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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id f13sm832999pje.11.2019.05.29.19.04.18 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 19:04:18 -0700 (PDT) Date: Wed, 29 May 2019 19:04:17 -0700 From: Kees Cook To: Kristina Martsenko Subject: Re: [RFC v2 2/7] arm64: install user ptrauth keys at kernel exit time Message-ID: <201905291901.0430DB6E@keescook> References: <20190529190332.29753-1-kristina.martsenko@arm.com> <20190529190332.29753-3-kristina.martsenko@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190529190332.29753-3-kristina.martsenko@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190529_190422_288813_D1A1EFD8 X-CRM114-Status: GOOD ( 23.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Ard Biesheuvel , Catalin Marinas , Suzuki K Poulose , Will Deacon , Ramana Radhakrishnan , Amit Kachhap , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 29, 2019 at 08:03:27PM +0100, Kristina Martsenko wrote: > As we're going to enable pointer auth within the kernel and use a > different APIAKey for the kernel itself, then move the user APIAKey > switch to EL0 exception return. > > The other 4 keys could remain switched during task switch, but are also > moved to keep things simple. > > Signed-off-by: Kristina Martsenko Reviewed-by: Kees Cook -Kees > --- > > Changes since RFC v1: > - Install all 5 keys on kernel_exit > - Updated prctl to have keys installed on kernel exit > - Renamed ptrauth-asm.h to asm_pointer_auth.h > - Minor cleanups > - Updated the commit message > > arch/arm64/include/asm/asm_pointer_auth.h | 43 +++++++++++++++++++++++++++++++ > arch/arm64/include/asm/pointer_auth.h | 23 +---------------- > arch/arm64/kernel/asm-offsets.c | 11 ++++++++ > arch/arm64/kernel/entry.S | 3 +++ > arch/arm64/kernel/pointer_auth.c | 3 --- > arch/arm64/kernel/process.c | 1 - > 6 files changed, 58 insertions(+), 26 deletions(-) > create mode 100644 arch/arm64/include/asm/asm_pointer_auth.h > > diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h > new file mode 100644 > index 000000000000..e3bfddfe80b6 > --- /dev/null > +++ b/arch/arm64/include/asm/asm_pointer_auth.h > @@ -0,0 +1,43 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef __ASM_ASM_POINTER_AUTH_H > +#define __ASM_ASM_POINTER_AUTH_H > + > +#include > +#include > +#include > +#include > + > +#ifdef CONFIG_ARM64_PTR_AUTH > + > + .macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3 > + mov \tmp1, #THREAD_KEYS_USER > + add \tmp1, \tsk, \tmp1 > +alternative_if ARM64_HAS_ADDRESS_AUTH > + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KEY_APIA] > + msr_s SYS_APIAKEYLO_EL1, \tmp2 > + msr_s SYS_APIAKEYHI_EL1, \tmp3 > + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KEY_APIB] > + msr_s SYS_APIBKEYLO_EL1, \tmp2 > + msr_s SYS_APIBKEYHI_EL1, \tmp3 > + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KEY_APDA] > + msr_s SYS_APDAKEYLO_EL1, \tmp2 > + msr_s SYS_APDAKEYHI_EL1, \tmp3 > + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KEY_APDB] > + msr_s SYS_APDBKEYLO_EL1, \tmp2 > + msr_s SYS_APDBKEYHI_EL1, \tmp3 > +alternative_else_nop_endif > +alternative_if ARM64_HAS_GENERIC_AUTH > + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KEY_APGA] > + msr_s SYS_APGAKEYLO_EL1, \tmp2 > + msr_s SYS_APGAKEYHI_EL1, \tmp3 > +alternative_else_nop_endif > + .endm > + > +#else /* CONFIG_ARM64_PTR_AUTH */ > + > + .macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3 > + .endm > + > +#endif /* CONFIG_ARM64_PTR_AUTH */ > + > +#endif /* __ASM_ASM_POINTER_AUTH_H */ > diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h > index 15d49515efdd..fc8dc70cc19f 100644 > --- a/arch/arm64/include/asm/pointer_auth.h > +++ b/arch/arm64/include/asm/pointer_auth.h > @@ -50,19 +50,6 @@ do { \ > write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \ > } while (0) > > -static inline void ptrauth_keys_switch(struct ptrauth_keys *keys) > -{ > - if (system_supports_address_auth()) { > - __ptrauth_key_install(APIA, keys->apia); > - __ptrauth_key_install(APIB, keys->apib); > - __ptrauth_key_install(APDA, keys->apda); > - __ptrauth_key_install(APDB, keys->apdb); > - } > - > - if (system_supports_generic_auth()) > - __ptrauth_key_install(APGA, keys->apga); > -} > - > extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg); > > /* > @@ -78,20 +65,12 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr) > } > > #define ptrauth_thread_init_user(tsk) \ > -do { \ > - struct task_struct *__ptiu_tsk = (tsk); \ > - ptrauth_keys_init(&__ptiu_tsk->thread.keys_user); \ > - ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user); \ > -} while (0) > - > -#define ptrauth_thread_switch(tsk) \ > - ptrauth_keys_switch(&(tsk)->thread.keys_user) > + ptrauth_keys_init(&(tsk)->thread.keys_user) > > #else /* CONFIG_ARM64_PTR_AUTH */ > #define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL) > #define ptrauth_strip_insn_pac(lr) (lr) > #define ptrauth_thread_init_user(tsk) > -#define ptrauth_thread_switch(tsk) > #endif /* CONFIG_ARM64_PTR_AUTH */ > > #endif /* __ASM_POINTER_AUTH_H */ > diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c > index 7f40dcbdd51d..edc471e4acb1 100644 > --- a/arch/arm64/kernel/asm-offsets.c > +++ b/arch/arm64/kernel/asm-offsets.c > @@ -51,6 +51,9 @@ int main(void) > #endif > BLANK(); > DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context)); > +#ifdef CONFIG_ARM64_PTR_AUTH > + DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user)); > +#endif > BLANK(); > DEFINE(S_X0, offsetof(struct pt_regs, regs[0])); > DEFINE(S_X2, offsetof(struct pt_regs, regs[2])); > @@ -153,5 +156,13 @@ int main(void) > DEFINE(SDEI_EVENT_INTREGS, offsetof(struct sdei_registered_event, interrupted_regs)); > DEFINE(SDEI_EVENT_PRIORITY, offsetof(struct sdei_registered_event, priority)); > #endif > +#ifdef CONFIG_ARM64_PTR_AUTH > + DEFINE(PTRAUTH_KEY_APIA, offsetof(struct ptrauth_keys, apia)); > + DEFINE(PTRAUTH_KEY_APIB, offsetof(struct ptrauth_keys, apib)); > + DEFINE(PTRAUTH_KEY_APDA, offsetof(struct ptrauth_keys, apda)); > + DEFINE(PTRAUTH_KEY_APDB, offsetof(struct ptrauth_keys, apdb)); > + DEFINE(PTRAUTH_KEY_APGA, offsetof(struct ptrauth_keys, apga)); > + BLANK(); > +#endif > return 0; > } > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index c50a7a75f2e0..73a28d88f78d 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -25,6 +25,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -336,6 +337,8 @@ alternative_if ARM64_WORKAROUND_845719 > alternative_else_nop_endif > #endif > 3: > + ptrauth_keys_install_user tsk, x0, x1, x2 > + > apply_ssbd 0, x0, x1 > .endif > > diff --git a/arch/arm64/kernel/pointer_auth.c b/arch/arm64/kernel/pointer_auth.c > index c507b584259d..95985be67891 100644 > --- a/arch/arm64/kernel/pointer_auth.c > +++ b/arch/arm64/kernel/pointer_auth.c > @@ -19,7 +19,6 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg) > > if (!arg) { > ptrauth_keys_init(keys); > - ptrauth_keys_switch(keys); > return 0; > } > > @@ -41,7 +40,5 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg) > if (arg & PR_PAC_APGAKEY) > get_random_bytes(&keys->apga, sizeof(keys->apga)); > > - ptrauth_keys_switch(keys); > - > return 0; > } > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index 3767fb21a5b8..a9b30111b725 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -481,7 +481,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, > contextidr_thread_switch(next); > entry_task_switch(next); > uao_thread_switch(next); > - ptrauth_thread_switch(next); > > /* > * Complete any pending TLB or cache maintenance on this CPU in case > -- > 2.11.0 > -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel