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From: Richard Lewis <richard.lewis.debian@googlemail.com>
Date: Sat, 16 Oct 2021 23:51:50 +0100
Subject: chkutmp
Last-Updated: 2024-11-06
Various, minor, patches to improve chkutmp.
0) Improve output -- the message needs 'was' not 'were' because "The tty" is singular
Author: Richard Lewis <richard.lewis.debian@googlemail.com>
Date: Sat, 16 Oct 2021 23:51:50 +0100
1a) Improve parser
- Use larger arrays for ps_tty, ps_user, ps_args to avoid overflow
- Use 'ps axk' (not really necessary)
- replace newlines with \0 on parsing
From: "Aaron M. Ucko" <team+pkg-security@tracker.debian.org>
Date: Sun, 9 Jul 2017 18:42:55 +0200
1b) From an unknown author, in Debian since 2017 or earlier
- when grabbing pid, limit size to UT_PIDSIZE not UT_LINESIZE
(avoid possible overflow in pid)
2) avoid various compilation warnings
These were contributed by =?utf-8?q?Christian_G=C3=B6ttsche?= <cgzones@googlemail.com>
on Date: Fri, 24 Jul 2020 16:28:53 +0200
a) declare cmd as 'const'
b) make signature of main be void, since argc and argv are unused
c) remove unused variable
3) Improve output -- the message needs 'was' not 'were' because "The tty" is singular
Author: Richard Lewis <richard.lewis.debian@googlemail.com>
Date: Sat, 16 Oct 2021 23:51:50 +0100
4) chkutmp: do not silently do nothing on unsupported platforms
Author: Richard Lewis <richard.lewis.debian@googlemail.com>, Nov 2024
Forwarded: yes
(Forwarded by email: 21 Dec 2024)
---
chkutmp.c | 51 +++++++++++++++++++++++++--------------------------
1 file changed, 25 insertions(+), 26 deletions(-)
diff --git a/chkutmp.c b/chkutmp.c
index 5c81a72..4deff10 100644
--- a/chkutmp.c
+++ b/chkutmp.c
@@ -28,12 +28,12 @@
*
*/
+#include <stdio.h>
#if !defined(__sun) && !defined(__linux__)
-int main () { return 0; }
+int main (void){ fprintf(stderr,"Unsupported operating system\n"); return 1; }
#else
#include <unistd.h>
#include <stdlib.h>
-#include <stdio.h>
#include <string.h>
#include <utmp.h>
#include <fcntl.h>
@@ -59,9 +59,9 @@ int main () { return 0; }
#endif
struct ps_line {
- char ps_tty[UT_LINESIZE];
- char ps_user[UT_NAMESIZE];
- char ps_args[MAXLENGTH];
+ char ps_tty[UT_LINESIZE+2];
+ char ps_user[UT_NAMESIZE+2];
+ char ps_args[MAXLENGTH+2];
int ps_pid;
};
struct utmp_line {
@@ -69,9 +69,9 @@ struct utmp_line {
int ut_pid;
int ut_type;
};
-static char *cmd[] = {
+static const char *cmd[] = {
"ps -ef -o \"tty,pid,ruser,args\"", /* solaris */
- "ps ax -o \"tty,pid,ruser,args\"" /* linux */
+ "ps axk \"tty,ruser,args\" -o \"tty,pid,ruser,args\"" /* linux */
};
int fetchps(struct ps_line *);
int fetchutmp(struct utmp_line *);
@@ -87,7 +87,7 @@ int fetchps(struct ps_line *psl_p)
i = 0;
if ((ps_fp = (popen(cmd[PS_CMD], "r"))) != NULL) {
- fgets(line, MAXREAD, ps_fp); /* skip header */
+ (void) !fgets(line, MAXREAD, ps_fp); /* skip header */
while (fgets(line, MAXREAD, ps_fp)) {
s = line;
if (*s != '\?' && curp <= endp) { /* only interested in lines that
@@ -99,7 +99,7 @@ int fetchps(struct ps_line *psl_p)
while (isspace(*s)) /* skip spaces */
s++;
d = pid;
- for (x = 0; (!isspace(*s)) && (*d++ = *s++) && x <= UT_LINESIZE; x++) /* grab pid */
+ for (x = 0; (!isspace(*s)) && (*d++ = *s++) && x <= UT_PIDSIZE; x++) /* grab pid */
;
*d = '\0';
curp->ps_pid = atoi(pid);
@@ -114,14 +114,16 @@ int fetchps(struct ps_line *psl_p)
s++;
for (x = 0; (*d++ = *s++) && x <= MAXLENGTH; x++) /* cmd + args */
;
+ if (d[-2] == '\n')
+ d[-2] = '\0';
i++;
curp++;
- /* if we didn't read the line, skip the rest */
- line_length = strlen(line);
- while (!(line_length == 0 || line[line_length -1] == '\n')) {
- fgets(line, MAXREAD, ps_fp);
- line_length = strlen(line);
- }
+ /* if we didn't read the line, skip the rest */
+ line_length = strlen(line);
+ while (!(line_length == 0 || line[line_length -1] == '\n')) {
+ (void) !fgets(line, MAXREAD, ps_fp);
+ line_length = strlen(line);
+ }
}
}
pclose(ps_fp);
@@ -175,7 +177,7 @@ int fetchutmp(struct utmp_line *utl_p)
return i;
}
-int main(int argc, char *argv[])
+int main(void)
{
struct ps_line ps_l[MAXBUF]; /* array of data from 'ps' */
struct utmp_line ut_l[MAXBUF]; /* array of data from utmp log */
@@ -201,16 +203,13 @@ int main(int argc, char *argv[])
}
}
if (!mtch_fnd) {
- if (!hdr_prntd) {
- printf
- (" The tty of the following user process(es) were not found\n");
- printf(" in %s !\n", UTMP);
- printf("! %-9s %7s %-6s %s\n", "RUID", "PID", "TTY",
- "CMD");
- hdr_prntd = 1;
- }
- printf("! %-9s %7d %-6s %s", ps_l[h].ps_user,
- ps_l[h].ps_pid, ps_l[h].ps_tty, ps_l[h].ps_args);
+ if (!hdr_prntd) {
+ printf("The tty of the following process(es) was not found in %s:\n", UTMP);
+ printf("! %-9s %7s %-6s %s\n", "RUID", "PID", "TTY", "CMD");
+ hdr_prntd = 1;
+ }
+ printf("! %-9s %7d %-6s %s\n", ps_l[h].ps_user,
+ ps_l[h].ps_pid, ps_l[h].ps_tty, ps_l[h].ps_args);
}
}
exit(EXIT_SUCCESS);
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