| Message ID | 20181207183931.4285-8-kristina.martsenko@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARMv8.3 pointer authentication userspace support | expand |
On 12/7/18 12:39 PM, Kristina Martsenko wrote: > From: Mark Rutland <mark.rutland@arm.com> > > This patch adds basic support for pointer authentication, allowing > userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and > APGAKey. The kernel maintains key values for each process (shared by all > threads within), which are initialised to random values at exec() time. > > The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, > to describe that pointer authentication instructions are available and > that the kernel is managing the keys. Two new hwcaps are added for the > same reason: PACA (for address authentication) and PACG (for generic > authentication). > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> > Tested-by: Adam Wallis <awallis@codeaurora.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > --- > arch/arm64/include/asm/pointer_auth.h | 75 +++++++++++++++++++++++++++++++++++ > arch/arm64/include/asm/thread_info.h | 4 ++ > arch/arm64/include/uapi/asm/hwcap.h | 2 + > arch/arm64/kernel/cpufeature.c | 13 ++++++ > arch/arm64/kernel/cpuinfo.c | 2 + > arch/arm64/kernel/process.c | 4 ++ > 6 files changed, 100 insertions(+) > create mode 100644 arch/arm64/include/asm/pointer_auth.h Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Fri 2018-12-07 18:39:25, Kristina Martsenko wrote: > From: Mark Rutland <mark.rutland@arm.com> > > This patch adds basic support for pointer authentication, allowing > userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and > APGAKey. The kernel maintains key values for each process (shared by all > threads within), which are initialised to random values at exec() time. ... > +/* > + * We give each process its own keys, which are shared by all threads. The keys > + * are inherited upon fork(), and reinitialised upon exec*(). > + */ > +struct ptrauth_keys { > + struct ptrauth_key apia; > + struct ptrauth_key apib; > + struct ptrauth_key apda; > + struct ptrauth_key apdb; > + struct ptrauth_key apga; > +}; intstruction_a, data_a, generic_a? Should be easier to understand than "apdb" ... Pavel
On 03/01/2019 20:29, Pavel Machek wrote: > On Fri 2018-12-07 18:39:25, Kristina Martsenko wrote: >> From: Mark Rutland <mark.rutland@arm.com> >> >> This patch adds basic support for pointer authentication, >> allowing userspace to make use of APIAKey, APIBKey, APDAKey, >> APDBKey, and APGAKey. The kernel maintains key values for each >> process (shared by all threads within), which are initialised to >> random values at exec() > time. > > ... > >> +/* + * We give each process its own keys, which are shared by >> all threads. The keys + * are inherited upon fork(), and >> reinitialised upon exec*(). + */ +struct ptrauth_keys { + struct >> ptrauth_key apia; + struct ptrauth_key apib; + struct ptrauth_key >> apda; + struct ptrauth_key apdb; + struct ptrauth_key apga; +}; > > intstruction_a, data_a, generic_a? Should be easier to understand > than "apdb" ... ... until you realize that these names do match the documentation, which makes it even easier to understand how the code uses the architecture. M.
On Fri 2019-01-04 09:21:30, Marc Zyngier wrote: > On 03/01/2019 20:29, Pavel Machek wrote: > > On Fri 2018-12-07 18:39:25, Kristina Martsenko wrote: > >> From: Mark Rutland <mark.rutland@arm.com> > >> > >> This patch adds basic support for pointer authentication, > >> allowing userspace to make use of APIAKey, APIBKey, APDAKey, > >> APDBKey, and APGAKey. The kernel maintains key values for each > >> process (shared by all threads within), which are initialised to > >> random values at exec() > > time. > > > > ... > > > >> +/* + * We give each process its own keys, which are shared by > >> all threads. The keys + * are inherited upon fork(), and > >> reinitialised upon exec*(). + */ +struct ptrauth_keys { + struct > >> ptrauth_key apia; + struct ptrauth_key apib; + struct ptrauth_key > >> apda; + struct ptrauth_key apdb; + struct ptrauth_key apga; +}; > > > > intstruction_a, data_a, generic_a? Should be easier to understand > > than "apdb" ... > > ... until you realize that these names do match the documentation, > which makes it even easier to understand how the code uses the > architecture. See how not even the commit log matches the documentation then? Naming something "apdb" is just bad... Just because the documentation is evil does not mean it should be followed... Pavel
On Fri, Jan 04, 2019 at 10:33:40AM +0100, Pavel Machek wrote: > On Fri 2019-01-04 09:21:30, Marc Zyngier wrote: > > On 03/01/2019 20:29, Pavel Machek wrote: > > > On Fri 2018-12-07 18:39:25, Kristina Martsenko wrote: > > >> From: Mark Rutland <mark.rutland@arm.com> > > >> > > >> This patch adds basic support for pointer authentication, > > >> allowing userspace to make use of APIAKey, APIBKey, APDAKey, > > >> APDBKey, and APGAKey. The kernel maintains key values for each > > >> process (shared by all threads within), which are initialised to > > >> random values at exec() > > > time. > > > > > > ... > > > > > >> +/* + * We give each process its own keys, which are shared by > > >> all threads. The keys + * are inherited upon fork(), and > > >> reinitialised upon exec*(). + */ +struct ptrauth_keys { + struct > > >> ptrauth_key apia; + struct ptrauth_key apib; + struct ptrauth_key > > >> apda; + struct ptrauth_key apdb; + struct ptrauth_key apga; +}; > > > > > > intstruction_a, data_a, generic_a? Should be easier to understand > > > than "apdb" ... > > > > ... until you realize that these names do match the documentation, > > which makes it even easier to understand how the code uses the > > architecture. > > See how not even the commit log matches the documentation then? The commit message exactly matches the documentation, as it refers to: APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey ... which are the architected names for those registers, in all the documentation. Searching "apga" in the ARM ARM finds all of the relevant information on APGAKey_EL1. Searching "generic_a" finds precisely nothing, as it's a term which you invented, that no-one else has previously used. Likewise for the other key names. > Naming something "apdb" is just bad... Just because the documentation > is evil does not mean it should be followed... It is in no way evil to use the documented names for things. It is unhelpful to make up terminology that no-one else uses. Mark.
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h new file mode 100644 index 000000000000..fc7ffe8e326f --- /dev/null +++ b/arch/arm64/include/asm/pointer_auth.h @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0 +#ifndef __ASM_POINTER_AUTH_H +#define __ASM_POINTER_AUTH_H + +#include <linux/random.h> + +#include <asm/cpufeature.h> +#include <asm/sysreg.h> + +#ifdef CONFIG_ARM64_PTR_AUTH +/* + * Each key is a 128-bit quantity which is split across a pair of 64-bit + * registers (Lo and Hi). + */ +struct ptrauth_key { + unsigned long lo, hi; +}; + +/* + * We give each process its own keys, which are shared by all threads. The keys + * are inherited upon fork(), and reinitialised upon exec*(). + */ +struct ptrauth_keys { + struct ptrauth_key apia; + struct ptrauth_key apib; + struct ptrauth_key apda; + struct ptrauth_key apdb; + struct ptrauth_key apga; +}; + +static inline void ptrauth_keys_init(struct ptrauth_keys *keys) +{ + if (system_supports_address_auth()) + get_random_bytes(keys, sizeof(struct ptrauth_key) * 4); + + if (system_supports_generic_auth()) + get_random_bytes(&keys->apga, sizeof(struct ptrauth_key)); +} + +#define __ptrauth_key_install(k, v) \ +do { \ + struct ptrauth_key __pki_v = (v); \ + write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \ + 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); +} + +#define ptrauth_thread_init_user(tsk) \ +do { \ + struct task_struct *__ptiu_tsk = (tsk); \ + ptrauth_keys_init(&__ptiu_tsk->thread_info.keys_user); \ + ptrauth_keys_switch(&__ptiu_tsk->thread_info.keys_user); \ +} while (0) + +#define ptrauth_thread_switch(tsk) \ + ptrauth_keys_switch(&(tsk)->thread_info.keys_user) + +#else /* CONFIG_ARM64_PTR_AUTH */ +#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/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index cb2c10a8f0a8..ea9272fb52d4 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -28,6 +28,7 @@ struct task_struct; #include <asm/memory.h> +#include <asm/pointer_auth.h> #include <asm/stack_pointer.h> #include <asm/types.h> @@ -43,6 +44,9 @@ struct thread_info { u64 ttbr0; /* saved TTBR0_EL1 */ #endif int preempt_count; /* 0 => preemptable, <0 => bug */ +#ifdef CONFIG_ARM64_PTR_AUTH + struct ptrauth_keys keys_user; +#endif }; #define thread_saved_pc(tsk) \ diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h index 2bcd6e4f3474..22efc70aa0a1 100644 --- a/arch/arm64/include/uapi/asm/hwcap.h +++ b/arch/arm64/include/uapi/asm/hwcap.h @@ -49,5 +49,7 @@ #define HWCAP_ILRCPC (1 << 26) #define HWCAP_FLAGM (1 << 27) #define HWCAP_SSBS (1 << 28) +#define HWCAP_PACA (1 << 29) +#define HWCAP_PACG (1 << 30) #endif /* _UAPI__ASM_HWCAP_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index f8e3c3568a79..6daa2f451eb9 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1154,6 +1154,12 @@ static void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused) #endif /* CONFIG_ARM64_RAS_EXTN */ #ifdef CONFIG_ARM64_PTR_AUTH +static void cpu_enable_address_auth(struct arm64_cpu_capabilities const *cap) +{ + sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | + SCTLR_ELx_ENDA | SCTLR_ELx_ENDB); +} + static bool has_address_auth(const struct arm64_cpu_capabilities *entry, int __unused) { @@ -1431,6 +1437,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .capability = ARM64_HAS_ADDRESS_AUTH, .type = ARM64_CPUCAP_SYSTEM_FEATURE, .matches = has_address_auth, + .cpu_enable = cpu_enable_address_auth, }, { .desc = "Generic authentication (architected algorithm)", @@ -1504,6 +1511,12 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = { HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, HWCAP_SVE), #endif HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_SSBS_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_SSBS_PSTATE_INSNS, CAP_HWCAP, HWCAP_SSBS), +#ifdef CONFIG_ARM64_PTR_AUTH + { .desc = "HWCAP_PACA", .type = ARM64_CPUCAP_SYSTEM_FEATURE, .matches = has_address_auth, + .hwcap_type = CAP_HWCAP, .hwcap = HWCAP_PACA }, + { .desc = "HWCAP_PACG", .type = ARM64_CPUCAP_SYSTEM_FEATURE, .matches = has_generic_auth, + .hwcap_type = CAP_HWCAP, .hwcap = HWCAP_PACG }, +#endif {}, }; diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index bcc2831399cb..e7c7cad8dd85 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -82,6 +82,8 @@ static const char *const hwcap_str[] = { "ilrcpc", "flagm", "ssbs", + "paca", + "pacg", NULL }; diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index d9a4c2d6dd8b..17a6b4dd6e46 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -57,6 +57,7 @@ #include <asm/fpsimd.h> #include <asm/mmu_context.h> #include <asm/processor.h> +#include <asm/pointer_auth.h> #include <asm/stacktrace.h> #ifdef CONFIG_STACKPROTECTOR @@ -429,6 +430,7 @@ __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 @@ -496,4 +498,6 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) void arch_setup_new_exec(void) { current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; + + ptrauth_thread_init_user(current); }