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author | Theodore Ts'o <tytso@mit.edu> | 2015-05-18 19:17:47 +0200 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2015-05-18 19:17:47 +0200 |
commit | b7236e21d55ff9008737621c84dd8ee6c37c7c6d (patch) | |
tree | 2bd49c631e0ae11f9c9641a954f692cb0d0bdca3 /fs/ext4/ext4_crypto.h | |
parent | ext4 crypto: separate kernel and userspace structure for the key (diff) | |
download | linux-b7236e21d55ff9008737621c84dd8ee6c37c7c6d.tar.xz linux-b7236e21d55ff9008737621c84dd8ee6c37c7c6d.zip |
ext4 crypto: reorganize how we store keys in the inode
This is a pretty massive patch which does a number of different things:
1) The per-inode encryption information is now stored in an allocated
data structure, ext4_crypt_info, instead of directly in the node.
This reduces the size usage of an in-memory inode when it is not
using encryption.
2) We drop the ext4_fname_crypto_ctx entirely, and use the per-inode
encryption structure instead. This remove an unnecessary memory
allocation and free for the fname_crypto_ctx as well as allowing us
to reuse the ctfm in a directory for multiple lookups and file
creations.
3) We also cache the inode's policy information in the ext4_crypt_info
structure so we don't have to continually read it out of the
extended attributes.
4) We now keep the keyring key in the inode's encryption structure
instead of releasing it after we are done using it to derive the
per-inode key. This allows us to test to see if the key has been
revoked; if it has, we prevent the use of the derived key and free
it.
5) When an inode is released (or when the derived key is freed), we
will use memset_explicit() to zero out the derived key, so it's not
left hanging around in memory. This implies that when a user logs
out, it is important to first revoke the key, and then unlink it,
and then finally, to use "echo 3 > /proc/sys/vm/drop_caches" to
release any decrypted pages and dcache entries from the system
caches.
6) All this, and we also shrink the number of lines of code by around
100. :-)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/ext4_crypto.h')
-rw-r--r-- | fs/ext4/ext4_crypto.h | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h index deecbe8968d1..d29687c232bd 100644 --- a/fs/ext4/ext4_crypto.h +++ b/fs/ext4/ext4_crypto.h @@ -76,7 +76,13 @@ struct ext4_encryption_key { struct ext4_crypt_info { unsigned char ci_mode; unsigned char ci_size; + char ci_data_mode; + char ci_filename_mode; + char ci_flags; + struct crypto_ablkcipher *ci_ctfm; + struct key *ci_keyring_key; char ci_raw[EXT4_MAX_KEY_SIZE]; + char ci_master_key[EXT4_KEY_DESCRIPTOR_SIZE]; }; #define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001 @@ -128,16 +134,6 @@ struct ext4_str { u32 len; }; -struct ext4_fname_crypto_ctx { - u32 lim; - struct crypto_ablkcipher *ctfm; - struct crypto_hash *htfm; - struct ext4_crypt_info ci; - unsigned flags : 8; - unsigned has_valid_key : 1; - unsigned ctfm_key_is_ready : 1; -}; - /** * For encrypted symlinks, the ciphertext length is stored at the beginning * of the string in little-endian format. |