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Message-Id: <20170322203834.67556-4-thgarnie@google.com> Date: Wed, 22 Mar 2017 13:38:34 -0700 From: Thomas Garnier <thgarnie@...gle.com> To: Martin Schwidefsky <schwidefsky@...ibm.com>, Heiko Carstens <heiko.carstens@...ibm.com>, Dave Hansen <dave.hansen@...el.com>, David Howells <dhowells@...hat.com>, Al Viro <viro@...iv.linux.org.uk>, Arnd Bergmann <arnd@...db.de>, Thomas Garnier <thgarnie@...gle.com>, René Nyffenegger <mail@...enyffenegger.ch>, Andrew Morton <akpm@...ux-foundation.org>, "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>, Ingo Molnar <mingo@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Oleg Nesterov <oleg@...hat.com>, Pavel Tikhomirov <ptikhomirov@...tuozzo.com>, Stephen Smalley <sds@...ho.nsa.gov>, Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>, Rik van Riel <riel@...hat.com>, Kees Cook <keescook@...omium.org>, Josh Poimboeuf <jpoimboe@...hat.com>, Borislav Petkov <bp@...en8.de>, Brian Gerst <brgerst@...il.com>, "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Christian Borntraeger <borntraeger@...ibm.com>, Russell King <linux@...linux.org.uk>, Vladimir Murzin <vladimir.murzin@....com>, Will Deacon <will.deacon@....com>, Catalin Marinas <catalin.marinas@....com>, Mark Rutland <mark.rutland@....com>, James Morse <james.morse@....com> Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org, linux-api@...r.kernel.org, x86@...nel.org, linux-arm-kernel@...ts.infradead.org, kernel-hardening@...ts.openwall.com Subject: [PATCH v4 4/4] arm64/syscalls: Specific usage of verify_pre_usermode_state Implement specific usage of verify_pre_usermode_state for user-mode returns for arm64. --- Based on next-20170322 --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/entry.S | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f2b0b528037d..0e86d87259f4 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -24,6 +24,7 @@ config ARM64 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION select ARCH_WANT_FRAME_POINTERS select ARCH_HAS_UBSAN_SANITIZE_ALL + select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE select ARM_AMBA select ARM_ARCH_TIMER select ARM_GIC diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 43512d4d7df2..685b43771ac9 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -744,6 +744,10 @@ ENDPROC(cpu_switch_to) ret_fast_syscall: disable_irq // disable interrupts str x0, [sp, #S_X0] // returned x0 + ldr x2, [tsk, #TSK_TI_ADDR_LIMIT] // check addr limit change + mov x1, #TASK_SIZE_64 + cmp x2, x1 + b.ne addr_limit_fail ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing and x2, x1, #_TIF_SYSCALL_WORK cbnz x2, ret_fast_syscall_trace @@ -771,6 +775,11 @@ work_pending: */ ret_to_user: disable_irq // disable interrupts + ldr x2, [tsk, #TSK_TI_ADDR_LIMIT] // check addr limit change + mov x1, #TASK_SIZE_64 + cmp x2, x1 + b.ne addr_limit_fail + ldr x1, [tsk, #TSK_TI_FLAGS] and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending @@ -779,6 +788,22 @@ finish_ret_to_user: kernel_exit 0 ENDPROC(ret_to_user) +addr_limit_fail: +#ifdef CONFIG_BUG_ON_DATA_CORRUPTION + stp x0, lr, [sp,#-16]! + bl verify_pre_usermode_state + ldp x0, lr, [sp],#16 +#else + /* + * Similar to set_fs(USER_DS) in verify_pre_usermode_state without a + * warning. + */ + mov x2, #TASK_SIZE_64 + str x2, [tsk, #TSK_TI_ADDR_LIMIT] + ALTERNATIVE(nop, SET_PSTATE_UAO(0), ARM64_HAS_UAO, CONFIG_ARM64_UAO) +#endif + ret lr + /* * This is how we return from a fork. */ -- 2.12.1.500.gab5fba24ee-goog
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