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