1361aa2e2
Denys Vlasenko
2009-11-26
Subject
udp_io: fix two more potential cases of unaligned accesses. 0 code size changes.
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Commit Diff GitHub →
libbb/udp_io.c+32 -21
| @@ -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 | |