From 7263dda41b5a28ae6566fd126d9b06ada73dd721 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 30 Aug 2013 15:43:03 -0700 Subject: x86, smap: Handle csum_partial_copy_*_user() Add SMAP annotations to csum_partial_copy_to/from_user(). These functions legitimately access user space and thus need to set the AC flag. TODO: add explicit checks that the side with the kernel space pointer really points into kernel space. Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/n/tip-2aps0u00eer658fd5xyanan7@git.kernel.org Cc: # v3.7+ diff --git a/arch/x86/include/asm/checksum_32.h b/arch/x86/include/asm/checksum_32.h index 46fc474..f50de69 100644 --- a/arch/x86/include/asm/checksum_32.h +++ b/arch/x86/include/asm/checksum_32.h @@ -49,9 +49,15 @@ static inline __wsum csum_partial_copy_from_user(const void __user *src, int len, __wsum sum, int *err_ptr) { + __wsum ret; + might_sleep(); - return csum_partial_copy_generic((__force void *)src, dst, - len, sum, err_ptr, NULL); + stac(); + ret = csum_partial_copy_generic((__force void *)src, dst, + len, sum, err_ptr, NULL); + clac(); + + return ret; } /* @@ -176,10 +182,16 @@ static inline __wsum csum_and_copy_to_user(const void *src, int len, __wsum sum, int *err_ptr) { + __wsum ret; + might_sleep(); - if (access_ok(VERIFY_WRITE, dst, len)) - return csum_partial_copy_generic(src, (__force void *)dst, - len, sum, NULL, err_ptr); + if (access_ok(VERIFY_WRITE, dst, len)) { + stac(); + ret = csum_partial_copy_generic(src, (__force void *)dst, + len, sum, NULL, err_ptr); + clac(); + return ret; + } if (len) *err_ptr = -EFAULT; diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c index 25b7ae8..7609e0e 100644 --- a/arch/x86/lib/csum-wrappers_64.c +++ b/arch/x86/lib/csum-wrappers_64.c @@ -6,6 +6,7 @@ */ #include #include +#include /** * csum_partial_copy_from_user - Copy and checksum from user space. @@ -52,8 +53,10 @@ csum_partial_copy_from_user(const void __user *src, void *dst, len -= 2; } } + stac(); isum = csum_partial_copy_generic((__force const void *)src, dst, len, isum, errp, NULL); + clac(); if (unlikely(*errp)) goto out_err; @@ -82,6 +85,8 @@ __wsum csum_partial_copy_to_user(const void *src, void __user *dst, int len, __wsum isum, int *errp) { + __wsum ret; + might_sleep(); if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) { @@ -105,8 +110,11 @@ csum_partial_copy_to_user(const void *src, void __user *dst, } *errp = 0; - return csum_partial_copy_generic(src, (void __force *)dst, - len, isum, NULL, errp); + stac(); + ret = csum_partial_copy_generic(src, (void __force *)dst, + len, isum, NULL, errp); + clac(); + return ret; } EXPORT_SYMBOL(csum_partial_copy_to_user); -- cgit v0.10.2 From bd1c149aa9915b9abb6d83d0f01dfd2ace0680b5 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 1 Sep 2013 20:35:01 +0100 Subject: Introduce [compat_]save_altstack_ex() to unbreak x86 SMAP For performance reasons, when SMAP is in use, SMAP is left open for an entire put_user_try { ... } put_user_catch(); block, however, calling __put_user() in the middle of that block will close SMAP as the STAC..CLAC constructs intentionally do not nest. Furthermore, using __put_user() rather than put_user_ex() here is bad for performance. Thus, introduce new [compat_]save_altstack_ex() helpers that replace __[compat_]save_altstack() for x86, being currently the only architecture which supports put_user_try { ... } put_user_catch(). Reported-by: H. Peter Anvin Signed-off-by: Al Viro Signed-off-by: H. Peter Anvin Cc: # v3.8+ Link: http://lkml.kernel.org/n/tip-es5p6y64if71k8p5u08agv9n@git.kernel.org diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index bccfca6..665a730 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -457,7 +457,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp); + compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index cf91358..d859eea 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -358,7 +358,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __save_altstack(&frame->uc.uc_stack, regs->sp); + save_altstack_ex(&frame->uc.uc_stack, regs->sp); /* Set up to return from userspace. */ restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn); @@ -423,7 +423,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __save_altstack(&frame->uc.uc_stack, regs->sp); + save_altstack_ex(&frame->uc.uc_stack, regs->sp); /* Set up to return from userspace. If provided, use a stub already in userspace. */ @@ -490,7 +490,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig, else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); - err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp); + compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp); put_user_ex(0, &frame->uc.uc__pad0); if (ksig->ka.sa.sa_flags & SA_RESTORER) { diff --git a/include/linux/compat.h b/include/linux/compat.h index 7f0c1dd..ec1aee4 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -669,6 +669,13 @@ asmlinkage long compat_sys_sigaltstack(const compat_stack_t __user *uss_ptr, int compat_restore_altstack(const compat_stack_t __user *uss); int __compat_save_altstack(compat_stack_t __user *, unsigned long); +#define compat_save_altstack_ex(uss, sp) do { \ + compat_stack_t __user *__uss = uss; \ + struct task_struct *t = current; \ + put_user_ex(ptr_to_compat((void __user *)t->sas_ss_sp), &__uss->ss_sp); \ + put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_size, &__uss->ss_size); \ +} while (0); asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid, struct compat_timespec __user *interval); diff --git a/include/linux/signal.h b/include/linux/signal.h index d897484..2ac423b 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -434,6 +434,14 @@ void signals_init(void); int restore_altstack(const stack_t __user *); int __save_altstack(stack_t __user *, unsigned long); +#define save_altstack_ex(uss, sp) do { \ + stack_t __user *__uss = uss; \ + struct task_struct *t = current; \ + put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \ + put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_size, &__uss->ss_size); \ +} while (0); + #ifdef CONFIG_PROC_FS struct seq_file; extern void render_sigset_t(struct seq_file *, const char *, sigset_t *); -- cgit v0.10.2