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
|
/*
* Copyright (C) 2014-2021 Firejail Authors
*
* This file is part of firejail project
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "firejail.h"
#include <sys/stat.h>
static char **paths = 0;
static unsigned int path_cnt = 0;
static unsigned int longest_path_elt = 0;
static char *elt = NULL; // moved from inside init_paths in order to get rid of scan-build warning
static void init_paths(void) {
const char *env_path = env_get("PATH");
char *p;
if (!env_path) {
env_path = "/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin";
env_store_name_val("PATH", env_path, SETENV);
}
char *path = strdup(env_path);
if (!path)
errExit("strdup");
// size the paths array
for (p = path; *p; p++)
if (*p == ':')
path_cnt++;
path_cnt += 2; // one because we were counting fenceposts, one for the NULL at the end
paths = calloc(path_cnt, sizeof(char *));
if (!paths)
errExit("calloc");
memset(paths, 0, path_cnt * sizeof(char *)); // get rid of false positive error from GCC static analyzer
// fill in 'paths' with pointers to elements of 'path'
unsigned int i = 0, j;
unsigned int len;
while ((elt = strsep(&path, ":")) != NULL) {
// skip any entry that is not absolute
if (elt[0] != '/')
goto skip;
// strip trailing slashes (this also prevents '/' from being a path entry).
len = strlen(elt);
while (len > 0 && elt[len-1] == '/')
elt[--len] = '\0';
if (len == 0)
goto skip;
// filter out duplicate entries
for (j = 0; j < i; j++)
if (strcmp(elt, paths[j]) == 0)
goto skip;
paths[i++] = elt;
if (len > longest_path_elt)
longest_path_elt = len;
skip:;
}
assert(paths[i] == NULL);
// path_cnt may be too big now, if entries were skipped above
path_cnt = i+1;
}
char **build_paths(void) {
if (!paths)
init_paths();
assert(paths);
return paths;
}
// Note: the NULL element at the end of 'paths' is included in this count.
unsigned int count_paths(void) {
if (!path_cnt)
init_paths();
assert(path_cnt);
return path_cnt;
}
// Return 1 if PROGRAM exists in $PATH and is runnable by the
// invoking user (not root).
// In other words, tests "will execvp(PROGRAM, ...) succeed?"
int program_in_path(const char *program) {
assert(program && *program);
assert(strchr(program, '/') == 0);
assert(strcmp(program, ".") != 0);
assert(strcmp(program, "..") != 0);
if (!paths)
init_paths();
assert(paths);
size_t proglen = strlen(program);
char *scratch = malloc(longest_path_elt + proglen + 2);
if (!scratch)
errExit("malloc");
int found = 0;
size_t dlen;
char **p;
for (p = paths; *p; p++) {
char *dir = *p;
dlen = strlen(dir);
// init_paths should ensure that this is true; as long
// as it is true, 'scratch' has enough space for "$p/$program".
assert(dlen <= longest_path_elt);
memcpy(scratch, dir, dlen);
scratch[dlen++] = '/';
// copy proglen+1 bytes to copy the nul terminator at
// the end of 'program'.
memcpy(scratch + dlen, program, proglen+1);
if (access(scratch, X_OK) == 0) {
// must also verify that this is a regular file
// ('x' permission means something different for directories).
// exec follows symlinks, so use stat, not lstat.
struct stat st;
if (stat(scratch, &st)) {
perror(scratch);
exit(1);
}
if (S_ISREG(st.st_mode)) {
found = 1;
break;
}
}
}
free(scratch);
return found;
}
|
