Author: pjd Date: Tue Feb 4 21:43:53 2014 New Revision: 261498 URL: http://svnweb.freebsd.org/changeset/base/261498
Log: Protect ping(8) using Capsicum and Casper. This is protection against malicious network packets that we parse and not against local users trying to gain root access through ping's set-uid bit - this is handled by dropping privileges very early in ping. Submitted by: Mikhail <m...@lenta.ru> Modified: head/sbin/ping/Makefile head/sbin/ping/ping.c Modified: head/sbin/ping/Makefile ============================================================================== --- head/sbin/ping/Makefile Tue Feb 4 21:23:12 2014 (r261497) +++ head/sbin/ping/Makefile Tue Feb 4 21:43:53 2014 (r261498) @@ -1,6 +1,8 @@ # @(#)Makefile 8.1 (Berkeley) 6/5/93 # $FreeBSD$ +.include <bsd.own.mk> + PROG= ping MAN= ping.8 BINOWN= root @@ -9,6 +11,12 @@ WARNS?= 2 DPADD= ${LIBM} LDADD= -lm +.if ${MK_CASPER} != "no" && !defined(RESCUE) +DPADD+= ${LIBCAPSICUM} +LDADD+= -lcapsicum +CFLAGS+=-DHAVE_LIBCAPSICUM +.endif + .if !defined(RELEASE_CRUNCH) CFLAGS+=-DIPSEC DPADD+= ${LIBIPSEC} Modified: head/sbin/ping/ping.c ============================================================================== --- head/sbin/ping/ping.c Tue Feb 4 21:23:12 2014 (r261497) +++ head/sbin/ping/ping.c Tue Feb 4 21:43:53 2014 (r261498) @@ -63,6 +63,7 @@ __FBSDID("$FreeBSD$"); */ #include <sys/param.h> /* NB: we rely on this for <sys/types.h> */ +#include <sys/capability.h> #include <sys/socket.h> #include <sys/sysctl.h> #include <sys/time.h> @@ -74,6 +75,11 @@ __FBSDID("$FreeBSD$"); #include <netinet/ip_icmp.h> #include <netinet/ip_var.h> #include <arpa/inet.h> +#ifdef HAVE_LIBCAPSICUM +#include <libcapsicum.h> +#include <libcapsicum_dns.h> +#include <libcapsicum_service.h> +#endif #ifdef IPSEC #include <netipsec/ipsec.h> @@ -157,7 +163,8 @@ char rcvd_tbl[MAX_DUP_CHK / 8]; struct sockaddr_in whereto; /* who to ping */ int datalen = DEFDATALEN; int maxpayload; -int s; /* socket file descriptor */ +int ssend; /* send socket file descriptor */ +int srecv; /* receive socket file descriptor */ u_char outpackhdr[IP_MAXPACKET], *outpack; char BBELL = '\a'; /* characters written for MISSED and AUDIBLE */ char BSPACE = '\b'; /* characters written for flood */ @@ -197,8 +204,15 @@ double tsumsq = 0.0; /* sum of all time volatile sig_atomic_t finish_up; /* nonzero if we've been told to finish up */ volatile sig_atomic_t siginfo_p; +#ifdef HAVE_LIBCAPSICUM +static cap_channel_t *capdns; +#endif + static void fill(char *, char *); static u_short in_cksum(u_short *, int); +#ifdef HAVE_LIBCAPSICUM +static cap_channel_t *capdns_setup(void); +#endif static void check_status(void); static void finish(void) __dead2; static void pinger(void); @@ -233,8 +247,8 @@ main(int argc, char *const *argv) struct sockaddr_in *to; double t; u_long alarmtimeout, ultmp; - int almost_done, ch, df, hold, i, icmp_len, mib[4], preload, sockerrno, - tos, ttl; + int almost_done, ch, df, hold, i, icmp_len, mib[4], preload; + int ssend_errno, srecv_errno, tos, ttl; char ctrl[CMSG_SPACE(sizeof(struct timeval))]; char hnamebuf[MAXHOSTNAMELEN], snamebuf[MAXHOSTNAMELEN]; #ifdef IP_OPTIONS @@ -246,14 +260,26 @@ main(int argc, char *const *argv) #ifdef IPSEC_POLICY_IPSEC policy_in = policy_out = NULL; #endif + cap_rights_t rights; + bool cansandbox; /* * Do the stuff that we need root priv's for *first*, and * then drop our setuid bit. Save error reporting for * after arg parsing. + * + * Historicaly ping was using one socket 's' for sending and for + * receiving. After capsicum(4) related changes we use two + * sockets. It was done for special ping use case - when user + * issue ping on multicast or broadcast address replies come + * from different addresses, not from the address we + * connect(2)'ed to, and send socket do not receive those + * packets. */ - s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); - sockerrno = errno; + ssend = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); + ssend_errno = errno; + srecv = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); + srecv_errno = errno; if (setuid(getuid()) != 0) err(EX_NOPERM, "setuid() failed"); @@ -527,13 +553,22 @@ main(int argc, char *const *argv) if (options & F_PINGFILLED) { fill((char *)datap, payload); } +#ifdef HAVE_LIBCAPSICUM + capdns = capdns_setup(); +#endif if (source) { bzero((char *)&sock_in, sizeof(sock_in)); sock_in.sin_family = AF_INET; if (inet_aton(source, &sock_in.sin_addr) != 0) { shostname = source; } else { - hp = gethostbyname2(source, AF_INET); +#ifdef HAVE_LIBCAPSICUM + if (capdns != NULL) + hp = cap_gethostbyname2(capdns, source, + AF_INET); + else +#endif + hp = gethostbyname2(source, AF_INET); if (!hp) errx(EX_NOHOST, "cannot resolve %s: %s", source, hstrerror(h_errno)); @@ -549,7 +584,8 @@ main(int argc, char *const *argv) snamebuf[sizeof(snamebuf) - 1] = '\0'; shostname = snamebuf; } - if (bind(s, (struct sockaddr *)&sock_in, sizeof sock_in) == -1) + if (bind(ssend, (struct sockaddr *)&sock_in, sizeof sock_in) == + -1) err(1, "bind"); } @@ -560,7 +596,12 @@ main(int argc, char *const *argv) if (inet_aton(target, &to->sin_addr) != 0) { hostname = target; } else { - hp = gethostbyname2(target, AF_INET); +#ifdef HAVE_LIBCAPSICUM + if (capdns != NULL) + hp = cap_gethostbyname2(capdns, target, AF_INET); + else +#endif + hp = gethostbyname2(target, AF_INET); if (!hp) errx(EX_NOHOST, "cannot resolve %s: %s", target, hstrerror(h_errno)); @@ -573,6 +614,30 @@ main(int argc, char *const *argv) hostname = hnamebuf; } +#ifdef HAVE_LIBCAPSICUM + /* From now on we will use only reverse DNS lookups. */ + if (capdns != NULL) { + const char *types[1]; + + types[0] = "ADDR"; + if (cap_dns_type_limit(capdns, types, 1) < 0) + err(1, "unable to limit access to system.dns service"); + } +#endif + + if (ssend < 0) { + errno = ssend_errno; + err(EX_OSERR, "ssend socket"); + } + + if (srecv < 0) { + errno = srecv_errno; + err(EX_OSERR, "srecv socket"); + } + + if (connect(ssend, (struct sockaddr *)&whereto, sizeof(whereto)) != 0) + err(1, "connect"); + if (options & F_FLOOD && options & F_INTERVAL) errx(EX_USAGE, "-f and -i: incompatible options"); @@ -593,16 +658,15 @@ main(int argc, char *const *argv) ident = getpid() & 0xFFFF; - if (s < 0) { - errno = sockerrno; - err(EX_OSERR, "socket"); - } hold = 1; - if (options & F_SO_DEBUG) - (void)setsockopt(s, SOL_SOCKET, SO_DEBUG, (char *)&hold, + if (options & F_SO_DEBUG) { + (void)setsockopt(ssend, SOL_SOCKET, SO_DEBUG, (char *)&hold, sizeof(hold)); + (void)setsockopt(srecv, SOL_SOCKET, SO_DEBUG, (char *)&hold, + sizeof(hold)); + } if (options & F_SO_DONTROUTE) - (void)setsockopt(s, SOL_SOCKET, SO_DONTROUTE, (char *)&hold, + (void)setsockopt(ssend, SOL_SOCKET, SO_DONTROUTE, (char *)&hold, sizeof(hold)); #ifdef IPSEC #ifdef IPSEC_POLICY_IPSEC @@ -612,7 +676,7 @@ main(int argc, char *const *argv) buf = ipsec_set_policy(policy_in, strlen(policy_in)); if (buf == NULL) errx(EX_CONFIG, "%s", ipsec_strerror()); - if (setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, + if (setsockopt(srecv, IPPROTO_IP, IP_IPSEC_POLICY, buf, ipsec_get_policylen(buf)) < 0) err(EX_CONFIG, "ipsec policy cannot be configured"); @@ -623,7 +687,7 @@ main(int argc, char *const *argv) buf = ipsec_set_policy(policy_out, strlen(policy_out)); if (buf == NULL) errx(EX_CONFIG, "%s", ipsec_strerror()); - if (setsockopt(s, IPPROTO_IP, IP_IPSEC_POLICY, + if (setsockopt(ssend, IPPROTO_IP, IP_IPSEC_POLICY, buf, ipsec_get_policylen(buf)) < 0) err(EX_CONFIG, "ipsec policy cannot be configured"); @@ -644,7 +708,7 @@ main(int argc, char *const *argv) if (sysctl(mib, 4, &ttl, &sz, NULL, 0) == -1) err(1, "sysctl(net.inet.ip.ttl)"); } - setsockopt(s, IPPROTO_IP, IP_HDRINCL, &hold, sizeof(hold)); + setsockopt(ssend, IPPROTO_IP, IP_HDRINCL, &hold, sizeof(hold)); ip->ip_v = IPVERSION; ip->ip_hl = sizeof(struct ip) >> 2; ip->ip_tos = tos; @@ -655,6 +719,35 @@ main(int argc, char *const *argv) ip->ip_src.s_addr = source ? sock_in.sin_addr.s_addr : INADDR_ANY; ip->ip_dst = to->sin_addr; } + + if (options & F_NUMERIC) + cansandbox = true; +#ifdef HAVE_LIBCAPSICUM + else if (capdns != NULL) + cansandbox = true; +#endif + else + cansandbox = false; + + /* + * Here we enter capability mode. Further down access to global + * namespaces (e.g filesystem) is restricted (see capsicum(4)). + * We must connect(2) our socket before this point. + */ + if (cansandbox && cap_enter() < 0 && errno != ENOSYS) + err(1, "cap_enter"); + + if (cap_sandboxed()) + fprintf(stderr, "capability mode sandbox enabled\n"); + + cap_rights_init(&rights, CAP_RECV, CAP_EVENT, CAP_SETSOCKOPT); + if (cap_rights_limit(srecv, &rights) < 0 && errno != ENOSYS) + err(1, "cap_rights_limit srecv"); + + cap_rights_init(&rights, CAP_SEND, CAP_SETSOCKOPT); + if (cap_rights_limit(ssend, &rights) < 0 && errno != ENOSYS) + err(1, "cap_rights_limit ssend"); + /* record route option */ if (options & F_RROUTE) { #ifdef IP_OPTIONS @@ -663,7 +756,7 @@ main(int argc, char *const *argv) rspace[IPOPT_OLEN] = sizeof(rspace) - 1; rspace[IPOPT_OFFSET] = IPOPT_MINOFF; rspace[sizeof(rspace) - 1] = IPOPT_EOL; - if (setsockopt(s, IPPROTO_IP, IP_OPTIONS, rspace, + if (setsockopt(ssend, IPPROTO_IP, IP_OPTIONS, rspace, sizeof(rspace)) < 0) err(EX_OSERR, "setsockopt IP_OPTIONS"); #else @@ -673,32 +766,32 @@ main(int argc, char *const *argv) } if (options & F_TTL) { - if (setsockopt(s, IPPROTO_IP, IP_TTL, &ttl, + if (setsockopt(ssend, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) < 0) { err(EX_OSERR, "setsockopt IP_TTL"); } } if (options & F_NOLOOP) { - if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, + if (setsockopt(ssend, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0) { err(EX_OSERR, "setsockopt IP_MULTICAST_LOOP"); } } if (options & F_MTTL) { - if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &mttl, + if (setsockopt(ssend, IPPROTO_IP, IP_MULTICAST_TTL, &mttl, sizeof(mttl)) < 0) { err(EX_OSERR, "setsockopt IP_MULTICAST_TTL"); } } if (options & F_MIF) { - if (setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, &ifaddr, + if (setsockopt(ssend, IPPROTO_IP, IP_MULTICAST_IF, &ifaddr, sizeof(ifaddr)) < 0) { err(EX_OSERR, "setsockopt IP_MULTICAST_IF"); } } #ifdef SO_TIMESTAMP { int on = 1; - if (setsockopt(s, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)) < 0) + if (setsockopt(srecv, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)) < 0) err(EX_OSERR, "setsockopt SO_TIMESTAMP"); } #endif @@ -733,11 +826,19 @@ main(int argc, char *const *argv) * as well. */ hold = IP_MAXPACKET + 128; - (void)setsockopt(s, SOL_SOCKET, SO_RCVBUF, (char *)&hold, + (void)setsockopt(srecv, SOL_SOCKET, SO_RCVBUF, (char *)&hold, sizeof(hold)); + /* CAP_SETSOCKOPT removed */ + cap_rights_init(&rights, CAP_RECV, CAP_EVENT); + if (cap_rights_limit(srecv, &rights) < 0 && errno != ENOSYS) + err(1, "cap_rights_limit srecv setsockopt"); if (uid == 0) - (void)setsockopt(s, SOL_SOCKET, SO_SNDBUF, (char *)&hold, + (void)setsockopt(ssend, SOL_SOCKET, SO_SNDBUF, (char *)&hold, sizeof(hold)); + /* CAP_SETSOCKOPT removed */ + cap_rights_init(&rights, CAP_SEND); + if (cap_rights_limit(ssend, &rights) < 0 && errno != ENOSYS) + err(1, "cap_rights_limit ssend setsockopt"); if (to->sin_family == AF_INET) { (void)printf("PING %s (%s)", hostname, @@ -817,10 +918,10 @@ main(int argc, char *const *argv) int cc, n; check_status(); - if ((unsigned)s >= FD_SETSIZE) + if ((unsigned)srecv >= FD_SETSIZE) errx(EX_OSERR, "descriptor too large"); FD_ZERO(&rfds); - FD_SET(s, &rfds); + FD_SET(srecv, &rfds); (void)gettimeofday(&now, NULL); timeout.tv_sec = last.tv_sec + intvl.tv_sec - now.tv_sec; timeout.tv_usec = last.tv_usec + intvl.tv_usec - now.tv_usec; @@ -834,7 +935,7 @@ main(int argc, char *const *argv) } if (timeout.tv_sec < 0) timerclear(&timeout); - n = select(s + 1, &rfds, NULL, NULL, &timeout); + n = select(srecv + 1, &rfds, NULL, NULL, &timeout); if (n < 0) continue; /* Must be EINTR. */ if (n == 1) { @@ -845,7 +946,7 @@ main(int argc, char *const *argv) msg.msg_controllen = sizeof(ctrl); #endif msg.msg_namelen = sizeof(from); - if ((cc = recvmsg(s, &msg, 0)) < 0) { + if ((cc = recvmsg(srecv, &msg, 0)) < 0) { if (errno == EINTR) continue; warn("recvmsg"); @@ -981,9 +1082,7 @@ pinger(void) ip->ip_sum = in_cksum((u_short *)outpackhdr, cc); packet = outpackhdr; } - i = sendto(s, (char *)packet, cc, 0, (struct sockaddr *)&whereto, - sizeof(whereto)); - + i = send(ssend, (char *)packet, cc, 0); if (i < 0 || i != cc) { if (i < 0) { if (options & F_FLOOD && errno == ENOBUFS) { @@ -1604,12 +1703,21 @@ pr_addr(struct in_addr ina) struct hostent *hp; static char buf[16 + 3 + MAXHOSTNAMELEN]; - if ((options & F_NUMERIC) || - !(hp = gethostbyaddr((char *)&ina, 4, AF_INET))) + if (options & F_NUMERIC) return inet_ntoa(ina); + +#ifdef HAVE_LIBCAPSICUM + if (capdns != NULL) + hp = cap_gethostbyaddr(capdns, (char *)&ina, 4, AF_INET); else - (void)snprintf(buf, sizeof(buf), "%s (%s)", hp->h_name, - inet_ntoa(ina)); +#endif + hp = gethostbyaddr((char *)&ina, 4, AF_INET); + + if (hp == NULL) + return inet_ntoa(ina); + + (void)snprintf(buf, sizeof(buf), "%s (%s)", hp->h_name, + inet_ntoa(ina)); return(buf); } @@ -1682,6 +1790,36 @@ fill(char *bp, char *patp) } } +#ifdef HAVE_LIBCAPSICUM +static cap_channel_t * +capdns_setup(void) +{ + cap_channel_t *capcas, *capdnsloc; + const char *types[2]; + int families[1]; + + capcas = cap_init(); + if (capcas == NULL) { + warn("unable to contact casperd"); + return (NULL); + } + capdnsloc = cap_service_open(capcas, "system.dns"); + /* Casper capability no longer needed. */ + cap_close(capcas); + if (capdnsloc == NULL) + err(1, "unable to open system.dns service"); + types[0] = "NAME"; + types[1] = "ADDR"; + if (cap_dns_type_limit(capdnsloc, types, 2) < 0) + err(1, "unable to limit access to system.dns service"); + families[0] = AF_INET; + if (cap_dns_family_limit(capdnsloc, families, 1) < 0) + err(1, "unable to limit access to system.dns service"); + + return (capdnsloc); +} +#endif /* HAVE_LIBCAPSICUM */ + #if defined(IPSEC) && defined(IPSEC_POLICY_IPSEC) #define SECOPT " [-P policy]" #else _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"