On 9/4/23 09:40, Roberto Sassu wrote:
From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Before the security field of kernel objects could be shared among LSMs with
the LSM stacking feature, IMA and EVM had to rely on an alternative storage
of inode metadata. The association between inode metadata and inode is
maintained through an rbtree.
With the reservation mechanism offered by the LSM infrastructure, the
rbtree is no longer necessary, as each LSM could reserve a space in the
security blob for each inode. Thus, request from the 'integrity' LSM a
space in the security blob for the pointer of inode metadata
(integrity_iint_cache structure).
Prefer this to allocating the integrity_iint_cache structure directly, as
IMA would require it only for a subset of inodes. Always allocating it
would cause a waste of memory.
Introduce two primitives for getting and setting the pointer of
integrity_iint_cache in the security blob, respectively
integrity_inode_get_iint() and integrity_inode_set_iint(). This would make
the code more understandable, as they directly replace rbtree operations.
Locking is not needed, as access to inode metadata is not shared, it is per
inode.
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Reviewed-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
---
@@ -145,10 +91,8 @@ static void integrity_inode_free(struct inode *inode)
if (!IS_IMA(inode))
return;
I think you can remove this check !IS_IMA() as well since the next
function called here integrity_iint_find() already has this check:
struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
{
if (!IS_IMA(inode))
return NULL;
return integrity_inode_get_iint(inode);
}
- write_lock(&integrity_iint_lock);
- iint = __integrity_iint_find(inode);
- rb_erase(&iint->rb_node, &integrity_iint_tree);
- write_unlock(&integrity_iint_lock);
+ iint = integrity_iint_find(inode); <--------------
+ integrity_inode_set_iint(inode, NULL);
iint_free(iint);
}
