Revert "x86/mm/ASLR: Propagate base load address calculation"

This reverts commit:

  f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")

The main reason for the revert is that the new boot flag does not work
at all currently, and in order to make this work, we need non-trivial
changes to the x86 boot code which we didn't manage to get done in
time for merging.

And even if we did, they would've been too risky so instead of
rushing things and break booting 4.1 on boxes left and right, we
will be very strict and conservative and will take our time with
this to fix and test it properly.

Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: H. Peter Anvin <hpa@linux.intel.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Junjie Mao <eternal.n08@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/20150316100628.GD22995@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index 7083c16cccba0b2b144ea5e03e160ebafe81e855..bb1376381985edb9f96e49c0a1b0269e56bd0f9e 100644 (file)
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -14,13 +14,6 @@
 static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
                LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
 
-struct kaslr_setup_data {
-       __u64 next;
-       __u32 type;
-       __u32 len;
-       __u8 data[1];
-} kaslr_setup_data;
-
 #define I8254_PORT_CONTROL     0x43
 #define I8254_PORT_COUNTER0    0x40
 #define I8254_CMD_READBACK     0xC0
@@ -302,29 +295,7 @@ static unsigned long find_random_addr(unsigned long minimum,
        return slots_fetch_random();
 }
 
-static void add_kaslr_setup_data(struct boot_params *params, __u8 enabled)
-{
-       struct setup_data *data;
-
-       kaslr_setup_data.type = SETUP_KASLR;
-       kaslr_setup_data.len = 1;
-       kaslr_setup_data.next = 0;
-       kaslr_setup_data.data[0] = enabled;
-
-       data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
-
-       while (data && data->next)
-               data = (struct setup_data *)(unsigned long)data->next;
-
-       if (data)
-               data->next = (unsigned long)&kaslr_setup_data;
-       else
-               params->hdr.setup_data = (unsigned long)&kaslr_setup_data;
-
-}
-
-unsigned char *choose_kernel_location(struct boot_params *params,
-                                     unsigned char *input,
+unsigned char *choose_kernel_location(unsigned char *input,
                                      unsigned long input_size,
                                      unsigned char *output,
                                      unsigned long output_size)
@@ -335,17 +306,14 @@ unsigned char *choose_kernel_location(struct boot_params *params,
 #ifdef CONFIG_HIBERNATION
        if (!cmdline_find_option_bool("kaslr")) {
                debug_putstr("KASLR disabled by default...\n");
-               add_kaslr_setup_data(params, 0);
                goto out;
        }
 #else
        if (cmdline_find_option_bool("nokaslr")) {
                debug_putstr("KASLR disabled by cmdline...\n");
-               add_kaslr_setup_data(params, 0);
                goto out;
        }
 #endif
-       add_kaslr_setup_data(params, 1);
 
        /* Record the various known unsafe memory ranges. */
        mem_avoid_init((unsigned long)input, input_size,

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 5903089c818f6843b9d1cc7c83507cf0d28a3e26..a950864a64dab3d558197c77bef3c56a07961494 100644 (file)
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -401,8 +401,7 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
         * the entire decompressed kernel plus relocation table, or the
         * entire decompressed kernel plus .bss and .brk sections.
         */
-       output = choose_kernel_location(real_mode, input_data, input_len,
-                                       output,
+       output = choose_kernel_location(input_data, input_len, output,
                                        output_len > run_size ? output_len
                                                              : run_size);
 

diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index ee3576b2666b8139eedf25077ce769da10712c11..04477d68403f1fe6197d82276033ce27338c1bac 100644 (file)
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -57,8 +57,7 @@ int cmdline_find_option_bool(const char *option);
 
 #if CONFIG_RANDOMIZE_BASE
 /* aslr.c */
-unsigned char *choose_kernel_location(struct boot_params *params,
-                                     unsigned char *input,
+unsigned char *choose_kernel_location(unsigned char *input,
                                      unsigned long input_size,
                                      unsigned char *output,
                                      unsigned long output_size);
@@ -66,8 +65,7 @@ unsigned char *choose_kernel_location(struct boot_params *params,
 bool has_cpuflag(int flag);
 #else
 static inline
-unsigned char *choose_kernel_location(struct boot_params *params,
-                                     unsigned char *input,
+unsigned char *choose_kernel_location(unsigned char *input,
                                      unsigned long input_size,
                                      unsigned char *output,
                                      unsigned long output_size)

diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
index 95e11f79f123c6aadd5ed8888a51e1870405deeb..f97fbe3abb67f5059d4e6f0a37261d6113df19de 100644 (file)
--- a/arch/x86/include/asm/page_types.h
+++ b/arch/x86/include/asm/page_types.h
@@ -51,8 +51,6 @@ extern int devmem_is_allowed(unsigned long pagenr);
 extern unsigned long max_low_pfn_mapped;
 extern unsigned long max_pfn_mapped;
 
-extern bool kaslr_enabled;
-
 static inline phys_addr_t get_max_mapped(void)
 {
        return (phys_addr_t)max_pfn_mapped << PAGE_SHIFT;

diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index 44e6dd7e36a23becd48def85b218b1d70ac938e6..225b0988043a0a78ac9092a9af7a265122c685cd 100644 (file)
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -7,7 +7,6 @@
 #define SETUP_DTB                      2
 #define SETUP_PCI                      3
 #define SETUP_EFI                      4
-#define SETUP_KASLR                    5
 
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK       0x07FF

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 9bbb9b35c144a4f721ed4e7dcfc07aee6abdc2cb..d1ac80b72c72184a0b999c2b299b5e265d26de7a 100644 (file)
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -47,13 +47,21 @@ do {                                                        \
 
 #ifdef CONFIG_RANDOMIZE_BASE
 static unsigned long module_load_offset;
+static int randomize_modules = 1;
 
 /* Mutex protects the module_load_offset. */
 static DEFINE_MUTEX(module_kaslr_mutex);
 
+static int __init parse_nokaslr(char *p)
+{
+       randomize_modules = 0;
+       return 0;
+}
+early_param("nokaslr", parse_nokaslr);
+
 static unsigned long int get_module_load_offset(void)
 {
-       if (kaslr_enabled) {
+       if (randomize_modules) {
                mutex_lock(&module_kaslr_mutex);
                /*
                 * Calculate the module_load_offset the first time this

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 98dc9317286e1e0fad25f3d10efaa3134a9134c0..0a2421cca01fad095bbb7caa8e7c779d910d751b 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -122,8 +122,6 @@
 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
@@ -427,11 +425,6 @@ 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;
@@ -457,9 +450,6 @@ 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;
                }
@@ -842,14 +832,10 @@ static void __init trim_low_memory_range(void)
 static int
 dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 {
-       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");
+       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);
 
        return 0;
 }