[PATCH 0/4] fscrypt: make '-o test_dummy_encryption' support v2 policies

[PATCH 0/4] fscrypt: make '-o test_dummy_encryption' support v2 policies

[Eric Biggers]

v1 encryption policies are deprecated in favor of v2, and some new
features (e.g. encryption+casefolding) are only being added for v2.

As a result, the "test_dummy_encryption" mount option (which is used for
encryption I/O testing with xfstests) needs to support v2 policies.

Therefore, this patchset adds support for specifying
"test_dummy_encryption=v2" (or "test_dummy_encryption=v1").
To make this possible, it reworks the way the test_dummy_encryption
mount option is handled to make it more flexible than a flag, and to
automatically add the test dummy key to the filesystem's keyring.

Patch 4 additionally changes the default to "v2".

This patchset applies to v5.7-rc4.

Eric Biggers (4):
  linux/parser.h: add include guards
  fscrypt: add fscrypt_add_test_dummy_key()
  fscrypt: support test_dummy_encryption=v2
  fscrypt: make test_dummy_encryption use v2 by default

 Documentation/filesystems/f2fs.rst |   6 +-
 fs/crypto/fscrypt_private.h        |   3 +
 fs/crypto/keyring.c                | 117 +++++++++++++++++----------
 fs/crypto/keysetup.c               |  15 ++--
 fs/crypto/policy.c                 | 125 +++++++++++++++++++++++++++++
 fs/ext4/ext4.h                     |   7 +-
 fs/ext4/super.c                    |  68 ++++++++++++----
 fs/f2fs/f2fs.h                     |   4 +-
 fs/f2fs/super.c                    |  85 ++++++++++++++------
 include/linux/fscrypt.h            |  52 ++++++++++--
 include/linux/parser.h             |   5 +-
 11 files changed, 383 insertions(+), 104 deletions(-)

-- 
2.26.2

[PATCH 1/4] linux/parser.h: add include guards

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

<linux/parser.h> is missing include guards.  Add them.

This is needed to allow declaring a function in <linux/fscrypt.h> that
takes a substring_t parameter.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 include/linux/parser.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/parser.h b/include/linux/parser.h
index 12fc3482f5fc7a..89e2b23fb888e8 100644
--- a/include/linux/parser.h
+++ b/include/linux/parser.h
@@ -7,7 +7,8 @@
  * but could potentially be used anywhere else that simple option=arg
  * parsing is required.
  */
-
+#ifndef _LINUX_PARSER_H
+#define _LINUX_PARSER_H
 
 /* associates an integer enumerator with a pattern string. */
 struct match_token {
@@ -34,3 +35,5 @@ int match_hex(substring_t *, int *result);
 bool match_wildcard(const char *pattern, const char *str);
 size_t match_strlcpy(char *, const substring_t *, size_t);
 char *match_strdup(const substring_t *);
+
+#endif /* _LINUX_PARSER_H */
-- 
2.26.2

[PATCH 2/4] fscrypt: add fscrypt_add_test_dummy_key()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Currently, the test_dummy_encryption mount option (which is used for
encryption I/O testing with xfstests) uses v1 encryption policies, and
it relies on userspace inserting a test key into the session keyring.

We need test_dummy_encryption to support v2 encryption policies too.
Requiring userspace to add the test key doesn't work well with v2
policies, since v2 policies only support the filesystem keyring (not the
session keyring), and keys in the filesystem keyring are lost when the
filesystem is unmounted.  Hooking all test code that unmounts and
re-mounts the filesystem would be difficult.

Instead, let's make the filesystem automatically add the test key to its
keyring when test_dummy_encryption is enabled.

That puts the responsibility for choosing the test key on the kernel.
We could just hard-code a key.  But out of paranoia, let's first try
using a per-boot random key, to prevent this code from being misused.
A per-boot key will work as long as no one expects dummy-encrypted files
to remain accessible after a reboot.  (gce-xfstests doesn't.)

Therefore, this patch adds a function fscrypt_add_test_dummy_key() which
implements the above.  The next patch will use it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/fscrypt_private.h |   3 +
 fs/crypto/keyring.c         | 117 +++++++++++++++++++++++-------------
 2 files changed, 77 insertions(+), 43 deletions(-)

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index dbced2937ec895..1bdb4a3a9b9fd6 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -440,6 +440,9 @@ extern struct key *
 fscrypt_find_master_key(struct super_block *sb,
 			const struct fscrypt_key_specifier *mk_spec);
 
+int fscrypt_add_test_dummy_key(struct super_block *sb,
+			       struct fscrypt_key_specifier *key_spec);
+
 extern int fscrypt_verify_key_added(struct super_block *sb,
 				    const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
 
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index ab41b25d4fa1ba..c983ddfde8ad8d 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -20,6 +20,7 @@
 
 #include <crypto/skcipher.h>
 #include <linux/key-type.h>
+#include <linux/random.h>
 #include <linux/seq_file.h>
 
 #include "fscrypt_private.h"
@@ -424,9 +425,9 @@ static int add_existing_master_key(struct fscrypt_master_key *mk,
 	return 0;
 }
 
-static int add_master_key(struct super_block *sb,
-			  struct fscrypt_master_key_secret *secret,
-			  const struct fscrypt_key_specifier *mk_spec)
+static int do_add_master_key(struct super_block *sb,
+			     struct fscrypt_master_key_secret *secret,
+			     const struct fscrypt_key_specifier *mk_spec)
 {
 	static DEFINE_MUTEX(fscrypt_add_key_mutex);
 	struct key *key;
@@ -465,6 +466,35 @@ static int add_master_key(struct super_block *sb,
 	return err;
 }
 
+static int add_master_key(struct super_block *sb,
+			  struct fscrypt_master_key_secret *secret,
+			  struct fscrypt_key_specifier *key_spec)
+{
+	int err;
+
+	if (key_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
+		err = fscrypt_init_hkdf(&secret->hkdf, secret->raw,
+					secret->size);
+		if (err)
+			return err;
+
+		/*
+		 * Now that the HKDF context is initialized, the raw key is no
+		 * longer needed.
+		 */
+		memzero_explicit(secret->raw, secret->size);
+
+		/* Calculate the key identifier */
+		err = fscrypt_hkdf_expand(&secret->hkdf,
+					  HKDF_CONTEXT_KEY_IDENTIFIER, NULL, 0,
+					  key_spec->u.identifier,
+					  FSCRYPT_KEY_IDENTIFIER_SIZE);
+		if (err)
+			return err;
+	}
+	return do_add_master_key(sb, secret, key_spec);
+}
+
 static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep)
 {
 	const struct fscrypt_provisioning_key_payload *payload = prep->data;
@@ -609,6 +639,15 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg)
 	if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved)))
 		return -EINVAL;
 
+	/*
+	 * Only root can add keys that are identified by an arbitrary descriptor
+	 * rather than by a cryptographic hash --- since otherwise a malicious
+	 * user could add the wrong key.
+	 */
+	if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
 	memset(&secret, 0, sizeof(secret));
 	if (arg.key_id) {
 		if (arg.raw_size != 0)
@@ -626,54 +665,46 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg)
 			goto out_wipe_secret;
 	}
 
-	switch (arg.key_spec.type) {
-	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
-		/*
-		 * Only root can add keys that are identified by an arbitrary
-		 * descriptor rather than by a cryptographic hash --- since
-		 * otherwise a malicious user could add the wrong key.
-		 */
-		err = -EACCES;
-		if (!capable(CAP_SYS_ADMIN))
-			goto out_wipe_secret;
-		break;
-	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
-		err = fscrypt_init_hkdf(&secret.hkdf, secret.raw, secret.size);
-		if (err)
-			goto out_wipe_secret;
-
-		/*
-		 * Now that the HKDF context is initialized, the raw key is no
-		 * longer needed.
-		 */
-		memzero_explicit(secret.raw, secret.size);
-
-		/* Calculate the key identifier and return it to userspace. */
-		err = fscrypt_hkdf_expand(&secret.hkdf,
-					  HKDF_CONTEXT_KEY_IDENTIFIER,
-					  NULL, 0, arg.key_spec.u.identifier,
-					  FSCRYPT_KEY_IDENTIFIER_SIZE);
-		if (err)
-			goto out_wipe_secret;
-		err = -EFAULT;
-		if (copy_to_user(uarg->key_spec.u.identifier,
-				 arg.key_spec.u.identifier,
-				 FSCRYPT_KEY_IDENTIFIER_SIZE))
-			goto out_wipe_secret;
-		break;
-	default:
-		WARN_ON(1);
-		err = -EINVAL;
+	err = add_master_key(sb, &secret, &arg.key_spec);
+	if (err)
 		goto out_wipe_secret;
-	}
 
-	err = add_master_key(sb, &secret, &arg.key_spec);
+	/* Return the key identifier to userspace, if applicable */
+	err = -EFAULT;
+	if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER &&
+	    copy_to_user(uarg->key_spec.u.identifier, arg.key_spec.u.identifier,
+			 FSCRYPT_KEY_IDENTIFIER_SIZE))
+		goto out_wipe_secret;
+	err = 0;
 out_wipe_secret:
 	wipe_master_key_secret(&secret);
 	return err;
 }
 EXPORT_SYMBOL_GPL(fscrypt_ioctl_add_key);
 
+/*
+ * Add the key for '-o test_dummy_encryption' to the filesystem keyring.
+ *
+ * Use a per-boot random key to prevent people from misusing this option.
+ */
+int fscrypt_add_test_dummy_key(struct super_block *sb,
+			       struct fscrypt_key_specifier *key_spec)
+{
+	static u8 test_key[FSCRYPT_MAX_KEY_SIZE];
+	struct fscrypt_master_key_secret secret;
+	int err;
+
+	get_random_once(test_key, FSCRYPT_MAX_KEY_SIZE);
+
+	memset(&secret, 0, sizeof(secret));
+	secret.size = FSCRYPT_MAX_KEY_SIZE;
+	memcpy(secret.raw, test_key, FSCRYPT_MAX_KEY_SIZE);
+
+	err = add_master_key(sb, &secret, key_spec);
+	wipe_master_key_secret(&secret);
+	return err;
+}
+
 /*
  * Verify that the current user has added a master key with the given identifier
  * (returns -ENOKEY if not).  This is needed to prevent a user from encrypting
-- 
2.26.2

[PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

v1 encryption policies are deprecated in favor of v2, and some new
features (e.g. encryption+casefolding) are only being added for v2.

Therefore, the "test_dummy_encryption" mount option (which is used for
encryption I/O testing with xfstests) needs to support v2 policies.

To do this, extend its syntax to be "test_dummy_encryption=v1" or
"test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
argument) also continues to be accepted, to specify the default setting
-- currently v1, but the next patch changes it to v2.

To cleanly support both v1 and v2 while also making it easy to support
specifying other encryption settings in the future (say, accepting
"$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
pointer to the dummy fscrypt_context rather than using mount flags.

To avoid concurrency issues, don't allow test_dummy_encryption to be set
or changed during a remount.  (The former restriction is new, but
xfstests doesn't run into it, so no one should notice.)

Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
there are two regressions, both of which are test bugs: ext4/023 and
ext4/028 fail because they set an xattr and expect it to be stored
inline, but the increase in size of the fscrypt_context from
24 to 40 bytes causes this xattr to be spilled into an external block.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 Documentation/filesystems/f2fs.rst |   6 +-
 fs/crypto/keysetup.c               |  15 ++--
 fs/crypto/policy.c                 | 125 +++++++++++++++++++++++++++++
 fs/ext4/ext4.h                     |   7 +-
 fs/ext4/super.c                    |  68 ++++++++++++----
 fs/f2fs/f2fs.h                     |   4 +-
 fs/f2fs/super.c                    |  85 ++++++++++++++------
 include/linux/fscrypt.h            |  52 ++++++++++--
 8 files changed, 302 insertions(+), 60 deletions(-)

diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index 87d794bc75a479..4218ac65862934 100644
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -225,8 +225,12 @@ fsync_mode=%s          Control the policy of fsync. Currently supports "posix",
                        pass, but the performance will regress. "nobarrier" is
                        based on "posix", but doesn't issue flush command for
                        non-atomic files likewise "nobarrier" mount option.
-test_dummy_encryption  Enable dummy encryption, which provides a fake fscrypt
+test_dummy_encryption
+test_dummy_encryption=%s
+                       Enable dummy encryption, which provides a fake fscrypt
                        context. The fake fscrypt context is used by xfstests.
+                       The argument may be either "v1" or "v2", in order to
+                       select the corresponding fscrypt policy version.
 checkpoint=%s[:%u[%]]  Set to "disable" to turn off checkpointing. Set to "enable"
                        to reenable checkpointing. Is enabled by default. While
                        disabled, any unmounting or unexpected shutdowns will cause
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 302375e9f719eb..cbfb3c7c4a13a6 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -395,21 +395,18 @@ int fscrypt_get_encryption_info(struct inode *inode)
 
 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
 	if (res < 0) {
-		if (!fscrypt_dummy_context_enabled(inode) ||
-		    IS_ENCRYPTED(inode)) {
+		const union fscrypt_context *dummy_ctx =
+			fscrypt_get_dummy_context(inode->i_sb);
+
+		if (IS_ENCRYPTED(inode) || !dummy_ctx) {
 			fscrypt_warn(inode,
 				     "Error %d getting encryption context",
 				     res);
 			return res;
 		}
 		/* Fake up a context for an unencrypted directory */
-		memset(&ctx, 0, sizeof(ctx));
-		ctx.version = FSCRYPT_CONTEXT_V1;
-		ctx.v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
-		ctx.v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
-		memset(ctx.v1.master_key_descriptor, 0x42,
-		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
-		res = sizeof(ctx.v1);
+		res = fscrypt_context_size(dummy_ctx);
+		memcpy(&ctx, dummy_ctx, res);
 	}
 
 	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 10ccf945020ce5..ca0ee337c9627f 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/random.h>
+#include <linux/seq_file.h>
 #include <linux/string.h>
 #include <linux/mount.h>
 #include "fscrypt_private.h"
@@ -605,3 +606,127 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child,
 	return preload ? fscrypt_get_encryption_info(child): 0;
 }
 EXPORT_SYMBOL(fscrypt_inherit_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.
+ *	 If no argument was specified, then @arg->from == NULL.
+ * @dummy_ctx: the filesystem's current dummy context (input/output, see below)
+ *
+ * Handle the test_dummy_encryption mount option by creating a dummy encryption
+ * context, saving it in @dummy_ctx, and adding the corresponding dummy
+ * encryption key to the filesystem.  If the @dummy_ctx is already set, then
+ * instead validate that it matches @arg.  Don't support changing it via
+ * remount, as that is difficult to do safely.
+ *
+ * The reason we use an fscrypt_context rather than an fscrypt_policy is because
+ * we mustn't generate a new nonce each time we access a dummy-encrypted
+ * directory, as that would change the way filenames are encrypted.
+ *
+ * Return: 0 on success (dummy context set, or the same context is already set);
+ *         -EEXIST if a different dummy context is already set;
+ *         or another -errno value.
+ */
+int fscrypt_set_test_dummy_encryption(struct super_block *sb,
+				      const substring_t *arg,
+				      struct fscrypt_dummy_context *dummy_ctx)
+{
+	const char *argstr = "v1";
+	const char *argstr_to_free = NULL;
+	struct fscrypt_key_specifier key_spec = { 0 };
+	int version;
+	union fscrypt_context *ctx = NULL;
+	int err;
+
+	if (arg->from) {
+		argstr = argstr_to_free = match_strdup(arg);
+		if (!argstr)
+			return -ENOMEM;
+	}
+
+	if (!strcmp(argstr, "v1")) {
+		version = FSCRYPT_CONTEXT_V1;
+		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
+		memset(key_spec.u.descriptor, 0x42,
+		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
+	} else if (!strcmp(argstr, "v2")) {
+		version = FSCRYPT_CONTEXT_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;
+	}
+
+	if (dummy_ctx->ctx) {
+		/*
+		 * Note: if we ever make test_dummy_encryption support
+		 * specifying other encryption settings, such as the encryption
+		 * modes, we'll need to compare those settings here.
+		 */
+		if (dummy_ctx->ctx->version == version)
+			err = 0;
+		else
+			err = -EEXIST;
+		goto out;
+	}
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = fscrypt_add_test_dummy_key(sb, &key_spec);
+	if (err)
+		goto out;
+
+	ctx->version = version;
+	switch (ctx->version) {
+	case FSCRYPT_CONTEXT_V1:
+		ctx->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
+		ctx->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
+		memcpy(ctx->v1.master_key_descriptor, key_spec.u.descriptor,
+		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
+		break;
+	case FSCRYPT_CONTEXT_V2:
+		ctx->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
+		ctx->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
+		memcpy(ctx->v2.master_key_identifier, key_spec.u.identifier,
+		       FSCRYPT_KEY_IDENTIFIER_SIZE);
+		break;
+	default:
+		WARN_ON(1);
+		err = -EINVAL;
+		goto out;
+	}
+	dummy_ctx->ctx = ctx;
+	ctx = NULL;
+	err = 0;
+out:
+	kfree(ctx);
+	kfree(argstr_to_free);
+	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_context *ctx = fscrypt_get_dummy_context(sb);
+
+	if (!ctx)
+		return;
+	seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, ctx->version);
+}
+EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 91eb4381cae5b7..546504cba84211 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1357,11 +1357,9 @@ struct ext4_super_block {
  */
 #define EXT4_MF_MNTDIR_SAMPLED		0x0001
 #define EXT4_MF_FS_ABORTED		0x0002	/* Fatal error detected */
-#define EXT4_MF_TEST_DUMMY_ENCRYPTION	0x0004
 
 #ifdef CONFIG_FS_ENCRYPTION
-#define DUMMY_ENCRYPTION_ENABLED(sbi) (unlikely((sbi)->s_mount_flags & \
-						EXT4_MF_TEST_DUMMY_ENCRYPTION))
+#define DUMMY_ENCRYPTION_ENABLED(sbi) ((sbi)->s_dummy_enc_ctx.ctx != NULL)
 #else
 #define DUMMY_ENCRYPTION_ENABLED(sbi) (0)
 #endif
@@ -1551,6 +1549,9 @@ struct ext4_sb_info {
 	struct ratelimit_state s_warning_ratelimit_state;
 	struct ratelimit_state s_msg_ratelimit_state;
 
+	/* Encryption context for '-o test_dummy_encryption' */
+	struct fscrypt_dummy_context s_dummy_enc_ctx;
+
 	/*
 	 * Barrier between writepages ops and changing any inode's JOURNAL_DATA
 	 * or EXTENTS flag.
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index bf5fcb477f6672..4a3d21972011bb 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1106,6 +1106,7 @@ static void ext4_put_super(struct super_block *sb)
 		crypto_free_shash(sbi->s_chksum_driver);
 	kfree(sbi->s_blockgroup_lock);
 	fs_put_dax(sbi->s_daxdev);
+	fscrypt_free_dummy_context(&sbi->s_dummy_enc_ctx);
 #ifdef CONFIG_UNICODE
 	utf8_unload(sbi->s_encoding);
 #endif
@@ -1389,9 +1390,10 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 	return res;
 }
 
-static bool ext4_dummy_context(struct inode *inode)
+static const union fscrypt_context *
+ext4_get_dummy_context(struct super_block *sb)
 {
-	return DUMMY_ENCRYPTION_ENABLED(EXT4_SB(inode->i_sb));
+	return EXT4_SB(sb)->s_dummy_enc_ctx.ctx;
 }
 
 static bool ext4_has_stable_inodes(struct super_block *sb)
@@ -1410,7 +1412,7 @@ static const struct fscrypt_operations ext4_cryptops = {
 	.key_prefix		= "ext4:",
 	.get_context		= ext4_get_context,
 	.set_context		= ext4_set_context,
-	.dummy_context		= ext4_dummy_context,
+	.get_dummy_context	= ext4_get_dummy_context,
 	.empty_dir		= ext4_empty_dir,
 	.max_namelen		= EXT4_NAME_LEN,
 	.has_stable_inodes	= ext4_has_stable_inodes,
@@ -1605,6 +1607,7 @@ static const match_table_t tokens = {
 	{Opt_init_itable, "init_itable"},
 	{Opt_noinit_itable, "noinit_itable"},
 	{Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
+	{Opt_test_dummy_encryption, "test_dummy_encryption=%s"},
 	{Opt_test_dummy_encryption, "test_dummy_encryption"},
 	{Opt_nombcache, "nombcache"},
 	{Opt_nombcache, "no_mbcache"},	/* for backward compatibility */
@@ -1816,7 +1819,7 @@ static const struct mount_opts {
 	{Opt_jqfmt_vfsv0, QFMT_VFS_V0, MOPT_QFMT},
 	{Opt_jqfmt_vfsv1, QFMT_VFS_V1, MOPT_QFMT},
 	{Opt_max_dir_size_kb, 0, MOPT_GTE0},
-	{Opt_test_dummy_encryption, 0, MOPT_GTE0},
+	{Opt_test_dummy_encryption, 0, MOPT_STRING},
 	{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
 	{Opt_err, 0, 0}
 };
@@ -1851,6 +1854,48 @@ static int ext4_sb_read_encoding(const struct ext4_super_block *es,
 }
 #endif
 
+static int ext4_set_test_dummy_encryption(struct super_block *sb,
+					  const char *opt,
+					  const substring_t *arg,
+					  bool is_remount)
+{
+#ifdef CONFIG_FS_ENCRYPTION
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int err;
+
+	/*
+	 * This mount option is just for testing, and it's not worthwhile to
+	 * implement the extra complexity (e.g. RCU protection) that would be
+	 * needed to allow it to be set or changed during remount.  We do allow
+	 * it to be specified during remount, but only if there is no change.
+	 */
+	if (is_remount && !sbi->s_dummy_enc_ctx.ctx) {
+		ext4_msg(sb, KERN_WARNING,
+			 "Can't set test_dummy_encryption on remount");
+		return -1;
+	}
+	err = fscrypt_set_test_dummy_encryption(sb, arg, &sbi->s_dummy_enc_ctx);
+	if (err) {
+		if (err == -EEXIST)
+			ext4_msg(sb, KERN_WARNING,
+				 "Can't change test_dummy_encryption on remount");
+		else if (err == -EINVAL)
+			ext4_msg(sb, KERN_WARNING,
+				 "Value of option \"%s\" is unrecognized", opt);
+		else
+			ext4_msg(sb, KERN_WARNING,
+				 "Error processing option \"%s\" [%d]",
+				 opt, err);
+		return -1;
+	}
+	ext4_msg(sb, KERN_WARNING, "Test dummy encryption mode enabled");
+#else
+	ext4_msg(sb, KERN_WARNING,
+		 "Test dummy encryption mount option ignored");
+#endif
+	return 1;
+}
+
 static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 			    substring_t *args, unsigned long *journal_devnum,
 			    unsigned int *journal_ioprio, int is_remount)
@@ -2047,14 +2092,8 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 		*journal_ioprio =
 			IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, arg);
 	} else if (token == Opt_test_dummy_encryption) {
-#ifdef CONFIG_FS_ENCRYPTION
-		sbi->s_mount_flags |= EXT4_MF_TEST_DUMMY_ENCRYPTION;
-		ext4_msg(sb, KERN_WARNING,
-			 "Test dummy encryption mode enabled");
-#else
-		ext4_msg(sb, KERN_WARNING,
-			 "Test dummy encryption mount option ignored");
-#endif
+		return ext4_set_test_dummy_encryption(sb, opt, &args[0],
+						      is_remount);
 	} else if (m->flags & MOPT_DATAJ) {
 		if (is_remount) {
 			if (!sbi->s_journal)
@@ -2311,8 +2350,8 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 		SEQ_OPTS_PRINT("max_dir_size_kb=%u", sbi->s_max_dir_size_kb);
 	if (test_opt(sb, DATA_ERR_ABORT))
 		SEQ_OPTS_PUTS("data_err=abort");
-	if (DUMMY_ENCRYPTION_ENABLED(sbi))
-		SEQ_OPTS_PUTS("test_dummy_encryption");
+
+	fscrypt_show_test_dummy_encryption(seq, sep, sb);
 
 	ext4_show_quota_options(seq, sb);
 	return 0;
@@ -4780,6 +4819,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	for (i = 0; i < EXT4_MAXQUOTAS; i++)
 		kfree(get_qf_name(sb, sbi, i));
 #endif
+	fscrypt_free_dummy_context(&sbi->s_dummy_enc_ctx);
 	ext4_blkdev_remove(sbi);
 	brelse(bh);
 out_fail:
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ba470d5687fe04..157eec34897046 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -138,7 +138,7 @@ struct f2fs_mount_info {
 	int fsync_mode;			/* fsync policy */
 	int fs_mode;			/* fs mode: LFS or ADAPTIVE */
 	int bggc_mode;			/* bggc mode: off, on or sync */
-	bool test_dummy_encryption;	/* test dummy encryption */
+	struct fscrypt_dummy_context dummy_enc_ctx; /* test dummy encryption */
 	block_t unusable_cap;		/* Amount of space allowed to be
 					 * unusable when disabling checkpoint
 					 */
@@ -1259,7 +1259,7 @@ enum fsync_mode {
 
 #ifdef CONFIG_FS_ENCRYPTION
 #define DUMMY_ENCRYPTION_ENABLED(sbi) \
-			(unlikely(F2FS_OPTION(sbi).test_dummy_encryption))
+	(unlikely(F2FS_OPTION(sbi).dummy_enc_ctx.ctx != NULL))
 #else
 #define DUMMY_ENCRYPTION_ENABLED(sbi) (0)
 #endif
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f2dfc21c6abb0a..8a9955902d849c 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -202,6 +202,7 @@ static match_table_t f2fs_tokens = {
 	{Opt_whint, "whint_mode=%s"},
 	{Opt_alloc, "alloc_mode=%s"},
 	{Opt_fsync, "fsync_mode=%s"},
+	{Opt_test_dummy_encryption, "test_dummy_encryption=%s"},
 	{Opt_test_dummy_encryption, "test_dummy_encryption"},
 	{Opt_checkpoint_disable, "checkpoint=disable"},
 	{Opt_checkpoint_disable_cap, "checkpoint=disable:%u"},
@@ -394,7 +395,52 @@ static int f2fs_check_quota_options(struct f2fs_sb_info *sbi)
 }
 #endif
 
-static int parse_options(struct super_block *sb, char *options)
+static int f2fs_set_test_dummy_encryption(struct super_block *sb,
+					  const char *opt,
+					  const substring_t *arg,
+					  bool is_remount)
+{
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+#ifdef CONFIG_FS_ENCRYPTION
+	int err;
+
+	if (!f2fs_sb_has_encrypt(sbi)) {
+		f2fs_err(sbi, "Encrypt feature is off");
+		return -EINVAL;
+	}
+
+	/*
+	 * This mount option is just for testing, and it's not worthwhile to
+	 * implement the extra complexity (e.g. RCU protection) that would be
+	 * needed to allow it to be set or changed during remount.  We do allow
+	 * it to be specified during remount, but only if there is no change.
+	 */
+	if (is_remount && !F2FS_OPTION(sbi).dummy_enc_ctx.ctx) {
+		f2fs_warn(sbi, "Can't set test_dummy_encryption on remount");
+		return -EINVAL;
+	}
+	err = fscrypt_set_test_dummy_encryption(
+		sb, arg, &F2FS_OPTION(sbi).dummy_enc_ctx);
+	if (err) {
+		if (err == -EEXIST)
+			f2fs_warn(sbi,
+				  "Can't change test_dummy_encryption on remount");
+		else if (err == -EINVAL)
+			f2fs_warn(sbi, "Value of option \"%s\" is unrecognized",
+				  opt);
+		else
+			f2fs_warn(sbi, "Error processing option \"%s\" [%d]",
+				  opt, err);
+		return -EINVAL;
+	}
+	f2fs_warn(sbi, "Test dummy encryption mode enabled");
+#else
+	f2fs_warn(sbi, "Test dummy encryption mount option ignored");
+#endif
+	return 0;
+}
+
+static int parse_options(struct super_block *sb, char *options, bool is_remount)
 {
 	struct f2fs_sb_info *sbi = F2FS_SB(sb);
 	substring_t args[MAX_OPT_ARGS];
@@ -403,9 +449,7 @@ static int parse_options(struct super_block *sb, char *options)
 	int arg = 0, ext_cnt;
 	kuid_t uid;
 	kgid_t gid;
-#ifdef CONFIG_QUOTA
 	int ret;
-#endif
 
 	if (!options)
 		return 0;
@@ -778,17 +822,10 @@ static int parse_options(struct super_block *sb, char *options)
 			kvfree(name);
 			break;
 		case Opt_test_dummy_encryption:
-#ifdef CONFIG_FS_ENCRYPTION
-			if (!f2fs_sb_has_encrypt(sbi)) {
-				f2fs_err(sbi, "Encrypt feature is off");
-				return -EINVAL;
-			}
-
-			F2FS_OPTION(sbi).test_dummy_encryption = true;
-			f2fs_info(sbi, "Test dummy encryption mode enabled");
-#else
-			f2fs_info(sbi, "Test dummy encryption mount option ignored");
-#endif
+			ret = f2fs_set_test_dummy_encryption(sb, p, &args[0],
+							     is_remount);
+			if (ret)
+				return ret;
 			break;
 		case Opt_checkpoint_disable_cap_perc:
 			if (args->from && match_int(args, &arg))
@@ -1213,6 +1250,7 @@ static void f2fs_put_super(struct super_block *sb)
 	for (i = 0; i < MAXQUOTAS; i++)
 		kvfree(F2FS_OPTION(sbi).s_qf_names[i]);
 #endif
+	fscrypt_free_dummy_context(&F2FS_OPTION(sbi).dummy_enc_ctx);
 	destroy_percpu_info(sbi);
 	for (i = 0; i < NR_PAGE_TYPE; i++)
 		kvfree(sbi->write_io[i]);
@@ -1543,10 +1581,8 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 		seq_printf(seq, ",whint_mode=%s", "user-based");
 	else if (F2FS_OPTION(sbi).whint_mode == WHINT_MODE_FS)
 		seq_printf(seq, ",whint_mode=%s", "fs-based");
-#ifdef CONFIG_FS_ENCRYPTION
-	if (F2FS_OPTION(sbi).test_dummy_encryption)
-		seq_puts(seq, ",test_dummy_encryption");
-#endif
+
+	fscrypt_show_test_dummy_encryption(seq, ',', sbi->sb);
 
 	if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_DEFAULT)
 		seq_printf(seq, ",alloc_mode=%s", "default");
@@ -1575,7 +1611,6 @@ static void default_options(struct f2fs_sb_info *sbi)
 	F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
 	F2FS_OPTION(sbi).alloc_mode = ALLOC_MODE_DEFAULT;
 	F2FS_OPTION(sbi).fsync_mode = FSYNC_MODE_POSIX;
-	F2FS_OPTION(sbi).test_dummy_encryption = false;
 	F2FS_OPTION(sbi).s_resuid = make_kuid(&init_user_ns, F2FS_DEF_RESUID);
 	F2FS_OPTION(sbi).s_resgid = make_kgid(&init_user_ns, F2FS_DEF_RESGID);
 	F2FS_OPTION(sbi).compress_algorithm = COMPRESS_LZ4;
@@ -1734,7 +1769,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	default_options(sbi);
 
 	/* parse mount options */
-	err = parse_options(sb, data);
+	err = parse_options(sb, data, true);
 	if (err)
 		goto restore_opts;
 	checkpoint_changed =
@@ -2410,9 +2445,10 @@ static int f2fs_set_context(struct inode *inode, const void *ctx, size_t len,
 				ctx, len, fs_data, XATTR_CREATE);
 }
 
-static bool f2fs_dummy_context(struct inode *inode)
+static const union fscrypt_context *
+f2fs_get_dummy_context(struct super_block *sb)
 {
-	return DUMMY_ENCRYPTION_ENABLED(F2FS_I_SB(inode));
+	return F2FS_OPTION(F2FS_SB(sb)).dummy_enc_ctx.ctx;
 }
 
 static bool f2fs_has_stable_inodes(struct super_block *sb)
@@ -2431,7 +2467,7 @@ static const struct fscrypt_operations f2fs_cryptops = {
 	.key_prefix		= "f2fs:",
 	.get_context		= f2fs_get_context,
 	.set_context		= f2fs_set_context,
-	.dummy_context		= f2fs_dummy_context,
+	.get_dummy_context	= f2fs_get_dummy_context,
 	.empty_dir		= f2fs_empty_dir,
 	.max_namelen		= F2FS_NAME_LEN,
 	.has_stable_inodes	= f2fs_has_stable_inodes,
@@ -3366,7 +3402,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 		goto free_sb_buf;
 	}
 
-	err = parse_options(sb, options);
+	err = parse_options(sb, options, false);
 	if (err)
 		goto free_options;
 
@@ -3769,6 +3805,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	for (i = 0; i < MAXQUOTAS; i++)
 		kvfree(F2FS_OPTION(sbi).s_qf_names[i]);
 #endif
+	fscrypt_free_dummy_context(&F2FS_OPTION(sbi).dummy_enc_ctx);
 	kvfree(options);
 free_sb_buf:
 	kvfree(raw_super);
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index e3c2d2a155250a..13672564564894 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -15,12 +15,15 @@
 
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/parser.h>
 #include <linux/slab.h>
 #include <uapi/linux/fscrypt.h>
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
+union fscrypt_context;
 struct fscrypt_info;
+struct seq_file;
 
 struct fscrypt_str {
 	unsigned char *name;
@@ -58,7 +61,8 @@ struct fscrypt_operations {
 	const char *key_prefix;
 	int (*get_context)(struct inode *, void *, size_t);
 	int (*set_context)(struct inode *, const void *, size_t, void *);
-	bool (*dummy_context)(struct inode *);
+	const union fscrypt_context *(*get_dummy_context)(
+		struct super_block *sb);
 	bool (*empty_dir)(struct inode *);
 	unsigned int max_namelen;
 	bool (*has_stable_inodes)(struct super_block *sb);
@@ -87,10 +91,12 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
 	return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
 }
 
-static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+static inline const union fscrypt_context *
+fscrypt_get_dummy_context(struct super_block *sb)
 {
-	return inode->i_sb->s_cop->dummy_context &&
-		inode->i_sb->s_cop->dummy_context(inode);
+	if (!sb->s_cop->get_dummy_context)
+		return NULL;
+	return sb->s_cop->get_dummy_context(sb);
 }
 
 /*
@@ -143,6 +149,23 @@ extern int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
 extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
 extern int fscrypt_inherit_context(struct inode *, struct inode *,
 					void *, bool);
+
+struct fscrypt_dummy_context {
+	const union fscrypt_context *ctx;
+};
+
+int fscrypt_set_test_dummy_encryption(struct super_block *sb,
+				      const substring_t *arg,
+				      struct fscrypt_dummy_context *dummy_ctx);
+void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
+					struct super_block *sb);
+static inline void
+fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
+{
+	kfree(dummy_ctx->ctx);
+	dummy_ctx->ctx = NULL;
+}
+
 /* keyring.c */
 extern void fscrypt_sb_free(struct super_block *sb);
 extern int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
@@ -222,9 +245,10 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
 	return false;
 }
 
-static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+static inline const union fscrypt_context *
+fscrypt_get_dummy_context(struct super_block *sb)
 {
-	return false;
+	return NULL;
 }
 
 static inline void fscrypt_handle_d_move(struct dentry *dentry)
@@ -319,6 +343,20 @@ static inline int fscrypt_inherit_context(struct inode *parent,
 	return -EOPNOTSUPP;
 }
 
+struct fscrypt_dummy_context {
+};
+
+static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
+						      char sep,
+						      struct super_block *sb)
+{
+}
+
+static inline void
+fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
+{
+}
+
 /* keyring.c */
 static inline void fscrypt_sb_free(struct super_block *sb)
 {
@@ -676,7 +714,7 @@ static inline int fscrypt_prepare_symlink(struct inode *dir,
 					  unsigned int max_len,
 					  struct fscrypt_str *disk_link)
 {
-	if (IS_ENCRYPTED(dir) || fscrypt_dummy_context_enabled(dir))
+	if (IS_ENCRYPTED(dir) || fscrypt_get_dummy_context(dir->i_sb) != NULL)
 		return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);
 
 	disk_link->name = (unsigned char *)target;
-- 
2.26.2

[PATCH 4/4] fscrypt: make test_dummy_encryption use v2 by default

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Since v1 encryption policies are deprecated, make test_dummy_encryption
test v2 policies by default.

Note that this causes ext4/023 and ext4/028 to start failing due to
known bugs in those tests (see previous commit).

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/crypto/policy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index ca0ee337c9627f..cb7fd8f7f0eca1 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -632,7 +632,7 @@ int fscrypt_set_test_dummy_encryption(struct super_block *sb,
 				      const substring_t *arg,
 				      struct fscrypt_dummy_context *dummy_ctx)
 {
-	const char *argstr = "v1";
+	const char *argstr = "v2";
 	const char *argstr_to_free = NULL;
 	struct fscrypt_key_specifier key_spec = { 0 };
 	int version;
-- 
2.26.2

Re: [PATCH 1/4] linux/parser.h: add include guards

[Theodore Y. Ts'o]

On Tue, May 12, 2020 at 04:32:48PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> <linux/parser.h> is missing include guards.  Add them.
> 
> This is needed to allow declaring a function in <linux/fscrypt.h> that
> takes a substring_t parameter.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Theodore Ts'o <tytso@mit.edu>

Re: [PATCH 2/4] fscrypt: add fscrypt_add_test_dummy_key()

[Theodore Y. Ts'o]

On Tue, May 12, 2020 at 04:32:49PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Currently, the test_dummy_encryption mount option (which is used for
> encryption I/O testing with xfstests) uses v1 encryption policies, and
> it relies on userspace inserting a test key into the session keyring.
> 
> We need test_dummy_encryption to support v2 encryption policies too.
> Requiring userspace to add the test key doesn't work well with v2
> policies, since v2 policies only support the filesystem keyring (not the
> session keyring), and keys in the filesystem keyring are lost when the
> filesystem is unmounted.  Hooking all test code that unmounts and
> re-mounts the filesystem would be difficult.
> 
> Instead, let's make the filesystem automatically add the test key to its
> keyring when test_dummy_encryption is enabled.
> 
> That puts the responsibility for choosing the test key on the kernel.
> We could just hard-code a key.  But out of paranoia, let's first try
> using a per-boot random key, to prevent this code from being misused.
> A per-boot key will work as long as no one expects dummy-encrypted files
> to remain accessible after a reboot.  (gce-xfstests doesn't.)
> 
> Therefore, this patch adds a function fscrypt_add_test_dummy_key() which
> implements the above.  The next patch will use it.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Theodore Ts'o <tytso@mit.edu>

Re: [PATCH 1/4] linux/parser.h: add include guards

[Jaegeuk Kim]

On 05/12, Theodore Y. Ts'o wrote:
> On Tue, May 12, 2020 at 04:32:48PM -0700, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > <linux/parser.h> is missing include guards.  Add them.
> > 
> > This is needed to allow declaring a function in <linux/fscrypt.h> that
> > takes a substring_t parameter.
> > 
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> 
> Reviewed-by: Theodore Ts'o <tytso@mit.edu>

Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>

Re: [PATCH 2/4] fscrypt: add fscrypt_add_test_dummy_key()

[Jaegeuk Kim]

On 05/12, Theodore Y. Ts'o wrote:
> On Tue, May 12, 2020 at 04:32:49PM -0700, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > Currently, the test_dummy_encryption mount option (which is used for
> > encryption I/O testing with xfstests) uses v1 encryption policies, and
> > it relies on userspace inserting a test key into the session keyring.
> > 
> > We need test_dummy_encryption to support v2 encryption policies too.
> > Requiring userspace to add the test key doesn't work well with v2
> > policies, since v2 policies only support the filesystem keyring (not the
> > session keyring), and keys in the filesystem keyring are lost when the
> > filesystem is unmounted.  Hooking all test code that unmounts and
> > re-mounts the filesystem would be difficult.
> > 
> > Instead, let's make the filesystem automatically add the test key to its
> > keyring when test_dummy_encryption is enabled.
> > 
> > That puts the responsibility for choosing the test key on the kernel.
> > We could just hard-code a key.  But out of paranoia, let's first try
> > using a per-boot random key, to prevent this code from being misused.
> > A per-boot key will work as long as no one expects dummy-encrypted files
> > to remain accessible after a reboot.  (gce-xfstests doesn't.)
> > 
> > Therefore, this patch adds a function fscrypt_add_test_dummy_key() which
> > implements the above.  The next patch will use it.
> > 
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> 
> Reviewed-by: Theodore Ts'o <tytso@mit.edu>

Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>

Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Jaegeuk Kim]

On 05/12, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> v1 encryption policies are deprecated in favor of v2, and some new
> features (e.g. encryption+casefolding) are only being added for v2.
> 
> Therefore, the "test_dummy_encryption" mount option (which is used for
> encryption I/O testing with xfstests) needs to support v2 policies.
> 
> To do this, extend its syntax to be "test_dummy_encryption=v1" or
> "test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
> argument) also continues to be accepted, to specify the default setting
> -- currently v1, but the next patch changes it to v2.
> 
> To cleanly support both v1 and v2 while also making it easy to support
> specifying other encryption settings in the future (say, accepting
> "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
> pointer to the dummy fscrypt_context rather than using mount flags.
> 
> To avoid concurrency issues, don't allow test_dummy_encryption to be set
> or changed during a remount.  (The former restriction is new, but
> xfstests doesn't run into it, so no one should notice.)
> 
> Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
> there are two regressions, both of which are test bugs: ext4/023 and
> ext4/028 fail because they set an xattr and expect it to be stored
> inline, but the increase in size of the fscrypt_context from
> 24 to 40 bytes causes this xattr to be spilled into an external block.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>

> ---
>  Documentation/filesystems/f2fs.rst |   6 +-
>  fs/crypto/keysetup.c               |  15 ++--
>  fs/crypto/policy.c                 | 125 +++++++++++++++++++++++++++++
>  fs/ext4/ext4.h                     |   7 +-
>  fs/ext4/super.c                    |  68 ++++++++++++----
>  fs/f2fs/f2fs.h                     |   4 +-
>  fs/f2fs/super.c                    |  85 ++++++++++++++------
>  include/linux/fscrypt.h            |  52 ++++++++++--
>  8 files changed, 302 insertions(+), 60 deletions(-)
> 
> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> index 87d794bc75a479..4218ac65862934 100644
> --- a/Documentation/filesystems/f2fs.rst
> +++ b/Documentation/filesystems/f2fs.rst
> @@ -225,8 +225,12 @@ fsync_mode=%s          Control the policy of fsync. Currently supports "posix",
>                         pass, but the performance will regress. "nobarrier" is
>                         based on "posix", but doesn't issue flush command for
>                         non-atomic files likewise "nobarrier" mount option.
> -test_dummy_encryption  Enable dummy encryption, which provides a fake fscrypt
> +test_dummy_encryption
> +test_dummy_encryption=%s
> +                       Enable dummy encryption, which provides a fake fscrypt
>                         context. The fake fscrypt context is used by xfstests.
> +                       The argument may be either "v1" or "v2", in order to
> +                       select the corresponding fscrypt policy version.
>  checkpoint=%s[:%u[%]]  Set to "disable" to turn off checkpointing. Set to "enable"
>                         to reenable checkpointing. Is enabled by default. While
>                         disabled, any unmounting or unexpected shutdowns will cause
> diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> index 302375e9f719eb..cbfb3c7c4a13a6 100644
> --- a/fs/crypto/keysetup.c
> +++ b/fs/crypto/keysetup.c
> @@ -395,21 +395,18 @@ int fscrypt_get_encryption_info(struct inode *inode)
>  
>  	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
>  	if (res < 0) {
> -		if (!fscrypt_dummy_context_enabled(inode) ||
> -		    IS_ENCRYPTED(inode)) {
> +		const union fscrypt_context *dummy_ctx =
> +			fscrypt_get_dummy_context(inode->i_sb);
> +
> +		if (IS_ENCRYPTED(inode) || !dummy_ctx) {
>  			fscrypt_warn(inode,
>  				     "Error %d getting encryption context",
>  				     res);
>  			return res;
>  		}
>  		/* Fake up a context for an unencrypted directory */
> -		memset(&ctx, 0, sizeof(ctx));
> -		ctx.version = FSCRYPT_CONTEXT_V1;
> -		ctx.v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
> -		ctx.v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
> -		memset(ctx.v1.master_key_descriptor, 0x42,
> -		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
> -		res = sizeof(ctx.v1);
> +		res = fscrypt_context_size(dummy_ctx);
> +		memcpy(&ctx, dummy_ctx, res);
>  	}
>  
>  	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
> diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
> index 10ccf945020ce5..ca0ee337c9627f 100644
> --- a/fs/crypto/policy.c
> +++ b/fs/crypto/policy.c
> @@ -11,6 +11,7 @@
>   */
>  
>  #include <linux/random.h>
> +#include <linux/seq_file.h>
>  #include <linux/string.h>
>  #include <linux/mount.h>
>  #include "fscrypt_private.h"
> @@ -605,3 +606,127 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child,
>  	return preload ? fscrypt_get_encryption_info(child): 0;
>  }
>  EXPORT_SYMBOL(fscrypt_inherit_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.
> + *	 If no argument was specified, then @arg->from == NULL.
> + * @dummy_ctx: the filesystem's current dummy context (input/output, see below)
> + *
> + * Handle the test_dummy_encryption mount option by creating a dummy encryption
> + * context, saving it in @dummy_ctx, and adding the corresponding dummy
> + * encryption key to the filesystem.  If the @dummy_ctx is already set, then
> + * instead validate that it matches @arg.  Don't support changing it via
> + * remount, as that is difficult to do safely.
> + *
> + * The reason we use an fscrypt_context rather than an fscrypt_policy is because
> + * we mustn't generate a new nonce each time we access a dummy-encrypted
> + * directory, as that would change the way filenames are encrypted.
> + *
> + * Return: 0 on success (dummy context set, or the same context is already set);
> + *         -EEXIST if a different dummy context is already set;
> + *         or another -errno value.
> + */
> +int fscrypt_set_test_dummy_encryption(struct super_block *sb,
> +				      const substring_t *arg,
> +				      struct fscrypt_dummy_context *dummy_ctx)
> +{
> +	const char *argstr = "v1";
> +	const char *argstr_to_free = NULL;
> +	struct fscrypt_key_specifier key_spec = { 0 };
> +	int version;
> +	union fscrypt_context *ctx = NULL;
> +	int err;
> +
> +	if (arg->from) {
> +		argstr = argstr_to_free = match_strdup(arg);
> +		if (!argstr)
> +			return -ENOMEM;
> +	}
> +
> +	if (!strcmp(argstr, "v1")) {
> +		version = FSCRYPT_CONTEXT_V1;
> +		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
> +		memset(key_spec.u.descriptor, 0x42,
> +		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
> +	} else if (!strcmp(argstr, "v2")) {
> +		version = FSCRYPT_CONTEXT_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;
> +	}
> +
> +	if (dummy_ctx->ctx) {
> +		/*
> +		 * Note: if we ever make test_dummy_encryption support
> +		 * specifying other encryption settings, such as the encryption
> +		 * modes, we'll need to compare those settings here.
> +		 */
> +		if (dummy_ctx->ctx->version == version)
> +			err = 0;
> +		else
> +			err = -EEXIST;
> +		goto out;
> +	}
> +
> +	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx) {
> +		err = -ENOMEM;
> +		goto out;
> +	}
> +
> +	err = fscrypt_add_test_dummy_key(sb, &key_spec);
> +	if (err)
> +		goto out;
> +
> +	ctx->version = version;
> +	switch (ctx->version) {
> +	case FSCRYPT_CONTEXT_V1:
> +		ctx->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
> +		ctx->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
> +		memcpy(ctx->v1.master_key_descriptor, key_spec.u.descriptor,
> +		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
> +		break;
> +	case FSCRYPT_CONTEXT_V2:
> +		ctx->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS;
> +		ctx->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS;
> +		memcpy(ctx->v2.master_key_identifier, key_spec.u.identifier,
> +		       FSCRYPT_KEY_IDENTIFIER_SIZE);
> +		break;
> +	default:
> +		WARN_ON(1);
> +		err = -EINVAL;
> +		goto out;
> +	}
> +	dummy_ctx->ctx = ctx;
> +	ctx = NULL;
> +	err = 0;
> +out:
> +	kfree(ctx);
> +	kfree(argstr_to_free);
> +	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_context *ctx = fscrypt_get_dummy_context(sb);
> +
> +	if (!ctx)
> +		return;
> +	seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, ctx->version);
> +}
> +EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption);
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 91eb4381cae5b7..546504cba84211 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1357,11 +1357,9 @@ struct ext4_super_block {
>   */
>  #define EXT4_MF_MNTDIR_SAMPLED		0x0001
>  #define EXT4_MF_FS_ABORTED		0x0002	/* Fatal error detected */
> -#define EXT4_MF_TEST_DUMMY_ENCRYPTION	0x0004
>  
>  #ifdef CONFIG_FS_ENCRYPTION
> -#define DUMMY_ENCRYPTION_ENABLED(sbi) (unlikely((sbi)->s_mount_flags & \
> -						EXT4_MF_TEST_DUMMY_ENCRYPTION))
> +#define DUMMY_ENCRYPTION_ENABLED(sbi) ((sbi)->s_dummy_enc_ctx.ctx != NULL)
>  #else
>  #define DUMMY_ENCRYPTION_ENABLED(sbi) (0)
>  #endif
> @@ -1551,6 +1549,9 @@ struct ext4_sb_info {
>  	struct ratelimit_state s_warning_ratelimit_state;
>  	struct ratelimit_state s_msg_ratelimit_state;
>  
> +	/* Encryption context for '-o test_dummy_encryption' */
> +	struct fscrypt_dummy_context s_dummy_enc_ctx;
> +
>  	/*
>  	 * Barrier between writepages ops and changing any inode's JOURNAL_DATA
>  	 * or EXTENTS flag.
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index bf5fcb477f6672..4a3d21972011bb 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1106,6 +1106,7 @@ static void ext4_put_super(struct super_block *sb)
>  		crypto_free_shash(sbi->s_chksum_driver);
>  	kfree(sbi->s_blockgroup_lock);
>  	fs_put_dax(sbi->s_daxdev);
> +	fscrypt_free_dummy_context(&sbi->s_dummy_enc_ctx);
>  #ifdef CONFIG_UNICODE
>  	utf8_unload(sbi->s_encoding);
>  #endif
> @@ -1389,9 +1390,10 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
>  	return res;
>  }
>  
> -static bool ext4_dummy_context(struct inode *inode)
> +static const union fscrypt_context *
> +ext4_get_dummy_context(struct super_block *sb)
>  {
> -	return DUMMY_ENCRYPTION_ENABLED(EXT4_SB(inode->i_sb));
> +	return EXT4_SB(sb)->s_dummy_enc_ctx.ctx;
>  }
>  
>  static bool ext4_has_stable_inodes(struct super_block *sb)
> @@ -1410,7 +1412,7 @@ static const struct fscrypt_operations ext4_cryptops = {
>  	.key_prefix		= "ext4:",
>  	.get_context		= ext4_get_context,
>  	.set_context		= ext4_set_context,
> -	.dummy_context		= ext4_dummy_context,
> +	.get_dummy_context	= ext4_get_dummy_context,
>  	.empty_dir		= ext4_empty_dir,
>  	.max_namelen		= EXT4_NAME_LEN,
>  	.has_stable_inodes	= ext4_has_stable_inodes,
> @@ -1605,6 +1607,7 @@ static const match_table_t tokens = {
>  	{Opt_init_itable, "init_itable"},
>  	{Opt_noinit_itable, "noinit_itable"},
>  	{Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
> +	{Opt_test_dummy_encryption, "test_dummy_encryption=%s"},
>  	{Opt_test_dummy_encryption, "test_dummy_encryption"},
>  	{Opt_nombcache, "nombcache"},
>  	{Opt_nombcache, "no_mbcache"},	/* for backward compatibility */
> @@ -1816,7 +1819,7 @@ static const struct mount_opts {
>  	{Opt_jqfmt_vfsv0, QFMT_VFS_V0, MOPT_QFMT},
>  	{Opt_jqfmt_vfsv1, QFMT_VFS_V1, MOPT_QFMT},
>  	{Opt_max_dir_size_kb, 0, MOPT_GTE0},
> -	{Opt_test_dummy_encryption, 0, MOPT_GTE0},
> +	{Opt_test_dummy_encryption, 0, MOPT_STRING},
>  	{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
>  	{Opt_err, 0, 0}
>  };
> @@ -1851,6 +1854,48 @@ static int ext4_sb_read_encoding(const struct ext4_super_block *es,
>  }
>  #endif
>  
> +static int ext4_set_test_dummy_encryption(struct super_block *sb,
> +					  const char *opt,
> +					  const substring_t *arg,
> +					  bool is_remount)
> +{
> +#ifdef CONFIG_FS_ENCRYPTION
> +	struct ext4_sb_info *sbi = EXT4_SB(sb);
> +	int err;
> +
> +	/*
> +	 * This mount option is just for testing, and it's not worthwhile to
> +	 * implement the extra complexity (e.g. RCU protection) that would be
> +	 * needed to allow it to be set or changed during remount.  We do allow
> +	 * it to be specified during remount, but only if there is no change.
> +	 */
> +	if (is_remount && !sbi->s_dummy_enc_ctx.ctx) {
> +		ext4_msg(sb, KERN_WARNING,
> +			 "Can't set test_dummy_encryption on remount");
> +		return -1;
> +	}
> +	err = fscrypt_set_test_dummy_encryption(sb, arg, &sbi->s_dummy_enc_ctx);
> +	if (err) {
> +		if (err == -EEXIST)
> +			ext4_msg(sb, KERN_WARNING,
> +				 "Can't change test_dummy_encryption on remount");
> +		else if (err == -EINVAL)
> +			ext4_msg(sb, KERN_WARNING,
> +				 "Value of option \"%s\" is unrecognized", opt);
> +		else
> +			ext4_msg(sb, KERN_WARNING,
> +				 "Error processing option \"%s\" [%d]",
> +				 opt, err);
> +		return -1;
> +	}
> +	ext4_msg(sb, KERN_WARNING, "Test dummy encryption mode enabled");
> +#else
> +	ext4_msg(sb, KERN_WARNING,
> +		 "Test dummy encryption mount option ignored");
> +#endif
> +	return 1;
> +}
> +
>  static int handle_mount_opt(struct super_block *sb, char *opt, int token,
>  			    substring_t *args, unsigned long *journal_devnum,
>  			    unsigned int *journal_ioprio, int is_remount)
> @@ -2047,14 +2092,8 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
>  		*journal_ioprio =
>  			IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, arg);
>  	} else if (token == Opt_test_dummy_encryption) {
> -#ifdef CONFIG_FS_ENCRYPTION
> -		sbi->s_mount_flags |= EXT4_MF_TEST_DUMMY_ENCRYPTION;
> -		ext4_msg(sb, KERN_WARNING,
> -			 "Test dummy encryption mode enabled");
> -#else
> -		ext4_msg(sb, KERN_WARNING,
> -			 "Test dummy encryption mount option ignored");
> -#endif
> +		return ext4_set_test_dummy_encryption(sb, opt, &args[0],
> +						      is_remount);
>  	} else if (m->flags & MOPT_DATAJ) {
>  		if (is_remount) {
>  			if (!sbi->s_journal)
> @@ -2311,8 +2350,8 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
>  		SEQ_OPTS_PRINT("max_dir_size_kb=%u", sbi->s_max_dir_size_kb);
>  	if (test_opt(sb, DATA_ERR_ABORT))
>  		SEQ_OPTS_PUTS("data_err=abort");
> -	if (DUMMY_ENCRYPTION_ENABLED(sbi))
> -		SEQ_OPTS_PUTS("test_dummy_encryption");
> +
> +	fscrypt_show_test_dummy_encryption(seq, sep, sb);
>  
>  	ext4_show_quota_options(seq, sb);
>  	return 0;
> @@ -4780,6 +4819,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	for (i = 0; i < EXT4_MAXQUOTAS; i++)
>  		kfree(get_qf_name(sb, sbi, i));
>  #endif
> +	fscrypt_free_dummy_context(&sbi->s_dummy_enc_ctx);
>  	ext4_blkdev_remove(sbi);
>  	brelse(bh);
>  out_fail:
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index ba470d5687fe04..157eec34897046 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -138,7 +138,7 @@ struct f2fs_mount_info {
>  	int fsync_mode;			/* fsync policy */
>  	int fs_mode;			/* fs mode: LFS or ADAPTIVE */
>  	int bggc_mode;			/* bggc mode: off, on or sync */
> -	bool test_dummy_encryption;	/* test dummy encryption */
> +	struct fscrypt_dummy_context dummy_enc_ctx; /* test dummy encryption */
>  	block_t unusable_cap;		/* Amount of space allowed to be
>  					 * unusable when disabling checkpoint
>  					 */
> @@ -1259,7 +1259,7 @@ enum fsync_mode {
>  
>  #ifdef CONFIG_FS_ENCRYPTION
>  #define DUMMY_ENCRYPTION_ENABLED(sbi) \
> -			(unlikely(F2FS_OPTION(sbi).test_dummy_encryption))
> +	(unlikely(F2FS_OPTION(sbi).dummy_enc_ctx.ctx != NULL))
>  #else
>  #define DUMMY_ENCRYPTION_ENABLED(sbi) (0)
>  #endif
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index f2dfc21c6abb0a..8a9955902d849c 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -202,6 +202,7 @@ static match_table_t f2fs_tokens = {
>  	{Opt_whint, "whint_mode=%s"},
>  	{Opt_alloc, "alloc_mode=%s"},
>  	{Opt_fsync, "fsync_mode=%s"},
> +	{Opt_test_dummy_encryption, "test_dummy_encryption=%s"},
>  	{Opt_test_dummy_encryption, "test_dummy_encryption"},
>  	{Opt_checkpoint_disable, "checkpoint=disable"},
>  	{Opt_checkpoint_disable_cap, "checkpoint=disable:%u"},
> @@ -394,7 +395,52 @@ static int f2fs_check_quota_options(struct f2fs_sb_info *sbi)
>  }
>  #endif
>  
> -static int parse_options(struct super_block *sb, char *options)
> +static int f2fs_set_test_dummy_encryption(struct super_block *sb,
> +					  const char *opt,
> +					  const substring_t *arg,
> +					  bool is_remount)
> +{
> +	struct f2fs_sb_info *sbi = F2FS_SB(sb);
> +#ifdef CONFIG_FS_ENCRYPTION
> +	int err;
> +
> +	if (!f2fs_sb_has_encrypt(sbi)) {
> +		f2fs_err(sbi, "Encrypt feature is off");
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * This mount option is just for testing, and it's not worthwhile to
> +	 * implement the extra complexity (e.g. RCU protection) that would be
> +	 * needed to allow it to be set or changed during remount.  We do allow
> +	 * it to be specified during remount, but only if there is no change.
> +	 */
> +	if (is_remount && !F2FS_OPTION(sbi).dummy_enc_ctx.ctx) {
> +		f2fs_warn(sbi, "Can't set test_dummy_encryption on remount");
> +		return -EINVAL;
> +	}
> +	err = fscrypt_set_test_dummy_encryption(
> +		sb, arg, &F2FS_OPTION(sbi).dummy_enc_ctx);
> +	if (err) {
> +		if (err == -EEXIST)
> +			f2fs_warn(sbi,
> +				  "Can't change test_dummy_encryption on remount");
> +		else if (err == -EINVAL)
> +			f2fs_warn(sbi, "Value of option \"%s\" is unrecognized",
> +				  opt);
> +		else
> +			f2fs_warn(sbi, "Error processing option \"%s\" [%d]",
> +				  opt, err);
> +		return -EINVAL;
> +	}
> +	f2fs_warn(sbi, "Test dummy encryption mode enabled");
> +#else
> +	f2fs_warn(sbi, "Test dummy encryption mount option ignored");
> +#endif
> +	return 0;
> +}
> +
> +static int parse_options(struct super_block *sb, char *options, bool is_remount)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_SB(sb);
>  	substring_t args[MAX_OPT_ARGS];
> @@ -403,9 +449,7 @@ static int parse_options(struct super_block *sb, char *options)
>  	int arg = 0, ext_cnt;
>  	kuid_t uid;
>  	kgid_t gid;
> -#ifdef CONFIG_QUOTA
>  	int ret;
> -#endif
>  
>  	if (!options)
>  		return 0;
> @@ -778,17 +822,10 @@ static int parse_options(struct super_block *sb, char *options)
>  			kvfree(name);
>  			break;
>  		case Opt_test_dummy_encryption:
> -#ifdef CONFIG_FS_ENCRYPTION
> -			if (!f2fs_sb_has_encrypt(sbi)) {
> -				f2fs_err(sbi, "Encrypt feature is off");
> -				return -EINVAL;
> -			}
> -
> -			F2FS_OPTION(sbi).test_dummy_encryption = true;
> -			f2fs_info(sbi, "Test dummy encryption mode enabled");
> -#else
> -			f2fs_info(sbi, "Test dummy encryption mount option ignored");
> -#endif
> +			ret = f2fs_set_test_dummy_encryption(sb, p, &args[0],
> +							     is_remount);
> +			if (ret)
> +				return ret;
>  			break;
>  		case Opt_checkpoint_disable_cap_perc:
>  			if (args->from && match_int(args, &arg))
> @@ -1213,6 +1250,7 @@ static void f2fs_put_super(struct super_block *sb)
>  	for (i = 0; i < MAXQUOTAS; i++)
>  		kvfree(F2FS_OPTION(sbi).s_qf_names[i]);
>  #endif
> +	fscrypt_free_dummy_context(&F2FS_OPTION(sbi).dummy_enc_ctx);
>  	destroy_percpu_info(sbi);
>  	for (i = 0; i < NR_PAGE_TYPE; i++)
>  		kvfree(sbi->write_io[i]);
> @@ -1543,10 +1581,8 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
>  		seq_printf(seq, ",whint_mode=%s", "user-based");
>  	else if (F2FS_OPTION(sbi).whint_mode == WHINT_MODE_FS)
>  		seq_printf(seq, ",whint_mode=%s", "fs-based");
> -#ifdef CONFIG_FS_ENCRYPTION
> -	if (F2FS_OPTION(sbi).test_dummy_encryption)
> -		seq_puts(seq, ",test_dummy_encryption");
> -#endif
> +
> +	fscrypt_show_test_dummy_encryption(seq, ',', sbi->sb);
>  
>  	if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_DEFAULT)
>  		seq_printf(seq, ",alloc_mode=%s", "default");
> @@ -1575,7 +1611,6 @@ static void default_options(struct f2fs_sb_info *sbi)
>  	F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
>  	F2FS_OPTION(sbi).alloc_mode = ALLOC_MODE_DEFAULT;
>  	F2FS_OPTION(sbi).fsync_mode = FSYNC_MODE_POSIX;
> -	F2FS_OPTION(sbi).test_dummy_encryption = false;
>  	F2FS_OPTION(sbi).s_resuid = make_kuid(&init_user_ns, F2FS_DEF_RESUID);
>  	F2FS_OPTION(sbi).s_resgid = make_kgid(&init_user_ns, F2FS_DEF_RESGID);
>  	F2FS_OPTION(sbi).compress_algorithm = COMPRESS_LZ4;
> @@ -1734,7 +1769,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>  	default_options(sbi);
>  
>  	/* parse mount options */
> -	err = parse_options(sb, data);
> +	err = parse_options(sb, data, true);
>  	if (err)
>  		goto restore_opts;
>  	checkpoint_changed =
> @@ -2410,9 +2445,10 @@ static int f2fs_set_context(struct inode *inode, const void *ctx, size_t len,
>  				ctx, len, fs_data, XATTR_CREATE);
>  }
>  
> -static bool f2fs_dummy_context(struct inode *inode)
> +static const union fscrypt_context *
> +f2fs_get_dummy_context(struct super_block *sb)
>  {
> -	return DUMMY_ENCRYPTION_ENABLED(F2FS_I_SB(inode));
> +	return F2FS_OPTION(F2FS_SB(sb)).dummy_enc_ctx.ctx;
>  }
>  
>  static bool f2fs_has_stable_inodes(struct super_block *sb)
> @@ -2431,7 +2467,7 @@ static const struct fscrypt_operations f2fs_cryptops = {
>  	.key_prefix		= "f2fs:",
>  	.get_context		= f2fs_get_context,
>  	.set_context		= f2fs_set_context,
> -	.dummy_context		= f2fs_dummy_context,
> +	.get_dummy_context	= f2fs_get_dummy_context,
>  	.empty_dir		= f2fs_empty_dir,
>  	.max_namelen		= F2FS_NAME_LEN,
>  	.has_stable_inodes	= f2fs_has_stable_inodes,
> @@ -3366,7 +3402,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  		goto free_sb_buf;
>  	}
>  
> -	err = parse_options(sb, options);
> +	err = parse_options(sb, options, false);
>  	if (err)
>  		goto free_options;
>  
> @@ -3769,6 +3805,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  	for (i = 0; i < MAXQUOTAS; i++)
>  		kvfree(F2FS_OPTION(sbi).s_qf_names[i]);
>  #endif
> +	fscrypt_free_dummy_context(&F2FS_OPTION(sbi).dummy_enc_ctx);
>  	kvfree(options);
>  free_sb_buf:
>  	kvfree(raw_super);
> diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
> index e3c2d2a155250a..13672564564894 100644
> --- a/include/linux/fscrypt.h
> +++ b/include/linux/fscrypt.h
> @@ -15,12 +15,15 @@
>  
>  #include <linux/fs.h>
>  #include <linux/mm.h>
> +#include <linux/parser.h>
>  #include <linux/slab.h>
>  #include <uapi/linux/fscrypt.h>
>  
>  #define FS_CRYPTO_BLOCK_SIZE		16
>  
> +union fscrypt_context;
>  struct fscrypt_info;
> +struct seq_file;
>  
>  struct fscrypt_str {
>  	unsigned char *name;
> @@ -58,7 +61,8 @@ struct fscrypt_operations {
>  	const char *key_prefix;
>  	int (*get_context)(struct inode *, void *, size_t);
>  	int (*set_context)(struct inode *, const void *, size_t, void *);
> -	bool (*dummy_context)(struct inode *);
> +	const union fscrypt_context *(*get_dummy_context)(
> +		struct super_block *sb);
>  	bool (*empty_dir)(struct inode *);
>  	unsigned int max_namelen;
>  	bool (*has_stable_inodes)(struct super_block *sb);
> @@ -87,10 +91,12 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
>  	return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
>  }
>  
> -static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
> +static inline const union fscrypt_context *
> +fscrypt_get_dummy_context(struct super_block *sb)
>  {
> -	return inode->i_sb->s_cop->dummy_context &&
> -		inode->i_sb->s_cop->dummy_context(inode);
> +	if (!sb->s_cop->get_dummy_context)
> +		return NULL;
> +	return sb->s_cop->get_dummy_context(sb);
>  }
>  
>  /*
> @@ -143,6 +149,23 @@ extern int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
>  extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
>  extern int fscrypt_inherit_context(struct inode *, struct inode *,
>  					void *, bool);
> +
> +struct fscrypt_dummy_context {
> +	const union fscrypt_context *ctx;
> +};
> +
> +int fscrypt_set_test_dummy_encryption(struct super_block *sb,
> +				      const substring_t *arg,
> +				      struct fscrypt_dummy_context *dummy_ctx);
> +void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
> +					struct super_block *sb);
> +static inline void
> +fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
> +{
> +	kfree(dummy_ctx->ctx);
> +	dummy_ctx->ctx = NULL;
> +}
> +
>  /* keyring.c */
>  extern void fscrypt_sb_free(struct super_block *sb);
>  extern int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
> @@ -222,9 +245,10 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
>  	return false;
>  }
>  
> -static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
> +static inline const union fscrypt_context *
> +fscrypt_get_dummy_context(struct super_block *sb)
>  {
> -	return false;
> +	return NULL;
>  }
>  
>  static inline void fscrypt_handle_d_move(struct dentry *dentry)
> @@ -319,6 +343,20 @@ static inline int fscrypt_inherit_context(struct inode *parent,
>  	return -EOPNOTSUPP;
>  }
>  
> +struct fscrypt_dummy_context {
> +};
> +
> +static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
> +						      char sep,
> +						      struct super_block *sb)
> +{
> +}
> +
> +static inline void
> +fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
> +{
> +}
> +
>  /* keyring.c */
>  static inline void fscrypt_sb_free(struct super_block *sb)
>  {
> @@ -676,7 +714,7 @@ static inline int fscrypt_prepare_symlink(struct inode *dir,
>  					  unsigned int max_len,
>  					  struct fscrypt_str *disk_link)
>  {
> -	if (IS_ENCRYPTED(dir) || fscrypt_dummy_context_enabled(dir))
> +	if (IS_ENCRYPTED(dir) || fscrypt_get_dummy_context(dir->i_sb) != NULL)
>  		return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);
>  
>  	disk_link->name = (unsigned char *)target;
> -- 
> 2.26.2

Re: [PATCH 4/4] fscrypt: make test_dummy_encryption use v2 by default

[Jaegeuk Kim]

On 05/12, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Since v1 encryption policies are deprecated, make test_dummy_encryption
> test v2 policies by default.
> 
> Note that this causes ext4/023 and ext4/028 to start failing due to
> known bugs in those tests (see previous commit).
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>

> ---
>  fs/crypto/policy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
> index ca0ee337c9627f..cb7fd8f7f0eca1 100644
> --- a/fs/crypto/policy.c
> +++ b/fs/crypto/policy.c
> @@ -632,7 +632,7 @@ int fscrypt_set_test_dummy_encryption(struct super_block *sb,
>  				      const substring_t *arg,
>  				      struct fscrypt_dummy_context *dummy_ctx)
>  {
> -	const char *argstr = "v1";
> +	const char *argstr = "v2";
>  	const char *argstr_to_free = NULL;
>  	struct fscrypt_key_specifier key_spec = { 0 };
>  	int version;
> -- 
> 2.26.2

Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Theodore Y. Ts'o]

On Tue, May 12, 2020 at 04:32:50PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> v1 encryption policies are deprecated in favor of v2, and some new
> features (e.g. encryption+casefolding) are only being added for v2.
> 
> Therefore, the "test_dummy_encryption" mount option (which is used for
> encryption I/O testing with xfstests) needs to support v2 policies.
> 
> To do this, extend its syntax to be "test_dummy_encryption=v1" or
> "test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
> argument) also continues to be accepted, to specify the default setting
> -- currently v1, but the next patch changes it to v2.
> 
> To cleanly support both v1 and v2 while also making it easy to support
> specifying other encryption settings in the future (say, accepting
> "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
> pointer to the dummy fscrypt_context rather than using mount flags.
> 
> To avoid concurrency issues, don't allow test_dummy_encryption to be set
> or changed during a remount.  (The former restriction is new, but
> xfstests doesn't run into it, so no one should notice.)
> 
> Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
> there are two regressions, both of which are test bugs: ext4/023 and
> ext4/028 fail because they set an xattr and expect it to be stored
> inline, but the increase in size of the fscrypt_context from
> 24 to 40 bytes causes this xattr to be spilled into an external block.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Looks good, but could you do me a favor and merge in this?

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 04bfaf63752c..6c9fc9e21c13 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -293,6 +293,7 @@ EXT4_ATTR_FEATURE(batched_discard);
 EXT4_ATTR_FEATURE(meta_bg_resize);
 #ifdef CONFIG_FS_ENCRYPTION
 EXT4_ATTR_FEATURE(encryption);
+EXT4_ATTR_FEATURE(test_dummy_encryption_v2);
 #endif
 #ifdef CONFIG_UNICODE
 EXT4_ATTR_FEATURE(casefold);
@@ -308,6 +309,7 @@ static struct attribute *ext4_feat_attrs[] = {
 	ATTR_LIST(meta_bg_resize),
 #ifdef CONFIG_FS_ENCRYPTION
 	ATTR_LIST(encryption),
+	ATTR_LIST(test_dummy_encryption_v2),
 #endif
 #ifdef CONFIG_UNICODE
 	ATTR_LIST(casefold),

This will make it easier to have the gce-xfstests test runner know
whether or not test_dummy_encryption=v1 / test_dummy_encryption=v2
will work, and whether test_dummy_encryption tests v1 or v2.

Thanks!

					- Ted

Re: [PATCH 4/4] fscrypt: make test_dummy_encryption use v2 by default

[Theodore Y. Ts'o]

On Tue, May 12, 2020 at 04:32:51PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Since v1 encryption policies are deprecated, make test_dummy_encryption
> test v2 policies by default.
> 
> Note that this causes ext4/023 and ext4/028 to start failing due to
> known bugs in those tests (see previous commit).
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

					- Ted

Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Eric Biggers]

On Mon, May 18, 2020 at 10:53:55PM -0400, Theodore Y. Ts'o wrote:
> On Tue, May 12, 2020 at 04:32:50PM -0700, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > v1 encryption policies are deprecated in favor of v2, and some new
> > features (e.g. encryption+casefolding) are only being added for v2.
> > 
> > Therefore, the "test_dummy_encryption" mount option (which is used for
> > encryption I/O testing with xfstests) needs to support v2 policies.
> > 
> > To do this, extend its syntax to be "test_dummy_encryption=v1" or
> > "test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
> > argument) also continues to be accepted, to specify the default setting
> > -- currently v1, but the next patch changes it to v2.
> > 
> > To cleanly support both v1 and v2 while also making it easy to support
> > specifying other encryption settings in the future (say, accepting
> > "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
> > pointer to the dummy fscrypt_context rather than using mount flags.
> > 
> > To avoid concurrency issues, don't allow test_dummy_encryption to be set
> > or changed during a remount.  (The former restriction is new, but
> > xfstests doesn't run into it, so no one should notice.)
> > 
> > Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
> > there are two regressions, both of which are test bugs: ext4/023 and
> > ext4/028 fail because they set an xattr and expect it to be stored
> > inline, but the increase in size of the fscrypt_context from
> > 24 to 40 bytes causes this xattr to be spilled into an external block.
> > 
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> 
> Looks good, but could you do me a favor and merge in this?
> 
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index 04bfaf63752c..6c9fc9e21c13 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -293,6 +293,7 @@ EXT4_ATTR_FEATURE(batched_discard);
>  EXT4_ATTR_FEATURE(meta_bg_resize);
>  #ifdef CONFIG_FS_ENCRYPTION
>  EXT4_ATTR_FEATURE(encryption);
> +EXT4_ATTR_FEATURE(test_dummy_encryption_v2);
>  #endif
>  #ifdef CONFIG_UNICODE
>  EXT4_ATTR_FEATURE(casefold);
> @@ -308,6 +309,7 @@ static struct attribute *ext4_feat_attrs[] = {
>  	ATTR_LIST(meta_bg_resize),
>  #ifdef CONFIG_FS_ENCRYPTION
>  	ATTR_LIST(encryption),
> +	ATTR_LIST(test_dummy_encryption_v2),
>  #endif
>  #ifdef CONFIG_UNICODE
>  	ATTR_LIST(casefold),
> 
> This will make it easier to have the gce-xfstests test runner know
> whether or not test_dummy_encryption=v1 / test_dummy_encryption=v2
> will work, and whether test_dummy_encryption tests v1 or v2.
> 

Thanks, I'll add that.  I assume you meant "Reviewed-by"?

- Eric

Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Eric Biggers]

On Mon, May 18, 2020 at 08:02:05PM -0700, Eric Biggers wrote:
> On Mon, May 18, 2020 at 10:53:55PM -0400, Theodore Y. Ts'o wrote:
> > On Tue, May 12, 2020 at 04:32:50PM -0700, Eric Biggers wrote:
> > > From: Eric Biggers <ebiggers@google.com>
> > > 
> > > v1 encryption policies are deprecated in favor of v2, and some new
> > > features (e.g. encryption+casefolding) are only being added for v2.
> > > 
> > > Therefore, the "test_dummy_encryption" mount option (which is used for
> > > encryption I/O testing with xfstests) needs to support v2 policies.
> > > 
> > > To do this, extend its syntax to be "test_dummy_encryption=v1" or
> > > "test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
> > > argument) also continues to be accepted, to specify the default setting
> > > -- currently v1, but the next patch changes it to v2.
> > > 
> > > To cleanly support both v1 and v2 while also making it easy to support
> > > specifying other encryption settings in the future (say, accepting
> > > "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
> > > pointer to the dummy fscrypt_context rather than using mount flags.
> > > 
> > > To avoid concurrency issues, don't allow test_dummy_encryption to be set
> > > or changed during a remount.  (The former restriction is new, but
> > > xfstests doesn't run into it, so no one should notice.)
> > > 
> > > Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
> > > there are two regressions, both of which are test bugs: ext4/023 and
> > > ext4/028 fail because they set an xattr and expect it to be stored
> > > inline, but the increase in size of the fscrypt_context from
> > > 24 to 40 bytes causes this xattr to be spilled into an external block.
> > > 
> > > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > 
> > Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> > 
> > Looks good, but could you do me a favor and merge in this?
> > 
> > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> > index 04bfaf63752c..6c9fc9e21c13 100644
> > --- a/fs/ext4/sysfs.c
> > +++ b/fs/ext4/sysfs.c
> > @@ -293,6 +293,7 @@ EXT4_ATTR_FEATURE(batched_discard);
> >  EXT4_ATTR_FEATURE(meta_bg_resize);
> >  #ifdef CONFIG_FS_ENCRYPTION
> >  EXT4_ATTR_FEATURE(encryption);
> > +EXT4_ATTR_FEATURE(test_dummy_encryption_v2);
> >  #endif
> >  #ifdef CONFIG_UNICODE
> >  EXT4_ATTR_FEATURE(casefold);
> > @@ -308,6 +309,7 @@ static struct attribute *ext4_feat_attrs[] = {
> >  	ATTR_LIST(meta_bg_resize),
> >  #ifdef CONFIG_FS_ENCRYPTION
> >  	ATTR_LIST(encryption),
> > +	ATTR_LIST(test_dummy_encryption_v2),
> >  #endif
> >  #ifdef CONFIG_UNICODE
> >  	ATTR_LIST(casefold),
> > 
> > This will make it easier to have the gce-xfstests test runner know
> > whether or not test_dummy_encryption=v1 / test_dummy_encryption=v2
> > will work, and whether test_dummy_encryption tests v1 or v2.
> > 
> 
> Thanks, I'll add that.  I assume you meant "Reviewed-by"?

Jaegeuk, do you want /sys/fs/f2fs/features/test_dummy_encryption_v2 as well, to
match what Ted wants for ext4?  It would be the following change:

diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index e3bbbef9b4f09e4..3162f46b3c9bfc1 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -446,6 +446,7 @@ enum feat_id {
 	FEAT_SB_CHECKSUM,
 	FEAT_CASEFOLD,
 	FEAT_COMPRESSION,
+	FEAT_TEST_DUMMY_ENCRYPTION_V2,
 };
 
 static ssize_t f2fs_feature_show(struct f2fs_attr *a,
@@ -466,6 +467,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
 	case FEAT_SB_CHECKSUM:
 	case FEAT_CASEFOLD:
 	case FEAT_COMPRESSION:
+	case FEAT_TEST_DUMMY_ENCRYPTION_V2:
 		return sprintf(buf, "supported\n");
 	}
 	return 0;
@@ -563,6 +565,7 @@ F2FS_GENERAL_RO_ATTR(avg_vblocks);
 
 #ifdef CONFIG_FS_ENCRYPTION
 F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO);
+F2FS_FEATURE_RO_ATTR(test_dummy_encryption_v2, FEAT_TEST_DUMMY_ENCRYPTION_V2);
 #endif
 #ifdef CONFIG_BLK_DEV_ZONED
 F2FS_FEATURE_RO_ATTR(block_zoned, FEAT_BLKZONED);
@@ -647,6 +650,7 @@ ATTRIBUTE_GROUPS(f2fs);
 static struct attribute *f2fs_feat_attrs[] = {
 #ifdef CONFIG_FS_ENCRYPTION
 	ATTR_LIST(encryption),
+	ATTR_LIST(test_dummy_encryption_v2),
 #endif
 #ifdef CONFIG_BLK_DEV_ZONED
 	ATTR_LIST(block_zoned),

Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Jaegeuk Kim]

On 05/18, Eric Biggers wrote:
> On Mon, May 18, 2020 at 08:02:05PM -0700, Eric Biggers wrote:
> > On Mon, May 18, 2020 at 10:53:55PM -0400, Theodore Y. Ts'o wrote:
> > > On Tue, May 12, 2020 at 04:32:50PM -0700, Eric Biggers wrote:
> > > > From: Eric Biggers <ebiggers@google.com>
> > > > 
> > > > v1 encryption policies are deprecated in favor of v2, and some new
> > > > features (e.g. encryption+casefolding) are only being added for v2.
> > > > 
> > > > Therefore, the "test_dummy_encryption" mount option (which is used for
> > > > encryption I/O testing with xfstests) needs to support v2 policies.
> > > > 
> > > > To do this, extend its syntax to be "test_dummy_encryption=v1" or
> > > > "test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
> > > > argument) also continues to be accepted, to specify the default setting
> > > > -- currently v1, but the next patch changes it to v2.
> > > > 
> > > > To cleanly support both v1 and v2 while also making it easy to support
> > > > specifying other encryption settings in the future (say, accepting
> > > > "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
> > > > pointer to the dummy fscrypt_context rather than using mount flags.
> > > > 
> > > > To avoid concurrency issues, don't allow test_dummy_encryption to be set
> > > > or changed during a remount.  (The former restriction is new, but
> > > > xfstests doesn't run into it, so no one should notice.)
> > > > 
> > > > Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
> > > > there are two regressions, both of which are test bugs: ext4/023 and
> > > > ext4/028 fail because they set an xattr and expect it to be stored
> > > > inline, but the increase in size of the fscrypt_context from
> > > > 24 to 40 bytes causes this xattr to be spilled into an external block.
> > > > 
> > > > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > > 
> > > Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> > > 
> > > Looks good, but could you do me a favor and merge in this?
> > > 
> > > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> > > index 04bfaf63752c..6c9fc9e21c13 100644
> > > --- a/fs/ext4/sysfs.c
> > > +++ b/fs/ext4/sysfs.c
> > > @@ -293,6 +293,7 @@ EXT4_ATTR_FEATURE(batched_discard);
> > >  EXT4_ATTR_FEATURE(meta_bg_resize);
> > >  #ifdef CONFIG_FS_ENCRYPTION
> > >  EXT4_ATTR_FEATURE(encryption);
> > > +EXT4_ATTR_FEATURE(test_dummy_encryption_v2);
> > >  #endif
> > >  #ifdef CONFIG_UNICODE
> > >  EXT4_ATTR_FEATURE(casefold);
> > > @@ -308,6 +309,7 @@ static struct attribute *ext4_feat_attrs[] = {
> > >  	ATTR_LIST(meta_bg_resize),
> > >  #ifdef CONFIG_FS_ENCRYPTION
> > >  	ATTR_LIST(encryption),
> > > +	ATTR_LIST(test_dummy_encryption_v2),
> > >  #endif
> > >  #ifdef CONFIG_UNICODE
> > >  	ATTR_LIST(casefold),
> > > 
> > > This will make it easier to have the gce-xfstests test runner know
> > > whether or not test_dummy_encryption=v1 / test_dummy_encryption=v2
> > > will work, and whether test_dummy_encryption tests v1 or v2.
> > > 
> > 
> > Thanks, I'll add that.  I assume you meant "Reviewed-by"?
> 
> Jaegeuk, do you want /sys/fs/f2fs/features/test_dummy_encryption_v2 as well, to
> match what Ted wants for ext4?  It would be the following change:

Yes, please. Thank you.

> 
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index e3bbbef9b4f09e4..3162f46b3c9bfc1 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -446,6 +446,7 @@ enum feat_id {
>  	FEAT_SB_CHECKSUM,
>  	FEAT_CASEFOLD,
>  	FEAT_COMPRESSION,
> +	FEAT_TEST_DUMMY_ENCRYPTION_V2,
>  };
>  
>  static ssize_t f2fs_feature_show(struct f2fs_attr *a,
> @@ -466,6 +467,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
>  	case FEAT_SB_CHECKSUM:
>  	case FEAT_CASEFOLD:
>  	case FEAT_COMPRESSION:
> +	case FEAT_TEST_DUMMY_ENCRYPTION_V2:
>  		return sprintf(buf, "supported\n");
>  	}
>  	return 0;
> @@ -563,6 +565,7 @@ F2FS_GENERAL_RO_ATTR(avg_vblocks);
>  
>  #ifdef CONFIG_FS_ENCRYPTION
>  F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO);
> +F2FS_FEATURE_RO_ATTR(test_dummy_encryption_v2, FEAT_TEST_DUMMY_ENCRYPTION_V2);
>  #endif
>  #ifdef CONFIG_BLK_DEV_ZONED
>  F2FS_FEATURE_RO_ATTR(block_zoned, FEAT_BLKZONED);
> @@ -647,6 +650,7 @@ ATTRIBUTE_GROUPS(f2fs);
>  static struct attribute *f2fs_feat_attrs[] = {
>  #ifdef CONFIG_FS_ENCRYPTION
>  	ATTR_LIST(encryption),
> +	ATTR_LIST(test_dummy_encryption_v2),
>  #endif
>  #ifdef CONFIG_BLK_DEV_ZONED
>  	ATTR_LIST(block_zoned),

Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2

[Theodore Y. Ts'o]

On Mon, May 18, 2020 at 08:02:05PM -0700, Eric Biggers wrote:
> 
> Thanks, I'll add that.  I assume you meant "Reviewed-by"?

Yes, thanks.

Reviewed-by: Theodore Ts'o <tytso@mit.edu>


				- Ted

Re: [PATCH 0/4] fscrypt: make '-o test_dummy_encryption' support v2 policies

[Eric Biggers]

On Tue, May 12, 2020 at 04:32:47PM -0700, Eric Biggers wrote:
> v1 encryption policies are deprecated in favor of v2, and some new
> features (e.g. encryption+casefolding) are only being added for v2.
> 
> As a result, the "test_dummy_encryption" mount option (which is used for
> encryption I/O testing with xfstests) needs to support v2 policies.
> 
> Therefore, this patchset adds support for specifying
> "test_dummy_encryption=v2" (or "test_dummy_encryption=v1").
> To make this possible, it reworks the way the test_dummy_encryption
> mount option is handled to make it more flexible than a flag, and to
> automatically add the test dummy key to the filesystem's keyring.
> 
> Patch 4 additionally changes the default to "v2".
> 
> This patchset applies to v5.7-rc4.
> 
> Eric Biggers (4):
>   linux/parser.h: add include guards
>   fscrypt: add fscrypt_add_test_dummy_key()
>   fscrypt: support test_dummy_encryption=v2
>   fscrypt: make test_dummy_encryption use v2 by default
> 

All applied to fscrypt.git#master for 5.8
(including the sysfs additions to patch 3, as was discussed)

- Eric