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dac494bf54
This adds the stub side for the new seccomp process management code. In this case we do register save/restore through the signal handler mcontext. Add special code for handling TLS, which for x86_64 means setting the FS_BASE/GS_BASE registers while for i386 it means calling the set_thread_area syscall. Co-authored-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250602130052.545733-3-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
154 lines
3.2 KiB
C
154 lines
3.2 KiB
C
/*
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* Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
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* Licensed under the GPL
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*/
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#ifndef __SYSDEP_STUB_H
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#define __SYSDEP_STUB_H
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#include <stddef.h>
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#include <sysdep/ptrace_user.h>
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#include <generated/asm-offsets.h>
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#include <linux/stddef.h>
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#include <asm/prctl.h>
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#define STUB_MMAP_NR __NR_mmap
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#define MMAP_OFFSET(o) (o)
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#define __syscall_clobber "r11","rcx","memory"
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#define __syscall "syscall"
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static __always_inline long stub_syscall0(long syscall)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall) : __syscall_clobber );
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return ret;
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}
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static __always_inline long stub_syscall1(long syscall, long arg1)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1) : __syscall_clobber );
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return ret;
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}
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static __always_inline long stub_syscall2(long syscall, long arg1, long arg2)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2) : __syscall_clobber );
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return ret;
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}
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static __always_inline long stub_syscall3(long syscall, long arg1, long arg2,
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long arg3)
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{
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long ret;
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__asm__ volatile (__syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3)
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: __syscall_clobber );
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return ret;
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}
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static __always_inline long stub_syscall4(long syscall, long arg1, long arg2, long arg3,
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long arg4)
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{
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long ret;
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__asm__ volatile ("movq %5,%%r10 ; " __syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
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"g" (arg4)
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: __syscall_clobber, "r10" );
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return ret;
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}
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static __always_inline long stub_syscall5(long syscall, long arg1, long arg2,
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long arg3, long arg4, long arg5)
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{
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long ret;
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__asm__ volatile ("movq %5,%%r10 ; movq %6,%%r8 ; " __syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
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"g" (arg4), "g" (arg5)
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: __syscall_clobber, "r10", "r8" );
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return ret;
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}
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static __always_inline long stub_syscall6(long syscall, long arg1, long arg2,
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long arg3, long arg4, long arg5,
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long arg6)
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{
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long ret;
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__asm__ volatile ("movq %5,%%r10 ; movq %6,%%r8 ; movq %7,%%r9 ; "
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__syscall
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: "=a" (ret)
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: "0" (syscall), "D" (arg1), "S" (arg2), "d" (arg3),
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"g" (arg4), "g" (arg5), "g" (arg6)
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: __syscall_clobber, "r10", "r8", "r9");
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return ret;
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}
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static __always_inline void trap_myself(void)
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{
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__asm("int3");
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}
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static __always_inline void *get_stub_data(void)
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{
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unsigned long ret;
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asm volatile (
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"lea 0(%%rip), %0;"
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"andq %1, %0 ;"
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"addq %2, %0 ;"
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: "=a" (ret)
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: "g" (~(UM_KERN_PAGE_SIZE - 1)),
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"g" (UM_KERN_PAGE_SIZE));
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return (void *)ret;
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}
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#define stub_start(fn) \
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asm volatile ( \
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"subq %0,%%rsp ;" \
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"movq %1,%%rax ;" \
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"call *%%rax ;" \
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:: "i" ((1 + STUB_DATA_PAGES) * UM_KERN_PAGE_SIZE), \
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"i" (&fn))
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static __always_inline void
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stub_seccomp_restore_state(struct stub_data_arch *arch)
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{
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/*
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* We could use _writefsbase_u64/_writegsbase_u64 if the host reports
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* support in the hwcaps (HWCAP2_FSGSBASE).
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*/
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if (arch->sync & STUB_SYNC_FS_BASE)
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stub_syscall2(__NR_arch_prctl, ARCH_SET_FS, arch->fs_base);
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if (arch->sync & STUB_SYNC_GS_BASE)
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stub_syscall2(__NR_arch_prctl, ARCH_SET_GS, arch->gs_base);
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arch->sync = 0;
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}
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#endif
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