git: f804f2365081 - main - syslogd: Centralize operations into a kevent loop
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Date: Thu, 28 Sep 2023 15:52:25 UTC
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=f804f23650815dd3a96b3ab2b24152d25c7364c3
commit f804f23650815dd3a96b3ab2b24152d25c7364c3
Author: Jake Freeland <jfree@FreeBSD.org>
AuthorDate: 2023-09-01 02:49:29 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2023-09-28 15:51:52 +0000
syslogd: Centralize operations into a kevent loop
Use kqueue(2) for socket I/O and signal notification. Previously,
select(2) and traditional signal handlers were being used.
This change centralizes all of the async notification delivery into a
single loop so future Capsicum sandboxing will be easier. It also
simplifies the code by removing boiler-plate cruft that comes with the
older interfaces.
Reviewed by: Slawa Olhovchenkov, markj, emaste
MFC after: 3 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D41363
---
usr.sbin/syslogd/syslogd.c | 226 +++++++++++++++++----------------------------
1 file changed, 86 insertions(+), 140 deletions(-)
diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index c8420298f117..21e2d48b0c37 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -104,6 +104,7 @@ static char sccsid[] = "@(#)syslogd.c 8.3 (Berkeley) 4/4/94";
#define RCVBUF_MINSIZE (80 * 1024) /* minimum size of dgram rcv buffer */
#include <sys/param.h>
+#include <sys/event.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/queue.h>
@@ -371,6 +372,16 @@ static const char *TypeNames[] = {
"FORW", "USERS", "WALL", "PIPE"
};
+static const int sigcatch[] = {
+ SIGHUP,
+ SIGINT,
+ SIGQUIT,
+ SIGPIPE,
+ SIGALRM,
+ SIGTERM,
+ SIGCHLD,
+};
+
static bool Debug; /* debug flag */
static bool Foreground = false; /* Run in foreground, instead of daemonizing */
static bool resolve = true; /* resolve hostname */
@@ -402,13 +413,10 @@ static bool UniquePriority; /* Only log specified priority? */
static int LogFacPri; /* Put facility and priority in log message: */
/* 0=no, 1=numeric, 2=names */
static bool KeepKernFac; /* Keep remotely logged kernel facility */
-static bool needdofsync = false; /* Are any file(s) waiting to be fsynced? */
+static bool needdofsync = true; /* Are any file(s) waiting to be fsynced? */
static struct pidfh *pfh;
-static int sigpipe[2]; /* Pipe to catch a signal during select(). */
static bool RFC3164OutputFormat = true; /* Use legacy format by default. */
-static volatile sig_atomic_t MarkSet, WantDie, WantInitialize, WantReapchild;
-
struct iovlist;
static int allowaddr(char *);
@@ -421,9 +429,7 @@ static int deadq_remove(struct deadq_entry *);
static int deadq_removebypid(pid_t);
static int decode(const char *, const CODE *);
static void die(int) __dead2;
-static void dodie(int);
static void dofsync(void);
-static void domark(int);
static void fprintlog_first(struct filed *, const char *, const char *,
const char *, const char *, const char *, const char *, int);
static void fprintlog_write(struct filed *, struct iovlist *, int);
@@ -437,8 +443,6 @@ static void markit(void);
static int socksetup(struct peer *);
static int socklist_recv_file(struct socklist *);
static int socklist_recv_sock(struct socklist *);
-static int socklist_recv_signal(struct socklist *);
-static void sighandler(int);
static int skip_message(const char *, const char *, int);
static int evaluate_prop_filter(const struct prop_filter *filter,
const char *value);
@@ -526,14 +530,14 @@ addsock(struct addrinfo *ai, struct socklist *sl0)
int
main(int argc, char *argv[])
{
- int ch, i, s, fdsrmax = 0;
- bool bflag = false, pflag = false, Sflag = false;
- fd_set *fdsr = NULL;
- struct timeval tv, *tvp;
- struct peer *pe;
+ sigset_t sigset = { };
+ struct kevent ev;
struct socklist *sl;
- pid_t ppid = 1, spid;
+ struct peer *pe;
+ pid_t ppid = -1, spid;
+ int ch, kq, s;
char *p;
+ bool bflag = false, pflag = false, Sflag = false;
if (madvise(NULL, 0, MADV_PROTECT) != 0)
dprintf("madvise() failed: %s\n", strerror(errno));
@@ -705,17 +709,6 @@ main(int argc, char *argv[])
if (RFC3164OutputFormat && MaxForwardLen > 1024)
errx(1, "RFC 3164 messages may not exceed 1024 bytes");
- /* Pipe to catch a signal during select(). */
- s = pipe2(sigpipe, O_CLOEXEC);
- if (s < 0) {
- err(1, "cannot open a pipe for signals");
- } else {
- addsock(NULL, &(struct socklist){
- .sl_socket = sigpipe[0],
- .sl_recv = socklist_recv_signal
- });
- }
-
/* Listen by default: /dev/klog. */
s = open(_PATH_KLOG, O_RDONLY | O_NONBLOCK | O_CLOEXEC, 0);
if (s < 0) {
@@ -767,108 +760,82 @@ main(int argc, char *argv[])
(void)strlcpy(consfile.fu_fname, ctty + sizeof _PATH_DEV - 1,
sizeof(consfile.fu_fname));
(void)strlcpy(bootfile, getbootfile(), sizeof(bootfile));
- (void)signal(SIGTERM, dodie);
- (void)signal(SIGINT, Debug ? dodie : SIG_IGN);
- (void)signal(SIGQUIT, Debug ? dodie : SIG_IGN);
- (void)signal(SIGHUP, sighandler);
- (void)signal(SIGCHLD, sighandler);
- (void)signal(SIGALRM, domark);
- (void)signal(SIGPIPE, SIG_IGN); /* We'll catch EPIPE instead. */
+
+ kq = kqueue();
+ if (kq == -1) {
+ warn("failed to initialize kqueue");
+ pidfile_remove(pfh);
+ exit(1);
+ }
+ STAILQ_FOREACH(sl, &shead, next) {
+ EV_SET(&ev, sl->sl_socket, EVFILT_READ, EV_ADD, 0, 0, sl);
+ if (kevent(kq, &ev, 1, NULL, 0, NULL) == -1) {
+ warn("failed to add kevent to kqueue");
+ pidfile_remove(pfh);
+ exit(1);
+ }
+ }
+ for (size_t i = 0; i < nitems(sigcatch); ++i) {
+ EV_SET(&ev, sigcatch[i], EVFILT_SIGNAL, EV_ADD, 0, 0, NULL);
+ if (kevent(kq, &ev, 1, NULL, 0, NULL) == -1) {
+ warn("failed to add kevent to kqueue");
+ pidfile_remove(pfh);
+ exit(1);
+ }
+ (void)sigaddset(&sigset, sigcatch[i]);
+ }
+ if (sigprocmask(SIG_BLOCK, &sigset, NULL) != 0) {
+ warn("failed to apply signal mask");
+ pidfile_remove(pfh);
+ exit(1);
+ }
(void)alarm(TIMERINTVL);
/* tuck my process id away */
pidfile_write(pfh);
dprintf("off & running....\n");
-
- tvp = &tv;
- tv.tv_sec = tv.tv_usec = 0;
-
- STAILQ_FOREACH(sl, &shead, next) {
- if (sl->sl_socket > fdsrmax)
- fdsrmax = sl->sl_socket;
- }
- fdsr = (fd_set *)calloc(howmany(fdsrmax+1, NFDBITS),
- sizeof(*fdsr));
- if (fdsr == NULL)
- errx(1, "calloc fd_set");
-
+ init(false);
for (;;) {
- if (!Initialized)
- init(0);
- else if (WantInitialize)
- init(WantInitialize);
- if (WantReapchild)
- reapchild(WantReapchild);
- if (MarkSet)
- markit();
- if (WantDie) {
- free(fdsr);
- die(WantDie);
- }
-
- bzero(fdsr, howmany(fdsrmax+1, NFDBITS) *
- sizeof(*fdsr));
-
- STAILQ_FOREACH(sl, &shead, next) {
- if (sl->sl_socket != -1 && sl->sl_recv != NULL)
- FD_SET(sl->sl_socket, fdsr);
- }
- i = select(fdsrmax + 1, fdsr, NULL, NULL,
- needdofsync ? &tv : tvp);
- switch (i) {
- case 0:
+ if (needdofsync) {
dofsync();
- needdofsync = false;
- if (tvp) {
- tvp = NULL;
- if (ppid != 1)
- kill(ppid, SIGALRM);
+ if (ppid != -1) {
+ kill(ppid, SIGALRM);
+ ppid = -1;
}
- continue;
- case -1:
+ }
+ if (kevent(kq, NULL, 0, &ev, 1, NULL) == -1) {
if (errno != EINTR)
- logerror("select");
+ logerror("kevent");
continue;
}
- STAILQ_FOREACH(sl, &shead, next) {
- if (FD_ISSET(sl->sl_socket, fdsr))
- (*sl->sl_recv)(sl);
- }
- }
- free(fdsr);
-}
-
-static int
-socklist_recv_signal(struct socklist *sl __unused)
-{
- ssize_t len;
- int i, nsig, signo;
-
- if (ioctl(sigpipe[0], FIONREAD, &i) != 0) {
- logerror("ioctl(FIONREAD)");
- err(1, "signal pipe read failed");
- }
- nsig = i / sizeof(signo);
- dprintf("# of received signals = %d\n", nsig);
- for (i = 0; i < nsig; i++) {
- len = read(sigpipe[0], &signo, sizeof(signo));
- if (len != sizeof(signo)) {
- logerror("signal pipe read failed");
- err(1, "signal pipe read failed");
- }
- dprintf("Received signal: %d from fd=%d\n", signo,
- sigpipe[0]);
- switch (signo) {
- case SIGHUP:
- WantInitialize = 1;
+ switch (ev.filter) {
+ case EVFILT_READ:
+ sl = ev.udata;
+ if (sl->sl_socket != -1 && sl->sl_recv != NULL)
+ sl->sl_recv(sl);
break;
- case SIGCHLD:
- WantReapchild = 1;
+ case EVFILT_SIGNAL:
+ switch (ev.ident) {
+ case SIGHUP:
+ init(true);
+ break;
+ case SIGINT:
+ case SIGQUIT:
+ case SIGTERM:
+ if (ev.ident == SIGTERM || Debug)
+ die(ev.ident);
+ break;
+ case SIGALRM:
+ markit();
+ break;
+ case SIGCHLD:
+ reapchild(ev.ident);
+ break;
+ }
break;
}
}
- return (0);
}
static int
@@ -1758,6 +1725,7 @@ dofsync(void)
(void)fsync(f->f_file);
}
}
+ needdofsync = false;
}
/*
@@ -2259,7 +2227,6 @@ reapchild(int signo __unused)
}
}
}
- WantReapchild = 0;
}
/*
@@ -2298,20 +2265,6 @@ cvthname(struct sockaddr *f)
return (hname);
}
-static void
-dodie(int signo)
-{
-
- WantDie = signo;
-}
-
-static void
-domark(int signo __unused)
-{
-
- MarkSet = 1;
-}
-
/*
* Print syslogd errors some place.
*/
@@ -2536,14 +2489,6 @@ readconfigfile(const char *path)
}
}
-static void
-sighandler(int signo)
-{
-
- /* Send an wake-up signal to the select() loop. */
- write(sigpipe[1], &signo, sizeof(signo));
-}
-
/*
* INIT -- Initialize syslogd from configuration table
*/
@@ -2558,7 +2503,6 @@ init(int signo)
char bootfileMsg[MAXLINE + 1];
dprintf("init\n");
- WantInitialize = 0;
/*
* Load hostname (may have changed).
@@ -3245,7 +3189,6 @@ markit(void)
dq->dq_timeout--;
}
}
- MarkSet = 0;
(void)alarm(TIMERINTVL);
}
@@ -3621,6 +3564,7 @@ validate(struct sockaddr *sa, const char *hname)
static int
p_open(const char *prog, pid_t *rpid)
{
+ sigset_t sigset = { };
int pfd[2], nulldesc;
pid_t pid;
char *argv[4]; /* sh -c cmd NULL */
@@ -3650,10 +3594,12 @@ p_open(const char *prog, pid_t *rpid)
alarm(0);
- /* Restore signals marked as SIG_IGN. */
- (void)signal(SIGINT, SIG_DFL);
- (void)signal(SIGQUIT, SIG_DFL);
- (void)signal(SIGPIPE, SIG_DFL);
+ for (size_t i = 0; i < nitems(sigcatch); ++i)
+ (void)sigaddset(&sigset, sigcatch[i]);
+ if (sigprocmask(SIG_UNBLOCK, &sigset, NULL) != 0) {
+ logerror("sigprocmask");
+ exit(1);
+ }
dup2(pfd[0], STDIN_FILENO);
dup2(nulldesc, STDOUT_FILENO);