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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175// SPDX-License-Identifier: GPL-2.0/* * Copyright (C) 2020 Collabora Ltd. */
#include <linux/entry-common.h>#include <linux/sched.h>#include <linux/prctl.h>#include <linux/ptrace.h>#include <linux/syscall_user_dispatch.h>#include <linux/uaccess.h>#include <linux/signal.h>#include <linux/elf.h>
#include <linux/sched/signal.h>#include <linux/sched/task_stack.h>
#include <asm/syscall.h>
static void trigger_sigsys(struct pt_regs *regs){ struct kernel_siginfo info;
clear_siginfo(&info); info.si_signo = SIGSYS; info.si_code = SYS_USER_DISPATCH; info.si_call_addr = (void __user *)KSTK_EIP(current); info.si_errno = 0; info.si_arch = syscall_get_arch(current); info.si_syscall = syscall_get_nr(current, regs);
force_sig_info(&info);}
bool syscall_user_dispatch(struct pt_regs *regs){ struct syscall_user_dispatch *sd = ¤t->syscall_dispatch; char state;
if (likely(instruction_pointer(regs) - sd->offset < sd->len)) return false;
if (unlikely(arch_syscall_is_vdso_sigreturn(regs))) return false;
if (likely(sd->selector)) { /* * access_ok() is performed once, at prctl time, when * the selector is loaded by userspace. */ if (unlikely(__get_user(state, sd->selector))) { force_exit_sig(SIGSEGV); return true; }
if (likely(state == SYSCALL_DISPATCH_FILTER_ALLOW)) return false;
if (state != SYSCALL_DISPATCH_FILTER_BLOCK) { force_exit_sig(SIGSYS); return true; } }
sd->on_dispatch = true; syscall_rollback(current, regs); trigger_sigsys(regs);
return true;}
static int task_set_syscall_user_dispatch(struct task_struct *task, unsigned long mode, unsigned long offset, unsigned long len, char __user *selector){ switch (mode) { case PR_SYS_DISPATCH_OFF: if (offset || len || selector) return -EINVAL; break; case PR_SYS_DISPATCH_EXCLUSIVE_ON: /* * Validate the direct dispatcher region just for basic * sanity against overflow and a 0-sized dispatcher * region. If the user is able to submit a syscall from * an address, that address is obviously valid. */ if (offset && offset + len <= offset) return -EINVAL; break; case PR_SYS_DISPATCH_INCLUSIVE_ON: if (len == 0 || offset + len <= offset) return -EINVAL; /* * Invert the range, the check in syscall_user_dispatch() * supports wrap-around. */ offset = offset + len; len = -len; break; default: return -EINVAL; }
/* * access_ok() will clear memory tags for tagged addresses * if current has memory tagging enabled. * * To enable a tracer to set a tracees selector the * selector address must be untagged for access_ok(), * otherwise an untagged tracer will always fail to set a * tagged tracees selector. */ if (mode != PR_SYS_DISPATCH_OFF && selector && !access_ok(untagged_addr(selector), sizeof(*selector))) return -EFAULT;
task->syscall_dispatch.selector = selector; task->syscall_dispatch.offset = offset; task->syscall_dispatch.len = len; task->syscall_dispatch.on_dispatch = false;
if (mode != PR_SYS_DISPATCH_OFF) set_task_syscall_work(task, SYSCALL_USER_DISPATCH); else clear_task_syscall_work(task, SYSCALL_USER_DISPATCH);
return 0;}
int set_syscall_user_dispatch(unsigned long mode, unsigned long offset, unsigned long len, char __user *selector){ return task_set_syscall_user_dispatch(current, mode, offset, len, selector);}
int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size, void __user *data){ struct syscall_user_dispatch *sd = &task->syscall_dispatch; struct ptrace_sud_config cfg;
if (size != sizeof(cfg)) return -EINVAL;
if (test_task_syscall_work(task, SYSCALL_USER_DISPATCH)) cfg.mode = PR_SYS_DISPATCH_ON; else cfg.mode = PR_SYS_DISPATCH_OFF;
cfg.offset = sd->offset; cfg.len = sd->len; cfg.selector = (__u64)(uintptr_t)sd->selector;
if (copy_to_user(data, &cfg, sizeof(cfg))) return -EFAULT;
return 0;}
int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size, void __user *data){ struct ptrace_sud_config cfg;
if (size != sizeof(cfg)) return -EINVAL;
if (copy_from_user(&cfg, data, sizeof(cfg))) return -EFAULT;
return task_set_syscall_user_dispatch(task, cfg.mode, cfg.offset, cfg.len, (char __user *)(uintptr_t)cfg.selector);}