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Subject[PATCH] hfsplus: fix attr searching failed of xattr key name with ':'
Date
From: BingJing Chang <bingjingc@synology.com>

Some OSX extended attributes couldn't be displayed in ubuntu:
$ mount -t hfsplus /dev/sdb3 /mnt
$ cd /mnt
$ getfattr -d -m ".*" picture.png
Here, /dev/sdb is a usb stick from OSX computer.

Output:
osx.com.apple.FinderInfo=0sAAAAAAAAAAAEHAAAAAAAAAAAAABgf5OhAAAAAAAAAAg=
osx.com.apple.lastuseddate#PS=0soCWGYAAAAAATBhINAAAAAA==
osx.com.apple.macl=0sAgCH2+S5OA9OG5WnnVb5d67AAAAAAAAAAAAAAAAAAAAAAAAAAA...
Voronoi.png: osx.com.apple.metadata:_kMDItemUserTags: No such attribute
Voronoi.png: osx.com.apple.metadata:kMDItemIsScreenCapture: No suchattr...
Voronoi.png: osx.com.apple.metadata:kMDItemScreenCaptureGlobalRect: No ...
Voronoi.png: osx.com.apple.metadata:kMDItemScreenCaptureType: No such a...
osx.com.apple.quarantine="0082;608625a1;Preview;"

Here are 8 extended attributes in this file. However, some contents of
them could not be retrieved.

The problem is caused by the name-mangling scheme of ascii-unicode
conversions in fs/hfsplus/unicode.c. The character '/' is illegal in
Linux filenames but valid in OSX filenames. In contrast, the character ':'
is opposite. So a simple name-mangling scheme can be applied to
hfsplus filenames by replacing unicode '/' by ascii ':' and ascii ':' by
unicode '/'. However, there're no such constraints in attribute names.
Forcely converting ':' to '/' will cause the xattr lookup failures.

To fix this, we introduce a new parameter name_mangling in
hfsplus_uni2asc() and hfsplus_asc2uni() to indicate whether to perform
such name-mangling scheme or not. And we give the hints not to perform
the scheme for attribute keys.

Reviewed-by: Chung-Chiang Cheng <cccheng@synology.com>
Signed-off-by: BingJing Chang <bingjingc@synology.com>
---
fs/hfsplus/attributes.c | 7 ++++---
fs/hfsplus/catalog.c | 4 ++--
fs/hfsplus/dir.c | 3 ++-
fs/hfsplus/hfsplus_fs.h | 5 +++--
fs/hfsplus/unicode.c | 22 ++++++++++++----------
fs/hfsplus/xattr.c | 5 +++--
6 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/fs/hfsplus/attributes.c b/fs/hfsplus/attributes.c
index eeebe80..234badf 100644
--- a/fs/hfsplus/attributes.c
+++ b/fs/hfsplus/attributes.c
@@ -55,9 +55,10 @@ int hfsplus_attr_build_key(struct super_block *sb, hfsplus_btree_key *key,
memset(key, 0, sizeof(struct hfsplus_attr_key));
key->attr.cnid = cpu_to_be32(cnid);
if (name) {
- int res = hfsplus_asc2uni(sb,
- (struct hfsplus_unistr *)&key->attr.key_name,
- HFSPLUS_ATTR_MAX_STRLEN, name, strlen(name));
+ int res = hfsplus_asc2uni(sb, (struct hfsplus_unistr *)
+ &key->attr.key_name,
+ HFSPLUS_ATTR_MAX_STRLEN,
+ name, strlen(name), false);
if (res)
return res;
len = be16_to_cpu(key->attr.key_name.length);
diff --git a/fs/hfsplus/catalog.c b/fs/hfsplus/catalog.c
index 35472cb..f40fc9e 100644
--- a/fs/hfsplus/catalog.c
+++ b/fs/hfsplus/catalog.c
@@ -47,7 +47,7 @@ int hfsplus_cat_build_key(struct super_block *sb,

key->cat.parent = cpu_to_be32(parent);
err = hfsplus_asc2uni(sb, &key->cat.name, HFSPLUS_MAX_STRLEN,
- str->name, str->len);
+ str->name, str->len, true);
if (unlikely(err < 0))
return err;

@@ -183,7 +183,7 @@ static int hfsplus_fill_cat_thread(struct super_block *sb,
entry->thread.reserved = 0;
entry->thread.parentID = cpu_to_be32(parentid);
err = hfsplus_asc2uni(sb, &entry->thread.nodeName, HFSPLUS_MAX_STRLEN,
- str->name, str->len);
+ str->name, str->len, true);
if (unlikely(err < 0))
return err;

diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index 03e6c04..505b4e6 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -204,7 +204,8 @@ static int hfsplus_readdir(struct file *file, struct dir_context *ctx)
fd.entrylength);
type = be16_to_cpu(entry.type);
len = NLS_MAX_CHARSET_SIZE * HFSPLUS_MAX_STRLEN;
- err = hfsplus_uni2asc(sb, &fd.key->cat.name, strbuf, &len);
+ err = hfsplus_uni2asc(sb, &fd.key->cat.name, strbuf, &len,
+ true);
if (err)
goto out;
if (type == HFSPLUS_FOLDER) {
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 12b2047..1481d0a 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -522,9 +522,10 @@ int hfsplus_strcasecmp(const struct hfsplus_unistr *s1,
int hfsplus_strcmp(const struct hfsplus_unistr *s1,
const struct hfsplus_unistr *s2);
int hfsplus_uni2asc(struct super_block *sb, const struct hfsplus_unistr *ustr,
- char *astr, int *len_p);
+ char *astr, int *len_p, bool name_mangling);
int hfsplus_asc2uni(struct super_block *sb, struct hfsplus_unistr *ustr,
- int max_unistr_len, const char *astr, int len);
+ int max_unistr_len, const char *astr, int len,
+ bool name_mangling);
int hfsplus_hash_dentry(const struct dentry *dentry, struct qstr *str);
int hfsplus_compare_dentry(const struct dentry *dentry, unsigned int len,
const char *str, const struct qstr *name);
diff --git a/fs/hfsplus/unicode.c b/fs/hfsplus/unicode.c
index 73342c9..52d9186 100644
--- a/fs/hfsplus/unicode.c
+++ b/fs/hfsplus/unicode.c
@@ -121,7 +121,7 @@ static u16 *hfsplus_compose_lookup(u16 *p, u16 cc)

int hfsplus_uni2asc(struct super_block *sb,
const struct hfsplus_unistr *ustr,
- char *astr, int *len_p)
+ char *astr, int *len_p, bool name_mangling)
{
const hfsplus_unichr *ip;
struct nls_table *nls = HFSPLUS_SB(sb)->nls;
@@ -187,7 +187,8 @@ int hfsplus_uni2asc(struct super_block *sb,
c0 = 0x2400;
break;
case '/':
- c0 = ':';
+ if (name_mangling)
+ c0 = ':';
break;
}
res = nls->uni2char(c0, op, len);
@@ -253,8 +254,8 @@ int hfsplus_uni2asc(struct super_block *sb,
* Convert one or more ASCII characters into a single unicode character.
* Returns the number of ASCII characters corresponding to the unicode char.
*/
-static inline int asc2unichar(struct super_block *sb, const char *astr, int len,
- wchar_t *uc)
+static inline int asc2unichar(struct super_block *sb, const char *astr,
+ int len, wchar_t *uc, bool name_mangling)
{
int size = HFSPLUS_SB(sb)->nls->char2uni(astr, len, uc);
if (size <= 0) {
@@ -266,7 +267,8 @@ static inline int asc2unichar(struct super_block *sb, const char *astr, int len,
*uc = 0;
break;
case ':':
- *uc = '/';
+ if (name_mangling)
+ *uc = '/';
break;
}
return size;
@@ -343,7 +345,7 @@ static u16 *decompose_unichar(wchar_t uc, int *size, u16 *hangul_buffer)

int hfsplus_asc2uni(struct super_block *sb,
struct hfsplus_unistr *ustr, int max_unistr_len,
- const char *astr, int len)
+ const char *astr, int len, bool name_mangling)
{
int size, dsize, decompose;
u16 *dstr, outlen = 0;
@@ -352,7 +354,7 @@ int hfsplus_asc2uni(struct super_block *sb,

decompose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);
while (outlen < max_unistr_len && len > 0) {
- size = asc2unichar(sb, astr, len, &c);
+ size = asc2unichar(sb, astr, len, &c, name_mangling);

if (decompose)
dstr = decompose_unichar(c, &dsize, dhangul);
@@ -399,7 +401,7 @@ int hfsplus_hash_dentry(const struct dentry *dentry, struct qstr *str)
len = str->len;
while (len > 0) {
int dsize;
- size = asc2unichar(sb, astr, len, &c);
+ size = asc2unichar(sb, astr, len, &c, true);
astr += size;
len -= size;

@@ -456,7 +458,7 @@ int hfsplus_compare_dentry(const struct dentry *dentry,

while (len1 > 0 && len2 > 0) {
if (!dsize1) {
- size = asc2unichar(sb, astr1, len1, &c);
+ size = asc2unichar(sb, astr1, len1, &c, true);
astr1 += size;
len1 -= size;

@@ -471,7 +473,7 @@ int hfsplus_compare_dentry(const struct dentry *dentry,
}

if (!dsize2) {
- size = asc2unichar(sb, astr2, len2, &c);
+ size = asc2unichar(sb, astr2, len2, &c, true);
astr2 += size;
len2 -= size;

diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 4d169c5..de6a1c9 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -735,8 +735,9 @@ ssize_t hfsplus_listxattr(struct dentry *dentry, char *buffer, size_t size)

xattr_name_len = NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN;
if (hfsplus_uni2asc(inode->i_sb,
- (const struct hfsplus_unistr *)&fd.key->attr.key_name,
- strbuf, &xattr_name_len)) {
+ (const struct hfsplus_unistr *)
+ &fd.key->attr.key_name, strbuf,
+ &xattr_name_len, false)) {
pr_err("unicode conversion failed\n");
res = -EIO;
goto end_listxattr;
--
2.7.4
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