From 9341fd2d300e97f2bcf8e4b804c918240de4fe33 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Wed, 3 Mar 2010 01:10:29 +0100 Subject: [PATCH] ping: do not leak data from stack; shrink FANCY ping: function old new delta common_ping_main 386 1732 +1346 sendping6 98 83 -15 sendping4 188 158 -30 ping4 575 - -575 ping6 756 - -756 ------------------------------------------------------------------------------ (add/remove: 0/2 grow/shrink: 1/2 up/down: 1346/-1376) Total: -30 bytes !FANCY ping: function old new delta hostname 4 - -4 common_ping_main 566 499 -67 Signed-off-by: Denys Vlasenko --- networking/ping.c | 104 +++++++++++++++++++++++++--------------------- 1 file changed, 57 insertions(+), 47 deletions(-) diff --git a/networking/ping.c b/networking/ping.c index 467b7f694..6a766a437 100644 --- a/networking/ping.c +++ b/networking/ping.c @@ -43,13 +43,12 @@ enum { DEFDATALEN = 56, MAXIPLEN = 60, MAXICMPLEN = 76, - MAXPACKET = 65468, MAX_DUP_CHK = (8 * 128), MAXWAIT = 10, PINGINTERVAL = 1, /* 1 second */ }; -/* common routines */ +/* Common routines */ static int in_cksum(unsigned short *buf, int sz) { @@ -76,40 +75,41 @@ static int in_cksum(unsigned short *buf, int sz) #if !ENABLE_FEATURE_FANCY_PING -/* simple version */ +/* Simple version */ -static char *hostname; +struct globals { + char *hostname; + char packet[DEFDATALEN + MAXIPLEN + MAXICMPLEN]; +} FIX_ALIASING; +#define G (*(struct globals*)&bb_common_bufsiz1) +#define INIT_G() do { } while (0) static void noresp(int ign UNUSED_PARAM) { - printf("No response from %s\n", hostname); + printf("No response from %s\n", G.hostname); exit(EXIT_FAILURE); } static void ping4(len_and_sockaddr *lsa) { - struct sockaddr_in pingaddr; struct icmp *pkt; int pingsock, c; - char packet[DEFDATALEN + MAXIPLEN + MAXICMPLEN]; pingsock = create_icmp_socket(); - pingaddr = lsa->u.sin; - pkt = (struct icmp *) packet; - memset(pkt, 0, sizeof(packet)); + pkt = (struct icmp *) G.packet; + memset(pkt, 0, sizeof(G.packet)); pkt->icmp_type = ICMP_ECHO; - pkt->icmp_cksum = in_cksum((unsigned short *) pkt, sizeof(packet)); + pkt->icmp_cksum = in_cksum((unsigned short *) pkt, sizeof(G.packet)); - c = xsendto(pingsock, packet, DEFDATALEN + ICMP_MINLEN, - (struct sockaddr *) &pingaddr, sizeof(pingaddr)); + xsendto(pingsock, G.packet, DEFDATALEN + ICMP_MINLEN, &lsa->u.sa, lsa->len); /* listen for replies */ while (1) { struct sockaddr_in from; socklen_t fromlen = sizeof(from); - c = recvfrom(pingsock, packet, sizeof(packet), 0, + c = recvfrom(pingsock, G.packet, sizeof(G.packet), 0, (struct sockaddr *) &from, &fromlen); if (c < 0) { if (errno != EINTR) @@ -117,9 +117,9 @@ static void ping4(len_and_sockaddr *lsa) continue; } if (c >= 76) { /* ip + icmp */ - struct iphdr *iphdr = (struct iphdr *) packet; + struct iphdr *iphdr = (struct iphdr *) G.packet; - pkt = (struct icmp *) (packet + (iphdr->ihl << 2)); /* skip ip hdr */ + pkt = (struct icmp *) (G.packet + (iphdr->ihl << 2)); /* skip ip hdr */ if (pkt->icmp_type == ICMP_ECHOREPLY) break; } @@ -131,31 +131,27 @@ static void ping4(len_and_sockaddr *lsa) #if ENABLE_PING6 static void ping6(len_and_sockaddr *lsa) { - struct sockaddr_in6 pingaddr; struct icmp6_hdr *pkt; int pingsock, c; int sockopt; - char packet[DEFDATALEN + MAXIPLEN + MAXICMPLEN]; pingsock = create_icmp6_socket(); - pingaddr = lsa->u.sin6; - pkt = (struct icmp6_hdr *) packet; - memset(pkt, 0, sizeof(packet)); + pkt = (struct icmp6_hdr *) G.packet; + memset(pkt, 0, sizeof(G.packet)); pkt->icmp6_type = ICMP6_ECHO_REQUEST; sockopt = offsetof(struct icmp6_hdr, icmp6_cksum); setsockopt(pingsock, SOL_RAW, IPV6_CHECKSUM, &sockopt, sizeof(sockopt)); - c = xsendto(pingsock, packet, DEFDATALEN + sizeof (struct icmp6_hdr), - (struct sockaddr *) &pingaddr, sizeof(pingaddr)); + xsendto(pingsock, G.packet, DEFDATALEN + sizeof(struct icmp6_hdr), &lsa->u.sa, lsa->len); /* listen for replies */ while (1) { struct sockaddr_in6 from; socklen_t fromlen = sizeof(from); - c = recvfrom(pingsock, packet, sizeof(packet), 0, + c = recvfrom(pingsock, G.packet, sizeof(G.packet), 0, (struct sockaddr *) &from, &fromlen); if (c < 0) { if (errno != EINTR) @@ -163,7 +159,7 @@ static void ping6(len_and_sockaddr *lsa) continue; } if (c >= ICMP_MINLEN) { /* icmp6_hdr */ - pkt = (struct icmp6_hdr *) packet; + pkt = (struct icmp6_hdr *) G.packet; if (pkt->icmp6_type == ICMP6_ECHO_REPLY) break; } @@ -180,6 +176,8 @@ static int common_ping_main(sa_family_t af, char **argv) { len_and_sockaddr *lsa; + INIT_G(); + #if ENABLE_PING6 while ((++argv)[0] && argv[0][0] == '-') { if (argv[0][1] == '4') { @@ -196,14 +194,14 @@ static int common_ping_main(sa_family_t af, char **argv) argv++; #endif - hostname = *argv; - if (!hostname) + G.hostname = *argv; + if (!G.hostname) bb_show_usage(); #if ENABLE_PING6 - lsa = xhost_and_af2sockaddr(hostname, 0, af); + lsa = xhost_and_af2sockaddr(G.hostname, 0, af); #else - lsa = xhost_and_af2sockaddr(hostname, 0, AF_INET); + lsa = xhost_and_af2sockaddr(G.hostname, 0, AF_INET); #endif /* Set timer _after_ DNS resolution */ signal(SIGALRM, noresp); @@ -215,7 +213,7 @@ static int common_ping_main(sa_family_t af, char **argv) else #endif ping4(lsa); - printf("%s is alive!\n", hostname); + printf("%s is alive!\n", G.hostname); return EXIT_SUCCESS; } @@ -223,7 +221,7 @@ static int common_ping_main(sa_family_t af, char **argv) #else /* FEATURE_FANCY_PING */ -/* full(er) version */ +/* Full(er) version */ #define OPT_STRING ("qvc:s:w:W:I:4" IF_PING6("6")) enum { @@ -253,6 +251,9 @@ struct globals { unsigned deadline; unsigned timeout; unsigned total_secs; + unsigned sizeof_rcv_packet; + char *rcv_packet; /* [datalen + MAXIPLEN + MAXICMPLEN] */ + void *snd_packet; /* [datalen + ipv4/ipv6_const] */ const char *hostname; const char *dotted; union { @@ -370,19 +371,20 @@ static void sendping_tail(void (*sp)(int), const void *pkt, int size_pkt) static void sendping4(int junk UNUSED_PARAM) { - /* +4 reserves a place for timestamp, which may end up sitting - * *after* packet. Saves one if() */ - struct icmp *pkt = alloca(datalen + ICMP_MINLEN + 4); + struct icmp *pkt = G.snd_packet; - memset(pkt, 0, datalen + ICMP_MINLEN + 4); + //memset(pkt, 0, datalen + ICMP_MINLEN + 4); - G.snd_packet was xzalloced pkt->icmp_type = ICMP_ECHO; /*pkt->icmp_code = 0;*/ - /*pkt->icmp_cksum = 0;*/ + pkt->icmp_cksum = 0; /* cksum is calculated with this field set to 0 */ pkt->icmp_seq = htons(ntransmitted); /* don't ++ here, it can be a macro */ pkt->icmp_id = myid; - /* We don't do hton, because we will read it back on the same machine */ + /* If datalen < 4, we store timestamp _past_ the packet, + * but it's ok - we allocated 4 extra bytes in xzalloc() just in case. + */ /*if (datalen >= 4)*/ + /* No hton: we'll read it back on the same machine */ *(uint32_t*)&pkt->icmp_dun = monotonic_us(); pkt->icmp_cksum = in_cksum((unsigned short *) pkt, datalen + ICMP_MINLEN); @@ -394,7 +396,7 @@ static void sendping6(int junk UNUSED_PARAM) { struct icmp6_hdr *pkt = alloca(datalen + sizeof(struct icmp6_hdr) + 4); - memset(pkt, 0, datalen + sizeof(struct icmp6_hdr) + 4); + //memset(pkt, 0, datalen + sizeof(struct icmp6_hdr) + 4); pkt->icmp6_type = ICMP6_ECHO_REQUEST; /*pkt->icmp6_code = 0;*/ /*pkt->icmp6_cksum = 0;*/ @@ -404,6 +406,8 @@ static void sendping6(int junk UNUSED_PARAM) /*if (datalen >= 4)*/ *(uint32_t*)(&pkt->icmp6_data8[4]) = monotonic_us(); + //TODO? pkt->icmp_cksum = in_cksum(...); + sendping_tail(sendping6, pkt, datalen + sizeof(struct icmp6_hdr)); } #endif @@ -561,7 +565,6 @@ static void unpack6(char *packet, int sz, /*struct sockaddr_in6 *from,*/ int hop static void ping4(len_and_sockaddr *lsa) { - char packet[datalen + MAXIPLEN + MAXICMPLEN]; int sockopt; pingsock = create_icmp_socket(); @@ -594,14 +597,14 @@ static void ping4(len_and_sockaddr *lsa) socklen_t fromlen = (socklen_t) sizeof(from); int c; - c = recvfrom(pingsock, packet, sizeof(packet), 0, + c = recvfrom(pingsock, G.rcv_packet, G.sizeof_rcv_packet, 0, (struct sockaddr *) &from, &fromlen); if (c < 0) { if (errno != EINTR) bb_perror_msg("recvfrom"); continue; } - unpack4(packet, c, &from); + unpack4(G.rcv_packet, c, &from); if (pingcount && nreceived >= pingcount) break; } @@ -610,7 +613,6 @@ static void ping4(len_and_sockaddr *lsa) extern int BUG_bad_offsetof_icmp6_cksum(void); static void ping6(len_and_sockaddr *lsa) { - char packet[datalen + MAXIPLEN + MAXICMPLEN]; int sockopt; struct msghdr msg; struct sockaddr_in6 from; @@ -670,8 +672,8 @@ static void ping6(len_and_sockaddr *lsa) msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = control_buf; - iov.iov_base = packet; - iov.iov_len = sizeof(packet); + iov.iov_base = G.rcv_packet; + iov.iov_len = G.sizeof_rcv_packet; while (1) { int c; struct cmsghdr *mp; @@ -694,7 +696,7 @@ static void ping6(len_and_sockaddr *lsa) move_from_unaligned_int(hoplimit, CMSG_DATA(mp)); } } - unpack6(packet, c, /*&from,*/ hoplimit); + unpack6(G.rcv_packet, c, /*&from,*/ hoplimit); if (pingcount && nreceived >= pingcount) break; } @@ -710,12 +712,20 @@ static void ping(len_and_sockaddr *lsa) } printf(": %d data bytes\n", datalen); + G.sizeof_rcv_packet = datalen + MAXIPLEN + MAXICMPLEN; + G.rcv_packet = xzalloc(G.sizeof_rcv_packet); #if ENABLE_PING6 - if (lsa->u.sa.sa_family == AF_INET6) + if (lsa->u.sa.sa_family == AF_INET6) { + /* +4 reserves a place for timestamp, which may end up sitting + * _after_ packet. Saves one if() - see sendping4/6() */ + G.snd_packet = xzalloc(datalen + sizeof(struct icmp6_hdr) + 4); ping6(lsa); - else + } else #endif + { + G.snd_packet = xzalloc(datalen + ICMP_MINLEN + 4); ping4(lsa); + } } static int common_ping_main(int opt, char **argv)