[PATCH 06/18] f2fs crypto: add encryption policy and password salt support

Jaegeuk Kim
2015-05-09T04:26:21Z

This patch adds encryption policy and password salt support through ioctl
implementation.

It adds three ioctls:
F2FS_IOC_SET_ENCRYPTION_POLICY,
F2FS_IOC_GET_ENCRYPTION_POLICY,
F2FS_IOC_GET_ENCRYPTION_PWSALT, which use xattr operations.

Note that, these definition and codes are taken from ext4 crypto support.
For f2fs, xattr operations and on-disk flags for superblock and inode were
changed.

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Ildar Muslukhov <muslukhovi@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
fs/f2fs/Makefile | 1 +
fs/f2fs/crypto_policy.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/f2fs/f2fs.h | 16 ++++
fs/f2fs/file.c | 91 +++++++++++++++++++++
fs/f2fs/xattr.c | 3 +
5 files changed, 317 insertions(+)
create mode 100644 fs/f2fs/crypto_policy.c

diff --git a/fs/f2fs/Makefile b/fs/f2fs/Makefile
index d923977..7864f4f 100644
--- a/fs/f2fs/Makefile
+++ b/fs/f2fs/Makefile
@@ -6,3 +6,4 @@ f2fs-$(CONFIG_F2FS_STAT_FS) += debug.o
f2fs-$(CONFIG_F2FS_FS_XATTR) += xattr.o
f2fs-$(CONFIG_F2FS_FS_POSIX_ACL) += acl.o
f2fs-$(CONFIG_F2FS_IO_TRACE) += trace.o
+f2fs-$(CONFIG_F2FS_FS_ENCRYPTION) += crypto_policy.o
diff --git a/fs/f2fs/crypto_policy.c b/fs/f2fs/crypto_policy.c
new file mode 100644
index 0000000..bef254b
--- /dev/null
+++ b/fs/f2fs/crypto_policy.c
@@ -0,0 +1,206 @@
+/*
+ * copied from linux/fs/ext4/crypto_policy.c
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility.
+ *
+ * This contains encryption policy functions for f2fs with some modifications
+ * to support f2fs-specific xattr APIs.
+ *
+ * Written by Michael Halcrow, 2015.
+ * Modified by Jaegeuk Kim, 2015.
+ */
+#include <linux/random.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/f2fs_fs.h>
+
+#include "f2fs.h"
+#include "xattr.h"
+
+static int f2fs_inode_has_encryption_context(struct inode *inode)
+{
+ int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
+ F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0, NULL);
+ return (res > 0);
+}
+
+/*
+ * check whether the policy is consistent with the encryption context
+ * for the inode
+ */
+static int f2fs_is_encryption_context_consistent_with_policy(
+ struct inode *inode, const struct f2fs_encryption_policy *policy)
+{
+ struct f2fs_encryption_context ctx;
+ int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
+ F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
+ sizeof(ctx), NULL);
+
+ if (res != sizeof(ctx))
+ return 0;
+
+ return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
+ F2FS_KEY_DESCRIPTOR_SIZE) == 0 &&
+ (ctx.flags == policy->flags) &&
+ (ctx.contents_encryption_mode ==
+ policy->contents_encryption_mode) &&
+ (ctx.filenames_encryption_mode ==
+ policy->filenames_encryption_mode));
+}
+
+static int f2fs_create_encryption_context_from_policy(
+ struct inode *inode, const struct f2fs_encryption_policy *policy)
+{
+ struct f2fs_encryption_context ctx;
+
+ ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
+ memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
+ F2FS_KEY_DESCRIPTOR_SIZE);
+
+ if (!f2fs_valid_contents_enc_mode(policy->contents_encryption_mode)) {
+ printk(KERN_WARNING
+ "%s: Invalid contents encryption mode %d\n", __func__,
+ policy->contents_encryption_mode);
+ return -EINVAL;
+ }
+
+ if (!f2fs_valid_filenames_enc_mode(policy->filenames_encryption_mode)) {
+ printk(KERN_WARNING
+ "%s: Invalid filenames encryption mode %d\n", __func__,
+ policy->filenames_encryption_mode);
+ return -EINVAL;
+ }
+
+ if (policy->flags & ~F2FS_POLICY_FLAGS_VALID)
+ return -EINVAL;
+
+ ctx.contents_encryption_mode = policy->contents_encryption_mode;
+ ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
+ ctx.flags = policy->flags;
+ BUILD_BUG_ON(sizeof(ctx.nonce) != F2FS_KEY_DERIVATION_NONCE_SIZE);
+ get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE);
+
+ return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
+ F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
+ sizeof(ctx), NULL, 0);
+}
+
+int f2fs_process_policy(const struct f2fs_encryption_policy *policy,
+ struct inode *inode)
+{
+ if (policy->version != 0)
+ return -EINVAL;
+
+ if (!f2fs_inode_has_encryption_context(inode)) {
+ if (!f2fs_empty_dir(inode))
+ return -ENOTEMPTY;
+ return f2fs_create_encryption_context_from_policy(inode,
+ policy);
+ }
+
+ if (f2fs_is_encryption_context_consistent_with_policy(inode, policy))
+ return 0;
+
+ printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
+ __func__);
+ return -EINVAL;
+}
+
+int f2fs_get_policy(struct inode *inode, struct f2fs_encryption_policy *policy)
+{
+ struct f2fs_encryption_context ctx;
+ int res;
+
+ if (!f2fs_encrypted_inode(inode))
+ return -ENODATA;
+
+ res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
+ F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
+ &ctx, sizeof(ctx), NULL);
+ if (res != sizeof(ctx))
+ return -ENODATA;
+ if (ctx.format != F2FS_ENCRYPTION_CONTEXT_FORMAT_V1)
+ return -EINVAL;
+
+ policy->version = 0;
+ 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,
+ F2FS_KEY_DESCRIPTOR_SIZE);
+ return 0;
+}
+
+int f2fs_is_child_context_consistent_with_parent(struct inode *parent,
+ struct inode *child)
+{
+ struct f2fs_crypt_info *parent_ci, *child_ci;
+ int res;
+
+ if ((parent == NULL) || (child == NULL)) {
+ pr_err("parent %p child %p\n", parent, child);
+ BUG_ON(1);
+ }
+
+ /* no restrictions if the parent directory is not encrypted */
+ if (!f2fs_encrypted_inode(parent))
+ return 1;
+ /* if the child directory is not encrypted, this is always a problem */
+ if (!f2fs_encrypted_inode(child))
+ return 0;
+ res = f2fs_get_encryption_info(parent);
+ if (res)
+ return 0;
+ res = f2fs_get_encryption_info(child);
+ if (res)
+ return 0;
+ parent_ci = F2FS_I(parent)->i_crypt_info;
+ child_ci = F2FS_I(child)->i_crypt_info;
+ if (!parent_ci && !child_ci)
+ return 1;
+ if (!parent_ci || !child_ci)
+ return 0;
+
+ return (memcmp(parent_ci->ci_master_key,
+ child_ci->ci_master_key,
+ F2FS_KEY_DESCRIPTOR_SIZE) == 0 &&
+ (parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
+ (parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
+ (parent_ci->ci_flags == child_ci->ci_flags));
+}
+
+/**
+ * f2fs_inherit_context() - Sets a child context from its parent
+ * @parent: Parent inode from which the context is inherited.
+ * @child: Child inode that inherits the context from @parent.
+ *
+ * Return: Zero on success, non-zero otherwise
+ */
+int f2fs_inherit_context(struct inode *parent, struct inode *child,
+ struct page *ipage)
+{
+ struct f2fs_encryption_context ctx;
+ struct f2fs_crypt_info *ci;
+ int res;
+
+ res = f2fs_get_encryption_info(parent);
+ if (res < 0)
+ return res;
+
+ ci = F2FS_I(parent)->i_crypt_info;
+ BUG_ON(ci == NULL);
+
+ ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
+
+ ctx.contents_encryption_mode = ci->ci_data_mode;
+ ctx.filenames_encryption_mode = ci->ci_filename_mode;
+ ctx.flags = ci->ci_flags;
+ memcpy(ctx.master_key_descriptor, ci->ci_master_key,
+ F2FS_KEY_DESCRIPTOR_SIZE);
+
+ get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE);
+ return f2fs_setxattr(child, F2FS_XATTR_INDEX_ENCRYPTION,
+ F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
+ sizeof(ctx), ipage, 0);
+}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c3c4deb..d8ce158 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -229,6 +229,13 @@ static inline bool __has_cursum_space(struct f2fs_summary_block *sum, int size,
#define F2FS_IOC_RELEASE_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 4)
#define F2FS_IOC_ABORT_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 5)

+#define F2FS_IOC_SET_ENCRYPTION_POLICY \
+ _IOR('f', 19, struct f2fs_encryption_policy)
+#define F2FS_IOC_GET_ENCRYPTION_PWSALT \
+ _IOW('f', 20, __u8[16])
+#define F2FS_IOC_GET_ENCRYPTION_POLICY \
+ _IOW('f', 21, struct f2fs_encryption_policy)
+
/*
* should be same as XFS_IOC_GOINGDOWN.
* Flags for going down operation used by FS_IOC_GOINGDOWN
@@ -367,6 +374,8 @@ struct f2fs_map_blocks {
#define F2FS_ENCRYPTION_MODE_AES_256_CBC 3
#define F2FS_ENCRYPTION_MODE_AES_256_CTS 4

+#include "f2fs_crypto.h"
+
#define DEF_DIR_LEVEL 0

struct f2fs_inode_info {
@@ -1945,4 +1954,11 @@ static inline int f2fs_sb_has_crypto(struct super_block *sb)
#else
return 0;
#endif
+
+/* crypto_policy.c */
+int f2fs_is_child_context_consistent_with_parent(struct inode *,
+ struct inode *);
+int f2fs_inherit_context(struct inode *, struct inode *, struct page *);
+int f2fs_process_policy(const struct f2fs_encryption_policy *, struct inode *);
+int f2fs_get_policy(struct inode *, struct f2fs_encryption_policy *);
#endif
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 7293746..7236be4 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -20,6 +20,7 @@
#include <linux/uaccess.h>
#include <linux/mount.h>
#include <linux/pagevec.h>
+#include <linux/random.h>

#include "f2fs.h"
#include "node.h"
@@ -1347,6 +1348,90 @@ static int f2fs_ioc_fitrim(struct file *filp, unsigned long arg)
return 0;
}

+static bool uuid_is_nonzero(__u8 u[16])
+{
+ int i;
+
+ for (i = 0; i < 16; i++)
+ if (u[i])
+ return true;
+ return false;
+}
+
+static int f2fs_ioc_set_encryption_policy(struct file *filp, unsigned long arg)
+{
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+ struct f2fs_encryption_policy policy;
+ struct inode *inode = file_inode(filp);
+
+ if (copy_from_user(&policy, (struct f2fs_encryption_policy __user *)arg,
+ sizeof(policy)))
+ return -EFAULT;
+
+ if (f2fs_has_inline_data(inode)) {
+ int ret = f2fs_convert_inline_inode(inode);
+ if (ret)
+ return ret;
+ }
+
+ return f2fs_process_policy(&policy, inode);
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static int f2fs_ioc_get_encryption_policy(struct file *filp, unsigned long arg)
+{
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+ struct f2fs_encryption_policy policy;
+ struct inode *inode = file_inode(filp);
+ int err;
+
+ err = f2fs_get_policy(inode, &policy);
+ if (err)
+ return err;
+
+ if (copy_to_user((void *)arg, &policy, sizeof(policy)))
+ return -EFAULT;
+ return 0;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static int f2fs_ioc_get_encryption_pwsalt(struct file *filp, unsigned long arg)
+{
+ struct inode *inode = file_inode(filp);
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ int err;
+
+ if (!f2fs_sb_has_crypto(inode->i_sb))
+ return -EOPNOTSUPP;
+
+ if (uuid_is_nonzero(sbi->raw_super->encrypt_pw_salt))
+ goto got_it;
+
+ err = mnt_want_write_file(filp);
+ if (err)
+ return err;
+
+ /* update superblock with uuid */
+ generate_random_uuid(sbi->raw_super->encrypt_pw_salt);
+
+ err = f2fs_commit_super(sbi);
+
+ mnt_drop_write_file(filp);
+ if (err) {
+ /* undo new data */
+ memset(sbi->raw_super->encrypt_pw_salt, 0, 16);
+ return err;
+ }
+got_it:
+ if (copy_to_user((void *)arg, sbi->raw_super->encrypt_pw_salt, 16))
+ return -EFAULT;
+ return 0;
+}
+
long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
switch (cmd) {
@@ -1370,6 +1455,12 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return f2fs_ioc_shutdown(filp, arg);
case FITRIM:
return f2fs_ioc_fitrim(filp, arg);
+ case F2FS_IOC_SET_ENCRYPTION_POLICY:
+ return f2fs_ioc_set_encryption_policy(filp, arg);
+ case F2FS_IOC_GET_ENCRYPTION_POLICY:
+ return f2fs_ioc_get_encryption_policy(filp, arg);
+ case F2FS_IOC_GET_ENCRYPTION_PWSALT:
+ return f2fs_ioc_get_encryption_pwsalt(filp, arg);
default:
return -ENOTTY;
}
diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index 9757f65..07449b98 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -584,6 +584,9 @@ static int __f2fs_setxattr(struct inode *inode, int index,
inode->i_ctime = CURRENT_TIME;
clear_inode_flag(fi, FI_ACL_MODE);
}
+ if (index == F2FS_XATTR_INDEX_ENCRYPTION &&
+ !strcmp(name, F2FS_XATTR_NAME_ENCRYPTION_CONTEXT))
+ f2fs_set_encrypted_inode(inode);

if (ipage)
update_inode(inode, ipage);
--
2.1.1