From: Russell Currey <ruscur@russell.cc>
To: linuxppc-dev@lists.ozlabs.org
Cc: Russell Currey <ruscur@russell.cc>,
christophe.leroy@c-s.fr, joel@jms.id.au, mpe@ellerman.id.au,
ajd@linux.ibm.com, dja@axtens.net, npiggin@gmail.com,
kernel-hardening@lists.openwall.com
Subject: [PATCH v6 3/5] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime
Date: Tue, 24 Dec 2019 16:55:43 +1100 [thread overview]
Message-ID: <20191224055545.178462-4-ruscur@russell.cc> (raw)
In-Reply-To: <20191224055545.178462-1-ruscur@russell.cc>
Very rudimentary, just
echo 1 > [debugfs]/check_wx_pages
and check the kernel log. Useful for testing strict module RWX.
Updated the Kconfig entry to reflect this.
Also fixed a typo.
Signed-off-by: Russell Currey <ruscur@russell.cc>
---
arch/powerpc/Kconfig.debug | 6 ++++--
arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++-
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 4e1d39847462..7c14c9728bc0 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -370,7 +370,7 @@ config PPC_PTDUMP
If you are unsure, say N.
config PPC_DEBUG_WX
- bool "Warn on W+X mappings at boot"
+ bool "Warn on W+X mappings at boot & enable manual checks at runtime"
depends on PPC_PTDUMP
help
Generate a warning if any W+X mappings are found at boot.
@@ -384,7 +384,9 @@ config PPC_DEBUG_WX
of other unfixed kernel bugs easier.
There is no runtime or memory usage effect of this option
- once the kernel has booted up - it's a one time check.
+ once the kernel has booted up, it only automatically checks once.
+
+ Enables the "check_wx_pages" debugfs entry for checking at runtime.
If in doubt, say "Y".
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 2f9ddc29c535..b6cba29ae4a0 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -4,7 +4,7 @@
*
* This traverses the kernel pagetables and dumps the
* information about the used sections of memory to
- * /sys/kernel/debug/kernel_pagetables.
+ * /sys/kernel/debug/kernel_page_tables.
*
* Derived from the arm64 implementation:
* Copyright (c) 2014, The Linux Foundation, Laura Abbott.
@@ -409,6 +409,25 @@ void ptdump_check_wx(void)
else
pr_info("Checked W+X mappings: passed, no W+X pages found\n");
}
+
+static int check_wx_debugfs_set(void *data, u64 val)
+{
+ if (val != 1ULL)
+ return -EINVAL;
+
+ ptdump_check_wx();
+
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n");
+
+static int ptdump_check_wx_init(void)
+{
+ return debugfs_create_file("check_wx_pages", 0200, NULL,
+ NULL, &check_wx_fops) ? 0 : -ENOMEM;
+}
+device_initcall(ptdump_check_wx_init);
#endif
static int ptdump_init(void)
--
2.24.1
next prev parent reply other threads:[~2019-12-24 5:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-24 5:55 [PATCH v6 0/5] Implement STRICT_MODULE_RWX for powerpc Russell Currey
2019-12-24 5:55 ` [PATCH v6 1/5] powerpc/mm: Implement set_memory() routines Russell Currey
2020-01-08 12:52 ` Christophe Leroy
2020-02-03 0:46 ` Russell Currey
2020-02-03 7:06 ` Christophe Leroy
2020-01-20 8:35 ` Christophe Leroy
2019-12-24 5:55 ` [PATCH v6 2/5] powerpc/kprobes: Mark newly allocated probes as RO Russell Currey
2020-01-08 16:48 ` Christophe Leroy
2019-12-24 5:55 ` Russell Currey [this message]
2019-12-31 17:14 ` [PATCH v6 3/5] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Christophe Leroy
2020-01-07 10:48 ` Michael Ellerman
2019-12-24 5:55 ` [PATCH v6 4/5] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Russell Currey
2019-12-24 5:55 ` [PATCH v6 5/5] powerpc/configs: Enable STRICT_MODULE_RWX in skiroot_defconfig Russell Currey
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