PERFORCE change 214152 for review

[Brooks Davis]

http://p4web.freebsd.org/@@214152?ac=10

Change 214152 by brooks at brooks_ecr_current on 2012/07/09 23:46:57

	Implement a basic Capsicum sandbox which protects the main process from
	a file that exploites the BADMAGIC back door in libvuln_magic and
	displays a toxic hazard icon.

Affected files ...

.. //depot/projects/ctsrd/beribsd/src/ctsrd/browser/browser.c#8 edit

Differences ...

==== //depot/projects/ctsrd/beribsd/src/ctsrd/browser/browser.c#8 (text+ko) ====

@@ -31,6 +31,7 @@
 
 #include <sys/types.h>
 #include <sys/param.h>
+#include <sys/capability.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 
@@ -44,12 +45,14 @@
 #include <fnmatch.h>
 #include <libutil.h>
 #include <magic.h>
+#define _WITH_DPRINTF
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
 #include <time.h>
 #include <unistd.h>
+#include <vis.h>
 
 #define	BASEIMG		"/usr/share/images/browser.png"
 #define	ICONS		"/usr/share/images/icons.png"
@@ -222,12 +225,71 @@
 static const char *
 get_magic(int fd)
 {
+	pid_t pid;
+	ssize_t rlen;
+	char buf[4096], *desc;
+	const char *cdesc;
+	int pfd[2], status;
 
+	rlen = read(fd, buf, sizeof(buf));
+	if (rlen == -1)
+		return "read-error";
+	if (rlen == 0)
+		return "empty";
+
 	switch (sbtype) {
 	case SB_NONE:
-		return magic_descriptor(magic, fd);
+		return magic_buffer(magic, buf, rlen);
 	case SB_CAPSICUM:
-		return "devil";
+		if (pipe(pfd) == -1)
+			err(1, "pipe()");
+		pid = fork();
+		if (pid < 0)
+			err(1, "fork()");
+		else if (pid == 0) {
+			close(fd);
+			close(pfd[0]);
+			fb_fini();
+			/* XXX: do more cleanup here */
+			cap_enter();
+
+			cdesc = magic_buffer(magic, buf, rlen);
+			if (cdesc == NULL)
+				dprintf(pfd[1], "badmagic");
+			else
+				dprintf(pfd[1], "%s", cdesc);
+			close(pfd[1]);
+			exit(0);
+		} else {
+			close(pfd[1]);
+			if (wait4(pid, &status, 0, NULL) == -1)
+				err(1, "wait4()");
+			if (WIFEXITED(status) &&
+			    WEXITSTATUS(status) != 0) {
+				warnx("child exited with %d",
+				    WEXITSTATUS(status));
+				close(pfd[0]);
+				return "badmagic";
+			}
+			else if(WIFSIGNALED(status)) {
+				warn("child killed by signal %d",
+				    WTERMSIG(status));
+				close(pfd[0]);
+				return "badmagic";
+			} else {
+				rlen = read(pfd[0], buf, 128);
+				close(pfd[0]);
+				if (rlen == -1)
+					return "read error";
+				if (rlen == 0 || rlen == 1)
+					return "unknown";
+				/* Don't trust the result */
+				desc = buf + rlen;
+				strvisx(desc, buf, rlen - 1, 0);
+				return (desc);
+			}
+		}
+		break;
 	case SB_CHERI:
 		return "devil";
 	default: