ext3: Add support for non-native signed/unsigned htree hash algorithms
Theodore Ts'o [Tue, 28 Oct 2008 17:21:55 +0000 (13:21 -0400)]
The original ext3 hash algorithms assumed that variables of type char
were signed, as God and K&R intended.  Unfortunately, this assumption
is not true on some architectures.  Userspace support for marking
filesystems with non-native signed/unsigned chars was added two years
ago, but the kernel-side support was never added (until now).

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org

fs/ext3/hash.c
fs/ext3/namei.c
fs/ext3/super.c
include/linux/ext3_fs.h
include/linux/ext3_fs_sb.h

index c30e149..7d215b4 100644 (file)
@@ -35,23 +35,71 @@ static void TEA_transform(__u32 buf[4], __u32 const in[])
 
 
 /* The old legacy hash */
-static __u32 dx_hack_hash (const char *name, int len)
+static __u32 dx_hack_hash_unsigned(const char *name, int len)
 {
-       __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+       __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+       const unsigned char *ucp = (const unsigned char *) name;
+
+       while (len--) {
+               hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
+
+               if (hash & 0x80000000)
+                       hash -= 0x7fffffff;
+               hash1 = hash0;
+               hash0 = hash;
+       }
+       return hash0 << 1;
+}
+
+static __u32 dx_hack_hash_signed(const char *name, int len)
+{
+       __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+       const signed char *scp = (const signed char *) name;
+
        while (len--) {
-               __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373));
+               hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
 
-               if (hash & 0x80000000) hash -= 0x7fffffff;
+               if (hash & 0x80000000)
+                       hash -= 0x7fffffff;
                hash1 = hash0;
                hash0 = hash;
        }
-       return (hash0 << 1);
+       return hash0 << 1;
 }
 
-static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
+static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
 {
        __u32   pad, val;
        int     i;
+       const signed char *scp = (const signed char *) msg;
+
+       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 = ((int) scp[i]) + (val << 8);
+               if ((i % 4) == 3) {
+                       *buf++ = val;
+                       val = pad;
+                       num--;
+               }
+       }
+       if (--num >= 0)
+               *buf++ = val;
+       while (--num >= 0)
+               *buf++ = pad;
+}
+
+static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
+{
+       __u32   pad, val;
+       int     i;
+       const unsigned char *ucp = (const unsigned char *) msg;
 
        pad = (__u32)len | ((__u32)len << 8);
        pad |= pad << 16;
@@ -62,7 +110,7 @@ static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)
        for (i=0; i < len; i++) {
                if ((i % 4) == 0)
                        val = pad;
-               val = msg[i] + (val << 8);
+               val = ((int) ucp[i]) + (val << 8);
                if ((i % 4) == 3) {
                        *buf++ = val;
                        val = pad;
@@ -95,6 +143,8 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
        const char      *p;
        int             i;
        __u32           in[8], buf[4];
+       void            (*str2hashbuf)(const char *, int, __u32 *, int) =
+                               str2hashbuf_signed;
 
        /* Initialize the default seed for the hash checksum functions */
        buf[0] = 0x67452301;
@@ -113,13 +163,18 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
        }
 
        switch (hinfo->hash_version) {
+       case DX_HASH_LEGACY_UNSIGNED:
+               hash = dx_hack_hash_unsigned(name, len);
+               break;
        case DX_HASH_LEGACY:
-               hash = dx_hack_hash(name, len);
+               hash = dx_hack_hash_signed(name, len);
                break;
+       case DX_HASH_HALF_MD4_UNSIGNED:
+               str2hashbuf = str2hashbuf_unsigned;
        case DX_HASH_HALF_MD4:
                p = name;
                while (len > 0) {
-                       str2hashbuf(p, len, in, 8);
+                       (*str2hashbuf)(p, len, in, 8);
                        half_md4_transform(buf, in);
                        len -= 32;
                        p += 32;
@@ -127,10 +182,12 @@ int ext3fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
                minor_hash = buf[2];
                hash = buf[1];
                break;
+       case DX_HASH_TEA_UNSIGNED:
+               str2hashbuf = str2hashbuf_unsigned;
        case DX_HASH_TEA:
                p = name;
                while (len > 0) {
-                       str2hashbuf(p, len, in, 4);
+                       (*str2hashbuf)(p, len, in, 4);
                        TEA_transform(buf, in);
                        len -= 16;
                        p += 16;
index 1dd2abe..287b304 100644 (file)
@@ -368,6 +368,8 @@ dx_probe(struct qstr *entry, struct inode *dir,
                goto fail;
        }
        hinfo->hash_version = root->info.hash_version;
+       if (hinfo->hash_version <= DX_HASH_TEA)
+               hinfo->hash_version += EXT3_SB(dir->i_sb)->s_hash_unsigned;
        hinfo->seed = EXT3_SB(dir->i_sb)->s_hash_seed;
        if (entry)
                ext3fs_dirhash(entry->name, entry->len, hinfo);
@@ -636,6 +638,9 @@ int ext3_htree_fill_tree(struct file *dir_file, __u32 start_hash,
        dir = dir_file->f_path.dentry->d_inode;
        if (!(EXT3_I(dir)->i_flags & EXT3_INDEX_FL)) {
                hinfo.hash_version = EXT3_SB(dir->i_sb)->s_def_hash_version;
+               if (hinfo.hash_version <= DX_HASH_TEA)
+                       hinfo.hash_version +=
+                               EXT3_SB(dir->i_sb)->s_hash_unsigned;
                hinfo.seed = EXT3_SB(dir->i_sb)->s_hash_seed;
                count = htree_dirblock_to_tree(dir_file, dir, 0, &hinfo,
                                               start_hash, start_minor_hash);
@@ -1398,6 +1403,8 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
 
        /* Initialize as for dx_probe */
        hinfo.hash_version = root->info.hash_version;
+       if (hinfo.hash_version <= DX_HASH_TEA)
+               hinfo.hash_version += EXT3_SB(dir->i_sb)->s_hash_unsigned;
        hinfo.seed = EXT3_SB(dir->i_sb)->s_hash_seed;
        ext3fs_dirhash(name, namelen, &hinfo);
        frame = frames;
index f6c94f2..541d5e4 100644 (file)
@@ -1744,6 +1744,18 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
        for (i=0; i < 4; i++)
                sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
        sbi->s_def_hash_version = es->s_def_hash_version;
+       i = le32_to_cpu(es->s_flags);
+       if (i & EXT2_FLAGS_UNSIGNED_HASH)
+               sbi->s_hash_unsigned = 3;
+       else if ((i & EXT2_FLAGS_SIGNED_HASH) == 0) {
+#ifdef __CHAR_UNSIGNED__
+               es->s_flags |= cpu_to_le32(EXT2_FLAGS_UNSIGNED_HASH);
+               sbi->s_hash_unsigned = 3;
+#else
+               es->s_flags |= cpu_to_le32(EXT2_FLAGS_SIGNED_HASH);
+#endif
+               sb->s_dirt = 1;
+       }
 
        if (sbi->s_blocks_per_group > blocksize * 8) {
                printk (KERN_ERR
index d14f029..9004794 100644 (file)
@@ -354,6 +354,13 @@ struct ext3_inode {
 #define        EXT3_ORPHAN_FS                  0x0004  /* Orphans being recovered */
 
 /*
+ * Misc. filesystem flags
+ */
+#define EXT2_FLAGS_SIGNED_HASH         0x0001  /* Signed dirhash in use */
+#define EXT2_FLAGS_UNSIGNED_HASH       0x0002  /* Unsigned dirhash in use */
+#define EXT2_FLAGS_TEST_FILESYS                0x0004  /* to test development code */
+
+/*
  * Mount flags
  */
 #define EXT3_MOUNT_CHECK               0x00001 /* Do mount-time checks */
@@ -489,7 +496,23 @@ struct ext3_super_block {
        __u16   s_reserved_word_pad;
        __le32  s_default_mount_opts;
        __le32  s_first_meta_bg;        /* First metablock block group */
-       __u32   s_reserved[190];        /* Padding to the end of the block */
+       __le32  s_mkfs_time;            /* When the filesystem was created */
+       __le32  s_jnl_blocks[17];       /* Backup of the journal inode */
+       /* 64bit support valid if EXT4_FEATURE_COMPAT_64BIT */
+/*150*/        __le32  s_blocks_count_hi;      /* Blocks count */
+       __le32  s_r_blocks_count_hi;    /* Reserved blocks count */
+       __le32  s_free_blocks_count_hi; /* Free blocks count */
+       __le16  s_min_extra_isize;      /* All inodes have at least # bytes */
+       __le16  s_want_extra_isize;     /* New inodes should reserve # bytes */
+       __le32  s_flags;                /* Miscellaneous flags */
+       __le16  s_raid_stride;          /* RAID stride */
+       __le16  s_mmp_interval;         /* # seconds to wait in MMP checking */
+       __le64  s_mmp_block;            /* Block for multi-mount protection */
+       __le32  s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/
+       __u8    s_log_groups_per_flex;  /* FLEX_BG group size */
+       __u8    s_reserved_char_pad2;
+       __le16  s_reserved_pad;
+       __u32   s_reserved[162];        /* Padding to the end of the block */
 };
 
 #ifdef __KERNEL__
@@ -694,6 +717,9 @@ static inline __le16 ext3_rec_len_to_disk(unsigned len)
 #define DX_HASH_LEGACY         0
 #define DX_HASH_HALF_MD4       1
 #define DX_HASH_TEA            2
+#define DX_HASH_LEGACY_UNSIGNED        3
+#define DX_HASH_HALF_MD4_UNSIGNED      4
+#define DX_HASH_TEA_UNSIGNED           5
 
 #ifdef __KERNEL__
 
index e024e38..a4e9216 100644 (file)
@@ -57,6 +57,7 @@ struct ext3_sb_info {
        u32 s_next_generation;
        u32 s_hash_seed[4];
        int s_def_hash_version;
+       int s_hash_unsigned;    /* 3 if hash should be signed, 0 if not */
        struct percpu_counter s_freeblocks_counter;
        struct percpu_counter s_freeinodes_counter;
        struct percpu_counter s_dirs_counter;