From: Zev Weiss <zev@bewilderbeest.net>
To: Andrew Jeffery <andrew@codeconstruct.com.au>,
Joel Stanley <joel@jms.id.au>
Cc: openbmc@lists.ozlabs.org
Subject: [PATCH linux dev-6.6 1/2] prctl: Generalize PR_SET_MDWE support check to be per-arch
Date: Tue, 26 Mar 2024 12:49:59 -0700 [thread overview]
Message-ID: <20240326194959.10777-5-zev@bewilderbeest.net> (raw)
In-Reply-To: <20240326194959.10777-4-zev@bewilderbeest.net>
There exist systems other than PARISC where MDWE may not be feasible
to support; rather than cluttering up the generic code with additional
arch-specific logic let's add a generic function for checking MDWE
support and allow each arch to override it as needed.
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Cc: <stable@vger.kernel.org> # v6.3+
---
arch/parisc/include/asm/mman.h | 14 ++++++++++++++
include/linux/mman.h | 8 ++++++++
kernel/sys.c | 7 +++++--
3 files changed, 27 insertions(+), 2 deletions(-)
create mode 100644 arch/parisc/include/asm/mman.h
diff --git a/arch/parisc/include/asm/mman.h b/arch/parisc/include/asm/mman.h
new file mode 100644
index 000000000000..47c5a1991d10
--- /dev/null
+++ b/arch/parisc/include/asm/mman.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MMAN_H__
+#define __ASM_MMAN_H__
+
+#include <uapi/asm/mman.h>
+
+/* PARISC cannot allow mdwe as it needs writable stacks */
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+ return false;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+
+#endif /* __ASM_MMAN_H__ */
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 40d94411d492..db4741007bef 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -161,6 +161,14 @@ calc_vm_flag_bits(unsigned long flags)
unsigned long vm_commit_limit(void);
+#ifndef arch_memory_deny_write_exec_supported
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+ return true;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+#endif
+
/*
* Denies creating a writable executable mapping or gaining executable permissions.
*
diff --git a/kernel/sys.c b/kernel/sys.c
index 7a4ae6d5aecd..44b575990333 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2395,8 +2395,11 @@ static inline int prctl_set_mdwe(unsigned long bits, unsigned long arg3,
if (bits & PR_MDWE_NO_INHERIT && !(bits & PR_MDWE_REFUSE_EXEC_GAIN))
return -EINVAL;
- /* PARISC cannot allow mdwe as it needs writable stacks */
- if (IS_ENABLED(CONFIG_PARISC))
+ /*
+ * EOPNOTSUPP might be more appropriate here in principle, but
+ * existing userspace depends on EINVAL specifically.
+ */
+ if (!arch_memory_deny_write_exec_supported())
return -EINVAL;
current_bits = get_current_mdwe();
--
2.44.0
next prev parent reply other threads:[~2024-03-26 19:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-26 19:49 [PATCH linux dev-6.6 0/2] ARM: prctl: Reject PR_SET_MDWE where not supported Zev Weiss
2024-03-26 19:49 ` Zev Weiss [this message]
2024-03-26 19:50 ` [PATCH linux dev-6.6 2/2] ARM: prctl: Reject PR_SET_MDWE on pre-ARMv6 Zev Weiss
2024-03-26 23:20 ` [PATCH linux dev-6.6 0/2] ARM: prctl: Reject PR_SET_MDWE where not supported Andrew Jeffery
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