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authorDjalal Harouni <tixxdz@opendz.org>2016-05-26 22:42:29 +0200
committerDjalal Harouni <tixxdz@opendz.org>2016-05-26 22:42:29 +0200
commitf011b0b87a5ab3b2c85849558d464fcfcad85923 (patch)
tree5ba5aaa56b684ee7655794cdb102b30474edf10f /src/nspawn/nspawn-seccomp.c
parent231bfb1b02e0ff3fc335018cc58d83d8ef085dd8 (diff)
nspawn: split out seccomp call into nspawn-seccomp.[ch]
Split seccomp into nspawn-seccomp.[ch]. Currently there are no changes, but this will make it easy in the future to share or use the seccomp logic from systemd core.
Diffstat (limited to 'src/nspawn/nspawn-seccomp.c')
-rw-r--r--src/nspawn/nspawn-seccomp.c143
1 files changed, 143 insertions, 0 deletions
diff --git a/src/nspawn/nspawn-seccomp.c b/src/nspawn/nspawn-seccomp.c
new file mode 100644
index 0000000000..2d145b68a7
--- /dev/null
+++ b/src/nspawn/nspawn-seccomp.c
@@ -0,0 +1,143 @@
+/***
+ 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[] = {
+ { CAP_SYS_RAWIO, SCMP_SYS(iopl) },
+ { CAP_SYS_RAWIO, SCMP_SYS(ioperm) },
+ { CAP_SYS_BOOT, SCMP_SYS(kexec_load) },
+ { CAP_SYS_ADMIN, SCMP_SYS(swapon) },
+ { CAP_SYS_ADMIN, SCMP_SYS(swapoff) },
+ { CAP_SYS_ADMIN, SCMP_SYS(open_by_handle_at) },
+ { CAP_SYS_MODULE, SCMP_SYS(init_module) },
+ { CAP_SYS_MODULE, SCMP_SYS(finit_module) },
+ { CAP_SYS_MODULE, SCMP_SYS(delete_module) },
+ { CAP_SYSLOG, SCMP_SYS(syslog) },
+ };
+
+ for (i = 0; i < ELEMENTSOF(blacklist); i++) {
+ if (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) {
+ log_error_errno(r, "Failed to block syscall: %m");
+ return r;
+ }
+ }
+
+ return 0;
+}
+
+int setup_seccomp(uint64_t cap_list_retain) {
+ scmp_filter_ctx seccomp;
+ int r;
+
+ seccomp = seccomp_init(SCMP_ACT_ALLOW);
+ if (!seccomp)
+ return log_oom();
+
+ r = seccomp_add_secondary_archs(seccomp);
+ if (r < 0) {
+ log_error_errno(r, "Failed to add secondary archs to seccomp filter: %m");
+ goto finish;
+ }
+
+ 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_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
+ if (r < 0) {
+ log_error_errno(r, "Failed to unset NO_NEW_PRIVS: %m");
+ goto finish;
+ }
+
+ r = seccomp_load(seccomp);
+ if (r == -EINVAL) {
+ log_debug_errno(r, "Kernel is probably not configured with CONFIG_SECCOMP. Disabling seccomp audit filter: %m");
+ r = 0;
+ goto finish;
+ }
+ 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