filename. The caller must have allocated
+ * enough space for this, e.g. using fscrypt_fname_alloc_buffer().
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int fname_decrypt(const struct inode *inode,
+ const struct fscrypt_str *iname,
+ struct fscrypt_str *oname)
+{
+ const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
+ struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm;
+ SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
+ union fscrypt_iv iv;
+ struct scatterlist src_sg, dst_sg;
+ int err;
+
+ fscrypt_generate_iv(&iv, 0, ci);
+
+ skcipher_request_set_callback(
+ req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ NULL, NULL);
+ sg_init_one(&src_sg, iname->name, iname->len);
+ sg_init_one(&dst_sg, oname->name, oname->len);
+ skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, &iv);
+ err = crypto_skcipher_decrypt(req);
+ if (err) {
+ fscrypt_err(inode, "Filename decryption failed: %d", err);
+ return err;
+ }
+
+ oname->len = strnlen(oname->name, iname->len);
+ return 0;
+}
+
+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);
+ u32 encrypted_len;
+
+ if (orig_len > max_len)
+ return false;
+ encrypted_len = max_t(u32, orig_len, FSCRYPT_FNAME_MIN_MSG_LEN);
+ encrypted_len = round_up(encrypted_len, padding);
+ *encrypted_len_ret = min(encrypted_len, max_len);
+ 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)
+{
+ const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
+
+ return __fscrypt_fname_encrypted_size(&ci->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
+ * used to present
+ * @crypto_str: (output) buffer to allocate
+ *
+ * Allocate a buffer that is large enough to hold any decrypted or encoded
+ * filename (null-terminated), for the given maximum encrypted filename length.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
+ struct fscrypt_str *crypto_str)
+{
+ u32 max_presented_len = max_t(u32, FSCRYPT_NOKEY_NAME_MAX_ENCODED,
+ max_encrypted_len);
+
+ crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
+ if (!crypto_str->name)
+ return -ENOMEM;
+ crypto_str->len = max_presented_len;
+ return 0;
+}
+EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
+
+/**
+ * fscrypt_fname_free_buffer() - free a buffer for presented filenames
+ * @crypto_str: the buffer to free
+ *
+ * Free a buffer that was allocated by fscrypt_fname_alloc_buffer().
+ */
+void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
+{
+ if (!crypto_str)
+ return;
+ kfree(crypto_str->name);
+ crypto_str->name = NULL;
+}
+EXPORT_SYMBOL(fscrypt_fname_free_buffer);
+
+/**
+ * fscrypt_fname_disk_to_usr() - convert an encrypted filename to
+ * user-presentable form
+ * @inode: inode of the parent directory (for regular filenames)
+ * or of the symlink (for symlink targets)
+ * @hash: first part of the name's dirhash, if applicable. This only needs to
+ * be provided if the filename is located in an indexed directory whose
+ * encryption key may be unavailable. Not needed for symlink targets.
+ * @minor_hash: second part of the name's dirhash, if applicable
+ * @iname: encrypted filename to convert. May also be "." or "..", which
+ * aren't actually encrypted.
+ * @oname: output buffer for the user-presentable filename. The caller must
+ * have allocated enough space for this, e.g. using
+ * fscrypt_fname_alloc_buffer().
+ *
+ * If the key is available, we'll decrypt the disk name. Otherwise, we'll
+ * encode it for presentation in fscrypt_nokey_name format.
+ * See struct fscrypt_nokey_name for details.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int fscrypt_fname_disk_to_usr(const struct inode *inode,
+ u32 hash, u32 minor_hash,
+ const struct fscrypt_str *iname,
+ struct fscrypt_str *oname)
+{
+ const struct qstr qname = FSTR_TO_QSTR(iname);
+ struct fscrypt_nokey_name nokey_name;
+ u32 size; /* size of the unencoded no-key name */
+
+ if (fscrypt_is_dot_dotdot(&qname)) {
+ oname->name[0] = '.';
+ oname->name[iname->len - 1] = '.';
+ oname->len = iname->len;
+ return 0;
+ }
+
+ if (iname->len < FSCRYPT_FNAME_MIN_MSG_LEN)
+ return -EUCLEAN;
+
+ if (fscrypt_has_encryption_key(inode))
+ return fname_decrypt(inode, iname, oname);
+
+ /*
+ * Sanity check that struct fscrypt_nokey_name doesn't have padding
+ * between fields and that its encoded size never exceeds NAME_MAX.
+ */
+ BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, dirhash) !=
+ offsetof(struct fscrypt_nokey_name, bytes));
+ BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, bytes) !=
+ offsetof(struct fscrypt_nokey_name, sha256));
+ BUILD_BUG_ON(FSCRYPT_NOKEY_NAME_MAX_ENCODED > NAME_MAX);
+
+ nokey_name.dirhash[0] = hash;
+ nokey_name.dirhash[1] = minor_hash;
+
+ if (iname->len <= sizeof(nokey_name.bytes)) {
+ memcpy(nokey_name.bytes, iname->name, iname->len);
+ size = offsetof(struct fscrypt_nokey_name, bytes[iname->len]);
+ } else {
+ memcpy(nokey_name.bytes, iname->name, sizeof(nokey_name.bytes));
+ /* Compute strong hash of remaining part of name. */
+ sha256(&iname->name[sizeof(nokey_name.bytes)],
+ iname->len - sizeof(nokey_name.bytes),
+ nokey_name.sha256);
+ size = FSCRYPT_NOKEY_NAME_MAX;
+ }
+ oname->len = base64_encode((const u8 *)&nokey_name, size,
+ oname->name, false, BASE64_URLSAFE);
+ return 0;
+}
+EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
+
+/**
+ * fscrypt_setup_filename() - prepare to search a possibly encrypted directory
+ * @dir: the directory that will be searched
+ * @iname: the user-provided filename being searched for
+ * @lookup: 1 if we're allowed to proceed without the key because it's
+ * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot
+ * proceed without the key because we're going to create the dir_entry.
+ * @fname: the filename information to be filled in
+ *
+ * Given a user-provided filename @iname, this function sets @fname->disk_name
+ * to the name that would be stored in the on-disk directory entry, if possible.
+ * If the directory is unencrypted this is simply @iname. Else, if we have the
+ * directory's encryption key, then @iname is the plaintext, so we encrypt it to
+ * get the disk_name.
+ *
+ * Else, for keyless @lookup operations, @iname should be a no-key name, so we
+ * decode it to get the struct fscrypt_nokey_name. Non-@lookup operations will
+ * be impossible in this case, so we fail them with ENOKEY.
+ *
+ * If successful, fscrypt_free_filename() must be called later to clean up.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
+ int lookup, struct fscrypt_name *fname)
+{
+ struct fscrypt_nokey_name *nokey_name;
+ int ret;
+
+ memset(fname, 0, sizeof(struct fscrypt_name));
+ fname->usr_fname = iname;
+
+ if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) {
+ fname->disk_name.name = (unsigned char *)iname->name;
+ fname->disk_name.len = iname->len;
+ return 0;
+ }
+ ret = fscrypt_get_encryption_info(dir, lookup);
+ if (ret)
+ return ret;
+
+ if (fscrypt_has_encryption_key(dir)) {
+ 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,
+ GFP_NOFS);
+ if (!fname->crypto_buf.name)
+ return -ENOMEM;
+
+ ret = fscrypt_fname_encrypt(dir, iname, fname->crypto_buf.name,
+ fname->crypto_buf.len);
+ if (ret)
+ goto errout;
+ fname->disk_name.name = fname->crypto_buf.name;
+ fname->disk_name.len = fname->crypto_buf.len;
+ return 0;
+ }
+ if (!lookup)
+ return -ENOKEY;
+ fname->is_nokey_name = true;
+
+ /*
+ * We don't have the key and we are doing a lookup; decode the
+ * user-supplied name
+ */
+
+ if (iname->len > FSCRYPT_NOKEY_NAME_MAX_ENCODED)
+ return -ENOENT;
+
+ fname->crypto_buf.name = kmalloc(FSCRYPT_NOKEY_NAME_MAX, GFP_KERNEL);
+ if (fname->crypto_buf.name == NULL)
+ return -ENOMEM;
+
+ ret = base64_decode(iname->name, iname->len,
+ fname->crypto_buf.name, false, BASE64_URLSAFE);
+ if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) ||
+ (ret > offsetof(struct fscrypt_nokey_name, sha256) &&
+ ret != FSCRYPT_NOKEY_NAME_MAX)) {
+ ret = -ENOENT;
+ goto errout;
+ }
+ fname->crypto_buf.len = ret;
+
+ nokey_name = (void *)fname->crypto_buf.name;
+ fname->hash = nokey_name->dirhash[0];
+ fname->minor_hash = nokey_name->dirhash[1];
+ if (ret != FSCRYPT_NOKEY_NAME_MAX) {
+ /* The full ciphertext filename is available. */
+ fname->disk_name.name = nokey_name->bytes;
+ fname->disk_name.len =
+ ret - offsetof(struct fscrypt_nokey_name, bytes);
+ }
+ return 0;
+
+errout:
+ kfree(fname->crypto_buf.name);
+ return ret;
+}
+EXPORT_SYMBOL(fscrypt_setup_filename);
+
+/**
+ * fscrypt_match_name() - test whether the given name matches a directory entry
+ * @fname: the name being searched for
+ * @de_name: the name from the directory entry
+ * @de_name_len: the length of @de_name in bytes
+ *
+ * Normally @fname->disk_name will be set, and in that case we simply compare
+ * that to the name stored in the directory entry. The only exception is that
+ * if we don't have the key for an encrypted directory and the name we're
+ * looking for is very long, then we won't have the full disk_name and instead
+ * we'll need to match against a fscrypt_nokey_name that includes a strong hash.
+ *
+ * Return: %true if the name matches, otherwise %false.
+ */
+bool fscrypt_match_name(const struct fscrypt_name *fname,
+ const u8 *de_name, u32 de_name_len)
+{
+ const struct fscrypt_nokey_name *nokey_name =
+ (const void *)fname->crypto_buf.name;
+ u8 digest[SHA256_DIGEST_SIZE];
+
+ if (likely(fname->disk_name.name)) {
+ if (de_name_len != fname->disk_name.len)
+ return false;
+ return !memcmp(de_name, fname->disk_name.name, de_name_len);
+ }
+ if (de_name_len <= sizeof(nokey_name->bytes))
+ return false;
+ if (memcmp(de_name, nokey_name->bytes, sizeof(nokey_name->bytes)))
+ return false;
+ sha256(&de_name[sizeof(nokey_name->bytes)],
+ de_name_len - sizeof(nokey_name->bytes), digest);
+ return !memcmp(digest, nokey_name->sha256, sizeof(digest));
+}
+EXPORT_SYMBOL_GPL(fscrypt_match_name);
+
+/**
+ * fscrypt_fname_siphash() - calculate the SipHash of a filename
+ * @dir: the parent directory
+ * @name: the filename to calculate the SipHash of
+ *
+ * Given a plaintext filename @name and a directory @dir which uses SipHash as
+ * its dirhash method and has had its fscrypt key set up, this function
+ * calculates the SipHash of that name using the directory's secret dirhash key.
+ *
+ * Return: the SipHash of @name using the hash key of @dir
+ */
+u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name)
+{
+ const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(dir);
+
+ WARN_ON_ONCE(!ci->ci_dirhash_key_initialized);
+
+ return siphash(name->name, name->len, &ci->ci_dirhash_key);
+}
+EXPORT_SYMBOL_GPL(fscrypt_fname_siphash);
+
+/*
+ * Validate dentries in encrypted directories to make sure we aren't potentially
+ * caching stale dentries after a key has been added.
+ */
+int fscrypt_d_revalidate(struct inode *dir, const struct qstr *name,
+ struct dentry *dentry, unsigned int flags)
+{
+ int err;
+
+ /*
+ * Plaintext names are always valid, since fscrypt doesn't support
+ * reverting to no-key names without evicting the directory's inode
+ * -- which implies eviction of the dentries in the directory.
+ */
+ if (!(dentry->d_flags & DCACHE_NOKEY_NAME))
+ return 1;
+
+ /*
+ * No-key name; valid if the directory's key is still unavailable.
+ *
+ * Note in RCU mode we have to bail if we get here -
+ * fscrypt_get_encryption_info() may block.
+ */
+
+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ /*
+ * Pass allow_unsupported=true, so that files with an unsupported
+ * encryption policy can be deleted.
+ */
+ err = fscrypt_get_encryption_info(dir, true);
+ if (err < 0)
+ return err;
+
+ return !fscrypt_has_encryption_key(dir);
+}
+EXPORT_SYMBOL_GPL(fscrypt_d_revalidate);