Merge pull request #27253 from yuwata/cmsg-find-and-copy-data

socket-util: introduce CMSG_FIND_AND_COPY_DATA()

src/basic/socket-util.c

@@ -1171,6 +1171,24 @@ struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t leng
         return NULL;
 }
 
+void* cmsg_find_and_copy_data(struct msghdr *mh, int level, int type, void *buf, size_t buf_len) {
+        struct cmsghdr *cmsg;
+
+        assert(mh);
+        assert(buf);
+        assert(buf_len > 0);
+
+        /* This is similar to cmsg_find_data(), but copy the found data to buf. This should be typically used
+         * when reading possibly unaligned data such as timestamp, as time_t is 64bit and size_t is 32bit on
+         * RISCV32. See issue #27241. */
+
+        cmsg = cmsg_find(mh, level, type, CMSG_LEN(buf_len));
+        if (!cmsg)
+                return NULL;
+
+        return memcpy_safe(buf, CMSG_DATA(cmsg), buf_len);
+}
+
 int socket_ioctl_fd(void) {
         int fd;
 

src/basic/socket-util.h

@@ -183,17 +183,22 @@ int flush_accept(int fd);
  * riscv32. */
 #define CMSG_TYPED_DATA(cmsg, type)                                     \
         ({                                                              \
-                struct cmsghdr *_cmsg = cmsg;                           \
-                assert_cc(__alignof__(type) <= __alignof__(struct cmsghdr)); \
+                struct cmsghdr *_cmsg = (cmsg);                         \
+                assert_cc(alignof(type) <= alignof(struct cmsghdr));    \
                 _cmsg ? CAST_ALIGN_PTR(type, CMSG_DATA(_cmsg)) : (type*) NULL; \
         })
 
 struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length);
+void* cmsg_find_and_copy_data(struct msghdr *mh, int level, int type, void *buf, size_t buf_len);
 
 /* Type-safe, dereferencing version of cmsg_find() */
 #define CMSG_FIND_DATA(mh, level, type, ctype)                          \
         CMSG_TYPED_DATA(cmsg_find(mh, level, type, CMSG_LEN(sizeof(ctype))), ctype)
 
+/* Type-safe version of cmsg_find_and_copy_data() */
+#define CMSG_FIND_AND_COPY_DATA(mh, level, type, ctype)             \
+        (ctype*) cmsg_find_and_copy_data(mh, level, type, &(ctype){}, sizeof(ctype))
+
 /* Resolves to a type that can carry cmsghdr structures. Make sure things are properly aligned, i.e. the type
  * itself is placed properly in memory and the size is also aligned to what's appropriate for "cmsghdr"
  * structures. */

src/boot/efi/pe.c

@@ -191,7 +191,7 @@ static uint32_t get_compatibility_entry_address(const DosFileHeader *dos, const
                 uint32_t entry_point;
         } _packed_ LinuxPeCompat1;
 
-        while (size >= sizeof(LinuxPeCompat1) && addr % __alignof__(LinuxPeCompat1) == 0) {
+        while (size >= sizeof(LinuxPeCompat1) && addr % alignof(LinuxPeCompat1) == 0) {
                 LinuxPeCompat1 *compat = (LinuxPeCompat1 *) ((uint8_t *) dos + addr);
 
                 if (compat->type == 0 || compat->size == 0 || compat->size > size)

src/fundamental/macro-fundamental.h

@@ -6,12 +6,13 @@
 #endif
 
 #include <limits.h>
+#include <stdalign.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #define _align_(x) __attribute__((__aligned__(x)))
-#define _alignas_(x) __attribute__((__aligned__(__alignof__(x))))
+#define _alignas_(x) __attribute__((__aligned__(alignof(x))))
 #define _alignptr_ __attribute__((__aligned__(sizeof(void *))))
 #define _cleanup_(x) __attribute__((__cleanup__(x)))
 #define _const_ __attribute__((__const__))
@@ -343,9 +344,9 @@ static inline size_t ALIGN_TO(size_t l, size_t ali) {
 #define ALIGN_PTR(p) ((void*) ALIGN((uintptr_t) (p)))
 
 /* Checks if the specified pointer is aligned as appropriate for the specific type */
-#define IS_ALIGNED16(p) (((uintptr_t) p) % __alignof__(uint16_t) == 0)
-#define IS_ALIGNED32(p) (((uintptr_t) p) % __alignof__(uint32_t) == 0)
-#define IS_ALIGNED64(p) (((uintptr_t) p) % __alignof__(uint64_t) == 0)
+#define IS_ALIGNED16(p) (((uintptr_t) p) % alignof(uint16_t) == 0)
+#define IS_ALIGNED32(p) (((uintptr_t) p) % alignof(uint32_t) == 0)
+#define IS_ALIGNED64(p) (((uintptr_t) p) % alignof(uint64_t) == 0)
 
 /* Same as ALIGN_TO but callable in constant contexts. */
 #define CONST_ALIGN_TO(l, ali)                                         \
@@ -363,7 +364,7 @@ static inline size_t ALIGN_TO(size_t l, size_t ali) {
 #define CAST_ALIGN_PTR(t, p)                                    \
         ({                                                      \
                 const void *_p = (p);                           \
-                assert(((uintptr_t) _p) % __alignof__(t) == 0); \
+                assert(((uintptr_t) _p) % alignof(t) == 0); \
                 (t *) _p;                                       \
         })
 

src/journal/journald-server.c

@@ -1417,7 +1417,7 @@ int server_process_datagram(
         size_t label_len = 0, m;
         Server *s = ASSERT_PTR(userdata);
         struct ucred *ucred = NULL;
-        struct timeval *tv = NULL;
+        struct timeval tv_buf, *tv = NULL;
         struct cmsghdr *cmsg;
         char *label = NULL;
         struct iovec iovec;
@@ -1493,10 +1493,10 @@ int server_process_datagram(
                         label = CMSG_TYPED_DATA(cmsg, char);
                         label_len = cmsg->cmsg_len - CMSG_LEN(0);
                 } else if (cmsg->cmsg_level == SOL_SOCKET &&
-                           cmsg->cmsg_type == SO_TIMESTAMP &&
+                           cmsg->cmsg_type == SCM_TIMESTAMP &&
                            cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval))) {
                         assert(!tv);
-                        tv = CMSG_TYPED_DATA(cmsg, struct timeval);
+                        tv = memcpy(&tv_buf, CMSG_DATA(cmsg), sizeof(struct timeval));
                 } else if (cmsg->cmsg_level == SOL_SOCKET &&
                          cmsg->cmsg_type == SCM_RIGHTS) {
                         assert(!fds);

src/libsystemd-network/icmp6-util.c

@@ -199,9 +199,11 @@ int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *ret_dst,
                 }
 
                 if (cmsg->cmsg_level == SOL_SOCKET &&
-                    cmsg->cmsg_type == SO_TIMESTAMP &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
-                        triple_timestamp_from_realtime(&t, timeval_load(CMSG_TYPED_DATA(cmsg, struct timeval)));
+                    cmsg->cmsg_type == SCM_TIMESTAMP &&
+                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval))) {
+                        struct timeval *tv = memcpy(&(struct timeval) {}, CMSG_DATA(cmsg), sizeof(struct timeval));
+                        triple_timestamp_from_realtime(&t, timeval_load(tv));
+                }
         }
 
         if (!triple_timestamp_is_set(&t))

src/libsystemd-network/sd-dhcp-server.c

@@ -407,7 +407,7 @@ static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
                    rather than binding the socket. This will be mostly useful
                    when we gain support for arbitrary number of server addresses
                  */
-                pktinfo = (struct in_pktinfo*) CMSG_DATA(cmsg);
+                pktinfo = CMSG_TYPED_DATA(cmsg, struct in_pktinfo);
                 assert(pktinfo);
 
                 pktinfo->ipi_ifindex = server->ifindex;
@@ -1270,7 +1270,6 @@ static int server_receive_message(sd_event_source *s, int fd,
                 .msg_control = &control,
                 .msg_controllen = sizeof(control),
         };
-        struct cmsghdr *cmsg;
         ssize_t datagram_size, len;
         int r;
 
@@ -1306,19 +1305,10 @@ static int server_receive_message(sd_event_source *s, int fd,
         if ((size_t) len < sizeof(DHCPMessage))
                 return 0;
 
-        CMSG_FOREACH(cmsg, &msg)
-                if (cmsg->cmsg_level == IPPROTO_IP &&
-                    cmsg->cmsg_type == IP_PKTINFO &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct in_pktinfo))) {
-                        struct in_pktinfo *info = CMSG_TYPED_DATA(cmsg, struct in_pktinfo);
-
-                        /* TODO figure out if this can be done as a filter on
-                         * the socket, like for IPv6 */
-                        if (server->ifindex != info->ipi_ifindex)
-                                return 0;
-
-                        break;
-                }
+        /* TODO figure out if this can be done as a filter on the socket, like for IPv6 */
+        struct in_pktinfo *info = CMSG_FIND_DATA(&msg, IPPROTO_IP, IP_PKTINFO, struct in_pktinfo);
+        if (info && info->ipi_ifindex != server->ifindex)
+                return 0;
 
         if (sd_dhcp_server_is_in_relay_mode(server)) {
                 r = dhcp_server_relay_message(server, message, len - sizeof(DHCPMessage), buflen);

src/libsystemd-network/sd-dhcp6-client.c

@@ -1276,7 +1276,6 @@ static int client_receive_message(
                 .msg_control = &control,
                 .msg_controllen = sizeof(control),
         };
-        struct cmsghdr *cmsg;
         triple_timestamp t = {};
         _cleanup_free_ DHCP6Message *message = NULL;
         struct in6_addr *server_address = NULL;
@@ -1320,12 +1319,9 @@ static int client_receive_message(
                 server_address = &sa.in6.sin6_addr;
         }
 
-        CMSG_FOREACH(cmsg, &msg) {
-                if (cmsg->cmsg_level == SOL_SOCKET &&
-                    cmsg->cmsg_type == SO_TIMESTAMP &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
-                        triple_timestamp_from_realtime(&t, timeval_load(CMSG_TYPED_DATA(cmsg, struct timeval)));
-        }
+        struct timeval *tv = CMSG_FIND_AND_COPY_DATA(&msg, SOL_SOCKET, SCM_TIMESTAMP, struct timeval);
+        if (tv)
+                triple_timestamp_from_realtime(&t, timeval_load(tv));
 
         if (client->transaction_id != (message->transaction_id & htobe32(0x00ffffff)))
                 return 0;

src/libsystemd/sd-daemon/sd-daemon.c

@@ -567,7 +567,7 @@ _public_ int sd_pid_notify_with_fds(
                         cmsg->cmsg_type = SCM_CREDENTIALS;
                         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 
-                        ucred = (struct ucred*) CMSG_DATA(cmsg);
+                        ucred = CMSG_TYPED_DATA(cmsg, struct ucred);
                         ucred->pid = pid != 0 ? pid : getpid_cached();
                         ucred->uid = getuid();
                         ucred->gid = getgid();

src/network/networkd-nexthop.c

@@ -894,7 +894,7 @@ int manager_rtnl_process_nexthop(sd_netlink *rtnl, sd_netlink_message *message,
                         return 0;
                 }
 
-                assert((uintptr_t) group % __alignof__(struct nexthop_grp) == 0);
+                assert((uintptr_t) group % alignof(struct nexthop_grp) == 0);
 
                 n_group = raw_group_size / sizeof(struct nexthop_grp);
                 for (size_t i = 0; i < n_group; i++) {

src/resolve/resolved-manager.c

@@ -1017,7 +1017,7 @@ static int manager_ipv4_send(
                 cmsg->cmsg_level = IPPROTO_IP;
                 cmsg->cmsg_type = IP_PKTINFO;
 
-                pi = (struct in_pktinfo*) CMSG_DATA(cmsg);
+                pi = CMSG_TYPED_DATA(cmsg, struct in_pktinfo);
                 pi->ipi_ifindex = ifindex;
 
                 if (source)
@@ -1073,7 +1073,7 @@ static int manager_ipv6_send(
                 cmsg->cmsg_level = IPPROTO_IPV6;
                 cmsg->cmsg_type = IPV6_PKTINFO;
 
-                pi = (struct in6_pktinfo*) CMSG_DATA(cmsg);
+                pi = CMSG_TYPED_DATA(cmsg, struct in6_pktinfo);
                 pi->ipi6_ifindex = ifindex;
 
                 if (source)

src/test/test-sizeof.c

@@ -17,16 +17,16 @@
 DISABLE_WARNING_TYPE_LIMITS;
 
 #define info_no_sign(t)                                                 \
-        printf("%s → %zu bits, %zu byte alignment\n", STRINGIFY(t),     \
+        printf("%s → %zu bits, %zu byte alignment\n", STRINGIFY(t),    \
                sizeof(t)*CHAR_BIT,                                      \
-               __alignof__(t))
+               alignof(t))
 
 #define info(t)                                                         \
-        printf("%s → %zu bits%s, %zu byte alignment\n", STRINGIFY(t),   \
+        printf("%s → %zu bits%s, %zu byte alignment\n", STRINGIFY(t),  \
                sizeof(t)*CHAR_BIT,                                      \
                strstr(STRINGIFY(t), "signed") ? "" :                    \
                (t)-1 < (t)0 ? ", signed" : ", unsigned",                \
-               __alignof__(t))
+               alignof(t))
 
 enum Enum {
         enum_value,
@@ -44,7 +44,7 @@ enum BigEnum2 {
 int main(void) {
         int (*function_pointer)(void);
 
-        info_no_sign(function_pointer);
+        info_no_sign(typeof(function_pointer));
         info_no_sign(void*);
         info(char*);
 

src/timesync/timesyncd-manager.c

@@ -411,7 +411,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
                 .msg_name = &server_addr,
                 .msg_namelen = sizeof(server_addr),
         };
-        struct timespec *recv_time = NULL;
+        struct timespec *recv_time;
         triple_timestamp dts;
         ssize_t len;
         double origin, receive, trans, dest, delay, offset, root_distance;
@@ -446,7 +446,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
                 return 0;
         }
 
-        recv_time = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_TIMESTAMPNS, struct timespec);
+        recv_time = CMSG_FIND_AND_COPY_DATA(&msghdr, SOL_SOCKET, SCM_TIMESTAMPNS, struct timespec);
         if (!recv_time)
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Packet timestamp missing.");