142781e108
On syscall entry certain work needs to be done: - Establish state (lockdep, context tracking, tracing) - Conditional work (ptrace, seccomp, audit...) This code is needlessly duplicated and different in all architectures. Provide a generic version based on the x86 implementation which has all the RCU and instrumentation bits right. As interrupt/exception entry from user space needs parts of the same functionality, provide a function for this as well. syscall_enter_from_user_mode() and irqentry_enter_from_user_mode() must be called right after the low level ASM entry. The calling code must be non-instrumentable. After the functions returns state is correct and the subsequent functions can be instrumented. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20200722220519.513463269@linutronix.de
122 lines
3.7 KiB
C
122 lines
3.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_ENTRYCOMMON_H
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#define __LINUX_ENTRYCOMMON_H
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#include <linux/tracehook.h>
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#include <linux/syscalls.h>
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#include <linux/seccomp.h>
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#include <linux/sched.h>
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#include <asm/entry-common.h>
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/*
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* Define dummy _TIF work flags if not defined by the architecture or for
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* disabled functionality.
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*/
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#ifndef _TIF_SYSCALL_EMU
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# define _TIF_SYSCALL_EMU (0)
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#endif
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#ifndef _TIF_SYSCALL_TRACEPOINT
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# define _TIF_SYSCALL_TRACEPOINT (0)
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#endif
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#ifndef _TIF_SECCOMP
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# define _TIF_SECCOMP (0)
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#endif
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#ifndef _TIF_SYSCALL_AUDIT
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# define _TIF_SYSCALL_AUDIT (0)
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#endif
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/*
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* TIF flags handled in syscall_enter_from_usermode()
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*/
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#ifndef ARCH_SYSCALL_ENTER_WORK
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# define ARCH_SYSCALL_ENTER_WORK (0)
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#endif
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#define SYSCALL_ENTER_WORK \
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(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
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_TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \
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ARCH_SYSCALL_ENTER_WORK)
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/**
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* arch_check_user_regs - Architecture specific sanity check for user mode regs
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* @regs: Pointer to currents pt_regs
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*
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* Defaults to an empty implementation. Can be replaced by architecture
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* specific code.
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*
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* Invoked from syscall_enter_from_user_mode() in the non-instrumentable
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* section. Use __always_inline so the compiler cannot push it out of line
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* and make it instrumentable.
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*/
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static __always_inline void arch_check_user_regs(struct pt_regs *regs);
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#ifndef arch_check_user_regs
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static __always_inline void arch_check_user_regs(struct pt_regs *regs) {}
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#endif
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/**
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* arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry()
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* @regs: Pointer to currents pt_regs
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*
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* Returns: 0 on success or an error code to skip the syscall.
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*
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* Defaults to tracehook_report_syscall_entry(). Can be replaced by
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* architecture specific code.
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*
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* Invoked from syscall_enter_from_user_mode()
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*/
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static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs);
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#ifndef arch_syscall_enter_tracehook
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static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs)
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{
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return tracehook_report_syscall_entry(regs);
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}
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#endif
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/**
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* syscall_enter_from_user_mode - Check and handle work before invoking
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* a syscall
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* @regs: Pointer to currents pt_regs
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* @syscall: The syscall number
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*
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* Invoked from architecture specific syscall entry code with interrupts
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* disabled. The calling code has to be non-instrumentable. When the
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* function returns all state is correct and the subsequent functions can be
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* instrumented.
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*
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* Returns: The original or a modified syscall number
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*
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* If the returned syscall number is -1 then the syscall should be
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* skipped. In this case the caller may invoke syscall_set_error() or
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* syscall_set_return_value() first. If neither of those are called and -1
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* is returned, then the syscall will fail with ENOSYS.
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*
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* The following functionality is handled here:
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*
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* 1) Establish state (lockdep, RCU (context tracking), tracing)
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* 2) TIF flag dependent invocations of arch_syscall_enter_tracehook(),
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* __secure_computing(), trace_sys_enter()
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* 3) Invocation of audit_syscall_entry()
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*/
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long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall);
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/**
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* irqentry_enter_from_user_mode - Establish state before invoking the irq handler
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* @regs: Pointer to currents pt_regs
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*
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* Invoked from architecture specific entry code with interrupts disabled.
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* Can only be called when the interrupt entry came from user mode. The
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* calling code must be non-instrumentable. When the function returns all
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* state is correct and the subsequent functions can be instrumented.
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*
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* The function establishes state (lockdep, RCU (context tracking), tracing)
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*/
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void irqentry_enter_from_user_mode(struct pt_regs *regs);
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#endif
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