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Message-Id: <20200603051912.23296-5-cmr@informatik.wtf>
Date: Wed, 3 Jun 2020 00:19:11 -0500
From: "Christopher M. Riedl" <cmr@...ormatik.wtf>
To: linuxppc-dev@...ts.ozlabs.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 4/5] powerpc/lib: Add LKDTM accessor for patching addr
When live patching a STRICT_RWX kernel, a mapping is installed at a
"patching address" with temporary write permissions. Provide a
LKDTM-only accessor function for this address in preparation for a LKDTM
test which attempts to "hijack" this mapping by writing to it from
another CPU.
Signed-off-by: Christopher M. Riedl <cmr@...ormatik.wtf>
---
arch/powerpc/lib/code-patching.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index df0765845204..c23453049116 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -52,6 +52,13 @@ int raw_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
static struct mm_struct *patching_mm __ro_after_init;
static unsigned long patching_addr __ro_after_init;
+#ifdef CONFIG_LKDTM
+unsigned long read_cpu_patching_addr(unsigned int cpu)
+{
+ return patching_addr;
+}
+#endif
+
void __init poking_init(void)
{
spinlock_t *ptl; /* for protecting pte table */
--
2.26.2
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