1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
/* Check for executable stacks in DSOs.
Copyright (C) 2009, 2010 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contribute by Ulrich Drepper <drepper@redhat.com>. 2009.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <byteswap.h>
#include <elf.h>
#include <endian.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "check-execstack.h"
#ifdef BITS
# define AB(name) _AB (name, BITS)
# define _AB(name, bits) __AB (name, bits)
# define __AB(name, bits) name##bits
# define E(name) _E (name, BITS)
# define _E(name, bits) __E (name, bits)
# define __E(name, bits) Elf##bits##_##name
# define SWAP(val) \
({ __typeof (val) __res; \
if (((ehdr.e_ident[EI_DATA] == ELFDATA2MSB \
&& BYTE_ORDER == LITTLE_ENDIAN) \
|| (ehdr.e_ident[EI_DATA] == ELFDATA2LSB \
&& BYTE_ORDER == BIG_ENDIAN)) \
&& sizeof (val) != 1) \
{ \
if (sizeof (val) == 2) \
__res = bswap_16 (val); \
else if (sizeof (val) == 4) \
__res = bswap_32 (val); \
else \
__res = bswap_64 (val); \
} \
else \
__res = (val); \
__res; })
static int
AB(handle_file) (const char *fname, int fd)
{
E(Ehdr) ehdr;
if (pread (fd, &ehdr, sizeof (ehdr), 0) != sizeof (ehdr))
{
read_error:
printf ("%s: read error: %m\n", fname);
return 1;
}
const size_t phnum = SWAP (ehdr.e_phnum);
const size_t phentsize = SWAP (ehdr.e_phentsize);
/* Read the program header. */
E(Phdr) *phdr = alloca (phentsize * phnum);
if (pread (fd, phdr, phentsize * phnum, SWAP (ehdr.e_phoff))
!= phentsize * phnum)
goto read_error;
/* Search for the PT_GNU_STACK entry. */
for (size_t cnt = 0; cnt < phnum; ++cnt)
if (SWAP (phdr[cnt].p_type) == PT_GNU_STACK)
{
unsigned int flags = SWAP(phdr[cnt].p_flags);
if (flags & PF_X)
{
printf ("%s: executable stack signaled\n", fname);
return 1;
}
return 0;
}
if (DEFAULT_STACK_PERMS & PF_X)
{
printf ("%s: no PT_GNU_STACK entry\n", fname);
return 1;
}
return 0;
}
# undef BITS
#else
# define BITS 32
# include "check-execstack.c"
# define BITS 64
# include "check-execstack.c"
static int
handle_file (const char *fname)
{
int fd = open (fname, O_RDONLY);
if (fd == -1)
{
printf ("cannot open %s: %m\n", fname);
return 1;
}
/* Read was is supposed to be the ELF header. Read the initial
bytes to determine whether this is a 32 or 64 bit file. */
char ident[EI_NIDENT];
if (read (fd, ident, EI_NIDENT) != EI_NIDENT)
{
printf ("%s: read error: %m\n", fname);
close (fd);
return 1;
}
if (memcmp (&ident[EI_MAG0], ELFMAG, SELFMAG) != 0)
{
printf ("%s: not an ELF file\n", fname);
close (fd);
return 1;
}
int result;
if (ident[EI_CLASS] == ELFCLASS64)
result = handle_file64 (fname, fd);
else
result = handle_file32 (fname, fd);
close (fd);
return result;
}
int
main (int argc, char *argv[])
{
int cnt;
int result = 0;
for (cnt = 1; cnt < argc; ++cnt)
result |= handle_file (argv[cnt]);
return result;
}
#endif
|
