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authorJaegeuk Kim <jaegeuk@kernel.org>2016-05-04 22:05:01 -0700
committerJaegeuk Kim <jaegeuk@kernel.org>2016-05-07 10:32:33 -0700
commitb5a7aef1ef436ec005fef0efe31a676ec5f4ab31 (patch)
treec3eb022f963b70eadb066e8c87b7041236955289 /fs/f2fs
parent09210c973af30320edc03a6325422cdd0f03b580 (diff)
downloadop-kernel-dev-b5a7aef1ef436ec005fef0efe31a676ec5f4ab31.zip
op-kernel-dev-b5a7aef1ef436ec005fef0efe31a676ec5f4ab31.tar.gz
fscrypto/f2fs: allow fs-specific key prefix for fs encryption
This patch allows fscrypto to handle a second key prefix given by filesystem. The main reason is to provide backward compatibility, since previously f2fs used "f2fs:" as a crypto prefix instead of "fscrypt:". Later, ext4 should also provide key_prefix() to give "ext4:". One concern decribed by Ted would be kinda double check overhead of prefixes. In x86, for example, validate_user_key consumes 8 ms after boot-up, which turns out derive_key_aes() consumed most of the time to load specific crypto module. After such the cold miss, it shows almost zero latencies, which treats as a negligible overhead. Note that request_key() detects wrong prefix in prior to derive_key_aes() even. Cc: Ted Tso <tytso@mit.edu> Cc: stable@vger.kernel.org # v4.6 Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs')
-rw-r--r--fs/f2fs/f2fs.h8
-rw-r--r--fs/f2fs/super.c13
2 files changed, 21 insertions, 0 deletions
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index ccf8bf4..dbd277e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -711,6 +711,10 @@ enum {
MAX_TIME,
};
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+#define F2FS_KEY_DESC_PREFIX "f2fs:"
+#define F2FS_KEY_DESC_PREFIX_SIZE 5
+#endif
struct f2fs_sb_info {
struct super_block *sb; /* pointer to VFS super block */
struct proc_dir_entry *s_proc; /* proc entry */
@@ -718,6 +722,10 @@ struct f2fs_sb_info {
int valid_super_block; /* valid super block no */
int s_flag; /* flags for sbi */
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+ u8 key_prefix[F2FS_KEY_DESC_PREFIX_SIZE];
+ u8 key_prefix_size;
+#endif
/* for node-related operations */
struct f2fs_nm_info *nm_info; /* node manager */
struct inode *node_inode; /* cache node blocks */
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 8a28f79..28c8992 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -964,6 +964,12 @@ static int f2fs_get_context(struct inode *inode, void *ctx, size_t len)
ctx, len, NULL);
}
+static int f2fs_key_prefix(struct inode *inode, u8 **key)
+{
+ *key = F2FS_I_SB(inode)->key_prefix;
+ return F2FS_I_SB(inode)->key_prefix_size;
+}
+
static int f2fs_set_context(struct inode *inode, const void *ctx, size_t len,
void *fs_data)
{
@@ -980,6 +986,7 @@ static unsigned f2fs_max_namelen(struct inode *inode)
static struct fscrypt_operations f2fs_cryptops = {
.get_context = f2fs_get_context,
+ .key_prefix = f2fs_key_prefix,
.set_context = f2fs_set_context,
.is_encrypted = f2fs_encrypted_inode,
.empty_dir = f2fs_empty_dir,
@@ -1305,6 +1312,12 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
INIT_LIST_HEAD(&sbi->s_list);
mutex_init(&sbi->umount_mutex);
+
+#ifdef CONFIG_F2FS_FS_ENCRYPTION
+ memcpy(sbi->key_prefix, F2FS_KEY_DESC_PREFIX,
+ F2FS_KEY_DESC_PREFIX_SIZE);
+ sbi->key_prefix_size = F2FS_KEY_DESC_PREFIX_SIZE;
+#endif
}
/*
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