diff options
Diffstat (limited to 'src/firejail/dhcp.c')
-rw-r--r-- | src/firejail/dhcp.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/src/firejail/dhcp.c b/src/firejail/dhcp.c new file mode 100644 index 000000000..c9bbb4d8f --- /dev/null +++ b/src/firejail/dhcp.c | |||
@@ -0,0 +1,142 @@ | |||
1 | /* | ||
2 | * Copyright (C) 2014-2019 Firejail Authors | ||
3 | * | ||
4 | * This file is part of firejail project | ||
5 | * | ||
6 | * This program is free software; you can redistribute it and/or modify | ||
7 | * it under the terms of the GNU General Public License as published by | ||
8 | * the Free Software Foundation; either version 2 of the License, or | ||
9 | * (at your option) any later version. | ||
10 | * | ||
11 | * This program is distributed in the hope that it will be useful, | ||
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
14 | * GNU General Public License for more details. | ||
15 | * | ||
16 | * You should have received a copy of the GNU General Public License along | ||
17 | * with this program; if not, write to the Free Software Foundation, Inc., | ||
18 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | ||
19 | */ | ||
20 | #include "firejail.h" | ||
21 | #include <sys/types.h> | ||
22 | #include <sys/wait.h> | ||
23 | #include <errno.h> | ||
24 | #include <stddef.h> | ||
25 | #include <stdio.h> | ||
26 | #include <string.h> | ||
27 | |||
28 | pid_t dhclient4_pid = 0; | ||
29 | pid_t dhclient6_pid = 0; | ||
30 | |||
31 | typedef struct { | ||
32 | char *version_arg; | ||
33 | char *pid_file; | ||
34 | char *leases_file; | ||
35 | uint8_t generate_duid; | ||
36 | char *duid_leases_file; | ||
37 | pid_t *pid; | ||
38 | ptrdiff_t arg_offset; | ||
39 | } Dhclient; | ||
40 | |||
41 | static const Dhclient dhclient4 = { .version_arg = "-4", | ||
42 | .pid_file = RUN_DHCLIENT_4_PID_FILE, | ||
43 | .leases_file = RUN_DHCLIENT_4_LEASES_FILE, | ||
44 | .generate_duid = 1, | ||
45 | .pid = &dhclient4_pid, | ||
46 | .arg_offset = offsetof(Bridge, arg_ip_dhcp) | ||
47 | }; | ||
48 | |||
49 | static const Dhclient dhclient6 = { .version_arg = "-6", | ||
50 | .pid_file = RUN_DHCLIENT_6_PID_FILE, | ||
51 | .leases_file = RUN_DHCLIENT_6_LEASES_FILE, | ||
52 | .duid_leases_file = RUN_DHCLIENT_4_LEASES_FILE, | ||
53 | .pid = &dhclient6_pid, | ||
54 | .arg_offset = offsetof(Bridge, arg_ip6_dhcp) | ||
55 | }; | ||
56 | |||
57 | static void dhcp_run_dhclient(const Dhclient *client) { | ||
58 | char *argv[256] = { "dhclient", | ||
59 | client->version_arg, | ||
60 | "-pf", client->pid_file, | ||
61 | "-lf", client->leases_file, | ||
62 | }; | ||
63 | int i = 6; | ||
64 | if (client->generate_duid) | ||
65 | argv[i++] = "-i"; | ||
66 | if (client->duid_leases_file) { | ||
67 | argv[i++] = "-df"; | ||
68 | argv[i++] = client->duid_leases_file; | ||
69 | } | ||
70 | if (arg_debug) | ||
71 | argv[i++] = "-v"; | ||
72 | if (*(uint8_t *) ((char *) &cfg.bridge0 + client->arg_offset)) | ||
73 | argv[i++] = cfg.bridge0.devsandbox; | ||
74 | if (*(uint8_t *) ((char *) &cfg.bridge1 + client->arg_offset)) | ||
75 | argv[i++] = cfg.bridge1.devsandbox; | ||
76 | if (*(uint8_t *) ((char *) &cfg.bridge2 + client->arg_offset)) | ||
77 | argv[i++] = cfg.bridge2.devsandbox; | ||
78 | if (*(uint8_t *) ((char *) &cfg.bridge3 + client->arg_offset)) | ||
79 | argv[i++] = cfg.bridge3.devsandbox; | ||
80 | |||
81 | sbox_run_v(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_CAPS_NET_SERVICE | SBOX_SECCOMP, argv); | ||
82 | } | ||
83 | |||
84 | static pid_t dhcp_read_pidfile(const Dhclient *client) { | ||
85 | // We have to run dhclient as a forking daemon (not pass the -d option), | ||
86 | // because we want to be notified of a successful DHCP lease by the parent process exit. | ||
87 | // However, try to be extra paranoid with race conditions, | ||
88 | // because dhclient only writes the daemon pid into the pidfile | ||
89 | // after its parent process has exited. | ||
90 | int tries = 0; | ||
91 | pid_t found = 0; | ||
92 | while (found == 0 && tries < 10) { | ||
93 | if (tries >= 1) | ||
94 | usleep(100000); | ||
95 | FILE *pidfile = fopen(client->pid_file, "r"); | ||
96 | if (pidfile) { | ||
97 | long pid; | ||
98 | if (fscanf(pidfile, "%ld", &pid) == 1) { | ||
99 | char *pidname = pid_proc_comm((pid_t) pid); | ||
100 | if (pidname && strcmp(pidname, "dhclient") == 0) | ||
101 | found = (pid_t) pid; | ||
102 | } | ||
103 | fclose(pidfile); | ||
104 | } | ||
105 | ++tries; | ||
106 | } | ||
107 | if (found == 0) { | ||
108 | fprintf(stderr, "Error: Cannot get dhclient %s PID from %s\n", | ||
109 | client->version_arg, client->pid_file); | ||
110 | exit(1); | ||
111 | } | ||
112 | return found; | ||
113 | } | ||
114 | |||
115 | static void dhcp_start_dhclient(const Dhclient *client) { | ||
116 | dhcp_run_dhclient(client); | ||
117 | *(client->pid) = dhcp_read_pidfile(client); | ||
118 | } | ||
119 | |||
120 | void dhcp_start(void) { | ||
121 | if (!any_dhcp()) | ||
122 | return; | ||
123 | |||
124 | EUID_ROOT(); | ||
125 | if (mkdir(RUN_DHCLIENT_DIR, 0700)) | ||
126 | errExit("mkdir"); | ||
127 | |||
128 | if (any_ip_dhcp()) { | ||
129 | dhcp_start_dhclient(&dhclient4); | ||
130 | if (arg_debug) | ||
131 | printf("Running dhclient -4 in the background as pid %ld\n", (long) dhclient4_pid); | ||
132 | } | ||
133 | if (any_ip6_dhcp()) { | ||
134 | dhcp_start_dhclient(&dhclient6); | ||
135 | if (arg_debug) | ||
136 | printf("Running dhclient -6 in the background as pid %ld\n", (long) dhclient6_pid); | ||
137 | if (dhclient4_pid == dhclient6_pid) { | ||
138 | fprintf(stderr, "Error: dhclient -4 and -6 have the same PID: %ld\n", (long) dhclient4_pid); | ||
139 | exit(1); | ||
140 | } | ||
141 | } | ||
142 | } | ||