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authorDenys Vlasenko <vda.linux@googlemail.com>2009-11-26 15:52:25 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2009-11-26 15:52:25 (GMT)
commit1361aa2e2d80cb144b4158722de3c913855e6002 (patch)
tree6fddc0669c8032c4381ba6ba1a32cc407670d905
parent57be1eefab8494efd96bcec0f54a84cef3f61e95 (diff)
downloadbusybox-1361aa2e2d80cb144b4158722de3c913855e6002.tar.gz
busybox-1361aa2e2d80cb144b4158722de3c913855e6002.tar.bz2
udp_io: fix two more potential cases of unaligned accesses. 0 code size changes.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--libbb/udp_io.c53
1 files changed, 32 insertions, 21 deletions
diff --git a/libbb/udp_io.c b/libbb/udp_io.c
index b31f284..d9375ea 100644
--- a/libbb/udp_io.c
+++ b/libbb/udp_io.c
@@ -6,7 +6,6 @@
*
* Licensed under GPL version 2, see file LICENSE in this tarball for details.
*/
-
#include "libbb.h"
/*
@@ -32,22 +31,23 @@ send_to_from(int fd, void *buf, size_t len, int flags,
socklen_t tolen)
{
#ifndef IP_PKTINFO
+ (void)from; /* suppress "unused from" warning */
return sendto(fd, buf, len, flags, to, tolen);
#else
struct iovec iov[1];
struct msghdr msg;
union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
-#endif
+# endif
} u;
struct cmsghdr* cmsgptr;
if (from->sa_family != AF_INET
-#if ENABLE_FEATURE_IPV6
+# if ENABLE_FEATURE_IPV6
&& from->sa_family != AF_INET6
-#endif
+# endif
) {
/* ANY local address */
return sendto(fd, buf, len, flags, to, tolen);
@@ -76,20 +76,26 @@ send_to_from(int fd, void *buf, size_t len, int flags,
cmsgptr->cmsg_type = IP_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr));
- /* pktptr->ipi_ifindex = 0; -- already done by memset(cbuf...) */
+ /*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */
+ /* In general, CMSG_DATA() can be unaligned, but in this case
+ * we know for sure it is sufficiently aligned:
+ * CMSG_FIRSTHDR simply returns &u above,
+ * and CMSG_DATA returns &u + size_t + int + int.
+ * Thus direct assignment is ok:
+ */
pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr;
}
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
struct in6_pktinfo *pktptr;
cmsgptr->cmsg_level = IPPROTO_IPV6;
cmsgptr->cmsg_type = IPV6_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr));
- /* pktptr->ipi6_ifindex = 0; -- already done by memset(cbuf...) */
+ /* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */
pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
}
-#endif
+# endif
msg.msg_controllen = cmsgptr->cmsg_len;
return sendmsg(fd, &msg, flags);
@@ -106,15 +112,16 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
socklen_t sa_size)
{
#ifndef IP_PKTINFO
+ (void)to; /* suppress "unused to" warning */
return recvfrom(fd, buf, len, flags, from, &sa_size);
#else
/* man recvmsg and man cmsg is needed to make sense of code below */
struct iovec iov[1];
union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
-#endif
+# endif
} u;
struct cmsghdr *cmsgptr;
struct msghdr msg;
@@ -135,6 +142,8 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
if (recv_length < 0)
return recv_length;
+# define to4 ((struct sockaddr_in*)to)
+# define to6 ((struct sockaddr_in6*)to)
/* Here we try to retrieve destination IP and memorize it */
for (cmsgptr = CMSG_FIRSTHDR(&msg);
cmsgptr != NULL;
@@ -143,25 +152,27 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
if (cmsgptr->cmsg_level == IPPROTO_IP
&& cmsgptr->cmsg_type == IP_PKTINFO
) {
-#define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
+# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )
to->sa_family = AF_INET;
- ((struct sockaddr_in*)to)->sin_addr = pktinfo(cmsgptr)->ipi_addr;
- /* ((struct sockaddr_in*)to)->sin_port = 123; */
-#undef pktinfo
+ /*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
+ memcpy(&to4->sin_addr, &pktinfo(cmsgptr)->ipi_addr, sizeof(to4->sin_addr));
+ /*to4->sin_port = 123; - this data is not supplied by kernel */
+# undef pktinfo
break;
}
-#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
+# if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
if (cmsgptr->cmsg_level == IPPROTO_IPV6
&& cmsgptr->cmsg_type == IPV6_PKTINFO
) {
-#define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )
+# define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )
to->sa_family = AF_INET6;
- ((struct sockaddr_in6*)to)->sin6_addr = pktinfo(cmsgptr)->ipi6_addr;
- /* ((struct sockaddr_in6*)to)->sin6_port = 123; */
-#undef pktinfo
+ /*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
+ memcpy(&to6->sin6_addr, &pktinfo(cmsgptr)->ipi6_addr, sizeof(to6->sin6_addr));
+ /*to6->sin6_port = 123; */
+# undef pktinfo
break;
}
-#endif
+# endif
}
return recv_length;
#endif