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. */
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 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