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Merge pull request #15570 from poettering/cmsg-find

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CMSG_FIND_DATA() and cmsg_find() work
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2020-04-24 07:45:07 +02:00 committed by GitHub
commit 11f9379866
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10 changed files with 40 additions and 95 deletions
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13
src/basic/socket-util.c
View File

@ -887,7 +887,7 @@ ssize_t receive_one_fd_iov(
.msg_iov = iov,
.msg_iovlen = iovlen,
};
struct cmsghdr *cmsg, *found = NULL;
struct cmsghdr *found;
ssize_t k;
assert(transport_fd >= 0);
@ -905,16 +905,7 @@ ssize_t receive_one_fd_iov(
if (k < 0)
return k;
CMSG_FOREACH(cmsg, &mh) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
assert(!found);
found = cmsg;
break;
}
}
found = cmsg_find(&mh, SOL_SOCKET, SCM_RIGHTS, CMSG_LEN(sizeof(int)));
if (!found) {
cmsg_close_all(&mh);

8
src/basic/socket-util.h
View File

@ -158,6 +158,14 @@ int flush_accept(int fd);
struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length);
/* Type-safe, dereferencing version of cmsg_find() */
#define CMSG_FIND_DATA(mh, level, type, ctype) \
({ \
struct cmsghdr *_found; \
_found = cmsg_find(mh, level, type, CMSG_LEN(sizeof(ctype))); \
(ctype*) (_found ? CMSG_DATA(_found) : NULL); \
})
/*
* Certain hardware address types (e.g Infiniband) do not fit into sll_addr
* (8 bytes) and run over the structure. This macro returns the correct size that

12
src/coredump/coredump.c
View File

@ -921,19 +921,11 @@ static int process_socket(int fd) {
/* The final zero-length datagram carries the file descriptor and tells us
* that we're done. */
if (n == 0) {
struct cmsghdr *cmsg, *found = NULL;
struct cmsghdr *found;
free(iovec.iov_base);
CMSG_FOREACH(cmsg, &mh) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
assert(!found);
found = cmsg;
}
}
found = cmsg_find(&mh, SOL_SOCKET, SCM_RIGHTS, CMSG_LEN(sizeof(int)));
if (!found) {
cmsg_close_all(&mh);
r = log_error_errno(SYNTHETIC_ERRNO(EBADMSG),

10
src/import/importd.c
View File

@ -557,9 +557,8 @@ static int manager_on_notify(sd_event_source *s, int fd, uint32_t revents, void
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct ucred *ucred = NULL;
struct ucred *ucred;
Manager *m = userdata;
struct cmsghdr *cmsg;
char *p, *e;
Transfer *t;
Iterator i;
@ -574,17 +573,12 @@ static int manager_on_notify(sd_event_source *s, int fd, uint32_t revents, void
cmsg_close_all(&msghdr);
CMSG_FOREACH(cmsg, &msghdr)
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDENTIALS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)))
ucred = (struct ucred*) CMSG_DATA(cmsg);
if (msghdr.msg_flags & MSG_TRUNC) {
log_warning("Got overly long notification datagram, ignoring.");
return 0;
}
ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
if (!ucred || ucred->pid <= 0) {
log_warning("Got notification datagram lacking credential information, ignoring.");
return 0;

26
src/journal/journald-stream.c
View File

@ -491,8 +491,7 @@ static int stdout_stream_scan(StdoutStream *s, bool force_flush) {
static int stdout_stream_process(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
StdoutStream *s = userdata;
struct ucred *ucred = NULL;
struct cmsghdr *cmsg;
struct ucred *ucred;
struct iovec iovec;
size_t limit;
ssize_t l;
@ -541,25 +540,14 @@ static int stdout_stream_process(sd_event_source *es, int fd, uint32_t revents,
goto terminate;
}
CMSG_FOREACH(cmsg, &msghdr)
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDENTIALS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
assert(!ucred);
ucred = (struct ucred *)CMSG_DATA(cmsg);
break;
}
/* Invalidate the context if the pid of the sender changed.
* This happens when a forked process inherits stdout / stderr
* from a parent. In this case getpeercred returns the ucred
* of the parent, which can be invalid if the parent has exited
* in the meantime.
/* Invalidate the context if the pid of the sender changed. This happens when a forked process
* inherits stdout / stderr from a parent. In this case getpeercred returns the ucred of the parent,
* which can be invalid if the parent has exited in the meantime.
*/
ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
if (ucred && ucred->pid != s->ucred.pid) {
/* force out any previously half-written lines from a
* different process, before we switch to the new ucred
* structure for everything we just added */
/* force out any previously half-written lines from a different process, before we switch to
* the new ucred structure for everything we just added */
r = stdout_stream_scan(s, true);
if (r < 0)
goto terminate;

14
src/libsystemd-network/sd-dhcp-client.c
View File

@ -1937,15 +1937,11 @@ static int client_receive_message_raw(
if ((size_t) len < sizeof(DHCPPacket))
return 0;
CMSG_FOREACH(cmsg, &msg)
if (cmsg->cmsg_level == SOL_PACKET &&
cmsg->cmsg_type == PACKET_AUXDATA &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct tpacket_auxdata))) {
struct tpacket_auxdata *aux = (struct tpacket_auxdata*)CMSG_DATA(cmsg);
checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
break;
}
cmsg = cmsg_find(&msg, SOL_PACKET, PACKET_AUXDATA, CMSG_LEN(sizeof(struct tpacket_auxdata)));
if (cmsg) {
struct tpacket_auxdata *aux = (struct tpacket_auxdata*) CMSG_DATA(cmsg);
checksum = !(aux->tp_status & TP_STATUS_CSUMNOTREADY);
}
r = dhcp_packet_verify_headers(packet, len, checksum, client->port);
if (r < 0)

22
src/libsystemd/sd-netlink/netlink-socket.c
View File

@ -238,7 +238,7 @@ int socket_write_message(sd_netlink *nl, sd_netlink_message *m) {
return k;
}
static int socket_recv_message(int fd, struct iovec *iov, uint32_t *_group, bool peek) {
static int socket_recv_message(int fd, struct iovec *iov, uint32_t *ret_mcast_group, bool peek) {
union sockaddr_union sender;
uint8_t cmsg_buffer[CMSG_SPACE(sizeof(struct nl_pktinfo))];
struct msghdr msg = {
@ -249,8 +249,6 @@ static int socket_recv_message(int fd, struct iovec *iov, uint32_t *_group, bool
.msg_control = cmsg_buffer,
.msg_controllen = sizeof(cmsg_buffer),
};
struct cmsghdr *cmsg;
uint32_t group = 0;
ssize_t n;
assert(fd >= 0);
@ -281,20 +279,16 @@ static int socket_recv_message(int fd, struct iovec *iov, uint32_t *_group, bool
return 0;
}
CMSG_FOREACH(cmsg, &msg) {
if (cmsg->cmsg_level == SOL_NETLINK &&
cmsg->cmsg_type == NETLINK_PKTINFO &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct nl_pktinfo))) {
struct nl_pktinfo *pktinfo = (void *)CMSG_DATA(cmsg);
if (ret_mcast_group) {
struct cmsghdr *cmsg;
/* multi-cast group */
group = pktinfo->group;
}
cmsg = cmsg_find(&msg, SOL_NETLINK, NETLINK_PKTINFO, CMSG_LEN(sizeof(struct nl_pktinfo)));
if (ret_mcast_group)
*ret_mcast_group = ((struct nl_pktinfo*) CMSG_DATA(cmsg))->group;
else
*ret_mcast_group = 0;
}
if (_group)
*_group = group;
return (int) n;
}

13
src/nspawn/nspawn.c
View File

@ -3698,8 +3698,7 @@ static int nspawn_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t r
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg;
struct ucred *ucred = NULL;
struct ucred *ucred;
ssize_t n;
pid_t inner_child_pid;
_cleanup_strv_free_ char **tags = NULL;
@ -3721,15 +3720,7 @@ static int nspawn_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t r
cmsg_close_all(&msghdr);
CMSG_FOREACH(cmsg, &msghdr) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDENTIALS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
ucred = (struct ucred*) CMSG_DATA(cmsg);
}
}
ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
if (!ucred || ucred->pid != inner_child_pid) {
log_debug("Received notify message without valid credentials. Ignoring.");
return 0;

7
src/shared/ask-password-api.c
View File

@ -940,15 +940,12 @@ int ask_password_agent(
continue;
}
if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
control.cmsghdr.cmsg_level != SOL_SOCKET ||
control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
if (!ucred) {
log_debug("Received message without credentials. Ignoring.");
continue;
}
ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
if (ucred->uid != 0) {
log_debug("Got request from unprivileged user. Ignoring.");
continue;

10
src/udev/udevd.c
View File

@ -916,9 +916,8 @@ static int on_worker(sd_event_source *s, int fd, uint32_t revents, void *userdat
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg;
ssize_t size;
struct ucred *ucred = NULL;
struct ucred *ucred;
struct worker *worker;
size = recvmsg_safe(fd, &msghdr, MSG_DONTWAIT);
@ -937,12 +936,7 @@ static int on_worker(sd_event_source *s, int fd, uint32_t revents, void *userdat
continue;
}
CMSG_FOREACH(cmsg, &msghdr)
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDENTIALS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)))
ucred = (struct ucred*) CMSG_DATA(cmsg);
ucred = CMSG_FIND_DATA(&msghdr, SOL_SOCKET, SCM_CREDENTIALS, struct ucred);
if (!ucred || ucred->pid <= 0) {
log_warning("Ignoring worker message without valid PID");
continue;