ipe: enable support for fs-verity as a trust provider

Enable IPE policy authors to indicate trust for a singular fsverity
file, identified by the digest information, through "fsverity_digest"
and all files using valid fsverity builtin signatures via
"fsverity_signature".

This enables file-level integrity claims to be expressed in IPE,
allowing individual files to be authorized, giving some flexibility
for policy authors. Such file-level claims are important to be expressed
for enforcing the integrity of packages, as well as address some of the
scalability issues in a sole dm-verity based solution (# of loop back
devices, etc).

This solution cannot be done in userspace as the minimum threat that
IPE should mitigate is an attacker downloads malicious payload with
all required dependencies. These dependencies can lack the userspace
check, bypassing the protection entirely. A similar attack succeeds if
the userspace component is replaced with a version that does not
perform the check. As a result, this can only be done in the common
entry point - the kernel.

Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h
index 4d585fb6ada3..38d4a387d039 100644
--- a/security/ipe/hooks.h
+++ b/security/ipe/hooks.h
@@ -9,6 +9,7 @@
 #include <linux/binfmts.h>
 #include <linux/security.h>
 #include <linux/blk_types.h>
+#include <linux/fsverity.h>
 
 enum ipe_hook_type {
 	IPE_HOOK_BPRM_CHECK = 0,
@@ -43,4 +44,9 @@ int ipe_bdev_setintegrity(struct block_device *bdev, enum lsm_integrity_type typ
 			  const void *value, size_t len);
 #endif /* CONFIG_IPE_PROP_DM_VERITY */
 
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+int ipe_inode_setintegrity(const struct inode *inode, enum lsm_integrity_type type,
+			   const void *value, size_t size);
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
+
 #endif /* _IPE_HOOKS_H */