Commit b30ab0e0 authored by Michael Halcrow's avatar Michael Halcrow Committed by Theodore Ts'o

ext4 crypto: add ext4 encryption facilities

On encrypt, we will re-assign the buffer_heads to point to a bounce
page rather than the control_page (which is the original page to write
that contains the plaintext). The block I/O occurs against the bounce
page.  On write completion, we re-assign the buffer_heads to the
original plaintext page.

On decrypt, we will attach a read completion callback to the bio
struct. This read completion will decrypt the read contents in-place
prior to setting the page up-to-date.

The current encryption mode, AES-256-XTS, lacks cryptographic
integrity. AES-256-GCM is in-plan, but we will need to devise a
mechanism for handling the integrity data.
Signed-off-by: default avatarMichael Halcrow <mhalcrow@google.com>
Signed-off-by: default avatarIldar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o's avatarTheodore Ts'o <tytso@mit.edu>
parent 9bd8212f
......@@ -12,4 +12,4 @@ ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o
ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o
This diff is collapsed.
......@@ -52,6 +52,13 @@ static int ext4_create_encryption_context_from_policy(
ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
EXT4_KEY_DESCRIPTOR_SIZE);
if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid contents encryption mode %d\n", __func__,
policy->contents_encryption_mode);
res = -EINVAL;
goto out;
}
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
......@@ -60,6 +67,7 @@ static int ext4_create_encryption_context_from_policy(
res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), 0);
out:
if (!res)
ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
return res;
......
......@@ -951,6 +951,11 @@ struct ext4_inode_info {
/* Precomputed uuid+inum+igen checksum for seeding inode checksums */
__u32 i_csum_seed;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
/* Encryption params */
struct ext4_encryption_key i_encryption_key;
#endif
};
/*
......@@ -1366,6 +1371,12 @@ struct ext4_sb_info {
struct ratelimit_state s_err_ratelimit_state;
struct ratelimit_state s_warning_ratelimit_state;
struct ratelimit_state s_msg_ratelimit_state;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
/* Encryption */
uint32_t s_file_encryption_mode;
uint32_t s_dir_encryption_mode;
#endif
};
static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
......@@ -1481,6 +1492,18 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
#define EXT4_SB(sb) (sb)
#endif
/*
* Returns true if the inode is inode is encrypted
*/
static inline int ext4_encrypted_inode(struct inode *inode)
{
#ifdef CONFIG_EXT4_FS_ENCRYPTION
return ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT);
#else
return 0;
#endif
}
#define NEXT_ORPHAN(inode) EXT4_I(inode)->i_dtime
/*
......@@ -2026,6 +2049,35 @@ int ext4_process_policy(const struct ext4_encryption_policy *policy,
int ext4_get_policy(struct inode *inode,
struct ext4_encryption_policy *policy);
/* crypto.c */
bool ext4_valid_contents_enc_mode(uint32_t mode);
uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size);
extern struct workqueue_struct *ext4_read_workqueue;
struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode);
void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx);
void ext4_restore_control_page(struct page *data_page);
struct page *ext4_encrypt(struct inode *inode,
struct page *plaintext_page);
int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page);
int ext4_decrypt_one(struct inode *inode, struct page *page);
int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex);
#ifdef CONFIG_EXT4_FS_ENCRYPTION
int ext4_init_crypto(void);
void ext4_exit_crypto(void);
static inline int ext4_sb_has_crypto(struct super_block *sb)
{
return EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_ENCRYPT);
}
#else
static inline int ext4_init_crypto(void) { return 0; }
static inline void ext4_exit_crypto(void) { }
static inline int ext4_sb_has_crypto(struct super_block *sb)
{
return 0;
}
#endif
/* dir.c */
extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
struct file *,
......
......@@ -46,4 +46,59 @@ struct ext4_encryption_context {
char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
} __attribute__((__packed__));
/* Encryption parameters */
#define EXT4_XTS_TWEAK_SIZE 16
#define EXT4_AES_128_ECB_KEY_SIZE 16
#define EXT4_AES_256_GCM_KEY_SIZE 32
#define EXT4_AES_256_CBC_KEY_SIZE 32
#define EXT4_AES_256_CTS_KEY_SIZE 32
#define EXT4_AES_256_XTS_KEY_SIZE 64
#define EXT4_MAX_KEY_SIZE 64
struct ext4_encryption_key {
uint32_t mode;
char raw[EXT4_MAX_KEY_SIZE];
uint32_t size;
};
#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL 0x00000002
struct ext4_crypto_ctx {
struct crypto_tfm *tfm; /* Crypto API context */
struct page *bounce_page; /* Ciphertext page on write path */
struct page *control_page; /* Original page on write path */
struct bio *bio; /* The bio for this context */
struct work_struct work; /* Work queue for read complete path */
struct list_head free_list; /* Free list */
int flags; /* Flags */
int mode; /* Encryption mode for tfm */
};
struct ext4_completion_result {
struct completion completion;
int res;
};
#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
struct ext4_completion_result ecr = { \
COMPLETION_INITIALIZER((ecr).completion), 0 }
static inline int ext4_encryption_key_size(int mode)
{
switch (mode) {
case EXT4_ENCRYPTION_MODE_AES_256_XTS:
return EXT4_AES_256_XTS_KEY_SIZE;
case EXT4_ENCRYPTION_MODE_AES_256_GCM:
return EXT4_AES_256_GCM_KEY_SIZE;
case EXT4_ENCRYPTION_MODE_AES_256_CBC:
return EXT4_AES_256_CBC_KEY_SIZE;
case EXT4_ENCRYPTION_MODE_AES_256_CTS:
return EXT4_AES_256_CTS_KEY_SIZE;
default:
BUG();
}
return 0;
}
#endif /* _EXT4_CRYPTO_H */
......@@ -876,6 +876,9 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
atomic_set(&ei->i_ioend_count, 0);
atomic_set(&ei->i_unwritten, 0);
INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
#ifdef CONFIG_EXT4_FS_ENCRYPTION
ei->i_encryption_key.mode = EXT4_ENCRYPTION_MODE_INVALID;
#endif
return &ei->vfs_inode;
}
......@@ -3431,6 +3434,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
if (sb->s_bdev->bd_part)
sbi->s_sectors_written_start =
part_stat_read(sb->s_bdev->bd_part, sectors[1]);
#ifdef CONFIG_EXT4_FS_ENCRYPTION
/* Modes of operations for file and directory encryption. */
sbi->s_file_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
sbi->s_dir_encryption_mode = EXT4_ENCRYPTION_MODE_INVALID;
#endif
/* Cleanup superblock name */
for (cp = sb->s_id; (cp = strchr(cp, '/'));)
......
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