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3e7807d5a7
We are going to track per-extent information, so it'll be necessary to distinguish between inode infos and extent infos. Rename fscrypt_info to fscrypt_inode_info, adjusting any lines that now exceed 80 characters. Signed-off-by: Josef Bacik <josef@toxicpanda.com> [ebiggers: rebased onto fscrypt tree, renamed fscrypt_get_info(), adjusted two comments, and fixed some lines over 80 characters] Link: https://lore.kernel.org/r/20231005025757.33521-1-ebiggers@kernel.org Reviewed-by: Neal Gompa <neal@gompa.dev> Signed-off-by: Eric Biggers <ebiggers@google.com>
895 lines
27 KiB
C
895 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Encryption policy functions for per-file encryption support.
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*
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* Copyright (C) 2015, Google, Inc.
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* Copyright (C) 2015, Motorola Mobility.
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*
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* Originally written by Michael Halcrow, 2015.
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* Modified by Jaegeuk Kim, 2015.
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* Modified by Eric Biggers, 2019 for v2 policy support.
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*/
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#include <linux/fs_context.h>
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#include <linux/random.h>
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#include <linux/seq_file.h>
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#include <linux/string.h>
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#include <linux/mount.h>
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#include "fscrypt_private.h"
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/**
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* fscrypt_policies_equal() - check whether two encryption policies are the same
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* @policy1: the first policy
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* @policy2: the second policy
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*
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* Return: %true if equal, else %false
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*/
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bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
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const union fscrypt_policy *policy2)
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{
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if (policy1->version != policy2->version)
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return false;
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return !memcmp(policy1, policy2, fscrypt_policy_size(policy1));
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}
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int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
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struct fscrypt_key_specifier *key_spec)
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{
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switch (policy->version) {
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case FSCRYPT_POLICY_V1:
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key_spec->type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
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memcpy(key_spec->u.descriptor, policy->v1.master_key_descriptor,
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FSCRYPT_KEY_DESCRIPTOR_SIZE);
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return 0;
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case FSCRYPT_POLICY_V2:
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key_spec->type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
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memcpy(key_spec->u.identifier, policy->v2.master_key_identifier,
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FSCRYPT_KEY_IDENTIFIER_SIZE);
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return 0;
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default:
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WARN_ON_ONCE(1);
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return -EINVAL;
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}
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}
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const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb)
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{
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if (!sb->s_cop->get_dummy_policy)
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return NULL;
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return sb->s_cop->get_dummy_policy(sb);
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}
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/*
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* Return %true if the given combination of encryption modes is supported for v1
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* (and later) encryption policies.
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*
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* Do *not* add anything new here, since v1 encryption policies are deprecated.
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* New combinations of modes should go in fscrypt_valid_enc_modes_v2() only.
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*/
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static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode)
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{
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if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
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filenames_mode == FSCRYPT_MODE_AES_256_CTS)
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return true;
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if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
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filenames_mode == FSCRYPT_MODE_AES_128_CTS)
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return true;
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if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
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filenames_mode == FSCRYPT_MODE_ADIANTUM)
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return true;
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return false;
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}
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static bool fscrypt_valid_enc_modes_v2(u32 contents_mode, u32 filenames_mode)
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{
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if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
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filenames_mode == FSCRYPT_MODE_AES_256_HCTR2)
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return true;
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if (contents_mode == FSCRYPT_MODE_SM4_XTS &&
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filenames_mode == FSCRYPT_MODE_SM4_CTS)
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return true;
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return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode);
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}
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static bool supported_direct_key_modes(const struct inode *inode,
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u32 contents_mode, u32 filenames_mode)
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{
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const struct fscrypt_mode *mode;
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if (contents_mode != filenames_mode) {
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fscrypt_warn(inode,
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"Direct key flag not allowed with different contents and filenames modes");
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return false;
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}
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mode = &fscrypt_modes[contents_mode];
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if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) {
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fscrypt_warn(inode, "Direct key flag not allowed with %s",
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mode->friendly_name);
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return false;
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}
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return true;
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}
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static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
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const struct inode *inode)
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{
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const char *type = (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)
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? "IV_INO_LBLK_64" : "IV_INO_LBLK_32";
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struct super_block *sb = inode->i_sb;
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/*
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* IV_INO_LBLK_* exist only because of hardware limitations, and
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* currently the only known use case for them involves AES-256-XTS.
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* That's also all we test currently. For these reasons, for now only
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* allow AES-256-XTS here. This can be relaxed later if a use case for
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* IV_INO_LBLK_* with other encryption modes arises.
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*/
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if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) {
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fscrypt_warn(inode,
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"Can't use %s policy with contents mode other than AES-256-XTS",
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type);
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return false;
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}
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/*
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* It's unsafe to include inode numbers in the IVs if the filesystem can
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* potentially renumber inodes, e.g. via filesystem shrinking.
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*/
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if (!sb->s_cop->has_stable_inodes ||
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!sb->s_cop->has_stable_inodes(sb)) {
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fscrypt_warn(inode,
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"Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers",
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type, sb->s_id);
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return false;
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}
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/*
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* IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that inode numbers fit
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* in 32 bits. In principle, IV_INO_LBLK_32 could support longer inode
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* numbers because it hashes the inode number; however, currently the
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* inode number is gotten from inode::i_ino which is 'unsigned long'.
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* So for now the implementation limit is 32 bits.
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*/
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if (!sb->s_cop->has_32bit_inodes) {
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fscrypt_warn(inode,
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"Can't use %s policy on filesystem '%s' because its inode numbers are too long",
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type, sb->s_id);
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return false;
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}
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/*
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* IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that file data unit
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* indices fit in 32 bits.
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*/
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if (fscrypt_max_file_dun_bits(sb,
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fscrypt_policy_v2_du_bits(policy, inode)) > 32) {
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fscrypt_warn(inode,
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"Can't use %s policy on filesystem '%s' because its maximum file size is too large",
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type, sb->s_id);
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return false;
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}
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return true;
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}
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static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy,
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const struct inode *inode)
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{
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if (!fscrypt_valid_enc_modes_v1(policy->contents_encryption_mode,
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policy->filenames_encryption_mode)) {
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fscrypt_warn(inode,
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"Unsupported encryption modes (contents %d, filenames %d)",
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policy->contents_encryption_mode,
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policy->filenames_encryption_mode);
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return false;
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}
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if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK |
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FSCRYPT_POLICY_FLAG_DIRECT_KEY)) {
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fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)",
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policy->flags);
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return false;
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}
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if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) &&
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!supported_direct_key_modes(inode, policy->contents_encryption_mode,
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policy->filenames_encryption_mode))
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return false;
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if (IS_CASEFOLDED(inode)) {
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/* With v1, there's no way to derive dirhash keys. */
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fscrypt_warn(inode,
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"v1 policies can't be used on casefolded directories");
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return false;
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}
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return true;
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}
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static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
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const struct inode *inode)
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{
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int count = 0;
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if (!fscrypt_valid_enc_modes_v2(policy->contents_encryption_mode,
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policy->filenames_encryption_mode)) {
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fscrypt_warn(inode,
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"Unsupported encryption modes (contents %d, filenames %d)",
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policy->contents_encryption_mode,
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policy->filenames_encryption_mode);
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return false;
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}
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if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK |
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FSCRYPT_POLICY_FLAG_DIRECT_KEY |
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FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
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FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
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fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)",
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policy->flags);
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return false;
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}
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count += !!(policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY);
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count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64);
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count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32);
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if (count > 1) {
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fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)",
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policy->flags);
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return false;
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}
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if (policy->log2_data_unit_size) {
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if (!inode->i_sb->s_cop->supports_subblock_data_units) {
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fscrypt_warn(inode,
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"Filesystem does not support configuring crypto data unit size");
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return false;
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}
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if (policy->log2_data_unit_size > inode->i_blkbits ||
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policy->log2_data_unit_size < SECTOR_SHIFT /* 9 */) {
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fscrypt_warn(inode,
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"Unsupported log2_data_unit_size in encryption policy: %d",
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policy->log2_data_unit_size);
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return false;
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}
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if (policy->log2_data_unit_size != inode->i_blkbits &&
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(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
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/*
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* Not safe to enable yet, as we need to ensure that DUN
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* wraparound can only occur on a FS block boundary.
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*/
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fscrypt_warn(inode,
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"Sub-block data units not yet supported with IV_INO_LBLK_32");
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return false;
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}
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}
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if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) &&
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!supported_direct_key_modes(inode, policy->contents_encryption_mode,
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policy->filenames_encryption_mode))
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return false;
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if ((policy->flags & (FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
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FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) &&
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!supported_iv_ino_lblk_policy(policy, inode))
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return false;
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if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) {
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fscrypt_warn(inode, "Reserved bits set in encryption policy");
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return false;
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}
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return true;
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}
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/**
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* fscrypt_supported_policy() - check whether an encryption policy is supported
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* @policy_u: the encryption policy
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* @inode: the inode on which the policy will be used
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*
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* Given an encryption policy, check whether all its encryption modes and other
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* settings are supported by this kernel on the given inode. (But we don't
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* currently don't check for crypto API support here, so attempting to use an
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* algorithm not configured into the crypto API will still fail later.)
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*
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* Return: %true if supported, else %false
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*/
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bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
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const struct inode *inode)
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{
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switch (policy_u->version) {
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case FSCRYPT_POLICY_V1:
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return fscrypt_supported_v1_policy(&policy_u->v1, inode);
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case FSCRYPT_POLICY_V2:
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return fscrypt_supported_v2_policy(&policy_u->v2, inode);
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}
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return false;
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}
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/**
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* fscrypt_new_context() - create a new fscrypt_context
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* @ctx_u: output context
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* @policy_u: input policy
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* @nonce: nonce to use
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*
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* Create an fscrypt_context for an inode that is being assigned the given
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* encryption policy. @nonce must be a new random nonce.
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*
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* Return: the size of the new context in bytes.
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*/
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static int fscrypt_new_context(union fscrypt_context *ctx_u,
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const union fscrypt_policy *policy_u,
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const u8 nonce[FSCRYPT_FILE_NONCE_SIZE])
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{
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memset(ctx_u, 0, sizeof(*ctx_u));
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switch (policy_u->version) {
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case FSCRYPT_POLICY_V1: {
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const struct fscrypt_policy_v1 *policy = &policy_u->v1;
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struct fscrypt_context_v1 *ctx = &ctx_u->v1;
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ctx->version = FSCRYPT_CONTEXT_V1;
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ctx->contents_encryption_mode =
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policy->contents_encryption_mode;
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ctx->filenames_encryption_mode =
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policy->filenames_encryption_mode;
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ctx->flags = policy->flags;
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memcpy(ctx->master_key_descriptor,
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policy->master_key_descriptor,
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sizeof(ctx->master_key_descriptor));
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memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
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return sizeof(*ctx);
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}
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case FSCRYPT_POLICY_V2: {
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const struct fscrypt_policy_v2 *policy = &policy_u->v2;
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struct fscrypt_context_v2 *ctx = &ctx_u->v2;
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ctx->version = FSCRYPT_CONTEXT_V2;
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ctx->contents_encryption_mode =
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policy->contents_encryption_mode;
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ctx->filenames_encryption_mode =
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policy->filenames_encryption_mode;
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ctx->flags = policy->flags;
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ctx->log2_data_unit_size = policy->log2_data_unit_size;
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memcpy(ctx->master_key_identifier,
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policy->master_key_identifier,
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sizeof(ctx->master_key_identifier));
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memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
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return sizeof(*ctx);
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}
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}
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BUG();
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}
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/**
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* fscrypt_policy_from_context() - convert an fscrypt_context to
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* an fscrypt_policy
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* @policy_u: output policy
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* @ctx_u: input context
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* @ctx_size: size of input context in bytes
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*
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* Given an fscrypt_context, build the corresponding fscrypt_policy.
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*
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* Return: 0 on success, or -EINVAL if the fscrypt_context has an unrecognized
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* version number or size.
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*
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* This does *not* validate the settings within the policy itself, e.g. the
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* modes, flags, and reserved bits. Use fscrypt_supported_policy() for that.
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*/
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int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
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const union fscrypt_context *ctx_u,
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int ctx_size)
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{
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memset(policy_u, 0, sizeof(*policy_u));
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if (!fscrypt_context_is_valid(ctx_u, ctx_size))
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return -EINVAL;
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switch (ctx_u->version) {
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case FSCRYPT_CONTEXT_V1: {
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const struct fscrypt_context_v1 *ctx = &ctx_u->v1;
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struct fscrypt_policy_v1 *policy = &policy_u->v1;
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policy->version = FSCRYPT_POLICY_V1;
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policy->contents_encryption_mode =
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ctx->contents_encryption_mode;
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policy->filenames_encryption_mode =
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ctx->filenames_encryption_mode;
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policy->flags = ctx->flags;
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memcpy(policy->master_key_descriptor,
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ctx->master_key_descriptor,
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sizeof(policy->master_key_descriptor));
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return 0;
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}
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case FSCRYPT_CONTEXT_V2: {
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const struct fscrypt_context_v2 *ctx = &ctx_u->v2;
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struct fscrypt_policy_v2 *policy = &policy_u->v2;
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policy->version = FSCRYPT_POLICY_V2;
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policy->contents_encryption_mode =
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ctx->contents_encryption_mode;
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policy->filenames_encryption_mode =
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ctx->filenames_encryption_mode;
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policy->flags = ctx->flags;
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policy->log2_data_unit_size = ctx->log2_data_unit_size;
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memcpy(policy->__reserved, ctx->__reserved,
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sizeof(policy->__reserved));
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memcpy(policy->master_key_identifier,
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ctx->master_key_identifier,
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sizeof(policy->master_key_identifier));
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return 0;
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}
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}
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/* unreachable */
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return -EINVAL;
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}
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/* Retrieve an inode's encryption policy */
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static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy)
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{
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const struct fscrypt_inode_info *ci;
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union fscrypt_context ctx;
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int ret;
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ci = fscrypt_get_inode_info(inode);
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if (ci) {
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/* key available, use the cached policy */
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*policy = ci->ci_policy;
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return 0;
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}
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if (!IS_ENCRYPTED(inode))
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return -ENODATA;
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ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
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if (ret < 0)
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return (ret == -ERANGE) ? -EINVAL : ret;
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return fscrypt_policy_from_context(policy, &ctx, ret);
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}
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static int set_encryption_policy(struct inode *inode,
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const union fscrypt_policy *policy)
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{
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u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
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union fscrypt_context ctx;
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int ctxsize;
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int err;
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if (!fscrypt_supported_policy(policy, inode))
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return -EINVAL;
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switch (policy->version) {
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case FSCRYPT_POLICY_V1:
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/*
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* The original encryption policy version provided no way of
|
|
* verifying that the correct master key was supplied, which was
|
|
* insecure in scenarios where multiple users have access to the
|
|
* same encrypted files (even just read-only access). The new
|
|
* encryption policy version fixes this and also implies use of
|
|
* an improved key derivation function and allows non-root users
|
|
* to securely remove keys. So as long as compatibility with
|
|
* old kernels isn't required, it is recommended to use the new
|
|
* policy version for all new encrypted directories.
|
|
*/
|
|
pr_warn_once("%s (pid %d) is setting deprecated v1 encryption policy; recommend upgrading to v2.\n",
|
|
current->comm, current->pid);
|
|
break;
|
|
case FSCRYPT_POLICY_V2:
|
|
err = fscrypt_verify_key_added(inode->i_sb,
|
|
policy->v2.master_key_identifier);
|
|
if (err)
|
|
return err;
|
|
if (policy->v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)
|
|
pr_warn_once("%s (pid %d) is setting an IV_INO_LBLK_32 encryption policy. This should only be used if there are certain hardware limitations.\n",
|
|
current->comm, current->pid);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
return -EINVAL;
|
|
}
|
|
|
|
get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE);
|
|
ctxsize = fscrypt_new_context(&ctx, policy, nonce);
|
|
|
|
return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, NULL);
|
|
}
|
|
|
|
int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg)
|
|
{
|
|
union fscrypt_policy policy;
|
|
union fscrypt_policy existing_policy;
|
|
struct inode *inode = file_inode(filp);
|
|
u8 version;
|
|
int size;
|
|
int ret;
|
|
|
|
if (get_user(policy.version, (const u8 __user *)arg))
|
|
return -EFAULT;
|
|
|
|
size = fscrypt_policy_size(&policy);
|
|
if (size <= 0)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* We should just copy the remaining 'size - 1' bytes here, but a
|
|
* bizarre bug in gcc 7 and earlier (fixed by gcc r255731) causes gcc to
|
|
* think that size can be 0 here (despite the check above!) *and* that
|
|
* it's a compile-time constant. Thus it would think copy_from_user()
|
|
* is passed compile-time constant ULONG_MAX, causing the compile-time
|
|
* buffer overflow check to fail, breaking the build. This only occurred
|
|
* when building an i386 kernel with -Os and branch profiling enabled.
|
|
*
|
|
* Work around it by just copying the first byte again...
|
|
*/
|
|
version = policy.version;
|
|
if (copy_from_user(&policy, arg, size))
|
|
return -EFAULT;
|
|
policy.version = version;
|
|
|
|
if (!inode_owner_or_capable(&nop_mnt_idmap, inode))
|
|
return -EACCES;
|
|
|
|
ret = mnt_want_write_file(filp);
|
|
if (ret)
|
|
return ret;
|
|
|
|
inode_lock(inode);
|
|
|
|
ret = fscrypt_get_policy(inode, &existing_policy);
|
|
if (ret == -ENODATA) {
|
|
if (!S_ISDIR(inode->i_mode))
|
|
ret = -ENOTDIR;
|
|
else if (IS_DEADDIR(inode))
|
|
ret = -ENOENT;
|
|
else if (!inode->i_sb->s_cop->empty_dir(inode))
|
|
ret = -ENOTEMPTY;
|
|
else
|
|
ret = set_encryption_policy(inode, &policy);
|
|
} else if (ret == -EINVAL ||
|
|
(ret == 0 && !fscrypt_policies_equal(&policy,
|
|
&existing_policy))) {
|
|
/* The file already uses a different encryption policy. */
|
|
ret = -EEXIST;
|
|
}
|
|
|
|
inode_unlock(inode);
|
|
|
|
mnt_drop_write_file(filp);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_ioctl_set_policy);
|
|
|
|
/* Original ioctl version; can only get the original policy version */
|
|
int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
|
|
{
|
|
union fscrypt_policy policy;
|
|
int err;
|
|
|
|
err = fscrypt_get_policy(file_inode(filp), &policy);
|
|
if (err)
|
|
return err;
|
|
|
|
if (policy.version != FSCRYPT_POLICY_V1)
|
|
return -EINVAL;
|
|
|
|
if (copy_to_user(arg, &policy, sizeof(policy.v1)))
|
|
return -EFAULT;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_ioctl_get_policy);
|
|
|
|
/* Extended ioctl version; can get policies of any version */
|
|
int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *uarg)
|
|
{
|
|
struct fscrypt_get_policy_ex_arg arg;
|
|
union fscrypt_policy *policy = (union fscrypt_policy *)&arg.policy;
|
|
size_t policy_size;
|
|
int err;
|
|
|
|
/* arg is policy_size, then policy */
|
|
BUILD_BUG_ON(offsetof(typeof(arg), policy_size) != 0);
|
|
BUILD_BUG_ON(offsetofend(typeof(arg), policy_size) !=
|
|
offsetof(typeof(arg), policy));
|
|
BUILD_BUG_ON(sizeof(arg.policy) != sizeof(*policy));
|
|
|
|
err = fscrypt_get_policy(file_inode(filp), policy);
|
|
if (err)
|
|
return err;
|
|
policy_size = fscrypt_policy_size(policy);
|
|
|
|
if (copy_from_user(&arg, uarg, sizeof(arg.policy_size)))
|
|
return -EFAULT;
|
|
|
|
if (policy_size > arg.policy_size)
|
|
return -EOVERFLOW;
|
|
arg.policy_size = policy_size;
|
|
|
|
if (copy_to_user(uarg, &arg, sizeof(arg.policy_size) + policy_size))
|
|
return -EFAULT;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_policy_ex);
|
|
|
|
/* FS_IOC_GET_ENCRYPTION_NONCE: retrieve file's encryption nonce for testing */
|
|
int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg)
|
|
{
|
|
struct inode *inode = file_inode(filp);
|
|
union fscrypt_context ctx;
|
|
int ret;
|
|
|
|
ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
|
|
if (ret < 0)
|
|
return ret;
|
|
if (!fscrypt_context_is_valid(&ctx, ret))
|
|
return -EINVAL;
|
|
if (copy_to_user(arg, fscrypt_context_nonce(&ctx),
|
|
FSCRYPT_FILE_NONCE_SIZE))
|
|
return -EFAULT;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_nonce);
|
|
|
|
/**
|
|
* fscrypt_has_permitted_context() - is a file's encryption policy permitted
|
|
* within its directory?
|
|
*
|
|
* @parent: inode for parent directory
|
|
* @child: inode for file being looked up, opened, or linked into @parent
|
|
*
|
|
* Filesystems must call this before permitting access to an inode in a
|
|
* situation where the parent directory is encrypted (either before allowing
|
|
* ->lookup() to succeed, or for a regular file before allowing it to be opened)
|
|
* and before any operation that involves linking an inode into an encrypted
|
|
* directory, including link, rename, and cross rename. It enforces the
|
|
* constraint that within a given encrypted directory tree, all files use the
|
|
* same encryption policy. The pre-access check is needed to detect potentially
|
|
* malicious offline violations of this constraint, while the link and rename
|
|
* checks are needed to prevent online violations of this constraint.
|
|
*
|
|
* Return: 1 if permitted, 0 if forbidden.
|
|
*/
|
|
int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
|
|
{
|
|
union fscrypt_policy parent_policy, child_policy;
|
|
int err, err1, err2;
|
|
|
|
/* No restrictions on file types which are never encrypted */
|
|
if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
|
|
!S_ISLNK(child->i_mode))
|
|
return 1;
|
|
|
|
/* No restrictions if the parent directory is unencrypted */
|
|
if (!IS_ENCRYPTED(parent))
|
|
return 1;
|
|
|
|
/* Encrypted directories must not contain unencrypted files */
|
|
if (!IS_ENCRYPTED(child))
|
|
return 0;
|
|
|
|
/*
|
|
* Both parent and child are encrypted, so verify they use the same
|
|
* encryption policy. Compare the cached policies if the keys are
|
|
* available, otherwise retrieve and compare the fscrypt_contexts.
|
|
*
|
|
* Note that the fscrypt_context retrieval will be required frequently
|
|
* when accessing an encrypted directory tree without the key.
|
|
* Performance-wise this is not a big deal because we already don't
|
|
* really optimize for file access without the key (to the extent that
|
|
* such access is even possible), given that any attempted access
|
|
* already causes a fscrypt_context retrieval and keyring search.
|
|
*
|
|
* In any case, if an unexpected error occurs, fall back to "forbidden".
|
|
*/
|
|
|
|
err = fscrypt_get_encryption_info(parent, true);
|
|
if (err)
|
|
return 0;
|
|
err = fscrypt_get_encryption_info(child, true);
|
|
if (err)
|
|
return 0;
|
|
|
|
err1 = fscrypt_get_policy(parent, &parent_policy);
|
|
err2 = fscrypt_get_policy(child, &child_policy);
|
|
|
|
/*
|
|
* Allow the case where the parent and child both have an unrecognized
|
|
* encryption policy, so that files with an unrecognized encryption
|
|
* policy can be deleted.
|
|
*/
|
|
if (err1 == -EINVAL && err2 == -EINVAL)
|
|
return 1;
|
|
|
|
if (err1 || err2)
|
|
return 0;
|
|
|
|
return fscrypt_policies_equal(&parent_policy, &child_policy);
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_has_permitted_context);
|
|
|
|
/*
|
|
* Return the encryption policy that new files in the directory will inherit, or
|
|
* NULL if none, or an ERR_PTR() on error. If the directory is encrypted, also
|
|
* ensure that its key is set up, so that the new filename can be encrypted.
|
|
*/
|
|
const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
|
|
{
|
|
int err;
|
|
|
|
if (IS_ENCRYPTED(dir)) {
|
|
err = fscrypt_require_key(dir);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
return &dir->i_crypt_info->ci_policy;
|
|
}
|
|
|
|
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_inode_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
|
|
* @fs_data: private data given by FS and passed to ->set_context()
|
|
*
|
|
* This should be called after fscrypt_prepare_new_inode(), generally during a
|
|
* filesystem transaction. Everything here must be %GFP_NOFS-safe.
|
|
*
|
|
* Return: 0 on success, -errno on failure
|
|
*/
|
|
int fscrypt_set_context(struct inode *inode, void *fs_data)
|
|
{
|
|
struct fscrypt_inode_info *ci = inode->i_crypt_info;
|
|
union fscrypt_context ctx;
|
|
int ctxsize;
|
|
|
|
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
|
|
* delayed key setup that requires the inode number.
|
|
*/
|
|
if (ci->ci_policy.version == FSCRYPT_POLICY_V2 &&
|
|
(ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
|
|
fscrypt_hash_inode_number(ci, ci->ci_master_key);
|
|
|
|
return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data);
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscrypt_set_context);
|
|
|
|
/**
|
|
* fscrypt_parse_test_dummy_encryption() - parse the test_dummy_encryption mount option
|
|
* @param: the mount option
|
|
* @dummy_policy: (input/output) the place to write the dummy policy that will
|
|
* result from parsing the option. Zero-initialize this. If a policy is
|
|
* already set here (due to test_dummy_encryption being given multiple
|
|
* times), then this function will verify that the policies are the same.
|
|
*
|
|
* Return: 0 on success; -EINVAL if the argument is invalid; -EEXIST if the
|
|
* argument conflicts with one already specified; or -ENOMEM.
|
|
*/
|
|
int fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param,
|
|
struct fscrypt_dummy_policy *dummy_policy)
|
|
{
|
|
const char *arg = "v2";
|
|
union fscrypt_policy *policy;
|
|
int err;
|
|
|
|
if (param->type == fs_value_is_string && *param->string)
|
|
arg = param->string;
|
|
|
|
policy = kzalloc(sizeof(*policy), GFP_KERNEL);
|
|
if (!policy)
|
|
return -ENOMEM;
|
|
|
|
if (!strcmp(arg, "v1")) {
|
|
policy->version = FSCRYPT_POLICY_V1;
|
|
policy->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
|
|
policy->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
|
|
memset(policy->v1.master_key_descriptor, 0x42,
|
|
FSCRYPT_KEY_DESCRIPTOR_SIZE);
|
|
} else if (!strcmp(arg, "v2")) {
|
|
policy->version = FSCRYPT_POLICY_V2;
|
|
policy->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
|
|
policy->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
|
|
err = fscrypt_get_test_dummy_key_identifier(
|
|
policy->v2.master_key_identifier);
|
|
if (err)
|
|
goto out;
|
|
} else {
|
|
err = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
if (dummy_policy->policy) {
|
|
if (fscrypt_policies_equal(policy, dummy_policy->policy))
|
|
err = 0;
|
|
else
|
|
err = -EEXIST;
|
|
goto out;
|
|
}
|
|
dummy_policy->policy = policy;
|
|
policy = NULL;
|
|
err = 0;
|
|
out:
|
|
kfree(policy);
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscrypt_parse_test_dummy_encryption);
|
|
|
|
/**
|
|
* fscrypt_dummy_policies_equal() - check whether two dummy policies are equal
|
|
* @p1: the first test dummy policy (may be unset)
|
|
* @p2: the second test dummy policy (may be unset)
|
|
*
|
|
* Return: %true if the dummy policies are both set and equal, or both unset.
|
|
*/
|
|
bool fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1,
|
|
const struct fscrypt_dummy_policy *p2)
|
|
{
|
|
if (!p1->policy && !p2->policy)
|
|
return true;
|
|
if (!p1->policy || !p2->policy)
|
|
return false;
|
|
return fscrypt_policies_equal(p1->policy, p2->policy);
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscrypt_dummy_policies_equal);
|
|
|
|
/**
|
|
* fscrypt_show_test_dummy_encryption() - show '-o test_dummy_encryption'
|
|
* @seq: the seq_file to print the option to
|
|
* @sep: the separator character to use
|
|
* @sb: the filesystem whose options are being shown
|
|
*
|
|
* Show the test_dummy_encryption mount option, if it was specified.
|
|
* This is mainly used for /proc/mounts.
|
|
*/
|
|
void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
|
|
struct super_block *sb)
|
|
{
|
|
const union fscrypt_policy *policy = fscrypt_get_dummy_policy(sb);
|
|
int vers;
|
|
|
|
if (!policy)
|
|
return;
|
|
|
|
vers = policy->version;
|
|
if (vers == FSCRYPT_POLICY_V1) /* Handle numbering quirk */
|
|
vers = 1;
|
|
|
|
seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, vers);
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption);
|