Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 899 insertions, 0 deletions

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
new file mode 100644
index 000000000..6dd510f93
--- /dev/null
+++ b/fs/crypto/policy.c
@@ -0,0 +1,899 @@
+// 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/export.h>
+#include <linux/fs_context.h>
+#include <linux/mount.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+#include <linux/string.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 = (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)
+				? "IV_INO_LBLK_64" : "IV_INO_LBLK_32";
+	struct super_block *sb = inode->i_sb;
+
+	/*
+	 * 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;
+	}
+
+	/*
+	 * IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that inode numbers fit
+	 * in 32 bits.  In principle, IV_INO_LBLK_32 could support longer inode
+	 * numbers because it hashes the inode number; 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 (!sb->s_cop->has_32bit_inodes) {
+		fscrypt_warn(inode,
+			     "Can't use %s policy on filesystem '%s' because its inode numbers are too long",
+			     type, sb->s_id);
+		return false;
+	}
+
+	/*
+	 * IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that file data unit
+	 * indices fit in 32 bits.
+	 */
+	if (fscrypt_max_file_dun_bits(sb,
+			fscrypt_policy_v2_du_bits(policy, inode)) > 32) {
+		fscrypt_warn(inode,
+			     "Can't use %s policy on filesystem '%s' because its maximum file size is too large",
+			     type, sb->s_id);
+		return false;
+	}
+
+	/*
+	 * IV_INO_LBLK_32 isn't compatible with inline encryption when
+	 * s_blocksize != PAGE_SIZE.  In that case the DUN can wrap around in
+	 * the middle of a page, but sometimes fscrypt_mergeable_bio() is called
+	 * only for the first block per page.  Since IV_INO_LBLK_32 exists only
+	 * to support inline encryption hardware that is limited to 32-bit DUNs,
+	 * just disallow IV_INO_LBLK_32 with s_blocksize != PAGE_SIZE entirely.
+	 */
+	if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
+	    sb->s_blocksize != PAGE_SIZE) {
+		fscrypt_warn(inode,
+			     "Can't use %s policy on filesystem '%s' with block size != PAGE_SIZE",
+			     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->log2_data_unit_size) {
+		if (!inode->i_sb->s_cop->supports_subblock_data_units) {
+			fscrypt_warn(inode,
+				     "Filesystem does not support configuring crypto data unit size");
+			return false;
+		}
+		if (policy->log2_data_unit_size > inode->i_blkbits ||
+		    policy->log2_data_unit_size < SECTOR_SHIFT /* 9 */) {
+			fscrypt_warn(inode,
+				     "Unsupported log2_data_unit_size in encryption policy: %d",
+				     policy->log2_data_unit_size);
+			return false;
+		}
+		if (policy->log2_data_unit_size != inode->i_blkbits &&
+		    (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
+			/*
+			 * Not safe to enable yet, as we need to ensure that DUN
+			 * wraparound can only occur on a FS block boundary.
+			 */
+			fscrypt_warn(inode,
+				     "Sub-block data units not yet supported with IV_INO_LBLK_32");
+			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 |
+			      FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) &&
+	    !supported_iv_ino_lblk_policy(policy, inode))
+		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;
+		ctx->log2_data_unit_size = policy->log2_data_unit_size;
+		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;
+		policy->log2_data_unit_size = ctx->log2_data_unit_size;
+		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_inode_info *ci;
+	union fscrypt_context ctx;
+	int ret;
+
+	ci = fscrypt_get_inode_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);
+	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;
+
+	if (copy_from_user((u8 *)&policy + 1, (const u8 __user *)arg + 1,
+			   size - 1))
+		return -EFAULT;
+
+	if (!inode_owner_or_capable(file_mnt_idmap(filp), 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 cached policies 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 &fscrypt_get_inode_info_raw(dir)->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_inode_info *ci = fscrypt_get_inode_info_raw(inode);
+
+	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_inode_info *ci;
+	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.
+	 */
+	ci = fscrypt_get_inode_info_raw(inode);
+	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_obj(*policy);
+	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;
+		fscrypt_get_test_dummy_key_identifier(
+				policy->v2.master_key_identifier);
+	} 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);