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authorTheodore Ts'o <tytso@mit.edu>2015-05-18 20:17:47 +0300
committerTheodore Ts'o <tytso@mit.edu>2015-05-18 20:17:47 +0300
commitb7236e21d55ff9008737621c84dd8ee6c37c7c6d (patch)
tree2bd49c631e0ae11f9c9641a954f692cb0d0bdca3 /fs/ext4/dir.c
parente2881b1b51d871a72911faf2fc7e090655940506 (diff)
downloadlinux-b7236e21d55ff9008737621c84dd8ee6c37c7c6d.tar.xz
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 This allows us to test to see if the key has been revoked; if it has, we prevent the use of the derived key and free it. 5) When an inode is released (or when the derived key is freed), we will use memset_explicit()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/dir.c')
-rw-r--r--fs/ext4/dir.c21
1 files changed, 8 insertions, 13 deletions
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index d799d5d571e9..28cb94fbb1c9 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -110,7 +110,6 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
struct super_block *sb = inode->i_sb;
struct buffer_head *bh = NULL;
int dir_has_error = 0;
- struct ext4_fname_crypto_ctx *enc_ctx = NULL;
struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
if (is_dx_dir(inode)) {
@@ -134,16 +133,14 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
return err;
}
- enc_ctx = ext4_get_fname_crypto_ctx(inode, EXT4_NAME_LEN);
- if (IS_ERR(enc_ctx))
- return PTR_ERR(enc_ctx);
- if (enc_ctx) {
- err = ext4_fname_crypto_alloc_buffer(enc_ctx, EXT4_NAME_LEN,
+ err = ext4_setup_fname_crypto(inode);
+ if (err)
+ return err;
+ if (ext4_encrypted_inode(inode)) {
+ err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
&fname_crypto_str);
- if (err < 0) {
- ext4_put_fname_crypto_ctx(&enc_ctx);
+ if (err < 0)
return err;
- }
}
offset = ctx->pos & (sb->s_blocksize - 1);
@@ -239,8 +236,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
offset += ext4_rec_len_from_disk(de->rec_len,
sb->s_blocksize);
if (le32_to_cpu(de->inode)) {
- if (enc_ctx == NULL) {
- /* Directory is not encrypted */
+ if (!ext4_encrypted_inode(inode)) {
if (!dir_emit(ctx, de->name,
de->name_len,
le32_to_cpu(de->inode),
@@ -250,7 +246,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
int save_len = fname_crypto_str.len;
/* Directory is encrypted */
- err = ext4_fname_disk_to_usr(enc_ctx,
+ err = ext4_fname_disk_to_usr(inode,
NULL, de, &fname_crypto_str);
fname_crypto_str.len = save_len;
if (err < 0)
@@ -275,7 +271,6 @@ done:
err = 0;
errout:
#ifdef CONFIG_EXT4_FS_ENCRYPTION
- ext4_put_fname_crypto_ctx(&enc_ctx);
ext4_fname_crypto_free_buffer(&fname_crypto_str);
#endif
brelse(bh);