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xfs: create structure verifier function for shortform xattrs

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Create a function to perform structure verification for short form
extended attributes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Darrick J. Wong 2018-01-08 10:51:05 -08:00
parent 71493b839e
commit 1e1bbd8e7e
2 changed files with 75 additions and 0 deletions
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74
fs/xfs/libxfs/xfs_attr_leaf.c
View File

@ -872,6 +872,80 @@ xfs_attr_shortform_allfit(
return xfs_attr_shortform_bytesfit(dp, bytes);
}
/* Verify the consistency of an inline attribute fork. */
xfs_failaddr_t
xfs_attr_shortform_verify(
struct xfs_inode *ip)
{
struct xfs_attr_shortform *sfp;
struct xfs_attr_sf_entry *sfep;
struct xfs_attr_sf_entry *next_sfep;
char *endp;
struct xfs_ifork *ifp;
int i;
int size;
ASSERT(ip->i_d.di_aformat == XFS_DINODE_FMT_LOCAL);
ifp = XFS_IFORK_PTR(ip, XFS_ATTR_FORK);
sfp = (struct xfs_attr_shortform *)ifp->if_u1.if_data;
size = ifp->if_bytes;
/*
* Give up if the attribute is way too short.
*/
if (size < sizeof(struct xfs_attr_sf_hdr))
return __this_address;
endp = (char *)sfp + size;
/* Check all reported entries */
sfep = &sfp->list[0];
for (i = 0; i < sfp->hdr.count; i++) {
/*
* struct xfs_attr_sf_entry has a variable length.
* Check the fixed-offset parts of the structure are
* within the data buffer.
*/
if (((char *)sfep + sizeof(*sfep)) >= endp)
return __this_address;
/* Don't allow names with known bad length. */
if (sfep->namelen == 0)
return __this_address;
/*
* Check that the variable-length part of the structure is
* within the data buffer. The next entry starts after the
* name component, so nextentry is an acceptable test.
*/
next_sfep = XFS_ATTR_SF_NEXTENTRY(sfep);
if ((char *)next_sfep > endp)
return __this_address;
/*
* Check for unknown flags. Short form doesn't support
* the incomplete or local bits, so we can use the namespace
* mask here.
*/
if (sfep->flags & ~XFS_ATTR_NSP_ONDISK_MASK)
return __this_address;
/*
* Check for invalid namespace combinations. We only allow
* one namespace flag per xattr, so we can just count the
* bits (i.e. hweight) here.
*/
if (hweight8(sfep->flags & XFS_ATTR_NSP_ONDISK_MASK) > 1)
return __this_address;
sfep = next_sfep;
}
if ((void *)sfep != (void *)endp)
return __this_address;
return NULL;
}
/*
* Convert a leaf attribute list to shortform attribute list
*/

1
fs/xfs/libxfs/xfs_attr_leaf.h
View File

@ -53,6 +53,7 @@ int xfs_attr_shortform_to_leaf(struct xfs_da_args *args,
int xfs_attr_shortform_remove(struct xfs_da_args *args);
int xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp);
int xfs_attr_shortform_bytesfit(struct xfs_inode *dp, int bytes);
xfs_failaddr_t xfs_attr_shortform_verify(struct xfs_inode *ip);
void xfs_attr_fork_remove(struct xfs_inode *ip, struct xfs_trans *tp);
/*