diff options
| author | Atish Patra <atish.patra@wdc.com> | 2020-11-04 16:04:38 -0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-11-25 16:05:28 -0800 |
| commit | 19a00869028f4a28a36f90649166631dff6e3ccd (patch) | |
| tree | ef4a68e11c94a44d7e9de3f6f83fe57877739ba9 /arch/riscv/mm | |
| parent | b6566dc1acca38ce6ed845ce8a270fb181ff6d41 (diff) | |
RISC-V: Protect all kernel sections including init early
Currently, .init.text & .init.data are intermixed which makes it impossible
apply different permissions to them. .init.data shouldn't need exec
permissions while .init.text shouldn't have write permission. Moreover,
the strict permission are only enforced /init starts. This leaves the
kernel vulnerable from possible buggy built-in modules.
Keep .init.text & .data in separate sections so that different permissions
are applied to each section. Apply permissions to individual sections as
early as possible. This improves the kernel protection under
CONFIG_STRICT_KERNEL_RWX. We also need to restore the permissions for the
entire _init section after it is freed so that those pages can be used
for other purpose.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Tested-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/mm')
| -rw-r--r-- | arch/riscv/mm/init.c | 21 | ||||
| -rw-r--r-- | arch/riscv/mm/pageattr.c | 6 |
2 files changed, 22 insertions, 5 deletions
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 563dbb13efe3..87c305c566ac 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -612,18 +612,29 @@ static inline void setup_vm_final(void) #endif /* CONFIG_MMU */ #ifdef CONFIG_STRICT_KERNEL_RWX -void mark_rodata_ro(void) +void protect_kernel_text_data(void) { - unsigned long text_start = (unsigned long)_text; - unsigned long text_end = (unsigned long)_etext; + unsigned long text_start = (unsigned long)_start; + unsigned long init_text_start = (unsigned long)__init_text_begin; + unsigned long init_data_start = (unsigned long)__init_data_begin; unsigned long rodata_start = (unsigned long)__start_rodata; unsigned long data_start = (unsigned long)_data; unsigned long max_low = (unsigned long)(__va(PFN_PHYS(max_low_pfn))); - set_memory_ro(text_start, (text_end - text_start) >> PAGE_SHIFT); - set_memory_ro(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT); + set_memory_ro(text_start, (init_text_start - text_start) >> PAGE_SHIFT); + set_memory_ro(init_text_start, (init_data_start - init_text_start) >> PAGE_SHIFT); + set_memory_nx(init_data_start, (rodata_start - init_data_start) >> PAGE_SHIFT); + /* rodata section is marked readonly in mark_rodata_ro */ set_memory_nx(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT); set_memory_nx(data_start, (max_low - data_start) >> PAGE_SHIFT); +} + +void mark_rodata_ro(void) +{ + unsigned long rodata_start = (unsigned long)__start_rodata; + unsigned long data_start = (unsigned long)_data; + + set_memory_ro(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT); debug_checkwx(); } diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c index 19fecb362d81..c64ec224fd0c 100644 --- a/arch/riscv/mm/pageattr.c +++ b/arch/riscv/mm/pageattr.c @@ -128,6 +128,12 @@ static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask, return ret; } +int set_memory_rw_nx(unsigned long addr, int numpages) +{ + return __set_memory(addr, numpages, __pgprot(_PAGE_READ | _PAGE_WRITE), + __pgprot(_PAGE_EXEC)); +} + int set_memory_ro(unsigned long addr, int numpages) { return __set_memory(addr, numpages, __pgprot(_PAGE_READ), |