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| author | Jiri Kosina <jkosina@suse.cz> | 2015-02-13 18:04:55 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2015-02-19 13:38:54 +0300 |
| commit | f47233c2d34f243ecdaac179c3408a39ff9216a7 (patch) | |
| tree | b42d4847dd27acbea3526134adfc3f7b5780c5cd /arch/x86/kernel/setup.c | |
| parent | bfa76d49576599a4b9f9b7a71f23d73d6dcff735 (diff) | |
| download | linux-f47233c2d34f243ecdaac179c3408a39ff9216a7.tar.xz | |
x86/mm/ASLR: Propagate base load address calculation
Commit:
e2b32e678513 ("x86, kaslr: randomize module base load address")
makes the base address for module to be unconditionally randomized in
case when CONFIG_RANDOMIZE_BASE is defined and "nokaslr" option isn't
present on the commandline.
This is not consistent with how choose_kernel_location() decides whether
it will randomize kernel load base.
Namely, CONFIG_HIBERNATION disables kASLR (unless "kaslr" option is
explicitly specified on kernel commandline), which makes the state space
larger than what module loader is looking at. IOW CONFIG_HIBERNATION &&
CONFIG_RANDOMIZE_BASE is a valid config option, kASLR wouldn't be applied
by default in that case, but module loader is not aware of that.
Instead of fixing the logic in module.c, this patch takes more generic
aproach. It introduces a new bootparam setup data_type SETUP_KASLR and
uses that to pass the information whether kaslr has been applied during
kernel decompression, and sets a global 'kaslr_enabled' variable
accordingly, so that any kernel code (module loading, livepatching, ...)
can make decisions based on its value.
x86 module loader is converted to make use of this flag.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Link: https://lkml.kernel.org/r/alpine.LNX.2.00.1502101411280.10719@pobox.suse.cz
[ Always dump correct kaslr status when panicking ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'arch/x86/kernel/setup.c')
| -rw-r--r-- | arch/x86/kernel/setup.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index ab4734e5411d..16b6043cb073 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -121,6 +121,8 @@ unsigned long max_low_pfn_mapped; unsigned long max_pfn_mapped; +bool __read_mostly kaslr_enabled = false; + #ifdef CONFIG_DMI RESERVE_BRK(dmi_alloc, 65536); #endif @@ -424,6 +426,11 @@ static void __init reserve_initrd(void) } #endif /* CONFIG_BLK_DEV_INITRD */ +static void __init parse_kaslr_setup(u64 pa_data, u32 data_len) +{ + kaslr_enabled = (bool)(pa_data + sizeof(struct setup_data)); +} + static void __init parse_setup_data(void) { struct setup_data *data; @@ -451,6 +458,9 @@ static void __init parse_setup_data(void) case SETUP_EFI: parse_efi_setup(pa_data, data_len); break; + case SETUP_KASLR: + parse_kaslr_setup(pa_data, data_len); + break; default: break; } @@ -833,10 +843,14 @@ static void __init trim_low_memory_range(void) static int dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) { - pr_emerg("Kernel Offset: 0x%lx from 0x%lx " - "(relocation range: 0x%lx-0x%lx)\n", - (unsigned long)&_text - __START_KERNEL, __START_KERNEL, - __START_KERNEL_map, MODULES_VADDR-1); + if (kaslr_enabled) + pr_emerg("Kernel Offset: 0x%lx from 0x%lx (relocation range: 0x%lx-0x%lx)\n", + (unsigned long)&_text - __START_KERNEL, + __START_KERNEL, + __START_KERNEL_map, + MODULES_VADDR-1); + else + pr_emerg("Kernel Offset: disabled\n"); return 0; } |