Annotation of src/usr.bin/ssh/sandbox-systrace.c, Revision 1.17
1.17 ! guenther 1: /* $OpenBSD: sandbox-systrace.c,v 1.16 2015/06/29 22:35:12 djm Exp $ */
1.1 djm 2: /*
3: * Copyright (c) 2011 Damien Miller <djm@mindrot.org>
4: *
5: * Permission to use, copy, modify, and distribute this software for any
6: * purpose with or without fee is hereby granted, provided that the above
7: * copyright notice and this permission notice appear in all copies.
8: *
9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16: */
17:
18: #include <sys/types.h>
19: #include <sys/ioctl.h>
20: #include <sys/syscall.h>
21: #include <sys/socket.h>
1.6 markus 22: #include <sys/wait.h>
1.1 djm 23:
24: #include <dev/systrace.h>
25:
26: #include <errno.h>
27: #include <fcntl.h>
28: #include <limits.h>
1.6 markus 29: #include <signal.h>
1.1 djm 30: #include <stdarg.h>
31: #include <stdio.h>
32: #include <stdlib.h>
33: #include <string.h>
34: #include <unistd.h>
1.14 deraadt 35: #include <limits.h>
1.1 djm 36:
37: #include "atomicio.h"
38: #include "log.h"
1.3 djm 39: #include "ssh-sandbox.h"
1.1 djm 40: #include "xmalloc.h"
41:
1.4 djm 42: struct sandbox_policy {
43: int syscall;
44: int action;
45: };
46:
47: /* Permitted syscalls in preauth. Unlisted syscalls get SYSTR_POLICY_KILL */
48: static const struct sandbox_policy preauth_policy[] = {
1.15 deraadt 49: { SYS_clock_gettime, SYSTR_POLICY_PERMIT },
1.4 djm 50: { SYS_close, SYSTR_POLICY_PERMIT },
51: { SYS_exit, SYSTR_POLICY_PERMIT },
1.15 deraadt 52: { SYS_getentropy, SYSTR_POLICY_PERMIT },
1.4 djm 53: { SYS_getpid, SYSTR_POLICY_PERMIT },
1.16 djm 54: { SYS_getpgid, SYSTR_POLICY_PERMIT },
1.4 djm 55: { SYS_gettimeofday, SYSTR_POLICY_PERMIT },
1.17 ! guenther 56: #ifdef SYS_kbind
! 57: { SYS_kbind, SYSTR_POLICY_PERMIT },
! 58: #endif
1.4 djm 59: { SYS_madvise, SYSTR_POLICY_PERMIT },
60: { SYS_mmap, SYSTR_POLICY_PERMIT },
61: { SYS_mprotect, SYSTR_POLICY_PERMIT },
1.5 dtucker 62: { SYS_mquery, SYSTR_POLICY_PERMIT },
1.15 deraadt 63: { SYS_munmap, SYSTR_POLICY_PERMIT },
64: { SYS_open, SYSTR_POLICY_NEVER },
1.4 djm 65: { SYS_poll, SYSTR_POLICY_PERMIT },
66: { SYS_read, SYSTR_POLICY_PERMIT },
67: { SYS_select, SYSTR_POLICY_PERMIT },
1.15 deraadt 68: { SYS_sendsyslog, SYSTR_POLICY_PERMIT },
1.8 djm 69: { SYS_shutdown, SYSTR_POLICY_PERMIT },
1.4 djm 70: { SYS_sigprocmask, SYSTR_POLICY_PERMIT },
71: { SYS_write, SYSTR_POLICY_PERMIT },
72: { -1, -1 }
1.1 djm 73: };
74:
75: struct ssh_sandbox {
76: int systrace_fd;
77: pid_t child_pid;
1.6 markus 78: void (*osigchld)(int);
1.1 djm 79: };
80:
81: struct ssh_sandbox *
82: ssh_sandbox_init(void)
83: {
84: struct ssh_sandbox *box;
85:
86: debug3("%s: preparing systrace sandbox", __func__);
87: box = xcalloc(1, sizeof(*box));
88: box->systrace_fd = -1;
89: box->child_pid = 0;
1.6 markus 90: box->osigchld = signal(SIGCHLD, SIG_IGN);
1.1 djm 91:
92: return box;
93: }
94:
95: void
96: ssh_sandbox_child(struct ssh_sandbox *box)
97: {
98: debug3("%s: ready", __func__);
1.6 markus 99: signal(SIGCHLD, box->osigchld);
100: if (kill(getpid(), SIGSTOP) != 0)
101: fatal("%s: kill(%d, SIGSTOP)", __func__, getpid());
1.1 djm 102: debug3("%s: started", __func__);
103: }
104:
105: static void
106: ssh_sandbox_parent(struct ssh_sandbox *box, pid_t child_pid,
1.4 djm 107: const struct sandbox_policy *allowed_syscalls)
1.1 djm 108: {
1.6 markus 109: int dev_systrace, i, j, found, status;
110: pid_t pid;
1.4 djm 111: struct systrace_policy policy;
1.1 djm 112:
1.6 markus 113: /* Wait for the child to send itself a SIGSTOP */
1.1 djm 114: debug3("%s: wait for child %ld", __func__, (long)child_pid);
1.6 markus 115: do {
116: pid = waitpid(child_pid, &status, WUNTRACED);
117: } while (pid == -1 && errno == EINTR);
118: signal(SIGCHLD, box->osigchld);
119: if (!WIFSTOPPED(status)) {
120: if (WIFSIGNALED(status))
121: fatal("%s: child terminated with signal %d",
122: __func__, WTERMSIG(status));
123: if (WIFEXITED(status))
124: fatal("%s: child exited with status %d",
125: __func__, WEXITSTATUS(status));
126: fatal("%s: child not stopped", __func__);
127: }
128: debug3("%s: child %ld stopped", __func__, (long)child_pid);
1.1 djm 129: box->child_pid = child_pid;
130:
131: /* Set up systracing of child */
132: if ((dev_systrace = open("/dev/systrace", O_RDONLY)) == -1)
133: fatal("%s: open(\"/dev/systrace\"): %s", __func__,
134: strerror(errno));
135: if (ioctl(dev_systrace, STRIOCCLONE, &box->systrace_fd) == -1)
136: fatal("%s: ioctl(STRIOCCLONE, %d): %s", __func__,
137: dev_systrace, strerror(errno));
138: close(dev_systrace);
139: debug3("%s: systrace attach, fd=%d", __func__, box->systrace_fd);
140: if (ioctl(box->systrace_fd, STRIOCATTACH, &child_pid) == -1)
141: fatal("%s: ioctl(%d, STRIOCATTACH, %d): %s", __func__,
142: box->systrace_fd, child_pid, strerror(errno));
143:
144: /* Allocate and assign policy */
1.9 tedu 145: memset(&policy, 0, sizeof(policy));
1.4 djm 146: policy.strp_op = SYSTR_POLICY_NEW;
147: policy.strp_maxents = SYS_MAXSYSCALL;
148: if (ioctl(box->systrace_fd, STRIOCPOLICY, &policy) == -1)
1.1 djm 149: fatal("%s: ioctl(%d, STRIOCPOLICY (new)): %s", __func__,
150: box->systrace_fd, strerror(errno));
151:
1.4 djm 152: policy.strp_op = SYSTR_POLICY_ASSIGN;
153: policy.strp_pid = box->child_pid;
154: if (ioctl(box->systrace_fd, STRIOCPOLICY, &policy) == -1)
1.1 djm 155: fatal("%s: ioctl(%d, STRIOCPOLICY (assign)): %s",
156: __func__, box->systrace_fd, strerror(errno));
157:
158: /* Set per-syscall policy */
159: for (i = 0; i < SYS_MAXSYSCALL; i++) {
1.4 djm 160: found = 0;
161: for (j = 0; allowed_syscalls[j].syscall != -1; j++) {
162: if (allowed_syscalls[j].syscall == i) {
1.1 djm 163: found = 1;
1.4 djm 164: break;
165: }
1.1 djm 166: }
1.4 djm 167: policy.strp_op = SYSTR_POLICY_MODIFY;
168: policy.strp_code = i;
169: policy.strp_policy = found ?
170: allowed_syscalls[j].action : SYSTR_POLICY_KILL;
1.1 djm 171: if (found)
172: debug3("%s: policy: enable syscall %d", __func__, i);
1.4 djm 173: if (ioctl(box->systrace_fd, STRIOCPOLICY, &policy) == -1)
1.1 djm 174: fatal("%s: ioctl(%d, STRIOCPOLICY (modify)): %s",
175: __func__, box->systrace_fd, strerror(errno));
176: }
177:
178: /* Signal the child to start running */
179: debug3("%s: start child %ld", __func__, (long)child_pid);
1.6 markus 180: if (kill(box->child_pid, SIGCONT) != 0)
181: fatal("%s: kill(%d, SIGCONT)", __func__, box->child_pid);
1.1 djm 182: }
183:
184: void
185: ssh_sandbox_parent_finish(struct ssh_sandbox *box)
186: {
187: /* Closing this before the child exits will terminate it */
188: close(box->systrace_fd);
189:
190: free(box);
191: debug3("%s: finished", __func__);
192: }
193:
194: void
195: ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
196: {
197: ssh_sandbox_parent(box, child_pid, preauth_policy);
198: }
![[BACK]](/icons/back.gif){kind=icon}
Return to sandbox-systrace.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh