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
|
/*
* This file is part of the KDE libraries
* Copyright (c) 2006 Lubos Lunak <[email protected]>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License version 2 as published by the Free Software Foundation.
*
* This 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <config.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef TDEINIT_OOM_PROTECT
/*
Prevent getting killed by bad heuristic in Linux OOM-killer.
This wrapper decreases the chance OOM killer kills it (or its children,
namely tdeinit), opens a pipe and forks. Child drops privileges
and launches tdeinit. Since processes started by tdeinit should
not have this protection, tdeinit will after forking send the new
PID using the pipe and wait for a signal. This parent will reset the protection
and SIGUSR1 the process to continue.
returns 1 if pid is valid
*/
static int set_protection( pid_t pid, int enable )
{
char buf[ 1024 ];
int procfile;
struct stat st;
/* Newer kernels (noticed in 2.6.36) */
sprintf( buf, "/proc/%d/oom_score_adj", pid );
if ( lstat (buf, &st) == 0) {
if( !enable ) {
/* Be paranoid and check that the pid we got from the pipe
belongs to this user. */
if( st.st_uid != getuid())
return 0;
}
procfile = open(buf, O_WRONLY);
if( enable )
write( procfile, "-300", sizeof( "-300" ));
else
write( procfile, "0", sizeof( "0" ));
close( procfile );
return 1;
}
sprintf( buf, "/proc/%d/stat", pid );
if( !enable ) {
/* Be paranoid and check that the pid we got from the pipe
belongs to this user. */
if( lstat( buf, &st ) < 0 || st.st_uid != getuid())
return 0;
}
sprintf( buf, "/proc/%d/oom_adj", pid );
procfile = open( buf, O_WRONLY );
if( procfile >= 0 ) {
if( enable )
write( procfile, "-5", sizeof( "-5" ));
else
write( procfile, "0", sizeof( "0" ));
close( procfile );
}
return 1;
}
int main(int argc, char **argv)
{
int pipes[ 2 ];
int new_argc;
const char** new_argv;
char helper_num[ 1024 ];
unsigned i;
char** orig_environ = NULL;
char header[ 7 ];
if( pipe( pipes ) < 0 ) {
perror( "pipe()" );
return 1;
}
if( argc < 0 || argc > 1000 )
abort(); /* paranoid */
set_protection( getpid(), 1 );
switch( fork()) {
case -1:
perror( "fork()" );
return 1;
default: /* parent, drop privileges and exec */
if (setgid(getgid())) {
perror("setgid()");
return 1;
}
if (setuid(getuid()) || geteuid() != getuid()) {
perror("setuid()");
return 1;
}
close( pipes[ 0 ] );
/* read original environment passed by start_tdeinit_wrapper */
if( read( 0, header, 7 ) == 7 && strncmp( header, "environ", 7 ) == 0 ) {
unsigned count;
if( read( 0, &count, sizeof( unsigned )) == sizeof( unsigned )
&& count && count < (1<<16)) {
char** env = malloc(( count + 1 ) * sizeof( char* ));
int ok = 1;
for( i = 0;
i < count && ok;
++i ) {
unsigned len;
if( read( 0, &len, sizeof( unsigned )) == sizeof( unsigned )
&& len && len < (1<<12)) {
env[ i ] = malloc( len + 1 );
if( (unsigned) read( 0, env[ i ], len ) == len ) {
env[ i ][ len ] = '\0';
} else {
ok = 0;
}
}
}
if( ok ) {
env[ i ] = NULL;
orig_environ = env;
}
}
}
if(argc == 0)
return 1;
new_argc = argc + 2;
new_argv = malloc( sizeof( char* ) * ( new_argc + 1 ));
if( new_argv == NULL )
return 1;
new_argv[ 0 ] = EXECUTE;
new_argv[ 1 ] = "--oom-pipe";
sprintf( helper_num, "%d", pipes[ 1 ] );
new_argv[ 2 ] = helper_num;
for( i = 1;
i <= (unsigned) argc;
++i )
new_argv[ i + 2 ] = argv[ i ];
if( orig_environ )
execve(EXECUTE, (char**)new_argv, orig_environ);
else
execv(EXECUTE, (char**)new_argv);
perror(EXECUTE);
return 1;
case 0: /* child, keep privileges and do the privileged work */
close( pipes[ 1 ] );
for(;;) {
pid_t pid = 0;
int ret = read( pipes[ 0 ], &pid, sizeof( pid_t ));
if( ret < 0 && errno == EINTR )
continue;
if( ret <= 0 ) /* pipe closed or error, exit */
_exit(0);
if( pid != 0 ) {
if (set_protection( pid, 0 ))
kill( pid, SIGUSR1 );
}
}
}
}
#else /* not Linux, the simple non-setuid case */
int main(int argc, char **argv)
{
if(argc == 0)
return 1;
argv[0] = (char*)EXECUTE;
execv(EXECUTE,argv);
perror(EXECUTE);
return 1;
}
#endif
|