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Diffstat (limited to 'fs/crypto/policy.c')
| -rw-r--r-- | fs/crypto/policy.c | 856 |
1 files changed, 856 insertions, 0 deletions
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c new file mode 100644 index 000000000..46757c305 --- /dev/null +++ b/fs/crypto/policy.c @@ -0,0 +1,856 @@ +// 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); |