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-rw-r--r--fs/crypto/policy.c867
1 files changed, 867 insertions, 0 deletions
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
new file mode 100644
index 0000000000..f4456ecb3f
--- /dev/null
+++ b/fs/crypto/policy.c
@@ -0,0 +1,867 @@
+// 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_ONCE(1);
+ return -EINVAL;
+ }
+}
+
+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_ONCE(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(&nop_mnt_idmap, 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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 06:23:27 +0000