| // 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); |
| } |
| |
| /* |
| * 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, |
| 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); |