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syslog(3): unbreak log generation using fabricated PID

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Recover application ability to supply fabricated PID
embedded into ident that was lost when libc switched
to generation of RFC 5424 log messages, for example:

logger -t "ident[$$]" -p user.notice "test"

It is essential for long running scripts.
Also, this change unbreaks matching resulted entries
by ident in syslog.conf:

!ident
*.* /var/log/ident.log

Without the fix, the log (and matching) was broken:

Aug  1 07:36:58 hostname ident[123][86483]: test

Now it works as expected and worked before breakage:

Aug  1 07:39:40 hostname ident[123]: test

Differential:	https://reviews.freebsd.org/D36005
MFC after:	2 weeks
This commit is contained in:
Eugene Grosbein 2022-08-09 05:21:02 +07:00
parent e87ff1ea22
commit e9ae9fa937
1 changed files with 51 additions and 3 deletions
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54
lib/libc/gen/syslog.c
View File

@ -65,7 +65,9 @@ static int LogFile = -1; /* fd for log */
static bool connected; /* have done connect */
static int opened; /* have done openlog() */
static int LogStat = 0; /* status bits, set by openlog() */
static pid_t LogPid = -1; /* process id to tag the entry with */
static const char *LogTag = NULL; /* string to tag the entry with */
static int LogTagLength = -1; /* usable part of LogTag */
static int LogFacility = LOG_USER; /* default facility code */
static int LogMask = 0xff; /* mask of priorities to be logged */
static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER;
@ -85,6 +87,7 @@ static pthread_mutex_t syslog_mutex = PTHREAD_MUTEX_INITIALIZER;
static void disconnectlog(void); /* disconnect from syslogd */
static void connectlog(void); /* (re)connect to syslogd */
static void openlog_unlocked(const char *, int, int);
static void parse_tag(void); /* parse ident[NNN] if needed */
/*
* Format of the magic cookie passed through the stdio hook
@ -204,13 +207,20 @@ vsyslog1(int pri, const char *fmt, va_list ap)
/* Application name. */
if (LogTag == NULL)
LogTag = _getprogname();
(void)fprintf(fp, "%s ", LogTag == NULL ? NILVALUE : LogTag);
else if (LogTagLength == -1)
parse_tag();
if (LogTagLength > 0)
(void)fprintf(fp, "%.*s ", LogTagLength, LogTag);
else
(void)fprintf(fp, "%s ", LogTag == NULL ? NILVALUE : LogTag);
/*
* Provide the process ID regardless of whether LOG_PID has been
* specified, as it provides valuable information. Many
* applications tend not to use this, even though they should.
*/
(void)fprintf(fp, "%d ", getpid());
if (LogPid == -1)
LogPid = getpid();
(void)fprintf(fp, "%d ", (int)LogPid);
/* Message ID. */
(void)fputs(NILVALUE " ", fp);
/* Structured data. */
@ -398,9 +408,12 @@ connectlog(void)
static void
openlog_unlocked(const char *ident, int logstat, int logfac)
{
if (ident != NULL)
if (ident != NULL) {
LogTag = ident;
LogTagLength = -1;
}
LogStat = logstat;
parse_tag();
if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
LogFacility = logfac;
@ -430,6 +443,7 @@ closelog(void)
LogFile = -1;
}
LogTag = NULL;
LogTagLength = -1;
connected = false;
THREAD_UNLOCK();
}
@ -447,3 +461,37 @@ setlogmask(int pmask)
THREAD_UNLOCK();
return (omask);
}
/*
* Obtain LogPid from LogTag formatted as following: ident[NNN]
*/
static void
parse_tag(void)
{
char *begin, *end, *p;
pid_t pid;
if (LogTag == NULL || (LogStat & LOG_PID) != 0)
return;
/*
* LogTagLength is -1 if LogTag was not parsed yet.
* Avoid multiple passes over same LogTag.
*/
LogTagLength = 0;
/* Check for presence of opening [ and non-empty ident. */
if ((begin = strchr(LogTag, '[')) == NULL || begin == LogTag)
return;
/* Check for presence of closing ] at the very end and non-empty pid. */
if ((end = strchr(begin + 1, ']')) == NULL || end[1] != 0 ||
(end - begin) < 2)
return;
/* Check for pid to contain digits only. */
pid = (pid_t)strtol(begin + 1, &p, 10);
if (p != end)
return;
LogPid = pid;
LogTagLength = begin - LogTag;
}