// SPDX-License-Identifier: GPL-2.0
/*
* Encryption policy functions for per-file encryption support.
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility.
*
* Originally written by Michael Halcrow, 2015.
* Modified by Jaegeuk Kim, 2015.
* Modified by Eric Biggers, 2019 for v2 policy support.
*/
#include <linux/fs_context.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/mount.h>
#include "fscrypt_private.h"
/**
* fscrypt_policies_equal() - check whether two encryption policies are the same
* @policy1: the first policy
* @policy2: the second policy
*
* Return: %true if equal, else %false
*/
bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
const union fscrypt_policy *policy2)
{
if (policy1->version != policy2->version)
return false;
return !memcmp(policy1, policy2, fscrypt_policy_size(policy1));
}
int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
struct fscrypt_key_specifier *key_spec)
{
switch (policy->version) {
case FSCRYPT_POLICY_V1:
key_spec->type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
memcpy(key_spec->u.descriptor, policy->v1.master_key_descriptor,
FSCRYPT_KEY_DESCRIPTOR_SIZE);
return 0;
case FSCRYPT_POLICY_V2:
key_spec->type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
memcpy(key_spec->u.identifier, policy->v2.master_key_identifier,
FSCRYPT_KEY_IDENTIFIER_SIZE);
return 0;
default:
WARN_ON_ONCE(1);
return -EINVAL;
}
}
const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb)
{
if (!sb->s_cop->get_dummy_policy)
return NULL;
return sb->s_cop->get_dummy_policy(sb);
}
/*
* Return %true if the given combination of encryption modes is supported for v1
* (and later) encryption policies.
*
* Do *not* add anything new here, since v1 encryption policies are deprecated.
* New combinations of modes should go in fscrypt_valid_enc_modes_v2() only.
*/
static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode)
{
if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
filenames_mode == FSCRYPT_MODE_AES_256_CTS)
return true;
if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
filenames_mode == FSCRYPT_MODE_AES_128_CTS)
return true;
if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
filenames_mode == FSCRYPT_MODE_ADIANTUM)
return true;
return false;
}
static bool fscrypt_valid_enc_modes_v2(u32 contents_mode, u32 filenames_mode)
{
if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
filenames_mode == FSCRYPT_MODE_AES_256_HCTR2)
return true;
if (contents_mode == FSCRYPT_MODE_SM4_XTS &&
filenames_mode == FSCRYPT_MODE_SM4_CTS)
return true;
return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode);
}
static bool supported_direct_key_modes(const struct inode *inode,
u32 contents_mode, u32 filenames_mode)
{
const struct fscrypt_mode *mode;
if (contents_mode != filenames_mode) {
fscrypt_warn(inode,
"Direct key flag not allowed with different contents and filenames modes");
return false;
}
mode = &fscrypt_modes[contents_mode];
if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) {
fscrypt_warn(inode, "Direct key flag not allowed with %s",
mode->friendly_name);
return false;
}
return true;
}
static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
const struct inode *inode)
{
const char *type = (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)
? "IV_INO_LBLK_64" : "IV_INO_LBLK_32";
struct super_block *sb = inode->i_sb;
/*
* IV_INO_LBLK_* exist only because of hardware limitations, and
* currently the only known use case for them involves AES-256-XTS.
* That's also all we test currently. For these reasons, for now only
* allow AES-256-XTS here. This can be relaxed later if a use case for
* IV_INO_LBLK_* with other encryption modes arises.
*/
if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) {
fscrypt_warn(inode,
"Can't use %s policy with contents mode other than AES-256-XTS",
type);
return false;
}
/*
* It's unsafe to include inode numbers in the IVs if the filesystem can
* potentially renumber inodes, e.g. via filesystem shrinking.
*/
if (!sb->s_cop->has_stable_inodes ||
!sb->s_cop->has_stable_inodes(sb)) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers",
type, sb->s_id);
return false;
}
/*
* IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that inode numbers fit
* in 32 bits. In principle, IV_INO_LBLK_32 could support longer inode
* numbers because it hashes the inode number; however, currently the
* inode number is gotten from inode::i_ino which is 'unsigned long'.
* So for now the implementation limit is 32 bits.
*/
if (!sb->s_cop->has_32bit_inodes) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because its inode numbers are too long",
type, sb->s_id);
return false;
}
/*
* IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that file data unit
* indices fit in 32 bits.
*/
if (fscrypt_max_file_dun_bits(sb,
fscrypt_policy_v2_du_bits(policy, inode)) > 32) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because its maximum file size is too large",
type, sb->s_id);
return false;
}
return true;
}
static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy,
const struct inode *inode)
{
if (!fscrypt_valid_enc_modes_v1(policy->contents_encryption_mode,
policy->filenames_encryption_mode)) {
fscrypt_warn(inode,
"Unsupported encryption modes (contents %d, filenames %d)",
policy->contents_encryption_mode,
policy->filenames_encryption_mode);
return false;
}
if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK |
FSCRYPT_POLICY_FLAG_DIRECT_KEY)) {
fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)",
policy->flags);
return false;
}
if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) &&
!supported_direct_key_modes(inode, policy->contents_encryption_mode,
policy->filenames_encryption_mode))
return false;
if (IS_CASEFOLDED(inode)) {
/* With v1, there's no way to derive dirhash keys. */
fscrypt_warn(inode,
"v1 policies can't be used on casefolded directories");
return false;
}
return true;
}
static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
const struct inode *inode)
{
int count = 0;
if (!fscrypt_valid_enc_modes_v2(policy->contents_encryption_mode,
policy->filenames_encryption_mode)) {
fscrypt_warn(inode,
"Unsupported encryption modes (contents %d, filenames %d)",
policy->contents_encryption_mode,
policy->filenames_encryption_mode);
return false;
}
if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK |
FSCRYPT_POLICY_FLAG_DIRECT_KEY |
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)",
policy->flags);
return false;
}
count += !!(policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY);
count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64);
count += !!(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32);
if (count > 1) {
fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)",
policy->flags);
return false;
}
if (policy->log2_data_unit_size) {
if (!inode->i_sb->s_cop->supports_subblock_data_units) {
fscrypt_warn(inode,
"Filesystem does not support configuring crypto data unit size");
return false;
}
if (policy->log2_data_unit_size > inode->i_blkbits ||
policy->log2_data_unit_size < SECTOR_SHIFT /* 9 */) {
fscrypt_warn(inode,
"Unsupported log2_data_unit_size in encryption policy: %d",
policy->log2_data_unit_size);
return false;
}
if (policy->log2_data_unit_size != inode->i_blkbits &&
(policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
/*
* Not safe to enable yet, as we need to ensure that DUN
* wraparound can only occur on a FS block boundary.
*/
fscrypt_warn(inode,
"Sub-block data units not yet supported with IV_INO_LBLK_32");
return false;
}
}
if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) &&
!supported_direct_key_modes(inode, policy->contents_encryption_mode,
policy->filenames_encryption_mode))
return false;
if ((policy->flags & (FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) &&
!supported_iv_ino_lblk_policy(policy, inode))
return false;
if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) {
fscrypt_warn(inode, "Reserved bits set in encryption policy");
return false;
}
return true;
}
/**
* fscrypt_supported_policy() - check whether an encryption policy is supported
* @policy_u: the encryption policy
* @inode: the inode on which the policy will be used
*
* Given an encryption policy, check whether all its encryption modes and other
* settings are supported by this kernel on the given inode. (But we don't
* currently don't check for crypto API support here, so attempting to use an
* algorithm not configured into the crypto API will still fail later.)
*
* Return: %true if supported, else %false
*/
bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
const struct inode *inode)
{
switch (policy_u->version) {
case FSCRYPT_POLICY_V1:
return fscrypt_supported_v1_policy(&policy_u->v1, inode);
case FSCRYPT_POLICY_V2:
return fscrypt_supported_v2_policy(&policy_u->v2, inode);
}
return false;
}
/**
* fscrypt_new_context() - create a new fscrypt_context
* @ctx_u: output context
* @policy_u: input policy
* @nonce: nonce to use
*
* Create an fscrypt_context for an inode that is being assigned the given
* encryption policy. @nonce must be a new random nonce.
*
* Return: the size of the new context in bytes.
*/
static int fscrypt_new_context(union fscrypt_context *ctx_u,
const union fscrypt_policy *policy_u,
const u8 nonce[FSCRYPT_FILE_NONCE_SIZE])
{
memset(ctx_u, 0, sizeof(*ctx_u));
switch (policy_u->version) {
case FSCRYPT_POLICY_V1: {
const struct fscrypt_policy_v1 *policy = &policy_u->v1;
struct fscrypt_context_v1 *ctx = &ctx_u->v1;
ctx->version = FSCRYPT_CONTEXT_V1;
ctx->contents_encryption_mode =
policy->contents_encryption_mode;
ctx->filenames_encryption_mode =
policy->filenames_encryption_mode;
ctx->flags = policy->flags;
memcpy(ctx->master_key_descriptor,
policy->master_key_descriptor,
sizeof(ctx->master_key_descriptor));
memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
return sizeof(*ctx);
}
case FSCRYPT_POLICY_V2: {
const struct fscrypt_policy_v2 *policy = &policy_u->v2;
struct fscrypt_context_v2 *ctx = &ctx_u->v2;
ctx->version = FSCRYPT_CONTEXT_V2;
ctx->contents_encryption_mode =
policy->contents_encryption_mode;
ctx->filenames_encryption_mode =
policy->filenames_encryption_mode;
ctx->flags = policy->flags;
ctx->log2_data_unit_size = policy->log2_data_unit_size;
memcpy(ctx->master_key_identifier,
policy->master_key_identifier,
sizeof(ctx->master_key_identifier));
memcpy(ctx->nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
return sizeof(*ctx);
}
}
BUG();
}
/**
* fscrypt_policy_from_context() - convert an fscrypt_context to
* an fscrypt_policy
* @policy_u: output policy
* @ctx_u: input context
* @ctx_size: size of input context in bytes
*
* Given an fscrypt_context, build the corresponding fscrypt_policy.
*
* Return: 0 on success, or -EINVAL if the fscrypt_context has an unrecognized
* version number or size.
*
* This does *not* validate the settings within the policy itself, e.g. the
* modes, flags, and reserved bits. Use fscrypt_supported_policy() for that.
*/
int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
const union fscrypt_context *ctx_u,
int ctx_size)
{
memset(policy_u, 0, sizeof(*policy_u));
if (!fscrypt_context_is_valid(ctx_u, ctx_size))
return -EINVAL;
switch (ctx_u->version) {
case FSCRYPT_CONTEXT_V1: {
const struct fscrypt_context_v1 *ctx = &ctx_u->v1;
struct fscrypt_policy_v1 *policy = &policy_u->v1;
policy->version = FSCRYPT_POLICY_V1;
policy->contents_encryption_mode =
ctx->contents_encryption_mode;
policy->filenames_encryption_mode =
ctx->filenames_encryption_mode;
policy->flags = ctx->flags;
memcpy(policy->master_key_descriptor,
ctx->master_key_descriptor,
sizeof(policy->master_key_descriptor));
return 0;
}
case FSCRYPT_CONTEXT_V2: {
const struct fscrypt_context_v2 *ctx = &ctx_u->v2;
struct fscrypt_policy_v2 *policy = &policy_u->v2;
policy->version = FSCRYPT_POLICY_V2;
policy->contents_encryption_mode =
ctx->contents_encryption_mode;
policy->filenames_encryption_mode =
ctx->filenames_encryption_mode;
policy->flags = ctx->flags;
policy->log2_data_unit_size = ctx->log2_data_unit_size;
memcpy(policy->__reserved, ctx->__reserved,
sizeof(policy->__reserved));
memcpy(policy->master_key_identifier,
ctx->master_key_identifier,
sizeof(policy->master_key_identifier));
return 0;
}
}
/* unreachable */
return -EINVAL;
}
/* Retrieve an inode's encryption policy */
static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy)
{
const struct fscrypt_inode_info *ci;
union fscrypt_context ctx;
int ret;
ci = fscrypt_get_inode_info(inode);
if (ci) {
/* key available, use the cached policy */
*policy = ci->ci_policy;
return 0;
}
if (!IS_ENCRYPTED(inode))
return -ENODATA;
ret = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
if (ret < 0)
return (ret == -ERANGE) ? -EINVAL : ret;
return fscrypt_policy_from_context(policy, &ctx, ret);
}
static int set_encryption_policy(struct inode *inode,
const union fscrypt_policy *policy)
{
u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
union fscrypt_context ctx;
int ctxsize;
int err;
if (!fscrypt_supported_policy(policy, inode))
return -EINVAL;
switch (policy->version) {
case FSCRYPT_POLICY_V1:
/*
* 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);
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