3d7d1b0f5f
commit e30e8d46cf605d216a799a28c77b8a41c328613a upstream. Due to inconsistencies in the way we manipulate compat GPRs, we have a few issues today: * For audit and tracing, where error codes are handled as a (native) long, negative error codes are expected to be sign-extended to the native 64-bits, or they may fail to be matched correctly. Thus a syscall which fails with an error may erroneously be identified as failing. * For ptrace, *all* compat return values should be sign-extended for consistency with 32-bit arm, but we currently only do this for negative return codes. * As we may transiently set the upper 32 bits of some compat GPRs while in the kernel, these can be sampled by perf, which is somewhat confusing. This means that where a syscall returns a pointer above 2G, this will be sign-extended, but will not be mistaken for an error as error codes are constrained to the inclusive range [-4096, -1] where no user pointer can exist. To fix all of these, we must consistently use helpers to get/set the compat GPRs, ensuring that we never write the upper 32 bits of the return code, and always sign-extend when reading the return code. This patch does so, with the following changes: * We re-organise syscall_get_return_value() to always sign-extend for compat tasks, and reimplement syscall_get_error() atop. We update syscall_trace_exit() to use syscall_get_return_value(). * We consistently use syscall_set_return_value() to set the return value, ensureing the upper 32 bits are never set unexpectedly. * As the core audit code currently uses regs_return_value() rather than syscall_get_return_value(), we special-case this for compat_user_mode(regs) such that this will do the right thing. Going forward, we should try to move the core audit code over to syscall_get_return_value(). Cc: <stable@vger.kernel.org> Reported-by: He Zhe <zhe.he@windriver.com> Reported-by: weiyuchen <weiyuchen3@huawei.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20210802104200.21390-1-mark.rutland@arm.com Signed-off-by: Will Deacon <will@kernel.org> [Mark: trivial conflict resolution for v5.10.y] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
99 lines
2.1 KiB
C
99 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2012 ARM Ltd.
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*/
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#ifndef __ASM_SYSCALL_H
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#define __ASM_SYSCALL_H
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#include <uapi/linux/audit.h>
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#include <linux/compat.h>
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#include <linux/err.h>
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typedef long (*syscall_fn_t)(const struct pt_regs *regs);
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extern const syscall_fn_t sys_call_table[];
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#ifdef CONFIG_COMPAT
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extern const syscall_fn_t compat_sys_call_table[];
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#endif
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static inline int syscall_get_nr(struct task_struct *task,
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struct pt_regs *regs)
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{
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return regs->syscallno;
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}
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static inline void syscall_rollback(struct task_struct *task,
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struct pt_regs *regs)
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{
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regs->regs[0] = regs->orig_x0;
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}
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static inline long syscall_get_return_value(struct task_struct *task,
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struct pt_regs *regs)
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{
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unsigned long val = regs->regs[0];
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if (is_compat_thread(task_thread_info(task)))
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val = sign_extend64(val, 31);
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return val;
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}
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static inline long syscall_get_error(struct task_struct *task,
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struct pt_regs *regs)
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{
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unsigned long error = syscall_get_return_value(task, regs);
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return IS_ERR_VALUE(error) ? error : 0;
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}
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static inline void syscall_set_return_value(struct task_struct *task,
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struct pt_regs *regs,
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int error, long val)
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{
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if (error)
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val = error;
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if (is_compat_thread(task_thread_info(task)))
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val = lower_32_bits(val);
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regs->regs[0] = val;
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}
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#define SYSCALL_MAX_ARGS 6
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static inline void syscall_get_arguments(struct task_struct *task,
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struct pt_regs *regs,
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unsigned long *args)
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{
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args[0] = regs->orig_x0;
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args++;
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memcpy(args, ®s->regs[1], 5 * sizeof(args[0]));
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}
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static inline void syscall_set_arguments(struct task_struct *task,
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struct pt_regs *regs,
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const unsigned long *args)
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{
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regs->orig_x0 = args[0];
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args++;
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memcpy(®s->regs[1], args, 5 * sizeof(args[0]));
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}
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/*
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* We don't care about endianness (__AUDIT_ARCH_LE bit) here because
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* AArch64 has the same system calls both on little- and big- endian.
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*/
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static inline int syscall_get_arch(struct task_struct *task)
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{
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if (is_compat_thread(task_thread_info(task)))
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return AUDIT_ARCH_ARM;
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return AUDIT_ARCH_AARCH64;
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}
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#endif /* __ASM_SYSCALL_H */
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