From: Anders Roxell anders.roxell@linaro.org
[ Upstream commit 966866892cf89d606544bca22d584ba2ef9ec208 ]
Commit 1404d6f13e47 ("arm64: dump: Add checking for writable and exectuable pages") has successfully identified code that leaves a page with W+X permissions.
[ 3.245140] arm64/mm: Found insecure W+X mapping at address (____ptrval____)/0xffff000000d90000 [ 3.245771] WARNING: CPU: 0 PID: 1 at ../arch/arm64/mm/dump.c:232 note_page+0x410/0x420 [ 3.246141] Modules linked in: [ 3.246653] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc5-next-20180928-00001-ge70ae259b853-dirty #62 [ 3.247008] Hardware name: linux,dummy-virt (DT) [ 3.247347] pstate: 80000005 (Nzcv daif -PAN -UAO) [ 3.247623] pc : note_page+0x410/0x420 [ 3.247898] lr : note_page+0x410/0x420 [ 3.248071] sp : ffff00000804bcd0 [ 3.248254] x29: ffff00000804bcd0 x28: ffff000009274000 [ 3.248578] x27: ffff00000921a000 x26: ffff80007dfff000 [ 3.248845] x25: ffff0000093f5000 x24: ffff000009526f6a [ 3.249109] x23: 0000000000000004 x22: ffff000000d91000 [ 3.249396] x21: ffff000000d90000 x20: 0000000000000000 [ 3.249661] x19: ffff00000804bde8 x18: 0000000000000400 [ 3.249924] x17: 0000000000000000 x16: 0000000000000000 [ 3.250271] x15: ffffffffffffffff x14: 295f5f5f5f6c6176 [ 3.250594] x13: 7274705f5f5f5f28 x12: 2073736572646461 [ 3.250941] x11: 20746120676e6970 x10: 70616d20582b5720 [ 3.251252] x9 : 6572756365736e69 x8 : 3039643030303030 [ 3.251519] x7 : 306666666678302f x6 : ffff0000095467b2 [ 3.251802] x5 : 0000000000000000 x4 : 0000000000000000 [ 3.252060] x3 : 0000000000000000 x2 : ffffffffffffffff [ 3.252323] x1 : 4d151327adc50b00 x0 : 0000000000000000 [ 3.252664] Call trace: [ 3.252953] note_page+0x410/0x420 [ 3.253186] walk_pgd+0x12c/0x238 [ 3.253417] ptdump_check_wx+0x68/0xf8 [ 3.253637] mark_rodata_ro+0x68/0x98 [ 3.253847] kernel_init+0x38/0x160 [ 3.254103] ret_from_fork+0x10/0x18
kprobes allocates a writable executable page with module_alloc() in order to store executable code. Reworked to that when allocate a page it sets mode RO. Inspired by commit 63fef14fc98a ("kprobes/x86: Make insn buffer always ROX and use text_poke()").
Suggested-by: Arnd Bergmann arnd@arndb.de Suggested-by: Ard Biesheuvel ard.biesheuvel@linaro.org Acked-by: Will Deacon will.deacon@arm.com Acked-by: Masami Hiramatsu mhiramat@kernel.org Reviewed-by: Laura Abbott labbott@redhat.com Signed-off-by: Anders Roxell anders.roxell@linaro.org [catalin.marinas@arm.com: removed unnecessary casts] Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/kernel/probes/kprobes.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 22a5921562c7..0417c929d21a 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -23,7 +23,9 @@ #include <linux/slab.h> #include <linux/stop_machine.h> #include <linux/sched/debug.h> +#include <linux/set_memory.h> #include <linux/stringify.h> +#include <linux/vmalloc.h> #include <asm/traps.h> #include <asm/ptrace.h> #include <asm/cacheflush.h> @@ -42,10 +44,21 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); static void __kprobes post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
+static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) +{ + void *addrs[1]; + u32 insns[1]; + + addrs[0] = addr; + insns[0] = opcode; + + return aarch64_insn_patch_text(addrs, insns, 1); +} + static void __kprobes arch_prepare_ss_slot(struct kprobe *p) { /* prepare insn slot */ - p->ainsn.api.insn[0] = cpu_to_le32(p->opcode); + patch_text(p->ainsn.api.insn, p->opcode);
flush_icache_range((uintptr_t) (p->ainsn.api.insn), (uintptr_t) (p->ainsn.api.insn) + @@ -118,15 +131,15 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) return 0; }
-static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) +void *alloc_insn_page(void) { - void *addrs[1]; - u32 insns[1]; + void *page;
- addrs[0] = (void *)addr; - insns[0] = (u32)opcode; + page = vmalloc_exec(PAGE_SIZE); + if (page) + set_memory_ro((unsigned long)page, 1);
- return aarch64_insn_patch_text(addrs, insns, 1); + return page; }
/* arm kprobe: install breakpoint in text */