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, 12 insertions, 0 deletions

diff --git a/security/ipe/eval.h b/security/ipe/eval.h
index 4901df0e1369..fef65a36468c 100644
--- a/security/ipe/eval.h
+++ b/security/ipe/eval.h
@@ -31,6 +31,12 @@ struct ipe_bdev {
 };
 #endif /* CONFIG_IPE_PROP_DM_VERITY */
 
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+struct ipe_inode {
+	bool fs_verity_signed;
+};
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
+
 struct ipe_eval_ctx {
 	enum ipe_op_type op;
 	enum ipe_hook_type hook;
@@ -40,6 +46,12 @@ struct ipe_eval_ctx {
 #ifdef CONFIG_IPE_PROP_DM_VERITY
 	const struct ipe_bdev *ipe_bdev;
 #endif /* CONFIG_IPE_PROP_DM_VERITY */
+#ifdef CONFIG_IPE_PROP_FS_VERITY
+	const struct inode *ino;
+#endif /* CONFIG_IPE_PROP_FS_VERITY */
+#ifdef CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG
+	const struct ipe_inode *ipe_inode;
+#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */
 };
 
 enum ipe_match {