Commit-ID: 4cdba14f84c9102c4434384731cd61018b970d59 Gitweb: http://git.kernel.org/tip/4cdba14f84c9102c4434384731cd61018b970d59 Author: Baoquan He <b...@redhat.com> AuthorDate: Sat, 13 May 2017 13:46:29 +0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 24 May 2017 09:50:27 +0200
x86/KASLR: Handle the memory limit specified by the 'memmap=' and 'mem=' boot options The 'mem=' boot option limits the max address a system can use - any memory region above the limit will be removed. Furthermore, the 'memmap=nn[KMG]' variant (with no offset specified) has the same behaviour as 'mem='. KASLR needs to consider this when choosing the random position for decompressing the kernel. Do it. Tested-by: Masayoshi Mizuma <m.miz...@jp.fujitsu.com> Signed-off-by: Baoquan He <b...@redhat.com> Acked-by: Kees Cook <keesc...@chromium.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: dan.j.willi...@intel.com Cc: douly.f...@cn.fujitsu.com Cc: dyo...@redhat.com Link: http://lkml.kernel.org/r/1494654390-23861-3-git-send-email-...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/boot/compressed/kaslr.c | 68 +++++++++++++++++++++++++++++----------- 1 file changed, 50 insertions(+), 18 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 106e13b..e0eba12 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -88,6 +88,10 @@ struct mem_vector { static bool memmap_too_large; +/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */ +unsigned long long mem_limit = ULLONG_MAX; + + enum mem_avoid_index { MEM_AVOID_ZO_RANGE = 0, MEM_AVOID_INITRD, @@ -138,16 +142,23 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size) return -EINVAL; switch (*p) { - case '@': - /* Skip this region, usable */ - *start = 0; - *size = 0; - return 0; case '#': case '$': case '!': *start = memparse(p + 1, &p); return 0; + case '@': + /* memmap=nn@ss specifies usable region, should be skipped */ + *size = 0; + /* Fall through */ + default: + /* + * If w/o offset, only size specified, memmap=nn[KMG] has the + * same behaviour as mem=nn[KMG]. It limits the max address + * system can use. Region above the limit should be avoided. + */ + *start = 0; + return 0; } return -EINVAL; @@ -173,9 +184,14 @@ static void mem_avoid_memmap(char *str) if (rc < 0) break; str = k; - /* A usable region that should not be skipped */ - if (size == 0) + + if (start == 0) { + /* Store the specified memory limit if size > 0 */ + if (size > 0) + mem_limit = size; + continue; + } mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start; mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size; @@ -187,19 +203,15 @@ static void mem_avoid_memmap(char *str) memmap_too_large = true; } - -/* - * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove - * this note later. - */ static int handle_mem_memmap(void) { char *args = (char *)get_cmd_line_ptr(); size_t len = strlen((char *)args); char *tmp_cmdline; char *param, *val; + u64 mem_size; - if (!strstr(args, "memmap=")) + if (!strstr(args, "memmap=") && !strstr(args, "mem=")) return 0; tmp_cmdline = malloc(len + 1); @@ -222,8 +234,20 @@ static int handle_mem_memmap(void) return -1; } - if (!strcmp(param, "memmap")) + if (!strcmp(param, "memmap")) { mem_avoid_memmap(val); + } else if (!strcmp(param, "mem")) { + char *p = val; + + if (!strcmp(p, "nopentium")) + continue; + mem_size = memparse(p, &p); + if (mem_size == 0) { + free(tmp_cmdline); + return -EINVAL; + } + mem_limit = mem_size; + } } free(tmp_cmdline); @@ -460,7 +484,8 @@ static void process_e820_entry(struct boot_e820_entry *entry, { struct mem_vector region, overlap; struct slot_area slot_area; - unsigned long start_orig; + unsigned long start_orig, end; + struct boot_e820_entry cur_entry; /* Skip non-RAM entries. */ if (entry->type != E820_TYPE_RAM) @@ -474,8 +499,15 @@ static void process_e820_entry(struct boot_e820_entry *entry, if (entry->addr + entry->size < minimum) return; - region.start = entry->addr; - region.size = entry->size; + /* Ignore entries above memory limit */ + end = min(entry->size + entry->addr, mem_limit); + if (entry->addr >= end) + return; + cur_entry.addr = entry->addr; + cur_entry.size = end - entry->addr; + + region.start = cur_entry.addr; + region.size = cur_entry.size; /* Give up if slot area array is full. */ while (slot_area_index < MAX_SLOT_AREA) { @@ -489,7 +521,7 @@ static void process_e820_entry(struct boot_e820_entry *entry, region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN); /* Did we raise the address above this e820 region? */ - if (region.start > entry->addr + entry->size) + if (region.start > cur_entry.addr + cur_entry.size) return; /* Reduce size by any delta from the original address. */
