--- /dev/null
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice immediately at the beginning of the file, without modification,
+ * this list of conditions, and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * libseccomp hooks.
+ */
+#include "file.h"
+
+#ifndef lint
+FILE_RCSID("@(#)$File: seccomp.c,v 1.1 2017/09/24 16:04:56 christos Exp $")
+#endif /* lint */
+
+#if HAVE_LIBSECCOMP
+#include <seccomp.h> /* libseccomp */
+#include <sys/prctl.h> /* prctl */
+#include <sys/socket.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#define DENY_RULE(call) \
+ do \
+ if (seccomp_rule_add (ctx, SCMP_ACT_KILL, SCMP_SYS(call), 0) == -1) \
+ goto out; \
+ while (/*CONSTCOND*/0)
+#define ALLOW_RULE(call) \
+ do \
+ if (seccomp_rule_add (ctx, SCMP_ACT_ALLOW, SCMP_SYS(call), 0) == -1) \
+ goto out; \
+ while (/*CONSTCOND*/0)
+
+static scmp_filter_ctx ctx;
+
+
+int
+enable_sandbox_basic(void)
+{
+
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
+ return -1;
+
+#if 0
+ // prevent escape via ptrace
+ prctl(PR_SET_DUMPABLE, 0);
+#endif
+
+ if (prctl (PR_SET_DUMPABLE, 0, 0, 0, 0) == -1)
+ return -1;
+
+ // initialize the filter
+ ctx = seccomp_init(SCMP_ACT_ALLOW);
+ if (ctx == NULL)
+ return 1;
+
+ DENY_RULE(_sysctl);
+ DENY_RULE(acct);
+ DENY_RULE(add_key);
+ DENY_RULE(adjtimex);
+ DENY_RULE(chroot);
+ DENY_RULE(clock_adjtime);
+ DENY_RULE(create_module);
+ DENY_RULE(delete_module);
+ DENY_RULE(fanotify_init);
+ DENY_RULE(finit_module);
+ DENY_RULE(get_kernel_syms);
+ DENY_RULE(get_mempolicy);
+ DENY_RULE(init_module);
+ DENY_RULE(io_cancel);
+ DENY_RULE(io_destroy);
+ DENY_RULE(io_getevents);
+ DENY_RULE(io_setup);
+ DENY_RULE(io_submit);
+ DENY_RULE(ioperm);
+ DENY_RULE(iopl);
+ DENY_RULE(ioprio_set);
+ DENY_RULE(kcmp);
+#ifdef __NR_kexec_file_load
+ DENY_RULE(kexec_file_load);
+#endif
+ DENY_RULE(kexec_load);
+ DENY_RULE(keyctl);
+ DENY_RULE(lookup_dcookie);
+ DENY_RULE(mbind);
+ DENY_RULE(nfsservctl);
+ DENY_RULE(migrate_pages);
+ DENY_RULE(modify_ldt);
+ DENY_RULE(mount);
+ DENY_RULE(move_pages);
+ DENY_RULE(name_to_handle_at);
+ DENY_RULE(open_by_handle_at);
+ DENY_RULE(perf_event_open);
+ DENY_RULE(pivot_root);
+ DENY_RULE(process_vm_readv);
+ DENY_RULE(process_vm_writev);
+ DENY_RULE(ptrace);
+ DENY_RULE(reboot);
+ DENY_RULE(remap_file_pages);
+ DENY_RULE(request_key);
+ DENY_RULE(set_mempolicy);
+ DENY_RULE(swapoff);
+ DENY_RULE(swapon);
+ DENY_RULE(sysfs);
+ DENY_RULE(syslog);
+ DENY_RULE(tuxcall);
+ DENY_RULE(umount2);
+ DENY_RULE(uselib);
+ DENY_RULE(vmsplice);
+
+ // blocking dangerous syscalls that file should not need
+ DENY_RULE (execve);
+ DENY_RULE (socket);
+ // ...
+
+
+ // applying filter...
+ if (seccomp_load (ctx) == -1)
+ goto out;
+ // free ctx after the filter has been loaded into the kernel
+ seccomp_release(ctx);
+ return 0;
+
+out:
+ seccomp_release(ctx);
+ return -1;
+}
+
+
+int
+enable_sandbox_full(void)
+{
+
+ // prevent child processes from getting more priv e.g. via setuid,
+ // capabilities, ...
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
+ return -1;
+
+ if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) == -1)
+ return -1;
+
+ // initialize the filter
+ ctx = seccomp_init(SCMP_ACT_KILL);
+ if (ctx == NULL)
+ return -1;
+
+ ALLOW_RULE(access);
+ ALLOW_RULE(brk);
+ ALLOW_RULE(close);
+ ALLOW_RULE(dup2);
+ ALLOW_RULE(exit);
+ ALLOW_RULE(exit_group);
+ ALLOW_RULE(fcntl);
+ ALLOW_RULE(fstat);
+ ALLOW_RULE(getdents);
+ ALLOW_RULE(ioctl);
+ ALLOW_RULE(lseek);
+ ALLOW_RULE(lstat);
+ ALLOW_RULE(mmap);
+ ALLOW_RULE(mprotect);
+ ALLOW_RULE(mremap);
+ ALLOW_RULE(munmap);
+ ALLOW_RULE(open);
+ ALLOW_RULE(openat);
+ ALLOW_RULE(pread64);
+ ALLOW_RULE(read);
+ ALLOW_RULE(rt_sigaction);
+ ALLOW_RULE(rt_sigprocmask);
+ ALLOW_RULE(rt_sigreturn);
+ ALLOW_RULE(select);
+ ALLOW_RULE(stat);
+ ALLOW_RULE(sysinfo);
+ ALLOW_RULE(unlink);
+ ALLOW_RULE(write);
+
+
+#if 0
+ // needed by valgrind
+ ALLOW_RULE(gettid);
+ ALLOW_RULE(getpid);
+ ALLOW_RULE(readlink);
+ ALLOW_RULE(rt_sigtimedwait);
+#endif
+
+#if 0
+ /* special restrictions for socket, only allow AF_UNIX/AF_LOCAL */
+ if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
+ SCMP_CMP(0, SCMP_CMP_EQ, AF_UNIX)) == -1)
+ goto out;
+
+ if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
+ SCMP_CMP(0, SCMP_CMP_EQ, AF_LOCAL)) == -1)
+ goto out;
+
+
+ /* special restrictions for open, prevent opening files for writing */
+ if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 1,
+ SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY | O_RDWR, 0)) == -1)
+ goto out;
+
+ if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), 1,
+ SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY, O_WRONLY)) == -1)
+ goto out;
+
+ if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), 1,
+ SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_RDWR, O_RDWR)) == -1)
+ goto out;
+
+
+ /* allow stderr */
+ if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(write), 1,
+ SCMP_CMP(0, SCMP_CMP_EQ, 2)) == -1)
+ goto out;
+#endif
+
+ // applying filter...
+ if (seccomp_load(ctx) == -1)
+ goto out;
+ // free ctx after the filter has been loaded into the kernel
+ seccomp_release(ctx);
+ return 0;
+
+out:
+ // something went wrong
+ seccomp_release(ctx);
+ return -1;
+}
+#endif
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