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
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
|
/*
* Manuel Novoa III Feb 2001
* Erik Andersen 2002-2004
*
* __uClibc_main is the routine to be called by all the arch-specific
* versions of crt0.S in uClibc.
*
* It is meant to handle any special initialization needed by the library
* such as setting the global variable(s) __environ (environ) and
* initializing the stdio package. Using weak symbols, the latter is
* avoided in the static library case.
*/
#define _ERRNO_H
#include <features.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <elf.h>
#include <bits/uClibc_page.h>
#include <paths.h>
#include <unistd.h>
#include <asm/errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#ifdef __UCLIBC_HAS_SSP__
extern void __guard_setup(void);
#endif
/*
* Prototypes.
*/
extern void weak_function _stdio_init(void);
extern int *weak_const_function __errno_location(void);
extern int *weak_const_function __h_errno_location(void);
#ifdef __UCLIBC_HAS_LOCALE__
extern void weak_function _locale_init(void);
#endif
#ifdef __UCLIBC_HAS_THREADS__
extern void weak_function __pthread_initialize_minimal(void);
#endif
/*
* Declare the __environ global variable and create a weak alias environ.
* Note: Apparently we must initialize __environ to ensure that the weak
* environ symbol is also included.
*/
char **__environ = 0;
weak_alias(__environ, environ);
size_t __pagesize = 0;
const char *__progname = 0;
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
extern int __libc_fcntl(int fd, int cmd, ...);
extern int __libc_open(const char *file, int flags, ...);
static void __check_one_fd(int fd, int mode)
{
/* Check if the specified fd is already open */
if (unlikely(__libc_fcntl(fd, F_GETFD)==-1 && *(__errno_location())==EBADF))
{
/* The descriptor is probably not open, so try to use /dev/null */
struct stat st;
int nullfd = __libc_open(_PATH_DEVNULL, mode);
/* /dev/null is major=1 minor=3. Make absolutely certain
* that is in fact the device that we have opened and not
* some other wierd file... */
if ( (nullfd!=fd) || fstat(fd, &st) || !S_ISCHR(st.st_mode) ||
(st.st_rdev != makedev(1, 3)))
{
/* Somebody is trying some trickery here... */
while (1) {
abort();
}
}
}
}
static int __check_suid(void)
{
uid_t uid, euid;
gid_t gid, egid;
uid = getuid();
euid = geteuid();
gid = getgid();
egid = getegid();
if(uid == euid && gid == egid) {
return 0;
}
return 1;
}
/* __uClibc_init completely initialize uClibc so it is ready to use.
*
* On ELF systems (with a dynamic loader) this function must be called
* from the dynamic loader (see TIS and ELF Specification), so that
* constructors of shared libraries (which depend on libc) can use all
* the libc code without restriction. For this we link the shared
* version of the uClibc with -init __uClibc_init so DT_INIT for
* uClibc is the address of __uClibc_init
*
* In all other cases we call it from the main stub
* __uClibc_start_main.
*/
void __uClibc_init(void)
{
static int been_there_done_that = 0;
if (been_there_done_that)
return;
been_there_done_that++;
/* Setup an initial value. This may not be perfect, but is
* better than malloc using __pagesize=0 for atexit, ctors, etc. */
__pagesize = PAGE_SIZE;
#ifdef __UCLIBC_HAS_THREADS__
/* Before we start initialzing uClibc we have to call
* __pthread_initialize_minimal so we can use pthread_locks
* whenever they are needed.
*/
if (likely(__pthread_initialize_minimal!=NULL))
__pthread_initialize_minimal();
#endif
#ifdef __UCLIBC_HAS_LOCALE__
/* Initialize the global locale structure. */
if (likely(_locale_init!=NULL))
_locale_init();
#endif
/*
* Initialize stdio here. In the static library case, this will
* be bypassed if not needed because of the weak alias above.
*/
if (likely(_stdio_init != NULL))
_stdio_init();
}
#ifdef __UCLIBC_CTOR_DTOR__
void attribute_hidden (*__app_fini)(void) = NULL;
#endif
void attribute_hidden (*__rtld_fini)(void) = NULL;
/* __uClibc_start_main is the new main stub for uClibc. This function is
* called from crt0 (version 0.9.16 or newer), after ALL shared libraries
* are initialized, just before we call the application's main function.
*/
void __attribute__ ((__noreturn__))
__uClibc_start_main(int (*main)(int argc, char **argv, char **envp),
int argc, char **argv, char **envp,
void (*app_init)(void), void (*app_fini)(void),
void (*rtld_fini)(void),
void *stack_end)
{
#ifdef __ARCH_HAS_MMU__
unsigned long *aux_dat;
Elf32_auxv_t auxvt[AT_EGID + 1];
#endif
/* We need to initialize uClibc. If we are dynamically linked this
* may have already been completed by the shared lib loader. We call
* __uClibc_init() regardless, to be sure the right thing happens. */
__uClibc_init();
__rtld_fini = rtld_fini;
/* If we are dynamically linked, then ldso already did this for us. */
if (__environ==NULL) {
/* Statically linked. */
__environ = envp;
}
/* Pull stuff from the ELF header when possible */
#ifdef __ARCH_HAS_MMU__
aux_dat = (unsigned long*)envp;
while (*aux_dat) {
aux_dat++;
}
aux_dat++;
while (*aux_dat) {
Elf32_auxv_t *auxv_entry = (Elf32_auxv_t *) aux_dat;
if (auxv_entry->a_type <= AT_EGID) {
memcpy(&(auxvt[auxv_entry->a_type]), auxv_entry, sizeof(Elf32_auxv_t));
}
aux_dat += 2;
}
/* Make certain getpagesize() gives the correct answer */
__pagesize = (auxvt[AT_PAGESZ].a_un.a_val)? auxvt[AT_PAGESZ].a_un.a_val : PAGE_SIZE;
/* Prevent starting SUID binaries where the stdin. stdout, and
* stderr file descriptors are not already opened. */
if ((auxvt[AT_UID].a_un.a_val==-1 && __check_suid()) ||
(auxvt[AT_UID].a_un.a_val != -1 &&
(auxvt[AT_UID].a_un.a_val != auxvt[AT_EUID].a_un.a_val ||
auxvt[AT_GID].a_un.a_val != auxvt[AT_EGID].a_un.a_val)))
{
__check_one_fd (STDIN_FILENO, O_RDONLY | O_NOFOLLOW);
__check_one_fd (STDOUT_FILENO, O_RDWR | O_NOFOLLOW);
__check_one_fd (STDERR_FILENO, O_RDWR | O_NOFOLLOW);
}
#endif
__progname = *argv;
#ifdef __UCLIBC_CTOR_DTOR__
/* Arrange for the application's dtors to run before we exit. */
__app_fini = app_fini;
/* Run all the application's ctors now. */
if (app_init!=NULL) {
app_init();
}
#endif
#ifdef __UCLIBC_HAS_SSP__
__guard_setup ();
#endif
/* Note: It is possible that any initialization done above could
* have resulted in errno being set nonzero, so set it to 0 before
* we call main.
*/
if (likely(__errno_location!=NULL))
*(__errno_location()) = 0;
/* Set h_errno to 0 as well */
if (likely(__h_errno_location!=NULL))
*(__h_errno_location()) = 0;
/*
* Finally, invoke application's main and then exit.
*/
exit(main(argc, argv, envp));
}
|
