+++ /dev/null
-/* $OpenBSD: kern_pledge.c,v 1.165 2016/04/28 14:25:08 beck Exp $ */
-
-/*
- * Copyright (c) 2015 Nicholas Marriott <nicm@openbsd.org>
- * Copyright (c) 2015 Theo de Raadt <deraadt@openbsd.org>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <seccomp.h>
-#include <errno.h>
-#include <unistd.h>
-#include <sys/syscall.h>
-#include <err.h>
-
-#include "openbsd.h"
-#include "pledge.h"
-
-#define SYS_MAXSYSCALL 1000
-
-/*
- * Ordered in blocks starting with least risky and most required.
- */
-const uint64_t pledge_syscalls[SYS_MAXSYSCALL] = {
- /*
- * Minimum required
- */
- [SYS_exit] = PLEDGE_ALWAYS,
- // [SYS_kbind] = PLEDGE_ALWAYS,
- // [SYS___get_tcb] = PLEDGE_ALWAYS,
- // [SYS_pledge] = PLEDGE_ALWAYS,
- // [SYS_sendsyslog] = PLEDGE_ALWAYS, /* stack protector reporting */
- // [SYS_osendsyslog] = PLEDGE_ALWAYS, /* obsolete sendsyslog */
- // [SYS_thrkill] = PLEDGE_ALWAYS, /* raise, abort, stack pro */
- // [SYS_utrace] = PLEDGE_ALWAYS, /* ltrace(1) from ld.so */
-
- /* "getting" information about self is considered safe */
- [SYS_getuid] = PLEDGE_STDIO,
- [SYS_geteuid] = PLEDGE_STDIO,
- [SYS_getresuid] = PLEDGE_STDIO,
- [SYS_getgid] = PLEDGE_STDIO,
- [SYS_getegid] = PLEDGE_STDIO,
- [SYS_getresgid] = PLEDGE_STDIO,
- [SYS_getgroups] = PLEDGE_STDIO,
- // [SYS_getlogin59] = PLEDGE_STDIO,
- // [SYS_getlogin_r] = PLEDGE_STDIO,
- [SYS_getpgrp] = PLEDGE_STDIO,
- [SYS_getpgid] = PLEDGE_STDIO,
- [SYS_getppid] = PLEDGE_STDIO,
- [SYS_getsid] = PLEDGE_STDIO,
- // [SYS_getthrid] = PLEDGE_STDIO,
- [SYS_getrlimit] = PLEDGE_STDIO,
- [SYS_gettimeofday] = PLEDGE_STDIO,
- // [SYS_getdtablecount] = PLEDGE_STDIO,
- [SYS_getrusage] = PLEDGE_STDIO,
- // [SYS_issetugid] = PLEDGE_STDIO,
- [SYS_clock_getres] = PLEDGE_STDIO,
- [SYS_clock_gettime] = PLEDGE_STDIO,
- [SYS_getpid] = PLEDGE_STDIO,
-
- /*
- * Almost exclusively read-only, Very narrow subset.
- * Use of "route", "inet", "dns", "ps", or "vminfo"
- * expands access.
- */
- // [SYS_sysctl] = PLEDGE_STDIO,
-
- /* Support for malloc(3) family of operations */
- // [SYS_getentropy] = PLEDGE_STDIO,
- [SYS_madvise] = PLEDGE_STDIO,
- // [SYS_minherit] = PLEDGE_STDIO,
- [SYS_mmap] = PLEDGE_STDIO,
- [SYS_mprotect] = PLEDGE_STDIO,
- // [SYS_mquery] = PLEDGE_STDIO,
- [SYS_munmap] = PLEDGE_STDIO,
- [SYS_msync] = PLEDGE_STDIO,
- // [SYS_break] = PLEDGE_STDIO,
-
- [SYS_umask] = PLEDGE_STDIO,
-
- /* read/write operations */
- [SYS_read] = PLEDGE_STDIO,
- [SYS_readv] = PLEDGE_STDIO,
- // [SYS_pread] = PLEDGE_STDIO,
- [SYS_preadv] = PLEDGE_STDIO,
- [SYS_write] = PLEDGE_STDIO,
- [SYS_writev] = PLEDGE_STDIO,
- // [SYS_pwrite] = PLEDGE_STDIO,
- [SYS_pwritev] = PLEDGE_STDIO,
- [SYS_recvmsg] = PLEDGE_STDIO,
- [SYS_recvfrom] = PLEDGE_STDIO | PLEDGE_YPACTIVE,
- [SYS_ftruncate] = PLEDGE_STDIO,
- [SYS_lseek] = PLEDGE_STDIO,
- // [SYS_fpathconf] = PLEDGE_STDIO,
-
- /*
- * Address selection required a network pledge ("inet",
- * "unix", "dns".
- */
- [SYS_sendto] = PLEDGE_STDIO | PLEDGE_YPACTIVE,
-
- /*
- * Address specification required a network pledge ("inet",
- * "unix", "dns". SCM_RIGHTS requires "sendfd" or "recvfd".
- */
- [SYS_sendmsg] = PLEDGE_STDIO,
-
- /* Common signal operations */
- [SYS_nanosleep] = PLEDGE_STDIO,
- [SYS_sigaltstack] = PLEDGE_STDIO,
- // [SYS_sigprocmask] = PLEDGE_STDIO,
- // [SYS_sigsuspend] = PLEDGE_STDIO,
- // [SYS_sigaction] = PLEDGE_STDIO,
- // [SYS_sigreturn] = PLEDGE_STDIO,
- // [SYS_sigpending] = PLEDGE_STDIO,
- [SYS_getitimer] = PLEDGE_STDIO,
- [SYS_setitimer] = PLEDGE_STDIO,
-
- /*
- * To support event driven programming.
- */
- [SYS_poll] = PLEDGE_STDIO,
- [SYS_ppoll] = PLEDGE_STDIO,
- // [SYS_kevent] = PLEDGE_STDIO,
- // [SYS_kqueue] = PLEDGE_STDIO,
- [SYS_select] = PLEDGE_STDIO,
- // [SYS_pselect] = PLEDGE_STDIO,
- [SYS_pselect6] = PLEDGE_STDIO,
- [SYS_epoll_create] = PLEDGE_STDIO,
- [SYS_epoll_create1] = PLEDGE_STDIO,
- [SYS_epoll_ctl] = PLEDGE_STDIO,
- [SYS_epoll_pwait] = PLEDGE_STDIO,
- [SYS_epoll_wait] = PLEDGE_STDIO,
- [SYS_eventfd] = PLEDGE_STDIO,
- [SYS_eventfd2] = PLEDGE_STDIO,
-
- [SYS_fstat] = PLEDGE_STDIO,
- [SYS_fsync] = PLEDGE_STDIO,
-
- [SYS_setsockopt] = PLEDGE_STDIO, /* narrow whitelist */
- [SYS_getsockopt] = PLEDGE_STDIO, /* narrow whitelist */
-
- /* F_SETOWN requires PLEDGE_PROC */
- [SYS_fcntl] = PLEDGE_STDIO,
-
- [SYS_close] = PLEDGE_STDIO,
- [SYS_dup] = PLEDGE_STDIO,
- [SYS_dup2] = PLEDGE_STDIO,
- [SYS_dup3] = PLEDGE_STDIO,
- // [SYS_closefrom] = PLEDGE_STDIO,
- [SYS_shutdown] = PLEDGE_STDIO,
- [SYS_fchdir] = PLEDGE_STDIO, /* XXX consider tightening */
-
- [SYS_pipe] = PLEDGE_STDIO,
- [SYS_pipe2] = PLEDGE_STDIO,
- [SYS_socketpair] = PLEDGE_STDIO,
-
- [SYS_wait4] = PLEDGE_STDIO,
-
- /*
- * Can kill self with "stdio". Killing another pid
- * requires "proc"
- */
- // [SYS_o58_kill] = PLEDGE_STDIO,
- [SYS_kill] = PLEDGE_STDIO,
-
- /*
- * FIONREAD/FIONBIO for "stdio"
- * A few non-tty ioctl available using "ioctl"
- * tty-centric ioctl available using "tty"
- */
- [SYS_ioctl] = PLEDGE_STDIO,
-
- /*
- * Path access/creation calls encounter many extensive
- * checks are done during namei()
- */
- [SYS_open] = PLEDGE_STDIO,
- [SYS_stat] = PLEDGE_STDIO,
- [SYS_access] = PLEDGE_STDIO,
- [SYS_readlink] = PLEDGE_STDIO,
-
- // [SYS_adjtime] = PLEDGE_STDIO, /* setting requires "settime" */
- // [SYS_adjfreq] = PLEDGE_SETTIME,
- [SYS_settimeofday] = PLEDGE_SETTIME,
-
- /*
- * Needed by threaded programs
- * XXX should we have a new "threads"?
- */
- // [SYS___tfork] = PLEDGE_STDIO,
- [SYS_sched_yield] = PLEDGE_STDIO,
- // [SYS___thrsleep] = PLEDGE_STDIO,
- // [SYS___thrwakeup] = PLEDGE_STDIO,
- // [SYS___threxit] = PLEDGE_STDIO,
- // [SYS___thrsigdivert] = PLEDGE_STDIO,
-
- [SYS_fork] = PLEDGE_PROC,
- [SYS_vfork] = PLEDGE_PROC,
- [SYS_setpgid] = PLEDGE_PROC,
- [SYS_setsid] = PLEDGE_PROC,
-
- [SYS_setrlimit] = PLEDGE_PROC | PLEDGE_ID,
- [SYS_getpriority] = PLEDGE_PROC | PLEDGE_ID,
-
- [SYS_setpriority] = PLEDGE_PROC | PLEDGE_ID,
-
- [SYS_setuid] = PLEDGE_ID,
- // [SYS_seteuid] = PLEDGE_ID,
- [SYS_setreuid] = PLEDGE_ID,
- [SYS_setresuid] = PLEDGE_ID,
- [SYS_setgid] = PLEDGE_ID,
- // [SYS_setegid] = PLEDGE_ID,
- [SYS_setregid] = PLEDGE_ID,
- [SYS_setresgid] = PLEDGE_ID,
- [SYS_setgroups] = PLEDGE_ID,
- // [SYS_setlogin] = PLEDGE_ID,
-
- [SYS_execve] = PLEDGE_EXEC,
-
- [SYS_chdir] = PLEDGE_RPATH,
- [SYS_openat] = PLEDGE_RPATH | PLEDGE_WPATH,
- // [SYS_fstatat] = PLEDGE_RPATH | PLEDGE_WPATH,
- [SYS_newfstatat] = PLEDGE_RPATH | PLEDGE_WPATH,
- [SYS_faccessat] = PLEDGE_RPATH | PLEDGE_WPATH,
- [SYS_readlinkat] = PLEDGE_RPATH | PLEDGE_WPATH,
- [SYS_lstat] = PLEDGE_RPATH | PLEDGE_WPATH | PLEDGE_TMPPATH,
- [SYS_truncate] = PLEDGE_WPATH,
- [SYS_rename] = PLEDGE_CPATH,
- [SYS_rmdir] = PLEDGE_CPATH,
- [SYS_renameat] = PLEDGE_CPATH,
- [SYS_link] = PLEDGE_CPATH,
- [SYS_linkat] = PLEDGE_CPATH,
- [SYS_symlink] = PLEDGE_CPATH,
- [SYS_unlink] = PLEDGE_CPATH | PLEDGE_TMPPATH,
- [SYS_unlinkat] = PLEDGE_CPATH,
- [SYS_mkdir] = PLEDGE_CPATH,
- [SYS_mkdirat] = PLEDGE_CPATH,
-
- // [SYS_mkfifo] = PLEDGE_DPATH,
- [SYS_mknod] = PLEDGE_DPATH,
-
- [SYS_chroot] = PLEDGE_ID, /* also requires PLEDGE_PROC */
-
- // [SYS_revoke] = PLEDGE_TTY, /* also requires PLEDGE_RPATH */
-
- /*
- * Classify as RPATH|WPATH, because of path information leakage.
- * WPATH due to unknown use of mk*temp(3) on non-/tmp paths..
- */
- // [SYS___getcwd] = PLEDGE_RPATH | PLEDGE_WPATH,
- [SYS_getcwd] = PLEDGE_RPATH | PLEDGE_WPATH,
-
- /* Classify as RPATH, because these leak path information */
- [SYS_getdents] = PLEDGE_RPATH,
- // [SYS_getfsstat] = PLEDGE_RPATH,
- [SYS_statfs] = PLEDGE_RPATH,
- [SYS_fstatfs] = PLEDGE_RPATH,
- // [SYS_pathconf] = PLEDGE_RPATH,
-
- [SYS_utimes] = PLEDGE_FATTR,
- // [SYS_futimes] = PLEDGE_FATTR,
- [SYS_futimesat] = PLEDGE_FATTR,
- [SYS_utimensat] = PLEDGE_FATTR,
- // [SYS_futimens] = PLEDGE_FATTR,
- [SYS_chmod] = PLEDGE_FATTR,
- [SYS_fchmod] = PLEDGE_FATTR,
- [SYS_fchmodat] = PLEDGE_FATTR,
- // [SYS_chflags] = PLEDGE_FATTR,
- //[SYS_chflagsat] = PLEDGE_FATTR,
- // [SYS_fchflags] = PLEDGE_FATTR,
- [SYS_chown] = PLEDGE_FATTR,
- [SYS_fchownat] = PLEDGE_FATTR,
- [SYS_lchown] = PLEDGE_FATTR,
- [SYS_fchown] = PLEDGE_FATTR,
-
- [SYS_socket] = PLEDGE_INET | PLEDGE_UNIX | PLEDGE_DNS | PLEDGE_YPACTIVE,
- [SYS_connect] = PLEDGE_INET | PLEDGE_UNIX | PLEDGE_DNS | PLEDGE_YPACTIVE,
- [SYS_bind] = PLEDGE_INET | PLEDGE_UNIX | PLEDGE_DNS | PLEDGE_YPACTIVE,
- [SYS_getsockname] = PLEDGE_INET | PLEDGE_UNIX | PLEDGE_DNS | PLEDGE_YPACTIVE,
-
- [SYS_listen] = PLEDGE_INET | PLEDGE_UNIX,
- [SYS_accept4] = PLEDGE_INET | PLEDGE_UNIX,
- [SYS_accept] = PLEDGE_INET | PLEDGE_UNIX,
- [SYS_getpeername] = PLEDGE_INET | PLEDGE_UNIX,
-
- [SYS_flock] = PLEDGE_FLOCK | PLEDGE_YPACTIVE,
-
- // [SYS_swapctl] = PLEDGE_VMINFO, /* XXX should limit to "get" operations */
-};
-
-
-static const struct {
- char *name;
- int flags;
-} pledgereq[] = {
- { "audio", PLEDGE_AUDIO },
- { "cpath", PLEDGE_CPATH },
- { "disklabel", PLEDGE_DISKLABEL },
- { "dns", PLEDGE_DNS },
- { "dpath", PLEDGE_DPATH },
- { "drm", PLEDGE_DRM },
- { "exec", PLEDGE_EXEC },
- { "fattr", PLEDGE_FATTR },
- { "flock", PLEDGE_FLOCK },
- { "getpw", PLEDGE_GETPW },
- { "id", PLEDGE_ID },
- { "inet", PLEDGE_INET },
- { "ioctl", PLEDGE_IOCTL },
- { "mcast", PLEDGE_MCAST },
- { "pf", PLEDGE_PF },
- { "proc", PLEDGE_PROC },
- { "prot_exec", PLEDGE_PROTEXEC },
- { "ps", PLEDGE_PS },
- { "recvfd", PLEDGE_RECVFD },
- { "route", PLEDGE_ROUTE },
- { "rpath", PLEDGE_RPATH },
- { "sendfd", PLEDGE_SENDFD },
- { "settime", PLEDGE_SETTIME },
- { "stdio", PLEDGE_STDIO },
- { "tmppath", PLEDGE_TMPPATH },
- { "tty", PLEDGE_TTY },
- { "unix", PLEDGE_UNIX },
- { "vminfo", PLEDGE_VMINFO },
- { "vmm", PLEDGE_VMM },
- { "wpath", PLEDGE_WPATH },
-};
-
-scmp_filter_ctx scmp_ctx = NULL;
-
-/* bsearch over pledgereq. return flags value if found, 0 else */
-static int
-pledgereq_flags(const char *req_name)
-{
- int base = 0, cmp, i, lim;
-
- for (lim = nitems(pledgereq); lim != 0; lim >>= 1) {
- i = base + (lim >> 1);
- cmp = strcmp(req_name, pledgereq[i].name);
- if (cmp == 0)
- return (pledgereq[i].flags);
- if (cmp > 0) { /* not found before, move right */
- base = i + 1;
- lim--;
- } /* else move left */
- }
- return (0);
-}
-
-/* whitelists syscalls returns -1 on error */
-int
-pledge(const char *promises, __UNUSED const char *paths[])
-{
- char *buf, *p;
- int rv = 0;
- uint64_t flags = 0;
-
- if (scmp_ctx == NULL) {
- /* inintialize new seccomp whitelist */
- if ((scmp_ctx = seccomp_init(SCMP_ACT_KILL)) == NULL)
- err(1, "seccomp_init");
- } else {
- /* reset previous rules */
- if (seccomp_reset(scmp_ctx, SCMP_ACT_KILL) < 0)
- err(1, "seccomp_reset");
- }
-
- /* make flags from prmises string */
- buf = strdup(promises);
- for (p = strtok(buf, " "); p;
- p = strtok(NULL, " ")) {
- flags |= pledgereq_flags(p);
- }
-
- for (int i = 0; i < SYS_MAXSYSCALL; i++) {
- /* skip not defined syscalls */
- if (pledge_syscalls[i] == 0)
- continue;
-
- /* skip not matching syscalls */
- if (!(pledge_syscalls[i] & flags))
- continue;
-
- /* seccomp whitelist syscall */
- if((rv = seccomp_rule_add_exact(scmp_ctx, SCMP_ACT_ALLOW, i, 0)) != 0)
- goto out;
- }
-
- /* seccomp_export_pfc(scmp_ctx, STDERR_FILENO); */
-
-out:
- free(buf);
- free(p);
-
- /* seccomp_release(scmp_ctx); */
-
- return (rv == 0 ? 0 : -1);
-}
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