32e8eaf263
Using clone will not undo features that have been enabled by libc. An example of this already happening is rseq, which could cause the kernel to read/write memory of the userspace process. In the future the standard library might also use mseal by default to protect itself, which would also thwart our attempts at unmapping everything. Solve all this by taking a step back and doing an execve into a tiny static binary that sets up the minimal environment required for the stub without using any standard library. That way we have a clean execution environment that is fully under the control of UML. Note that this changes things a bit as the FDs are not anymore shared with the kernel. Instead, we explicitly share the FDs for the physical memory and all existing iomem regions. Doing this is fine, as iomem regions cannot be added at runtime. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20240919124511.282088-3-benjamin@sipsolutions.net [use pipe() instead of pipe2(), remove unneeded close() calls] Signed-off-by: Johannes Berg <johannes.berg@intel.com>
60 lines
1.2 KiB
C
60 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
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* Copyright (C) 2005 Jeff Dike (jdike@karaya.com)
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*/
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#ifndef __STUB_DATA_H
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#define __STUB_DATA_H
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#include <linux/compiler_types.h>
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#include <as-layout.h>
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#include <sysdep/tls.h>
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struct stub_init_data {
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unsigned long stub_start;
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int stub_code_fd;
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unsigned long stub_code_offset;
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int stub_data_fd;
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unsigned long stub_data_offset;
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unsigned long segv_handler;
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};
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#define STUB_NEXT_SYSCALL(s) \
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((struct stub_syscall *) (((unsigned long) s) + (s)->cmd_len))
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enum stub_syscall_type {
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STUB_SYSCALL_UNSET = 0,
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STUB_SYSCALL_MMAP,
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STUB_SYSCALL_MUNMAP,
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STUB_SYSCALL_MPROTECT,
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};
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struct stub_syscall {
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struct {
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unsigned long addr;
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unsigned long length;
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unsigned long offset;
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int fd;
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int prot;
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} mem;
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enum stub_syscall_type syscall;
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};
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struct stub_data {
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unsigned long offset;
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long err, child_err;
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int syscall_data_len;
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/* 128 leaves enough room for additional fields in the struct */
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struct stub_syscall syscall_data[(UM_KERN_PAGE_SIZE - 128) / sizeof(struct stub_syscall)] __aligned(16);
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/* Stack for our signal handlers and for calling into . */
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unsigned char sigstack[UM_KERN_PAGE_SIZE] __aligned(UM_KERN_PAGE_SIZE);
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};
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#endif
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