lkml.org 
[lkml]   [2018]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 15/29] arm64: kaslr: Put kernel vectors address in separate data page
Date
From: Will Deacon <will.deacon@arm.com>

commit 6c27c4082f4f upstream.

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>
Signed-off-by: Alex Shi <alex.shi@linaro.org>

Conflicts:
remove ARM64_WORKAROUND_QCOM_FALKOR_E1003 fix
in arch/arm64/kernel/entry.S
---
arch/arm64/include/asm/fixmap.h | 1 +
arch/arm64/kernel/entry.S | 13 +++++++++++++
arch/arm64/kernel/vmlinux.lds.S | 5 ++++-
arch/arm64/mm/mmu.c | 10 +++++++++-
4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
index 7b1d88c..d8e5805 100644
--- a/arch/arm64/include/asm/fixmap.h
+++ b/arch/arm64/include/asm/fixmap.h
@@ -53,6 +53,7 @@ enum fixed_addresses {
FIX_TEXT_POKE0,

#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 54f35cc..996c605 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -903,7 +903,12 @@ __ni_sys_trace:
msr tpidrro_el0, x30 // Restored in kernel_ventry
.endif
tramp_map_kernel x30
+#ifdef CONFIG_RANDOMIZE_BASE
+ adr x30, tramp_vectors + PAGE_SIZE
+ ldr x30, [x30]
+#else
ldr x30, =vectors
+#endif
prfm plil1strm, [x30, #(1b - tramp_vectors)]
msr vbar_el1, x30
add x30, x30, #(1b - tramp_vectors)
@@ -946,6 +951,14 @@ 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 466a43a..6a58455 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -252,7 +252,10 @@ 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 84945c9..10db4bf 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -435,8 +435,16 @@ 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);
--
2.7.4
\
 
 \ /
  Last update: 2018-02-28 05:04    [W:0.178 / U:2.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site