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
|
/***
This file is part of systemd.
Copyright 2016 Lennart Poettering
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <linux/netlink.h>
#include <sys/capability.h>
#include <sys/types.h>
#ifdef HAVE_SECCOMP
#include <seccomp.h>
#endif
#include "log.h"
#ifdef HAVE_SECCOMP
#include "seccomp-util.h"
#endif
#include "nspawn-seccomp.h"
#ifdef HAVE_SECCOMP
static int seccomp_add_default_syscall_filter(scmp_filter_ctx ctx,
uint64_t cap_list_retain) {
unsigned i;
int r;
static const struct {
uint64_t capability;
int syscall_num;
} blacklist[] = {
{ 0, SCMP_SYS(_sysctl) }, /* obsolete syscall */
{ 0, SCMP_SYS(add_key) }, /* keyring is not namespaced */
{ 0, SCMP_SYS(afs_syscall) }, /* obsolete syscall */
{ 0, SCMP_SYS(bdflush) },
#ifdef __NR_bpf
{ 0, SCMP_SYS(bpf) },
#endif
{ 0, SCMP_SYS(break) }, /* obsolete syscall */
{ 0, SCMP_SYS(create_module) }, /* obsolete syscall */
{ 0, SCMP_SYS(ftime) }, /* obsolete syscall */
{ 0, SCMP_SYS(get_kernel_syms) }, /* obsolete syscall */
{ 0, SCMP_SYS(getpmsg) }, /* obsolete syscall */
{ 0, SCMP_SYS(gtty) }, /* obsolete syscall */
#ifdef __NR_kexec_file_load
{ 0, SCMP_SYS(kexec_file_load) },
#endif
{ 0, SCMP_SYS(kexec_load) },
{ 0, SCMP_SYS(keyctl) }, /* keyring is not namespaced */
{ 0, SCMP_SYS(lock) }, /* obsolete syscall */
{ 0, SCMP_SYS(lookup_dcookie) },
{ 0, SCMP_SYS(mpx) }, /* obsolete syscall */
{ 0, SCMP_SYS(nfsservctl) }, /* obsolete syscall */
{ 0, SCMP_SYS(open_by_handle_at) },
{ 0, SCMP_SYS(perf_event_open) },
{ 0, SCMP_SYS(prof) }, /* obsolete syscall */
{ 0, SCMP_SYS(profil) }, /* obsolete syscall */
{ 0, SCMP_SYS(putpmsg) }, /* obsolete syscall */
{ 0, SCMP_SYS(query_module) }, /* obsolete syscall */
{ 0, SCMP_SYS(quotactl) },
{ 0, SCMP_SYS(request_key) }, /* keyring is not namespaced */
{ 0, SCMP_SYS(security) }, /* obsolete syscall */
{ 0, SCMP_SYS(sgetmask) }, /* obsolete syscall */
{ 0, SCMP_SYS(ssetmask) }, /* obsolete syscall */
{ 0, SCMP_SYS(stty) }, /* obsolete syscall */
{ 0, SCMP_SYS(swapoff) },
{ 0, SCMP_SYS(swapon) },
{ 0, SCMP_SYS(sysfs) }, /* obsolete syscall */
{ 0, SCMP_SYS(tuxcall) }, /* obsolete syscall */
{ 0, SCMP_SYS(ulimit) }, /* obsolete syscall */
{ 0, SCMP_SYS(uselib) }, /* obsolete syscall */
{ 0, SCMP_SYS(ustat) }, /* obsolete syscall */
{ 0, SCMP_SYS(vserver) }, /* obsolete syscall */
{ CAP_SYSLOG, SCMP_SYS(syslog) },
{ CAP_SYS_MODULE, SCMP_SYS(delete_module) },
{ CAP_SYS_MODULE, SCMP_SYS(finit_module) },
{ CAP_SYS_MODULE, SCMP_SYS(init_module) },
{ CAP_SYS_PACCT, SCMP_SYS(acct) },
{ CAP_SYS_PTRACE, SCMP_SYS(process_vm_readv) },
{ CAP_SYS_PTRACE, SCMP_SYS(process_vm_writev) },
{ CAP_SYS_PTRACE, SCMP_SYS(ptrace) },
{ CAP_SYS_RAWIO, SCMP_SYS(ioperm) },
{ CAP_SYS_RAWIO, SCMP_SYS(iopl) },
{ CAP_SYS_RAWIO, SCMP_SYS(pciconfig_iobase) },
{ CAP_SYS_RAWIO, SCMP_SYS(pciconfig_read) },
{ CAP_SYS_RAWIO, SCMP_SYS(pciconfig_write) },
#ifdef __NR_s390_pci_mmio_read
{ CAP_SYS_RAWIO, SCMP_SYS(s390_pci_mmio_read) },
#endif
#ifdef __NR_s390_pci_mmio_write
{ CAP_SYS_RAWIO, SCMP_SYS(s390_pci_mmio_write) },
#endif
{ CAP_SYS_TIME, SCMP_SYS(adjtimex) },
{ CAP_SYS_TIME, SCMP_SYS(clock_adjtime) },
{ CAP_SYS_TIME, SCMP_SYS(clock_settime) },
{ CAP_SYS_TIME, SCMP_SYS(settimeofday) },
{ CAP_SYS_TIME, SCMP_SYS(stime) },
};
for (i = 0; i < ELEMENTSOF(blacklist); i++) {
if (blacklist[i].capability != 0 && (cap_list_retain & (1ULL << blacklist[i].capability)))
continue;
r = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), blacklist[i].syscall_num, 0);
if (r == -EFAULT)
continue; /* unknown syscall */
if (r < 0)
return log_error_errno(r, "Failed to block syscall: %m");
}
return 0;
}
int setup_seccomp(uint64_t cap_list_retain) {
scmp_filter_ctx seccomp;
int r;
if (!is_seccomp_available()) {
log_debug("SECCOMP features not detected in the kernel, disabling SECCOMP audit filter");
return 0;
}
r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
if (r < 0)
return log_error_errno(r, "Failed to allocate seccomp object: %m");
r = seccomp_add_default_syscall_filter(seccomp, cap_list_retain);
if (r < 0)
goto finish;
/*
Audit is broken in containers, much of the userspace audit
hookup will fail if running inside a container. We don't
care and just turn off creation of audit sockets.
This will make socket(AF_NETLINK, *, NETLINK_AUDIT) fail
with EAFNOSUPPORT which audit userspace uses as indication
that audit is disabled in the kernel.
*/
r = seccomp_rule_add(
seccomp,
SCMP_ACT_ERRNO(EAFNOSUPPORT),
SCMP_SYS(socket),
2,
SCMP_A0(SCMP_CMP_EQ, AF_NETLINK),
SCMP_A2(SCMP_CMP_EQ, NETLINK_AUDIT));
if (r < 0) {
log_error_errno(r, "Failed to add audit seccomp rule: %m");
goto finish;
}
r = seccomp_load(seccomp);
if (r < 0) {
log_error_errno(r, "Failed to install seccomp audit filter: %m");
goto finish;
}
finish:
seccomp_release(seccomp);
return r;
}
#else
int setup_seccomp(uint64_t cap_list_retain) {
return 0;
}
#endif
|
