From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Add a new taint flag TAINT_CONF_NO_LOCKDOWN that is set when
the default hardening against untrusted hosts in TDX is overridden
on the command line. The flag is set when the device or ACPI
filters are disabled.
The main use cases is for applications to detect that they
might run in a potentially insecure configuration through
/proc/sys/kernel/taint.
The setting is not intended for attestation, which should attest the
kernel command line anyways.
I picked 'Y' for the oops flag, although this type of taint is probably
not too useful for crashes, since there weren't any other good letters
left.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
Documentation/admin-guide/tainted-kernels.rst | 7 ++++++-
include/linux/panic.h | 3 ++-
kernel/panic.c | 1 +
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
index ceeed7b0798d..65c58092ec35 100644
--- a/Documentation/admin-guide/tainted-kernels.rst
+++ b/Documentation/admin-guide/tainted-kernels.rst
@@ -100,7 +100,8 @@ Bit Log Number Reason that got the kernel tainted
15 _/K 32768 kernel has been live patched
16 _/X 65536 auxiliary taint, defined for and used by distros
17 _/T 131072 kernel was built with the struct randomization plugin
-=== === ====== ========================================================
+ 18 _/Y 262144 confidential guest (like TDX guest) without full lockdown
+=== === ====== =========================================================
Note: The character ``_`` is representing a blank in this table to make reading
easier.
@@ -175,3 +176,7 @@ More detailed explanation for tainting
produce extremely unusual kernel structure layouts (even performance
pathological ones), which is important to know when debugging. Set at
build time.
+
+ 18) ``Y`` Kernel is running as a confidential guest on a untrusted
+ hypervisor (e.g. TDX), but has disabled some lock down options that could
+ make the kernel attackable from the host.
diff --git a/include/linux/panic.h b/include/linux/panic.h
index f5844908a089..9ac10689a432 100644
--- a/include/linux/panic.h
+++ b/include/linux/panic.h
@@ -74,7 +74,8 @@ static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
#define TAINT_LIVEPATCH 15
#define TAINT_AUX 16
#define TAINT_RANDSTRUCT 17
-#define TAINT_FLAGS_COUNT 18
+#define TAINT_CONF_NO_LOCKDOWN 18
+#define TAINT_FLAGS_COUNT 19
#define TAINT_FLAGS_MAX ((1UL << TAINT_FLAGS_COUNT) - 1)
struct taint_flag {
diff --git a/kernel/panic.c b/kernel/panic.c
index edad89660a2b..1557f864bec0 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -387,6 +387,7 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
[ TAINT_LIVEPATCH ] = { 'K', ' ', true },
[ TAINT_AUX ] = { 'X', ' ', true },
[ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
+ [ TAINT_CONF_NO_LOCKDOWN ] = { 'Y', ' ', true },
};
/**
--
2.25.1
