diff options
| author | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-07-09 21:43:21 +0300 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-12-11 23:28:08 +0300 |
| commit | 527701eda5f196588df9b36a30651804fea7d1a7 (patch) | |
| tree | d9afe5b4753aa0ca2ee1829072ead75c153e369b | |
| parent | bbf5c979011a099af5dc76498918ed7df445635b (diff) | |
| download | linux-527701eda5f196588df9b36a30651804fea7d1a7.tar.xz | |
lib: Add a generic version of devmem_is_allowed()
As part of adding support for STRICT_DEVMEM to the RISC-V port, Zong
provided a devmem_is_allowed() implementation that's exactly the same as
all the others I checked. Instead I'm adding a generic version, which
will soon be used.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
| -rw-r--r-- | include/asm-generic/io.h | 4 | ||||
| -rw-r--r-- | lib/Kconfig | 3 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 2 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/devmem_is_allowed.c | 27 |
5 files changed, 37 insertions, 1 deletions
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index dabf8cb7203b..da2e861dee1c 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -1122,6 +1122,10 @@ static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer, } #endif +#ifndef CONFIG_GENERIC_DEVMEM_IS_ALLOWED +extern int devmem_is_allowed(unsigned long pfn); +#endif + #endif /* __KERNEL__ */ #endif /* __ASM_GENERIC_IO_H */ diff --git a/lib/Kconfig b/lib/Kconfig index b4b98a03ff98..b26721cf51bc 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -681,6 +681,9 @@ config GENERIC_LIB_CMPDI2 config GENERIC_LIB_UCMPDI2 bool +config GENERIC_LIB_DEVMEM_IS_ALLOWED + bool + config PLDMFW bool default n diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 0c781f912f9f..87410f62b501 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1626,7 +1626,7 @@ config ARCH_HAS_DEVMEM_IS_ALLOWED config STRICT_DEVMEM bool "Filter access to /dev/mem" depends on MMU && DEVMEM - depends on ARCH_HAS_DEVMEM_IS_ALLOWED + depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED default y if PPC || X86 || ARM64 help If this option is disabled, you allow userspace (root) access to all diff --git a/lib/Makefile b/lib/Makefile index a4a4c6864f51..34011a11fbb3 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -348,3 +348,5 @@ obj-$(CONFIG_PLDMFW) += pldmfw/ obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o obj-$(CONFIG_BITS_TEST) += test_bits.o + +obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o diff --git a/lib/devmem_is_allowed.c b/lib/devmem_is_allowed.c new file mode 100644 index 000000000000..c0d67c541849 --- /dev/null +++ b/lib/devmem_is_allowed.c @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * A generic version of devmem_is_allowed. + * + * Based on arch/arm64/mm/mmap.c + * + * Copyright (C) 2020 Google, Inc. + * Copyright (C) 2012 ARM Ltd. + */ + +#include <linux/mm.h> +#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. We mimic x86 here by + * disallowing 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; +} |