15b631b1ff
commit 15956689a0e60aa0c795174f3c310b60d8794235 upstream. Although we zero the upper bits of x0 on entry to the kernel from an AArch32 task, we do not clear them on the exception return path and can therefore expose 64-bit sign extended syscall return values to userspace via interfaces such as the 'perf_regs' ABI, which deal exclusively with 64-bit registers. Explicitly clear the upper 32 bits of x0 on return from a compat system call. Cc: <stable@vger.kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Keno Fischer <keno@juliacomputing.com> Cc: Luis Machado <luis.machado@linaro.org> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
139 lines
3.2 KiB
C
139 lines
3.2 KiB
C
/*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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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_error(struct task_struct *task,
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struct pt_regs *regs)
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{
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unsigned long error = regs->regs[0];
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if (is_compat_thread(task_thread_info(task)))
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error = sign_extend64(error, 31);
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return IS_ERR_VALUE(error) ? error : 0;
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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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return regs->regs[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 int i, unsigned int n,
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unsigned long *args)
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{
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if (n == 0)
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return;
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if (i + n > SYSCALL_MAX_ARGS) {
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unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
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unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
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pr_warning("%s called with max args %d, handling only %d\n",
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__func__, i + n, SYSCALL_MAX_ARGS);
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memset(args_bad, 0, n_bad * sizeof(args[0]));
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}
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if (i == 0) {
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args[0] = regs->orig_x0;
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args++;
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i++;
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n--;
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}
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memcpy(args, ®s->regs[i], n * 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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unsigned int i, unsigned int n,
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const unsigned long *args)
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{
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if (n == 0)
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return;
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if (i + n > SYSCALL_MAX_ARGS) {
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pr_warning("%s called with max args %d, handling only %d\n",
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__func__, i + n, SYSCALL_MAX_ARGS);
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n = SYSCALL_MAX_ARGS - i;
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}
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if (i == 0) {
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regs->orig_x0 = args[0];
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args++;
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i++;
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n--;
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}
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memcpy(®s->regs[i], args, n * 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(void)
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{
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if (is_compat_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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