Branch data Line data Source code
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
42 : 37085583 : arch_get_scno(struct tcb *tcp)
43 : : {
44 : 37085583 : 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 [ + + ]: 37085583 : if (x86_io.iov_len == sizeof(i386_regs)) {
63 : 1639328 : scno = i386_regs.orig_eax;
64 : 1639328 : currpers = 1;
65 : : } else {
66 : 35446255 : scno = x86_64_regs.orig_rax;
67 : 35446255 : currpers = 0;
68 [ + + ]: 35446255 : 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 [ + - ]: 2 : if ((long long) x86_64_regs.orig_rax != -1) {
78 : 2 : scno -= __X32_SYSCALL_BIT;
79 : 2 : 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 : 37085583 : update_personality(tcp, currpers);
159 : 37085583 : tcp->scno = scno;
160 : 37085583 : return 1;
161 : : }
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