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sd-dameon: also sent ucred when our UID differs from EUID

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Let's be explicit, and always send the messages from our UID and never
our EUID. Previously this behaviour was conditionalized only on whether
the PID was specified, which made this non-obvious.
This commit is contained in:
Lennart Poettering 2018-01-05 13:24:58 +01:00
parent 15e23e8cdf
commit 9e1d021ee3
1 changed files with 19 additions and 10 deletions
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29
src/libsystemd/sd-daemon/sd-daemon.c
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@ -455,7 +455,13 @@ _public_ int sd_is_mq(int fd, const char *path) {
return 1;
}
_public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds) {
_public_ int sd_pid_notify_with_fds(
pid_t pid,
int unset_environment,
const char *state,
const int *fds,
unsigned n_fds) {
union sockaddr_union sockaddr = {
.sa.sa_family = AF_UNIX,
};
@ -470,7 +476,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
_cleanup_close_ int fd = -1;
struct cmsghdr *cmsg = NULL;
const char *e;
bool have_pid;
bool send_ucred;
int r;
if (!state) {
@ -504,7 +510,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
goto finish;
}
fd_inc_sndbuf(fd, SNDBUF_SIZE);
(void) fd_inc_sndbuf(fd, SNDBUF_SIZE);
iovec.iov_len = strlen(state);
@ -514,13 +520,16 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
msghdr.msg_namelen = SOCKADDR_UN_LEN(sockaddr.un);
have_pid = pid != 0 && pid != getpid_cached();
send_ucred =
(pid != 0 && pid != getpid_cached()) ||
getuid() != geteuid() ||
getgid() != getegid();
if (n_fds > 0 || have_pid) {
if (n_fds > 0 || send_ucred) {
/* CMSG_SPACE(0) may return value different than zero, which results in miscalculated controllen. */
msghdr.msg_controllen =
(n_fds > 0 ? CMSG_SPACE(sizeof(int) * n_fds) : 0) +
(have_pid ? CMSG_SPACE(sizeof(struct ucred)) : 0);
(send_ucred ? CMSG_SPACE(sizeof(struct ucred)) : 0);
msghdr.msg_control = alloca0(msghdr.msg_controllen);
@ -532,11 +541,11 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
memcpy(CMSG_DATA(cmsg), fds, sizeof(int) * n_fds);
if (have_pid)
if (send_ucred)
assert_se(cmsg = CMSG_NXTHDR(&msghdr, cmsg));
}
if (have_pid) {
if (send_ucred) {
struct ucred *ucred;
cmsg->cmsg_level = SOL_SOCKET;
@ -544,7 +553,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
ucred = (struct ucred*) CMSG_DATA(cmsg);
ucred->pid = pid;
ucred->pid = pid != 0 ? pid : getpid_cached();
ucred->uid = getuid();
ucred->gid = getgid();
}
@ -557,7 +566,7 @@ _public_ int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char
}
/* If that failed, try with our own ucred instead */
if (have_pid) {
if (send_ucred) {
msghdr.msg_controllen -= CMSG_SPACE(sizeof(struct ucred));
if (msghdr.msg_controllen == 0)
msghdr.msg_control = NULL;