1/* 2 * Copyright (c) 2002 Andi Kleen <ak@suse.de> 3 * Copyright (c) 2002 Michal Ludvig <mludvig@suse.cz> 4 * Copyright (c) 2002 Roland McGrath <roland@redhat.com> 5 * Copyright (c) 2008-2013 Denys Vlasenko <vda.linux@googlemail.com> 6 * Copyright (c) 2012 H.J. Lu <hongjiu.lu@intel.com> 7 * Copyright (c) 2010-2015 Dmitry V. Levin <ldv@altlinux.org> 8 * Copyright (c) 2015-2018 The strace developers. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34#ifdef X86_64 35# define X32_PERSONALITY_NUMBER 2 36#else 37# define X32_PERSONALITY_NUMBER 0 38#endif 39 40/* Return codes: 1 - ok, 0 - ignore, other - error. */ 41static int 42arch_get_scno(struct tcb *tcp) 43{ 44 kernel_ulong_t scno = 0; 45 unsigned int currpers; 46 47#ifndef __X32_SYSCALL_BIT 48# define __X32_SYSCALL_BIT 0x40000000 49#endif 50 51#if 1 52 /* 53 * GETREGSET of NT_PRSTATUS tells us regset size, 54 * which unambiguously detects i386. 55 * 56 * Linux kernel distinguishes x86-64 and x32 processes 57 * solely by looking at __X32_SYSCALL_BIT: 58 * arch/x86/include/asm/compat.h::is_x32_task(): 59 * if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT) 60 * return true; 61 */ 62 if (x86_io.iov_len == sizeof(i386_regs)) { 63 scno = i386_regs.orig_eax; 64 currpers = 1; 65 } else { 66 scno = x86_64_regs.orig_rax; 67 currpers = 0; 68 if (scno & __X32_SYSCALL_BIT) { 69 /* 70 * Syscall number -1 requires special treatment: 71 * it might be a side effect of SECCOMP_RET_ERRNO 72 * filtering that sets orig_rax to -1 73 * in some versions of linux kernel. 74 * If that is the case, then 75 * __X32_SYSCALL_BIT logic does not apply. 76 */ 77 if ((long long) x86_64_regs.orig_rax != -1) { 78 currpers = 2; 79 } else { 80# ifdef X32 81 currpers = 2; 82# endif 83 } 84 } 85 } 86 87#elif 0 88 /* 89 * cs = 0x33 for long mode (native 64 bit and x32) 90 * cs = 0x23 for compatibility mode (32 bit) 91 * ds = 0x2b for x32 mode (x86-64 in 32 bit) 92 */ 93 scno = x86_64_regs.orig_rax; 94 switch (x86_64_regs.cs) { 95 case 0x23: 96 currpers = 1; 97 break; 98 case 0x33: 99 if (x86_64_regs.ds == 0x2b) { 100 currpers = 2; 101 } else 102 currpers = 0; 103 break; 104 default: 105 error_msg("Unknown value CS=0x%08X while " 106 "detecting personality of process PID=%d", 107 (int)x86_64_regs.cs, tcp->pid); 108 currpers = current_personality; 109 break; 110 } 111#elif 0 112 /* 113 * This version analyzes the opcode of a syscall instruction. 114 * (int 0x80 on i386 vs. syscall on x86-64) 115 * It works, but is too complicated, and strictly speaking, unreliable. 116 */ 117 unsigned long call, rip = x86_64_regs.rip; 118 /* sizeof(syscall) == sizeof(int 0x80) == 2 */ 119 rip -= 2; 120 errno = 0; 121 call = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)rip, (char *)0); 122 if (errno) 123 perror_msg("ptrace_peektext failed"); 124 switch (call & 0xffff) { 125 /* x86-64: syscall = 0x0f 0x05 */ 126 case 0x050f: 127 currpers = 0; 128 break; 129 /* i386: int 0x80 = 0xcd 0x80 */ 130 case 0x80cd: 131 currpers = 1; 132 break; 133 default: 134 currpers = current_personality; 135 error_msg("Unknown syscall opcode (0x%04X) while " 136 "detecting personality of process PID=%d", 137 (int)call, tcp->pid); 138 break; 139 } 140#endif 141 142#ifdef X32 143 /* 144 * If we are built for a x32 system, then personality 0 is x32 145 * (not x86_64), and stracing of x86_64 apps is not supported. 146 * Stracing of i386 apps is still supported. 147 */ 148 if (currpers == 0) { 149 error_msg("syscall_%" PRI_klu "(...) in unsupported " 150 "64-bit mode of process PID=%d", scno, tcp->pid); 151 return 0; 152 } 153 currpers &= ~2; /* map 2,1 to 0,1 */ 154#endif /* X32 */ 155 156 update_personality(tcp, currpers); 157 tcp->scno = scno; 158 return 1; 159} 160