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udp_io: fix two more potential cases of unaligned accesses. 0 code size changes. 

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1_16_stable
Denys Vlasenko 2009-11-26 16:52:25 +01:00
parent 57be1eefab
commit 1361aa2e2d
1 changed files with 32 additions and 21 deletions
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53
libbb/udp_io.c
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@ -6,7 +6,6 @@
* *
* Licensed under GPL version 2, see file LICENSE in this tarball for details. * Licensed under GPL version 2, see file LICENSE in this tarball for details.
*/ */
#include "libbb.h" #include "libbb.h"
/* /*
@ -32,22 +31,23 @@ send_to_from(int fd, void *buf, size_t len, int flags,
socklen_t tolen) socklen_t tolen)
{ {
#ifndef IP_PKTINFO #ifndef IP_PKTINFO
(void)from; /* suppress "unused from" warning */
return sendto(fd, buf, len, flags, to, tolen); return sendto(fd, buf, len, flags, to, tolen);
#else #else
struct iovec iov[1]; struct iovec iov[1];
struct msghdr msg; struct msghdr msg;
union { union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))]; 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))]; char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
#endif # endif
} u; } u;
struct cmsghdr* cmsgptr; struct cmsghdr* cmsgptr;
if (from->sa_family != AF_INET if (from->sa_family != AF_INET
#if ENABLE_FEATURE_IPV6 # if ENABLE_FEATURE_IPV6
&& from->sa_family != AF_INET6 && from->sa_family != AF_INET6
#endif # endif
) { ) {
/* ANY local address */ /* ANY local address */
return sendto(fd, buf, len, flags, to, tolen); 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_type = IP_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo)); cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr)); 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; 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) { else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
struct in6_pktinfo *pktptr; struct in6_pktinfo *pktptr;
cmsgptr->cmsg_level = IPPROTO_IPV6; cmsgptr->cmsg_level = IPPROTO_IPV6;
cmsgptr->cmsg_type = IPV6_PKTINFO; cmsgptr->cmsg_type = IPV6_PKTINFO;
cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr)); 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; pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
} }
#endif # endif
msg.msg_controllen = cmsgptr->cmsg_len; msg.msg_controllen = cmsgptr->cmsg_len;
return sendmsg(fd, &msg, flags); 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) socklen_t sa_size)
{ {
#ifndef IP_PKTINFO #ifndef IP_PKTINFO
(void)to; /* suppress "unused to" warning */
return recvfrom(fd, buf, len, flags, from, &sa_size); return recvfrom(fd, buf, len, flags, from, &sa_size);
#else #else
/* man recvmsg and man cmsg is needed to make sense of code below */ /* man recvmsg and man cmsg is needed to make sense of code below */
struct iovec iov[1]; struct iovec iov[1];
union { union {
char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))]; 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))]; char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
#endif # endif
} u; } u;
struct cmsghdr *cmsgptr; struct cmsghdr *cmsgptr;
struct msghdr msg; struct msghdr msg;
@ -135,6 +142,8 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
if (recv_length < 0) if (recv_length < 0)
return recv_length; 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 */ /* Here we try to retrieve destination IP and memorize it */
for (cmsgptr = CMSG_FIRSTHDR(&msg); for (cmsgptr = CMSG_FIRSTHDR(&msg);
cmsgptr != NULL; cmsgptr != NULL;
@ -143,25 +152,27 @@ recv_from_to(int fd, void *buf, size_t len, int flags,
if (cmsgptr->cmsg_level == IPPROTO_IP if (cmsgptr->cmsg_level == IPPROTO_IP
&& cmsgptr->cmsg_type == IP_PKTINFO && 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; to->sa_family = AF_INET;
((struct sockaddr_in*)to)->sin_addr = pktinfo(cmsgptr)->ipi_addr; /*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
/* ((struct sockaddr_in*)to)->sin_port = 123; */ memcpy(&to4->sin_addr, &pktinfo(cmsgptr)->ipi_addr, sizeof(to4->sin_addr));
#undef pktinfo /*to4->sin_port = 123; - this data is not supplied by kernel */
# undef pktinfo
break; break;
} }
#if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
if (cmsgptr->cmsg_level == IPPROTO_IPV6 if (cmsgptr->cmsg_level == IPPROTO_IPV6
&& cmsgptr->cmsg_type == IPV6_PKTINFO && 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; to->sa_family = AF_INET6;
((struct sockaddr_in6*)to)->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; /*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
/* ((struct sockaddr_in6*)to)->sin6_port = 123; */ memcpy(&to6->sin6_addr, &pktinfo(cmsgptr)->ipi6_addr, sizeof(to6->sin6_addr));
#undef pktinfo /*to6->sin6_port = 123; */
# undef pktinfo
break; break;
} }
#endif # endif
} }
return recv_length; return recv_length;
#endif #endif