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Thu, 2 Apr 2020 09:34:20 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id CME2grp4VRse; Thu, 2 Apr 2020 09:34:19 +0200 (CEST) Received: from pc16570vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 9E8318B75E; Thu, 2 Apr 2020 09:34:19 +0200 (CEST) Received: by pc16570vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 6E5E8656BF; Thu, 2 Apr 2020 07:34:19 +0000 (UTC) Message-Id: In-Reply-To: <27106d62fdbd4ffb47796236050e418131cb837f.1585811416.git.christophe.leroy@c-s.fr> References: <27106d62fdbd4ffb47796236050e418131cb837f.1585811416.git.christophe.leroy@c-s.fr> From: Christophe Leroy Subject: [PATCH RESEND 4/4] powerpc/uaccess: Implement user_read_access_begin and user_write_access_begin To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , airlied@linux.ie, daniel@ffwll.ch, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, keescook@chromium.org, hpa@zytor.com Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-arch@vger.kernel.org Date: Thu, 2 Apr 2020 07:34:19 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Add support for selective read or write user access with user_read_access_begin/end and user_write_access_begin/end. Signed-off-by: Christophe Leroy Reviewed-by: Kees Cook --- arch/powerpc/include/asm/book3s/32/kup.h | 4 ++-- arch/powerpc/include/asm/kup.h | 14 +++++++++++++- arch/powerpc/include/asm/uaccess.h | 22 ++++++++++++++++++++++ 3 files changed, 37 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index 3c0ba22dc360..1617e73bee30 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -108,7 +108,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user u32 addr, end; BUILD_BUG_ON(!__builtin_constant_p(dir)); - BUILD_BUG_ON(dir == KUAP_CURRENT); + BUILD_BUG_ON(dir & ~KUAP_READ_WRITE); if (!(dir & KUAP_WRITE)) return; @@ -131,7 +131,7 @@ static __always_inline void prevent_user_access(void __user *to, const void __us BUILD_BUG_ON(!__builtin_constant_p(dir)); - if (dir == KUAP_CURRENT) { + if (dir & KUAP_CURRENT_WRITE) { u32 kuap = current->thread.kuap; if (unlikely(!kuap)) diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index 92bcd1a26d73..c745ee41ad66 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -10,7 +10,9 @@ * Use the current saved situation instead of the to/from/size params. * Used on book3s/32 */ -#define KUAP_CURRENT 4 +#define KUAP_CURRENT_READ 4 +#define KUAP_CURRENT_WRITE 8 +#define KUAP_CURRENT (KUAP_CURRENT_READ | KUAP_CURRENT_WRITE) #ifdef CONFIG_PPC64 #include @@ -101,6 +103,16 @@ static inline void prevent_current_access_user(void) prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT); } +static inline void prevent_current_read_from_user(void) +{ + prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT_READ); +} + +static inline void prevent_current_write_to_user(void) +{ + prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT_WRITE); +} + #endif /* !__ASSEMBLY__ */ #endif /* _ASM_POWERPC_KUAP_H_ */ diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 2f500debae21..4427d419eb1d 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -468,6 +468,28 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t #define user_access_save prevent_user_access_return #define user_access_restore restore_user_access +static __must_check inline bool +user_read_access_begin(const void __user *ptr, size_t len) +{ + if (unlikely(!access_ok(ptr, len))) + return false; + allow_read_from_user(ptr, len); + return true; +} +#define user_read_access_begin user_read_access_begin +#define user_read_access_end prevent_current_read_from_user + +static __must_check inline bool +user_write_access_begin(const void __user *ptr, size_t len) +{ + if (unlikely(!access_ok(ptr, len))) + return false; + allow_write_to_user((void __user *)ptr, len); + return true; +} +#define user_write_access_begin user_write_access_begin +#define user_write_access_end prevent_current_write_to_user + #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) #define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e) #define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e)