summaryrefslogtreecommitdiffstats
path: root/fs/f2fs/hash.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/f2fs/hash.c')
-rw-r--r--fs/f2fs/hash.c137
1 files changed, 137 insertions, 0 deletions
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
new file mode 100644
index 0000000000..049ce50cec
--- /dev/null
+++ b/fs/f2fs/hash.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/f2fs/hash.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ * http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext3/hash.c
+ *
+ * Copyright (C) 2002 by Theodore Ts'o
+ */
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/pagemap.h>
+#include <linux/unicode.h>
+
+#include "f2fs.h"
+
+/*
+ * Hashing code copied from ext3
+ */
+#define DELTA 0x9E3779B9
+
+static void TEA_transform(unsigned int buf[4], unsigned int const in[])
+{
+ __u32 sum = 0;
+ __u32 b0 = buf[0], b1 = buf[1];
+ __u32 a = in[0], b = in[1], c = in[2], d = in[3];
+ int n = 16;
+
+ do {
+ sum += DELTA;
+ b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
+ b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
+ } while (--n);
+
+ buf[0] += b0;
+ buf[1] += b1;
+}
+
+static void str2hashbuf(const unsigned char *msg, size_t len,
+ unsigned int *buf, int num)
+{
+ unsigned pad, val;
+ int i;
+
+ pad = (__u32)len | ((__u32)len << 8);
+ pad |= pad << 16;
+
+ val = pad;
+ if (len > num * 4)
+ len = num * 4;
+ for (i = 0; i < len; i++) {
+ if ((i % 4) == 0)
+ val = pad;
+ val = msg[i] + (val << 8);
+ if ((i % 4) == 3) {
+ *buf++ = val;
+ val = pad;
+ num--;
+ }
+ }
+ if (--num >= 0)
+ *buf++ = val;
+ while (--num >= 0)
+ *buf++ = pad;
+}
+
+static u32 TEA_hash_name(const u8 *p, size_t len)
+{
+ __u32 in[8], buf[4];
+
+ /* Initialize the default seed for the hash checksum functions */
+ buf[0] = 0x67452301;
+ buf[1] = 0xefcdab89;
+ buf[2] = 0x98badcfe;
+ buf[3] = 0x10325476;
+
+ while (1) {
+ str2hashbuf(p, len, in, 4);
+ TEA_transform(buf, in);
+ p += 16;
+ if (len <= 16)
+ break;
+ len -= 16;
+ }
+ return buf[0] & ~F2FS_HASH_COL_BIT;
+}
+
+/*
+ * Compute @fname->hash. For all directories, @fname->disk_name must be set.
+ * For casefolded directories, @fname->usr_fname must be set, and also
+ * @fname->cf_name if the filename is valid Unicode and is not "." or "..".
+ */
+void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
+{
+ const u8 *name = fname->disk_name.name;
+ size_t len = fname->disk_name.len;
+
+ WARN_ON_ONCE(!name);
+
+ if (is_dot_dotdot(name, len)) {
+ fname->hash = 0;
+ return;
+ }
+
+#if IS_ENABLED(CONFIG_UNICODE)
+ if (IS_CASEFOLDED(dir)) {
+ /*
+ * If the casefolded name is provided, hash it instead of the
+ * on-disk name. If the casefolded name is *not* provided, that
+ * should only be because the name wasn't valid Unicode or was
+ * "." or "..", so fall back to treating the name as an opaque
+ * byte sequence. Note that to handle encrypted directories,
+ * the fallback must use usr_fname (plaintext) rather than
+ * disk_name (ciphertext).
+ */
+ WARN_ON_ONCE(!fname->usr_fname->name);
+ if (fname->cf_name.name) {
+ name = fname->cf_name.name;
+ len = fname->cf_name.len;
+ } else {
+ name = fname->usr_fname->name;
+ len = fname->usr_fname->len;
+ }
+ if (IS_ENCRYPTED(dir)) {
+ struct qstr tmp = QSTR_INIT(name, len);
+
+ fname->hash =
+ cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
+ return;
+ }
+ }
+#endif
+ fname->hash = cpu_to_le32(TEA_hash_name(name, len));
+}