mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
856 lines
26 KiB
856 lines
26 KiB
// 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(1); |
|
return -EINVAL; |
|
} |
|
} |
|
|
|
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_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; |
|
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, |
|
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_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->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(&init_user_ns, 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_context_for_new_inode() - create an encryption context for a new inode |
|
* @ctx: where context should be written |
|
* @inode: inode from which to fetch policy and nonce |
|
* |
|
* Given an in-core "prepared" (via fscrypt_prepare_new_inode) inode, |
|
* generate a new context and write it to ctx. ctx _must_ be at least |
|
* FSCRYPT_SET_CONTEXT_MAX_SIZE bytes. |
|
* |
|
* Return: size of the resulting context or a negative error code. |
|
*/ |
|
int fscrypt_context_for_new_inode(void *ctx, struct inode *inode) |
|
{ |
|
struct fscrypt_info *ci = inode->i_crypt_info; |
|
|
|
BUILD_BUG_ON(sizeof(union fscrypt_context) != |
|
FSCRYPT_SET_CONTEXT_MAX_SIZE); |
|
|
|
/* fscrypt_prepare_new_inode() should have set up the key already. */ |
|
if (WARN_ON_ONCE(!ci)) |
|
return -ENOKEY; |
|
|
|
return fscrypt_new_context(ctx, &ci->ci_policy, ci->ci_nonce); |
|
} |
|
EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode); |
|
|
|
/** |
|
* fscrypt_set_context() - Set the fscrypt context of a new inode |
|
* @inode: a new inode |
|
* @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; |
|
|
|
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);
|
|
|