diff options
| -rw-r--r-- | arch/arm64/Kconfig | 14 | ||||
| -rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 2 | ||||
| -rw-r--r-- | arch/arm64/mm/mmu.c | 16 | ||||
| -rw-r--r-- | arch/arm64/mm/pageattr.c | 15 |
4 files changed, 45 insertions, 2 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 787d7850e064..bf57c48c77df 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -958,6 +958,20 @@ config ARM64_SSBD If unsure, say Y. +config RODATA_FULL_DEFAULT_ENABLED + bool "Apply r/o permissions of VM areas also to their linear aliases" + default y + help + Apply read-only attributes of VM areas to the linear alias of + the backing pages as well. This prevents code or read-only data + from being modified (inadvertently or intentionally) via another + mapping of the same memory page. This additional enhancement can + be turned off at runtime by passing rodata=[off|on] (and turned on + with rodata=full if this option is set to 'n') + + This requires the linear region to be mapped down to pages, + which may adversely affect performance in some cases. + menuconfig ARMV8_DEPRECATED bool "Emulate deprecated/obsolete ARMv8 instructions" depends on COMPAT diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index 1e58bf58c22b..dfcfeffd2080 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -35,6 +35,8 @@ #include <asm/sysreg.h> #include <asm/tlbflush.h> +extern bool rodata_full; + static inline void contextidr_thread_switch(struct task_struct *next) { if (!IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR)) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index d1d6601b385d..e1b2d58a311a 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -451,7 +451,7 @@ static void __init map_mem(pgd_t *pgdp) struct memblock_region *reg; int flags = 0; - if (debug_pagealloc_enabled()) + if (rodata_full || debug_pagealloc_enabled()) flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; /* @@ -552,7 +552,19 @@ static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end, static int __init parse_rodata(char *arg) { - return strtobool(arg, &rodata_enabled); + int ret = strtobool(arg, &rodata_enabled); + if (!ret) { + rodata_full = false; + return 0; + } + + /* permit 'full' in addition to boolean options */ + if (strcmp(arg, "full")) + return -EINVAL; + + rodata_enabled = true; + rodata_full = true; + return 0; } early_param("rodata", parse_rodata); diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 787f9e385e6d..6cd645edcf35 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -25,6 +25,8 @@ struct page_change_data { pgprot_t clear_mask; }; +bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED); + static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr, void *data) { @@ -64,6 +66,7 @@ static int change_memory_common(unsigned long addr, int numpages, unsigned long size = PAGE_SIZE*numpages; unsigned long end = start + size; struct vm_struct *area; + int i; if (!PAGE_ALIGNED(addr)) { start &= PAGE_MASK; @@ -94,6 +97,18 @@ static int change_memory_common(unsigned long addr, int numpages, return 0; /* + * If we are manipulating read-only permissions, apply the same + * change to the linear mapping of the pages that back this VM area. + */ + if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY || + pgprot_val(clear_mask) == PTE_RDONLY)) { + for (i = 0; i < area->nr_pages; i++) { + __change_memory_common((u64)page_address(area->pages[i]), + PAGE_SIZE, set_mask, clear_mask); + } + } + + /* * Get rid of potentially aliasing lazily unmapped vm areas that may * have permissions set that deviate from the ones we are setting here. */ |