linux-stable/fs/crypto/policy.c
Eric Biggers a14d0b6764 fscrypt: allow deleting files with unsupported encryption policy
Currently it's impossible to delete files that use an unsupported
encryption policy, as the kernel will just return an error when
performing any operation on the top-level encrypted directory, even just
a path lookup into the directory or opening the directory for readdir.

More specifically, this occurs in any of the following cases:

- The encryption context has an unrecognized version number.  Current
  kernels know about v1 and v2, but there could be more versions in the
  future.

- The encryption context has unrecognized encryption modes
  (FSCRYPT_MODE_*) or flags (FSCRYPT_POLICY_FLAG_*), an unrecognized
  combination of modes, or reserved bits set.

- The encryption key has been added and the encryption modes are
  recognized but aren't available in the crypto API -- for example, a
  directory is encrypted with FSCRYPT_MODE_ADIANTUM but the kernel
  doesn't have CONFIG_CRYPTO_ADIANTUM enabled.

It's desirable to return errors for most operations on files that use an
unsupported encryption policy, but the current behavior is too strict.
We need to allow enough to delete files, so that people can't be stuck
with undeletable files when downgrading kernel versions.  That includes
allowing directories to be listed and allowing dentries to be looked up.

Fix this by modifying the key setup logic to treat an unsupported
encryption policy in the same way as "key unavailable" in the cases that
are required for a recursive delete to work: preparing for a readdir or
a dentry lookup, revalidating a dentry, or checking whether an inode has
the same encryption policy as its parent directory.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20201203022041.230976-10-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-12-02 18:25:01 -08:00

818 lines
25 KiB
C

// 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/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));
}
static 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);
}
static bool fscrypt_valid_enc_modes(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 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,
int max_ino_bits, int max_lblk_bits)
{
struct super_block *sb = inode->i_sb;
int ino_bits = 64, lblk_bits = 64;
/*
* 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;
}
if (sb->s_cop->get_ino_and_lblk_bits)
sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits);
if (ino_bits > max_ino_bits) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because its inode numbers are too long",
type, sb->s_id);
return false;
}
if (lblk_bits > max_lblk_bits) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because its block numbers are too long",
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(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(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->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) &&
!supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64",
32, 32))
return false;
/*
* IV_INO_LBLK_32 hashes the inode number, so in principle it can
* support any ino_bits. 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 ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
!supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32",
32, 32))
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;
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;
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_info *ci;
union fscrypt_context ctx;
int ret;
ci = fscrypt_get_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(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(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 fscrypt_info structs 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_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_info *ci = inode->i_crypt_info;
union fscrypt_context ctx;
int ctxsize;
/* fscrypt_prepare_new_inode() should have set up the key already. */
if (WARN_ON_ONCE(!ci))
return -ENOKEY;
BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE);
ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, ci->ci_nonce);
/*
* 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)) {
const struct fscrypt_master_key *mk =
ci->ci_master_key->payload.data[0];
fscrypt_hash_inode_number(ci, mk);
}
return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data);
}
EXPORT_SYMBOL_GPL(fscrypt_set_context);
/**
* fscrypt_set_test_dummy_encryption() - handle '-o test_dummy_encryption'
* @sb: the filesystem on which test_dummy_encryption is being specified
* @arg: the argument to the test_dummy_encryption option. May be NULL.
* @dummy_policy: the filesystem's current dummy policy (input/output, see
* below)
*
* Handle the test_dummy_encryption mount option by creating a dummy encryption
* policy, saving it in @dummy_policy, and adding the corresponding dummy
* encryption key to the filesystem. If the @dummy_policy is already set, then
* instead validate that it matches @arg. Don't support changing it via
* remount, as that is difficult to do safely.
*
* Return: 0 on success (dummy policy set, or the same policy is already set);
* -EEXIST if a different dummy policy is already set;
* or another -errno value.
*/
int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
struct fscrypt_dummy_policy *dummy_policy)
{
struct fscrypt_key_specifier key_spec = { 0 };
int version;
union fscrypt_policy *policy = NULL;
int err;
if (!arg)
arg = "v2";
if (!strcmp(arg, "v1")) {
version = FSCRYPT_POLICY_V1;
key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
memset(key_spec.u.descriptor, 0x42,
FSCRYPT_KEY_DESCRIPTOR_SIZE);
} else if (!strcmp(arg, "v2")) {
version = FSCRYPT_POLICY_V2;
key_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
/* key_spec.u.identifier gets filled in when adding the key */
} else {
err = -EINVAL;
goto out;
}
policy = kzalloc(sizeof(*policy), GFP_KERNEL);
if (!policy) {
err = -ENOMEM;
goto out;
}
err = fscrypt_add_test_dummy_key(sb, &key_spec);
if (err)
goto out;
policy->version = version;
switch (policy->version) {
case FSCRYPT_POLICY_V1:
policy->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
policy->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
memcpy(policy->v1.master_key_descriptor, key_spec.u.descriptor,
FSCRYPT_KEY_DESCRIPTOR_SIZE);
break;
case FSCRYPT_POLICY_V2:
policy->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
policy->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
memcpy(policy->v2.master_key_identifier, key_spec.u.identifier,
FSCRYPT_KEY_IDENTIFIER_SIZE);
break;
default:
WARN_ON(1);
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_set_test_dummy_encryption);
/**
* 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);