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jfs: don't allow os2 xattr namespace overlap with others

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It's currently possible to bypass xattr namespace access rules by
prefixing valid xattr names with "os2.", since the os2 namespace stores
extended attributes in a legacy format with no prefix.

This patch adds checking to deny access to any valid namespace prefix
following "os2.".

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Reported-by: Sergey Vlasov <vsu@altlinux.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dave Kleikamp 2010-08-09 15:57:38 -05:00 committed by Linus Torvalds
parent 2f9e825d3e
commit aca0fa34bd
1 changed files with 38 additions and 49 deletions
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87
fs/jfs/xattr.c
View file

@ -86,46 +86,25 @@ struct ea_buffer {
#define EA_MALLOC 0x0008
static int is_known_namespace(const char *name)
{
if (strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) &&
strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) &&
strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
return false;
return true;
}
/*
* These three routines are used to recognize on-disk extended attributes
* that are in a recognized namespace. If the attribute is not recognized,
* "os2." is prepended to the name
*/
static inline int is_os2_xattr(struct jfs_ea *ea)
static int is_os2_xattr(struct jfs_ea *ea)
{
/*
* Check for "system."
*/
if ((ea->namelen >= XATTR_SYSTEM_PREFIX_LEN) &&
!strncmp(ea->name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return false;
/*
* Check for "user."
*/
if ((ea->namelen >= XATTR_USER_PREFIX_LEN) &&
!strncmp(ea->name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
return false;
/*
* Check for "security."
*/
if ((ea->namelen >= XATTR_SECURITY_PREFIX_LEN) &&
!strncmp(ea->name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN))
return false;
/*
* Check for "trusted."
*/
if ((ea->namelen >= XATTR_TRUSTED_PREFIX_LEN) &&
!strncmp(ea->name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
return false;
/*
* Add any other valid namespace prefixes here
*/
/*
* We assume it's OS/2's flat namespace
*/
return true;
return !is_known_namespace(ea->name);
}
static inline int name_size(struct jfs_ea *ea)
@ -764,13 +743,23 @@ static int can_set_xattr(struct inode *inode, const char *name,
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return can_set_system_xattr(inode, name, value, value_len);
if (!strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN)) {
/*
* This makes sure that we aren't trying to set an
* attribute in a different namespace by prefixing it
* with "os2."
*/
if (is_known_namespace(name + XATTR_OS2_PREFIX_LEN))
return -EOPNOTSUPP;
return 0;
}
/*
* Don't allow setting an attribute in an unknown namespace.
*/
if (strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) &&
strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) &&
strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN))
strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
return -EOPNOTSUPP;
return 0;
@ -952,19 +941,8 @@ ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
int xattr_size;
ssize_t size;
int namelen = strlen(name);
char *os2name = NULL;
char *value;
if (strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN) == 0) {
os2name = kmalloc(namelen - XATTR_OS2_PREFIX_LEN + 1,
GFP_KERNEL);
if (!os2name)
return -ENOMEM;
strcpy(os2name, name + XATTR_OS2_PREFIX_LEN);
name = os2name;
namelen -= XATTR_OS2_PREFIX_LEN;
}
down_read(&JFS_IP(inode)->xattr_sem);
xattr_size = ea_get(inode, &ea_buf, 0);
@ -1002,8 +980,6 @@ ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
out:
up_read(&JFS_IP(inode)->xattr_sem);
kfree(os2name);
return size;
}
@ -1012,6 +988,19 @@ ssize_t jfs_getxattr(struct dentry *dentry, const char *name, void *data,
{
int err;
if (strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN) == 0) {
/*
* skip past "os2." prefix
*/
name += XATTR_OS2_PREFIX_LEN;
/*
* Don't allow retrieving properly prefixed attributes
* by prepending them with "os2."
*/
if (is_known_namespace(name))
return -EOPNOTSUPP;
}
err = __jfs_getxattr(dentry->d_inode, name, data, buf_size);
return err;