From: Zong Li <zong.li@sifive.com>
To: paul.walmsley@sifive.com, palmer@dabbelt.com,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: Zong Li <zong.li@sifive.com>
Subject: [PATCH 2/2] riscv: Support CONFIG_STRICT_DEVMEM
Date: Tue, 16 Jun 2020 15:45:47 +0800 [thread overview]
Message-ID: <7faa60aa4a606b5c5c1ae374d82a7eee6c764b38.1592292685.git.zong.li@sifive.com> (raw)
In-Reply-To: <cover.1592292685.git.zong.li@sifive.com>
Implement the 'devmem_is_allowed()' interface for RISC-V, like some of
other architectures have done. It will be called from range_is_allowed()
when userpsace attempts to access /dev/mem.
Access to exclusive IOMEM and kernel RAM is denied unless
CONFIG_STRICT_DEVMEM is set to 'n'.
Test it by devmem, the result as follows:
- CONFIG_STRICT_DEVMEM=y
$ devmem 0x10010000
0x00000000
$ devmem 0x80200000
0x0000106F
- CONFIG_STRICT_DEVMEM is not set
$ devmem 0x10010000
devmem: mmap: Operation not permitted
$ devmem 0x80200000
devmem: mmap: Operation not permitted
Signed-off-by: Zong Li <zong.li@sifive.com>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/io.h | 2 ++
arch/riscv/mm/init.c | 19 +++++++++++++++++++
3 files changed, 22 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 128192e14ff2..ffd7841ede4c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -16,6 +16,7 @@ config RISCV
select ARCH_HAS_BINFMT_FLAT
select ARCH_HAS_DEBUG_VIRTUAL if MMU
select ARCH_HAS_DEBUG_WX
+ select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_HAS_MMIOWB
diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 3835c3295dc5..04ac65ab93ce 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -147,4 +147,6 @@ __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
#include <asm-generic/io.h>
+extern int devmem_is_allowed(unsigned long pfn);
+
#endif /* _ASM_RISCV_IO_H */
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index bbe816e03b2f..5e7e61519acc 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -517,6 +517,25 @@ void mark_rodata_ro(void)
}
#endif
+#ifdef CONFIG_STRICT_DEVMEM
+#include <linux/ioport.h>
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain address
+ * is valid. The argument is a physical page number.
+ *
+ * Disallow access to system RAM as well as device-exclusive MMIO regions.
+ * This effectively disable read()/write() on /dev/mem.
+ */
+int devmem_is_allowed(unsigned long pfn)
+{
+ if (iomem_is_exclusive(pfn << PAGE_SHIFT))
+ return 0;
+ if (!page_is_ram(pfn))
+ return 1;
+ return 0;
+}
+#endif
+
void __init resource_init(void)
{
struct memblock_region *region;
--
2.27.0
next prev parent reply other threads:[~2020-06-16 7:46 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 7:45 [PATCH 0/2] Add STRICT_DEVMEM support on RISC-V Zong Li
2020-06-16 7:45 ` [PATCH 1/2] riscv: Register System RAM as iomem resources Zong Li
2020-06-16 11:51 ` Nick Kossifidis
2020-06-16 11:51 ` Nick Kossifidis
2020-06-17 1:23 ` Zong Li
2020-06-17 1:23 ` Zong Li
2020-07-09 18:27 ` Palmer Dabbelt
2020-07-09 18:27 ` Palmer Dabbelt
2020-07-10 2:05 ` Nick Kossifidis
2020-07-10 2:05 ` Nick Kossifidis
2020-06-16 7:45 ` Zong Li [this message]
2020-06-16 12:27 ` [PATCH 2/2] riscv: Support CONFIG_STRICT_DEVMEM Nick Kossifidis
2020-06-16 12:27 ` Nick Kossifidis
2020-06-17 1:56 ` Zong Li
2020-06-17 1:56 ` Zong Li
2020-06-17 5:28 ` Nick Kossifidis
2020-06-17 5:28 ` Nick Kossifidis
2020-06-17 6:32 ` Zong Li
2020-06-17 6:32 ` Zong Li
2020-07-09 20:08 ` Palmer Dabbelt
2020-07-09 20:08 ` Palmer Dabbelt
2020-07-10 2:43 ` Zong Li
2020-07-10 2:43 ` Zong Li
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