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Diffstat (limited to 'src/systemd-nspawn/nspawn-seccomp.c')
-rw-r--r--src/systemd-nspawn/nspawn-seccomp.c186
1 files changed, 186 insertions, 0 deletions
diff --git a/src/systemd-nspawn/nspawn-seccomp.c b/src/systemd-nspawn/nspawn-seccomp.c
new file mode 100644
index 0000000000..e5cfe789a1
--- /dev/null
+++ b/src/systemd-nspawn/nspawn-seccomp.c
@@ -0,0 +1,186 @@
+/***
+ 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 <sys/capability.h>
+#include <sys/types.h>
+
+#include <linux/netlink.h>
+
+#ifdef HAVE_SECCOMP
+#include <seccomp.h>
+#endif
+
+#include "systemd-basic/log.h"
+
+#ifdef HAVE_SECCOMP
+#include "systemd-shared/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
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