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- // 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);
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