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) 2015-2017 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. */
41 static int
arch_get_scno(struct tcb * tcp)42 arch_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 scno -= __X32_SYSCALL_BIT;
79 currpers = 2;
80 } else {
81 # ifdef X32
82 currpers = 2;
83 # endif
84 }
85 }
86 }
87
88 #elif 0
89 /*
90 * cs = 0x33 for long mode (native 64 bit and x32)
91 * cs = 0x23 for compatibility mode (32 bit)
92 * ds = 0x2b for x32 mode (x86-64 in 32 bit)
93 */
94 scno = x86_64_regs.orig_rax;
95 switch (x86_64_regs.cs) {
96 case 0x23:
97 currpers = 1;
98 break;
99 case 0x33:
100 if (x86_64_regs.ds == 0x2b) {
101 currpers = 2;
102 scno &= ~__X32_SYSCALL_BIT;
103 } else
104 currpers = 0;
105 break;
106 default:
107 error_msg("Unknown value CS=0x%08X while "
108 "detecting personality of process PID=%d",
109 (int)x86_64_regs.cs, tcp->pid);
110 currpers = current_personality;
111 break;
112 }
113 #elif 0
114 /*
115 * This version analyzes the opcode of a syscall instruction.
116 * (int 0x80 on i386 vs. syscall on x86-64)
117 * It works, but is too complicated, and strictly speaking, unreliable.
118 */
119 unsigned long call, rip = x86_64_regs.rip;
120 /* sizeof(syscall) == sizeof(int 0x80) == 2 */
121 rip -= 2;
122 errno = 0;
123 call = ptrace(PTRACE_PEEKTEXT, tcp->pid, (char *)rip, (char *)0);
124 if (errno)
125 perror_msg("ptrace_peektext failed");
126 switch (call & 0xffff) {
127 /* x86-64: syscall = 0x0f 0x05 */
128 case 0x050f:
129 currpers = 0;
130 break;
131 /* i386: int 0x80 = 0xcd 0x80 */
132 case 0x80cd:
133 currpers = 1;
134 break;
135 default:
136 currpers = current_personality;
137 error_msg("Unknown syscall opcode (0x%04X) while "
138 "detecting personality of process PID=%d",
139 (int)call, tcp->pid);
140 break;
141 }
142 #endif
143
144 #ifdef X32
145 /*
146 * If we are built for a x32 system, then personality 0 is x32
147 * (not x86_64), and stracing of x86_64 apps is not supported.
148 * Stracing of i386 apps is still supported.
149 */
150 if (currpers == 0) {
151 error_msg("syscall_%" PRI_klu "(...) in unsupported "
152 "64-bit mode of process PID=%d", scno, tcp->pid);
153 return 0;
154 }
155 currpers &= ~2; /* map 2,1 to 0,1 */
156 #endif /* X32 */
157
158 update_personality(tcp, currpers);
159 tcp->scno = scno;
160 return 1;
161 }
162