The following patch makes cramfs little endian only. When trying to mount a big endian image,
an error message is produced.
The changes were tested on the following types of machines:
An i386 compatible box (little endian)
UltraSparc IIi (big endian)
Signed-off-by: Andi Drebes <andi@xxxxxxxxxxxxxxxxxxx>
---
inode.c | 163 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 136 insertions(+), 27 deletions(-)
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index 350680f..3fbf567 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -4,6 +4,10 @@
* Copyright (C) 1999 Linus Torvalds.
*
* This file is released under the GPL.
+ *
+ * Changelog:
+ * 11/07 - Andi Drebes <andi@xxxxxxxxxxxxxxxxxxx>
+ * Made cramfs little endian only.
*/
/*
@@ -40,6 +44,95 @@ static DEFINE_MUTEX(read_mutex);
#define CRAMINO(x) (((x)->offset && (x)->size)?(x)->offset<<2:1)
#define OFFSET(x) ((x)->i_ino)
+#ifdef __BIG_ENDIAN
+/* Converts a cramfs_info from little endian to big endian. */
+static inline void cramfs_convert_info_letobe(struct cramfs_info* info)
+{
+ info->crc = swab32(info->crc);
+ info->edition = swab32(info->edition);
+ info->blocks = swab32(info->blocks);
+ info->files = swab32(info->files);
+}
+
+/* Converts a cramfs_info from little endian to big endian. */
+static inline void cramfs_convert_inode_letobe(struct cramfs_inode* inode)
+{
+ u8* inode_bytes = (u8*)inode;
+ u8 old_nloffs[4];
+
+ inode->mode = swab16(inode->mode);
+ inode->uid = swab16(inode->uid);
+ inode->size = (inode_bytes[6] << 16) | (inode_bytes[5] << 8) | (inode_bytes[4]);
+
+ /* Save the old values of the namelength and the offset */
+ memcpy(old_nloffs, inode_bytes+8, 4);
+
+ /* Convert the namelength and the offset */
+ inode_bytes[8] = ((old_nloffs[0] & 0x3f) << 2) | ((old_nloffs[3] & 0xc0) >> 6);
+ inode_bytes[9] = ((old_nloffs[3] & 0x3f) << 2) | ((old_nloffs[2] & 0xc0) >> 6);
+ inode_bytes[10] = ((old_nloffs[2] & 0x3f) << 2) | ((old_nloffs[1] & 0xc0) >> 6);
+ inode_bytes[11] = ((old_nloffs[1] & 0x3f) << 2) | ((old_nloffs[0] & 0xc0) >> 6);
+}
+
+/* Converts a cramfs superblock from little endian to big endian. */
+static inline void cramfs_convert_super_letobe(struct cramfs_super* super)
+{
+ super->magic = swab32(super->magic);
+ super->size = swab32(super->size);
+ super->flags = swab32(super->flags);
+ super->future = swab32(super->future);
+ cramfs_convert_info_letobe(&super->fsid);
+ cramfs_convert_inode_letobe(&super->root);
+}
+
+/* Converts a 32 bit integer from little endian to big endian */
+static inline u32 cramfs_convert_u32_letobe(u32 val)
+{
+ return swab32(val);
+}
+
+static inline void cramfs_info_to_host(struct cramfs_info *info)
+{
+ cramfs_convert_info_letobe(info);
+}
+
+static inline void cramfs_inode_to_host(struct cramfs_inode *inode)
+{
+ cramfs_convert_inode_letobe(inode);
+}
+
+static inline void cramfs_super_to_host(struct cramfs_super *super)
+{
+ cramfs_convert_super_letobe(super);
+}
+
+static inline u32 cramfs_u32_to_host(u32 val)
+{
+ return cramfs_convert_u32_letobe(val);
+}
+
+#elif defined(__LITTLE_ENDIAN)
+
+static inline void cramfs_info_to_host(struct cramfs_info *info)
+{
+}
+
+static inline void cramfs_inode_to_host(struct cramfs_inode *inode)
+{
+}
+
+static inline void cramfs_super_to_host(struct cramfs_super *super)
+{
+}
+
+static inline u32 cramfs_u32_to_host(u32 val)
+{
+ return val;
+}
+
+#else
+#error "Neither __BIG_ENDIAN nor __LITTLE_ENDIAN defined."
+#endif
static int cramfs_iget5_test(struct inode *inode, void *opaque)
{
@@ -253,29 +346,35 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
/* Read the first block and get the superblock from it */
memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
+ cramfs_super_to_host(&super);
mutex_unlock(&read_mutex);
/* Do sanity checks on the superblock */
- if (super.magic != CRAMFS_MAGIC) {
- /* check for wrong endianess */
- if (super.magic == CRAMFS_MAGIC_WEND) {
- if (!silent)
- printk(KERN_ERR "cramfs: wrong endianess\n");
- goto out;
- }
-
+ if (super.magic != CRAMFS_MAGIC && super.magic != CRAMFS_MAGIC_WEND) {
/* check at 512 byte offset */
mutex_lock(&read_mutex);
memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
+ cramfs_super_to_host(&super);
mutex_unlock(&read_mutex);
- if (super.magic != CRAMFS_MAGIC) {
- if (super.magic == CRAMFS_MAGIC_WEND && !silent)
- printk(KERN_ERR "cramfs: wrong endianess\n");
- else if (!silent)
+
+ if (super.magic == CRAMFS_MAGIC_WEND) {
+ goto other_endian;
+ }
+ else if (super.magic != CRAMFS_MAGIC) {
+ if (!silent)
printk(KERN_ERR "cramfs: wrong magic\n");
+
goto out;
}
}
+ /* check for wrong endianess */
+ else if (super.magic == CRAMFS_MAGIC_WEND) {
+other_endian:
+ if (!silent)
+ printk(KERN_ERR "cramfs: filesystems in big endian format are not supported any longer.\n");
+
+ goto out;
+ }
/* get feature flags first */
if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
@@ -367,7 +466,8 @@ static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
copied = 0;
while (offset < inode->i_size) {
- struct cramfs_inode *de;
+ void *inode_data;
+ struct cramfs_inode de;
unsigned long nextoffset;
char *name;
ino_t ino;
@@ -375,20 +475,22 @@ static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
int namelen, error;
mutex_lock(&read_mutex);
- de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
- name = (char *)(de+1);
+ inode_data = cramfs_read(sb, OFFSET(inode) + offset, sizeof(de)+CRAMFS_MAXPATHLEN);
+ memcpy(&de, inode_data, sizeof(de));
+ name = inode_data+sizeof(de);
+ cramfs_inode_to_host(&de);
/*
* Namelengths on disk are shifted by two
* and the name padded out to 4-byte boundaries
* with zeroes.
*/
- namelen = de->namelen << 2;
+ namelen = de.namelen << 2;
memcpy(buf, name, namelen);
- ino = CRAMINO(de);
- mode = de->mode;
+ ino = CRAMINO(&de);
+ mode = de.mode;
mutex_unlock(&read_mutex);
- nextoffset = offset + sizeof(*de) + namelen;
+ nextoffset = offset + sizeof(de) + namelen;
for (;;) {
if (!namelen) {
kfree(buf);
@@ -421,19 +523,22 @@ static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, s
mutex_lock(&read_mutex);
sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
while (offset < dir->i_size) {
- struct cramfs_inode *de;
+ void* inode_data;
+ struct cramfs_inode de;
char *name;
int namelen, retval;
- de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
- name = (char *)(de+1);
+ inode_data = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(de)+CRAMFS_MAXPATHLEN);
+ memcpy(&de, inode_data, sizeof(de));
+ name = (char *)(inode_data+sizeof(de));
+ cramfs_inode_to_host(&de);
/* Try to take advantage of sorted directories */
if (sorted && (dentry->d_name.name[0] < name[0]))
break;
- namelen = de->namelen << 2;
- offset += sizeof(*de) + namelen;
+ namelen = de.namelen << 2;
+ offset += sizeof(de) + namelen;
/* Quick check that the name is roughly the right length */
if (((dentry->d_name.len + 3) & ~3) != namelen)
@@ -454,7 +559,7 @@ static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, s
if (retval > 0)
continue;
if (!retval) {
- struct cramfs_inode entry = *de;
+ struct cramfs_inode entry = de;
mutex_unlock(&read_mutex);
d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
return NULL;
@@ -483,9 +588,13 @@ static int cramfs_readpage(struct file *file, struct page * page)
start_offset = OFFSET(inode) + maxblock*4;
mutex_lock(&read_mutex);
- if (page->index)
+ if (page->index) {
start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, 4);
- compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) - start_offset);
+ start_offset = cramfs_u32_to_host(start_offset);
+ }
+
+ compr_len = cramfs_u32_to_host(*(u32 *) cramfs_read(sb, blkptr_offset, 4)) - start_offset;
+
mutex_unlock(&read_mutex);
pgdata = kmap(page);
if (compr_len == 0)
-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
