On 2020-07-09, Theo de Raadt wrote:
> Hang on. Do people ever want to force time calls, outside of ktrace?
> I doubt it. Should ktrace maybe have a flag, similar to -B with LD_BIND_NOW,
> which sets the new environment variable? Maybe -T? The problem smells very
> similar to the root cause for LD_BIND_NOW setting..
So taking into account most feedback, another round.
env variable is now _LIBC_NOUSERTC. It's not libc's concern that ktrace may
want this, so I didn't go with that. The feature in question is usertc,
so that seems the most direct name.
Call getenv before issetugid.
Added a -T option to ktrace for transparency. I got ambitious here and made
it take suboptions, anticipating that other transparency modifications may
be desired. Fold in -B perhaps? I think typing -Tt is not so burdensome,
and saves us some alphabet down the line.
As a bonus, fix ktrace usage. -B only works with second synopsis, with command.
Index: lib/libc/dlfcn/init.c
===================================================================
RCS file: /home/cvs/src/lib/libc/dlfcn/init.c,v
retrieving revision 1.8
diff -u -p -r1.8 init.c
--- lib/libc/dlfcn/init.c 6 Jul 2020 13:33:05 -0000 1.8
+++ lib/libc/dlfcn/init.c 10 Jul 2020 02:12:41 -0000
@@ -114,6 +114,8 @@ _libc_preinit(int argc, char **argv, cha
_timekeep->tk_version != TK_VERSION)
_timekeep = NULL;
}
+ if (getenv("_LIBC_NOUSERTC") && issetugid() == 0)
+ _timekeep = NULL;
break;
}
}
Index: usr.bin/ktrace/extern.h
===================================================================
RCS file: /home/cvs/src/usr.bin/ktrace/extern.h,v
retrieving revision 1.4
diff -u -p -r1.4 extern.h
--- usr.bin/ktrace/extern.h 26 Apr 2018 18:30:36 -0000 1.4
+++ usr.bin/ktrace/extern.h 10 Jul 2020 02:21:37 -0000
@@ -26,3 +26,4 @@
*/
int getpoints(const char *, int);
+int gettrans(const char *, int);
Index: usr.bin/ktrace/ktrace.1
===================================================================
RCS file: /home/cvs/src/usr.bin/ktrace/ktrace.1,v
retrieving revision 1.30
diff -u -p -r1.30 ktrace.1
--- usr.bin/ktrace/ktrace.1 15 May 2019 15:36:59 -0000 1.30
+++ usr.bin/ktrace/ktrace.1 10 Jul 2020 02:24:04 -0000
@@ -37,14 +37,15 @@
.Nd enable kernel process tracing
.Sh SYNOPSIS
.Nm ktrace
-.Op Fl aBCcdi
+.Op Fl aCcdi
.Op Fl f Ar trfile
.Op Fl g Ar pgid
.Op Fl p Ar pid
.Op Fl t Ar trstr
.Nm ktrace
-.Op Fl adi
+.Op Fl aBdi
.Op Fl f Ar trfile
+.Op Fl T Ar transopts
.Op Fl t Ar trstr
.Ar command
.Sh DESCRIPTION
@@ -109,6 +110,15 @@ processes.
Enable (disable) tracing on the indicated process ID (only one
.Fl p
flag is permitted).
+.It Fl T Ar transopts
+Request additional transparency from libc.
+By default, no options are enabled.
+The argument can contain one or more of the following letters.
+.Pp
+.Bl -tag -width flag -offset indent -compact
+.It Cm t
+Disable userland timecounters so that time related system calls are visible.
+.El
.It Fl t Ar trstr
Select which information to put into the dump file.
The argument can contain one or more of the following letters.
Index: usr.bin/ktrace/ktrace.c
===================================================================
RCS file: /home/cvs/src/usr.bin/ktrace/ktrace.c,v
retrieving revision 1.36
diff -u -p -r1.36 ktrace.c
--- usr.bin/ktrace/ktrace.c 28 Jun 2019 13:35:01 -0000 1.36
+++ usr.bin/ktrace/ktrace.c 10 Jul 2020 02:23:33 -0000
@@ -60,7 +60,7 @@ int
main(int argc, char *argv[])
{
enum { NOTSET, CLEAR, CLEARALL } clear;
- int append, ch, fd, inherit, ops, pidset, trpoints;
+ int append, ch, fd, inherit, ops, pidset, trpoints, transparency;
pid_t pid;
char *tracefile, *tracespec;
mode_t omask;
@@ -71,6 +71,7 @@ main(int argc, char *argv[])
clear = NOTSET;
append = ops = pidset = inherit = pid = 0;
trpoints = is_ltrace ? KTRFAC_USER : DEF_POINTS;
+ transparency = 0;
tracefile = DEF_TRACEFILE;
tracespec = NULL;
@@ -100,7 +101,7 @@ main(int argc, char *argv[])
usage();
}
} else {
- while ((ch = getopt(argc, argv, "aBCcdf:g:ip:t:")) != -1)
+ while ((ch = getopt(argc, argv, "aBCcdf:g:ip:t:T:")) != -1)
switch ((char)ch) {
case 'a':
append = 1;
@@ -140,6 +141,13 @@ main(int argc, char *argv[])
usage();
}
break;
+ case 'T':
+ transparency = gettrans(optarg, 0);
+ if (transparency < 0) {
+ warnx("unknown facility in %s", optarg);
+ usage();
+ }
+ break;
default:
usage();
}
@@ -154,6 +162,9 @@ main(int argc, char *argv[])
if (inherit)
trpoints |= KTRFAC_INHERIT;
+ if (transparency && TRANS_TIME)
+ putenv("_LIBC_NOUSERTC=");
+
(void)signal(SIGSYS, no_ktrace);
if (clear != NOTSET) {
if (clear == CLEARALL) {
@@ -240,9 +251,9 @@ usage(void)
" [-u trspec] command\n",
__progname);
else
- fprintf(stderr, "usage: %s [-aBCcdi] [-f trfile] [-g pgid]"
+ fprintf(stderr, "usage: %s [-aCcdi] [-f trfile] [-g pgid]"
" [-p pid] [-t trstr]\n"
- " %s [-adi] [-f trfile] [-t trstr] command\n",
+ " %s [-aBdi] [-f trfile] [-T transopts] [-t trstr]
command\n",
__progname, __progname);
exit(1);
}
Index: usr.bin/ktrace/ktrace.h
===================================================================
RCS file: /home/cvs/src/usr.bin/ktrace/ktrace.h,v
retrieving revision 1.10
diff -u -p -r1.10 ktrace.h
--- usr.bin/ktrace/ktrace.h 6 Mar 2016 20:25:27 -0000 1.10
+++ usr.bin/ktrace/ktrace.h 10 Jul 2020 02:18:01 -0000
@@ -38,3 +38,5 @@
#define ALL_POINTS (DEF_POINTS | KTRFAC_EXECENV)
#define DEF_TRACEFILE "ktrace.out"
+
+#define TRANS_TIME 1
Index: usr.bin/ktrace/subr.c
===================================================================
RCS file: /home/cvs/src/usr.bin/ktrace/subr.c,v
retrieving revision 1.14
diff -u -p -r1.14 subr.c
--- usr.bin/ktrace/subr.c 26 Apr 2018 12:42:51 -0000 1.14
+++ usr.bin/ktrace/subr.c 10 Jul 2020 02:15:44 -0000
@@ -86,3 +86,24 @@ getpoints(const char *s, int defpoints)
}
return (facs);
}
+
+int
+gettrans(const char *s, int deftrans)
+{
+ int trans = 0;
+
+ while (*s) {
+ switch(*s) {
+ case 't':
+ trans |= TRANS_TIME;
+ break;
+ case '+':
+ trans |= deftrans;
+ break;
+ default:
+ return (-1);
+ }
+ s++;
+ }
+ return (trans);
+}
