diff options
| author | Will Deacon <will.deacon@arm.com> | 2017-12-06 11:24:02 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2017-12-11 13:41:20 +0000 |
| commit | 6c27c4082f4f70b9f41df4d0adf51128b40351df (patch) | |
| tree | 339eb5355819f1bd6a842d8fc3c2fd6524c14327 /arch | |
| parent | b519538dfefc2f8478a1bcb458459c861d431784 (diff) | |
arm64: kaslr: Put kernel vectors address in separate data page
The literal pool entry for identifying the vectors base is the only piece
of information in the trampoline page that identifies the true location
of the kernel.
This patch moves it into a page-aligned region of the .rodata section
and maps this adjacent to the trampoline text via an additional fixmap
entry, which protects against any accidental leakage of the trampoline
contents.
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/fixmap.h | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 14 | ||||
| -rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 5 | ||||
| -rw-r--r-- | arch/arm64/mm/mmu.c | 10 |
4 files changed, 28 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h index 8119b49be98d..ec1e6d6fa14c 100644 --- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -59,6 +59,7 @@ enum fixed_addresses { #endif /* CONFIG_ACPI_APEI_GHES */ #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 + FIX_ENTRY_TRAMP_DATA, FIX_ENTRY_TRAMP_TEXT, #define TRAMP_VALIAS (__fix_to_virt(FIX_ENTRY_TRAMP_TEXT)) #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 3eabcb194c87..031392ee5f47 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -1030,7 +1030,13 @@ alternative_else_nop_endif msr tpidrro_el0, x30 // Restored in kernel_ventry .endif tramp_map_kernel x30 +#ifdef CONFIG_RANDOMIZE_BASE + adr x30, tramp_vectors + PAGE_SIZE +alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 + ldr x30, [x30] +#else ldr x30, =vectors +#endif prfm plil1strm, [x30, #(1b - tramp_vectors)] msr vbar_el1, x30 add x30, x30, #(1b - tramp_vectors) @@ -1073,6 +1079,14 @@ END(tramp_exit_compat) .ltorg .popsection // .entry.tramp.text +#ifdef CONFIG_RANDOMIZE_BASE + .pushsection ".rodata", "a" + .align PAGE_SHIFT + .globl __entry_tramp_data_start +__entry_tramp_data_start: + .quad vectors + .popsection // .rodata +#endif /* CONFIG_RANDOMIZE_BASE */ #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ /* diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 6b4260f22aab..ddfd3c0942f7 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -251,7 +251,10 @@ ASSERT(__idmap_text_end - (__idmap_text_start & ~(SZ_4K - 1)) <= SZ_4K, ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1)) <= SZ_4K, "Hibernate exit text too big or misaligned") #endif - +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE, + "Entry trampoline text too big") +#endif /* * If padding is applied before .head.text, virt<->phys conversions will fail. */ diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index fe68a48c64cb..916d9ced1c3f 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -541,8 +541,16 @@ static int __init map_entry_trampoline(void) __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE, prot, pgd_pgtable_alloc, 0); - /* ...as well as the kernel page table */ + /* Map both the text and data into the kernel page table */ __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot); + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { + extern char __entry_tramp_data_start[]; + + __set_fixmap(FIX_ENTRY_TRAMP_DATA, + __pa_symbol(__entry_tramp_data_start), + PAGE_KERNEL_RO); + } + return 0; } core_initcall(map_entry_trampoline); |