From: Kees Cook <keescook@chromium.org> To: linux-kernel@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, Rabin Vincent <rabin@rab.in>, Liu hua <sdu.liu@huawei.com>, Mark Salter <msalter@redhat.com>, Nikolay Borisov <Nikolay.Borisov@arm.com>, Nicolas Pitre <nicolas.pitre@linaro.org>, Leif Lindholm <leif.lindholm@linaro.org>, Tomasz Figa <t.figa@samsung.com>, Rob Herring <robh@kernel.org>, Doug Anderson <dianders@google.com>, Will Deacon <will.deacon@arm.com>, Laura Abbott <lauraa@codeaurora.org>, Catalin Marinas <catalin.marinas@arm.com>, Russell King - ARM Linux <linux@arm.linux.org.uk>, linux-arm-kernel@lists.infradead.org Subject: [PATCH 4/7] arm: use fixmap for text patching when text is RO Date: Wed, 6 Aug 2014 12:32:41 -0700 [thread overview] Message-ID: <1407353564-21478-5-git-send-email-keescook@chromium.org> (raw) In-Reply-To: <1407353564-21478-1-git-send-email-keescook@chromium.org> From: Rabin Vincent <rabin@rab.in> Use fixmaps for text patching when the kernel text is read-only, inspired by x86. This makes jump labels and kprobes work with the currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming CONFIG_DEBUG_RODATA options. Signed-off-by: Rabin Vincent <rabin@rab.in> [update for "ARM: 8031/2: change fixmap mapping region to support 32 CPUs"] Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/arm/include/asm/fixmap.h | 4 +++ arch/arm/kernel/jump_label.c | 2 +- arch/arm/kernel/patch.c | 70 ++++++++++++++++++++++++++++++++++++++----- arch/arm/kernel/patch.h | 12 +++++++- 4 files changed, 79 insertions(+), 9 deletions(-) diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h index 3ed08232be55..056f2be273a3 100644 --- a/arch/arm/include/asm/fixmap.h +++ b/arch/arm/include/asm/fixmap.h @@ -19,6 +19,10 @@ enum fixed_addresses { FIX_KMAP_BEGIN, FIX_KMAP_END = (FIX_KMAP_NR_PTES * FIX_KMAP_NR_CPUS) - 1, + /* Support writing RO kernel text via kprobes, jump labels, etc. */ + FIX_TEXT_POKE0, + FIX_TEXT_POKE1, + __end_of_fixed_addresses }; diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c index 4ce4f789446d..afeeb9ea6f43 100644 --- a/arch/arm/kernel/jump_label.c +++ b/arch/arm/kernel/jump_label.c @@ -19,7 +19,7 @@ static void __arch_jump_label_transform(struct jump_entry *entry, insn = arm_gen_nop(); if (is_static) - __patch_text(addr, insn); + __patch_text_early(addr, insn); else patch_text(addr, insn); } diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c index 07314af47733..03dd4e39c833 100644 --- a/arch/arm/kernel/patch.c +++ b/arch/arm/kernel/patch.c @@ -1,8 +1,11 @@ #include <linux/kernel.h> +#include <linux/spinlock.h> #include <linux/kprobes.h> +#include <linux/mm.h> #include <linux/stop_machine.h> #include <asm/cacheflush.h> +#include <asm/fixmap.h> #include <asm/smp_plat.h> #include <asm/opcodes.h> @@ -13,21 +16,69 @@ struct patch { unsigned int insn; }; -void __kprobes __patch_text(void *addr, unsigned int insn) +static DEFINE_SPINLOCK(patch_lock); + +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) +{ + unsigned int uintaddr = (uintptr_t) addr; + bool module = !core_kernel_text(uintaddr); + struct page *page; + + if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) + page = vmalloc_to_page(addr); + else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA)) + page = virt_to_page(addr); + else + return addr; + + if (flags) + spin_lock_irqsave(&patch_lock, *flags); + + set_fixmap(fixmap, page_to_phys(page)); + + return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK)); +} + +static void __kprobes patch_unmap(int fixmap, unsigned long *flags) +{ + clear_fixmap(fixmap); + + if (flags) + spin_unlock_irqrestore(&patch_lock, *flags); +} + +void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap) { bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL); + unsigned int uintaddr = (uintptr_t) addr; + bool twopage = false; + unsigned long flags; + void *waddr = addr; int size; + if (remap) + waddr = patch_map(addr, FIX_TEXT_POKE0, &flags); + if (thumb2 && __opcode_is_thumb16(insn)) { - *(u16 *)addr = __opcode_to_mem_thumb16(insn); + *(u16 *)waddr = __opcode_to_mem_thumb16(insn); size = sizeof(u16); - } else if (thumb2 && ((uintptr_t)addr & 2)) { + } else if (thumb2 && (uintaddr & 2)) { u16 first = __opcode_thumb32_first(insn); u16 second = __opcode_thumb32_second(insn); - u16 *addrh = addr; + u16 *addrh0 = waddr; + u16 *addrh1 = waddr + 2; - addrh[0] = __opcode_to_mem_thumb16(first); - addrh[1] = __opcode_to_mem_thumb16(second); + twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2; + if (twopage && remap) + addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL); + + *addrh0 = __opcode_to_mem_thumb16(first); + *addrh1 = __opcode_to_mem_thumb16(second); + + if (twopage && addrh1 != addr + 2) { + flush_kernel_vmap_range(addrh1, 2); + patch_unmap(FIX_TEXT_POKE1, NULL); + } size = sizeof(u32); } else { @@ -36,10 +87,15 @@ void __kprobes __patch_text(void *addr, unsigned int insn) else insn = __opcode_to_mem_arm(insn); - *(u32 *)addr = insn; + *(u32 *)waddr = insn; size = sizeof(u32); } + if (waddr != addr) { + flush_kernel_vmap_range(waddr, twopage ? size / 2 : size); + patch_unmap(FIX_TEXT_POKE0, &flags); + } + flush_icache_range((uintptr_t)(addr), (uintptr_t)(addr) + size); } diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h index b4731f2dac38..77e054c2f6cd 100644 --- a/arch/arm/kernel/patch.h +++ b/arch/arm/kernel/patch.h @@ -2,6 +2,16 @@ #define _ARM_KERNEL_PATCH_H void patch_text(void *addr, unsigned int insn); -void __patch_text(void *addr, unsigned int insn); +void __patch_text_real(void *addr, unsigned int insn, bool remap); + +static inline void __patch_text(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, true); +} + +static inline void __patch_text_early(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, false); +} #endif -- 1.9.1
WARNING: multiple messages have this Message-ID (diff)
From: keescook@chromium.org (Kees Cook) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 4/7] arm: use fixmap for text patching when text is RO Date: Wed, 6 Aug 2014 12:32:41 -0700 [thread overview] Message-ID: <1407353564-21478-5-git-send-email-keescook@chromium.org> (raw) In-Reply-To: <1407353564-21478-1-git-send-email-keescook@chromium.org> From: Rabin Vincent <rabin@rab.in> Use fixmaps for text patching when the kernel text is read-only, inspired by x86. This makes jump labels and kprobes work with the currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming CONFIG_DEBUG_RODATA options. Signed-off-by: Rabin Vincent <rabin@rab.in> [update for "ARM: 8031/2: change fixmap mapping region to support 32 CPUs"] Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/arm/include/asm/fixmap.h | 4 +++ arch/arm/kernel/jump_label.c | 2 +- arch/arm/kernel/patch.c | 70 ++++++++++++++++++++++++++++++++++++++----- arch/arm/kernel/patch.h | 12 +++++++- 4 files changed, 79 insertions(+), 9 deletions(-) diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h index 3ed08232be55..056f2be273a3 100644 --- a/arch/arm/include/asm/fixmap.h +++ b/arch/arm/include/asm/fixmap.h @@ -19,6 +19,10 @@ enum fixed_addresses { FIX_KMAP_BEGIN, FIX_KMAP_END = (FIX_KMAP_NR_PTES * FIX_KMAP_NR_CPUS) - 1, + /* Support writing RO kernel text via kprobes, jump labels, etc. */ + FIX_TEXT_POKE0, + FIX_TEXT_POKE1, + __end_of_fixed_addresses }; diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c index 4ce4f789446d..afeeb9ea6f43 100644 --- a/arch/arm/kernel/jump_label.c +++ b/arch/arm/kernel/jump_label.c @@ -19,7 +19,7 @@ static void __arch_jump_label_transform(struct jump_entry *entry, insn = arm_gen_nop(); if (is_static) - __patch_text(addr, insn); + __patch_text_early(addr, insn); else patch_text(addr, insn); } diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c index 07314af47733..03dd4e39c833 100644 --- a/arch/arm/kernel/patch.c +++ b/arch/arm/kernel/patch.c @@ -1,8 +1,11 @@ #include <linux/kernel.h> +#include <linux/spinlock.h> #include <linux/kprobes.h> +#include <linux/mm.h> #include <linux/stop_machine.h> #include <asm/cacheflush.h> +#include <asm/fixmap.h> #include <asm/smp_plat.h> #include <asm/opcodes.h> @@ -13,21 +16,69 @@ struct patch { unsigned int insn; }; -void __kprobes __patch_text(void *addr, unsigned int insn) +static DEFINE_SPINLOCK(patch_lock); + +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) +{ + unsigned int uintaddr = (uintptr_t) addr; + bool module = !core_kernel_text(uintaddr); + struct page *page; + + if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) + page = vmalloc_to_page(addr); + else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA)) + page = virt_to_page(addr); + else + return addr; + + if (flags) + spin_lock_irqsave(&patch_lock, *flags); + + set_fixmap(fixmap, page_to_phys(page)); + + return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK)); +} + +static void __kprobes patch_unmap(int fixmap, unsigned long *flags) +{ + clear_fixmap(fixmap); + + if (flags) + spin_unlock_irqrestore(&patch_lock, *flags); +} + +void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap) { bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL); + unsigned int uintaddr = (uintptr_t) addr; + bool twopage = false; + unsigned long flags; + void *waddr = addr; int size; + if (remap) + waddr = patch_map(addr, FIX_TEXT_POKE0, &flags); + if (thumb2 && __opcode_is_thumb16(insn)) { - *(u16 *)addr = __opcode_to_mem_thumb16(insn); + *(u16 *)waddr = __opcode_to_mem_thumb16(insn); size = sizeof(u16); - } else if (thumb2 && ((uintptr_t)addr & 2)) { + } else if (thumb2 && (uintaddr & 2)) { u16 first = __opcode_thumb32_first(insn); u16 second = __opcode_thumb32_second(insn); - u16 *addrh = addr; + u16 *addrh0 = waddr; + u16 *addrh1 = waddr + 2; - addrh[0] = __opcode_to_mem_thumb16(first); - addrh[1] = __opcode_to_mem_thumb16(second); + twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2; + if (twopage && remap) + addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL); + + *addrh0 = __opcode_to_mem_thumb16(first); + *addrh1 = __opcode_to_mem_thumb16(second); + + if (twopage && addrh1 != addr + 2) { + flush_kernel_vmap_range(addrh1, 2); + patch_unmap(FIX_TEXT_POKE1, NULL); + } size = sizeof(u32); } else { @@ -36,10 +87,15 @@ void __kprobes __patch_text(void *addr, unsigned int insn) else insn = __opcode_to_mem_arm(insn); - *(u32 *)addr = insn; + *(u32 *)waddr = insn; size = sizeof(u32); } + if (waddr != addr) { + flush_kernel_vmap_range(waddr, twopage ? size / 2 : size); + patch_unmap(FIX_TEXT_POKE0, &flags); + } + flush_icache_range((uintptr_t)(addr), (uintptr_t)(addr) + size); } diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h index b4731f2dac38..77e054c2f6cd 100644 --- a/arch/arm/kernel/patch.h +++ b/arch/arm/kernel/patch.h @@ -2,6 +2,16 @@ #define _ARM_KERNEL_PATCH_H void patch_text(void *addr, unsigned int insn); -void __patch_text(void *addr, unsigned int insn); +void __patch_text_real(void *addr, unsigned int insn, bool remap); + +static inline void __patch_text(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, true); +} + +static inline void __patch_text_early(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, false); +} #endif -- 1.9.1
next prev parent reply other threads:[~2014-08-06 19:35 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-08-06 19:32 [PATCH 0/7] arm: support CONFIG_RODATA Kees Cook 2014-08-06 19:32 ` Kees Cook 2014-08-06 19:32 ` [PATCH 1/7] arm: use generic fixmap.h Kees Cook 2014-08-06 19:32 ` Kees Cook 2014-08-07 2:24 ` Laura Abbott 2014-08-07 2:24 ` Laura Abbott 2014-08-07 14:35 ` Kees Cook 2014-08-07 14:35 ` Kees Cook 2014-08-07 15:15 ` Max Filippov 2014-08-07 15:15 ` Max Filippov 2014-08-07 15:22 ` Rob Herring 2014-08-07 15:22 ` Rob Herring 2014-08-07 15:32 ` Nicolas Pitre 2014-08-07 15:32 ` Nicolas Pitre 2014-08-07 15:42 ` Max Filippov 2014-08-07 15:42 ` Max Filippov 2014-08-07 17:23 ` Mark Salter 2014-08-07 17:23 ` Mark Salter 2014-08-06 19:32 ` [PATCH 2/7] arm: fixmap: implement __set_fixmap() Kees Cook 2014-08-06 19:32 ` Kees Cook 2014-08-06 19:32 ` [PATCH 3/7] arm: mm: reduce fixmap kmap from 32 to 16 CPUS Kees Cook 2014-08-06 19:32 ` Kees Cook 2014-08-06 19:32 ` Kees Cook [this message] 2014-08-06 19:32 ` [PATCH 4/7] arm: use fixmap for text patching when text is RO Kees Cook 2014-08-06 19:32 ` [PATCH 5/7] ARM: kexec: Make .text R/W in machine_kexec Kees Cook 2014-08-06 19:32 ` Kees Cook 2014-08-06 19:32 ` [PATCH 6/7] ARM: mm: allow non-text sections to be non-executable Kees Cook 2014-08-06 19:32 ` Kees Cook 2014-08-06 19:32 ` [PATCH 7/7] ARM: mm: allow text and rodata sections to be read-only Kees Cook 2014-08-06 19:32 ` Kees Cook
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