ext4 crypto: optimize filename encryption
Encrypt the filename as soon it is passed in by the user. This avoids
our needing to encrypt the filename 2 or 3 times while in the process
of creating a filename.
Similarly, when looking up a directory entry, encrypt the filename
early, or if the encryption key is not available, base-64 decode the
file syystem so that the hash value and the last 16 bytes of the
encrypted filename is available in the new struct ext4_filename data
structure.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/crypto_fname.c b/fs/ext4/crypto_fname.c
index fded02f..ad5e328 100644
--- a/fs/ext4/crypto_fname.c
+++ b/fs/ext4/crypto_fname.c
@@ -611,109 +611,82 @@
return -EACCES;
}
-/*
- * Calculate the htree hash from a filename from user space
- */
-int ext4_fname_usr_to_hash(struct ext4_fname_crypto_ctx *ctx,
- const struct qstr *iname,
- struct dx_hash_info *hinfo)
+int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
+ int lookup, struct ext4_filename *fname)
{
- struct ext4_str tmp;
- int ret = 0;
- char buf[EXT4_FNAME_CRYPTO_DIGEST_SIZE+1];
+ struct ext4_fname_crypto_ctx *ctx;
+ int ret = 0, bigname = 0;
- if (!ctx ||
+ memset(fname, 0, sizeof(struct ext4_filename));
+ fname->usr_fname = iname;
+
+ ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+ if ((ctx == NULL) ||
((iname->name[0] == '.') &&
((iname->len == 1) ||
((iname->name[1] == '.') && (iname->len == 2))))) {
- ext4fs_dirhash(iname->name, iname->len, hinfo);
- return 0;
+ fname->disk_name.name = (unsigned char *) iname->name;
+ fname->disk_name.len = iname->len;
+ goto out;
}
-
- if (!ctx->has_valid_key && iname->name[0] == '_') {
- if (iname->len != 33)
- return -ENOENT;
- ret = digest_decode(iname->name+1, iname->len, buf);
- if (ret != 24)
- return -ENOENT;
- memcpy(&hinfo->hash, buf, 4);
- memcpy(&hinfo->minor_hash, buf + 4, 4);
- return 0;
- }
-
- if (!ctx->has_valid_key && iname->name[0] != '_') {
- if (iname->len > 43)
- return -ENOENT;
- ret = digest_decode(iname->name, iname->len, buf);
- ext4fs_dirhash(buf, ret, hinfo);
- return 0;
- }
-
- /* First encrypt the plaintext name */
- ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len, &tmp);
- if (ret < 0)
- return ret;
-
- ret = ext4_fname_encrypt(ctx, iname, &tmp);
- if (ret >= 0) {
- ext4fs_dirhash(tmp.name, tmp.len, hinfo);
+ if (ctx->has_valid_key) {
+ ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len,
+ &fname->crypto_buf);
+ if (ret < 0)
+ goto out;
+ ret = ext4_fname_encrypt(ctx, iname, &fname->crypto_buf);
+ if (ret < 0)
+ goto out;
+ fname->disk_name.name = fname->crypto_buf.name;
+ fname->disk_name.len = fname->crypto_buf.len;
ret = 0;
+ goto out;
+ }
+ if (!lookup) {
+ ret = -EACCES;
+ goto out;
}
- ext4_fname_crypto_free_buffer(&tmp);
+ /* We don't have the key and we are doing a lookup; decode the
+ * user-supplied name
+ */
+ if (iname->name[0] == '_')
+ bigname = 1;
+ if ((bigname && (iname->len != 33)) ||
+ (!bigname && (iname->len > 43))) {
+ ret = -ENOENT;
+ }
+ fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
+ if (fname->crypto_buf.name == NULL) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = digest_decode(iname->name + bigname, iname->len - bigname,
+ fname->crypto_buf.name);
+ if (ret < 0) {
+ ret = -ENOENT;
+ goto out;
+ }
+ fname->crypto_buf.len = ret;
+ if (bigname) {
+ memcpy(&fname->hinfo.hash, fname->crypto_buf.name, 4);
+ memcpy(&fname->hinfo.minor_hash, fname->crypto_buf.name + 4, 4);
+ } else {
+ fname->disk_name.name = fname->crypto_buf.name;
+ fname->disk_name.len = fname->crypto_buf.len;
+ }
+ ret = 0;
+out:
+ ext4_put_fname_crypto_ctx(&ctx);
return ret;
}
-int ext4_fname_match(struct ext4_fname_crypto_ctx *ctx, struct ext4_str *cstr,
- int len, const char * const name,
- struct ext4_dir_entry_2 *de)
+void ext4_fname_free_filename(struct ext4_filename *fname)
{
- int ret = -ENOENT;
- int bigname = (*name == '_');
-
- if (ctx->has_valid_key) {
- if (cstr->name == NULL) {
- struct qstr istr;
-
- ret = ext4_fname_crypto_alloc_buffer(ctx, len, cstr);
- if (ret < 0)
- goto errout;
- istr.name = name;
- istr.len = len;
- ret = ext4_fname_encrypt(ctx, &istr, cstr);
- if (ret < 0)
- goto errout;
- }
- } else {
- if (cstr->name == NULL) {
- cstr->name = kmalloc(32, GFP_KERNEL);
- if (cstr->name == NULL)
- return -ENOMEM;
- if ((bigname && (len != 33)) ||
- (!bigname && (len > 43)))
- goto errout;
- ret = digest_decode(name+bigname, len-bigname,
- cstr->name);
- if (ret < 0) {
- ret = -ENOENT;
- goto errout;
- }
- cstr->len = ret;
- }
- if (bigname) {
- if (de->name_len < 16)
- return 0;
- ret = memcmp(de->name + de->name_len - 16,
- cstr->name + 8, 16);
- return (ret == 0) ? 1 : 0;
- }
- }
- if (de->name_len != cstr->len)
- return 0;
- ret = memcmp(de->name, cstr->name, cstr->len);
- return (ret == 0) ? 1 : 0;
-errout:
- kfree(cstr->name);
- cstr->name = NULL;
- return ret;
+ kfree(fname->crypto_buf.name);
+ fname->crypto_buf.name = NULL;
+ fname->usr_fname = NULL;
+ fname->disk_name.name = NULL;
}