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From: Christian Kastner <ckk@kvr.at>
Date: Fri, 25 Dec 2015 12:17:09 +0100
Subject: Cleanup tmpfiles
Install a signal handler that removes a temporarily created file upon exit.
Based on a fix originally provided by Daniel Jacobowitz together with symlink
attack prevention.
Forwarded: no
Last-Update: 2015-12-25
---
crontab.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/crontab.c b/crontab.c
index 5f9d977..7ec98d2 100644
--- a/crontab.c
+++ b/crontab.c
@@ -471,6 +471,7 @@ edit_cmd() {
(void)signal(SIGHUP, SIG_DFL);
(void)signal(SIGINT, SIG_DFL);
(void)signal(SIGQUIT, SIG_DFL);
+ (void)signal(SIGTSTP, SIG_DFL);
fprintf(stderr, "%s: installing new crontab\n", ProgramName);
switch (replace_cmd()) {
@@ -507,7 +508,14 @@ edit_cmd() {
done:
log_it(RealUser, Pid, "END EDIT", User);
}
-
+
+static char tn[MAX_FNAME];
+
+static void sig_handler(int x)
+{
+ unlink(tn);
+ exit(1);
+}
/* returns 0 on success
* -1 on syntax error
@@ -515,7 +523,7 @@ edit_cmd() {
*/
static int
replace_cmd() {
- char n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME];
+ char n[MAX_FNAME], envstr[MAX_ENVSTR];
FILE *tmp;
int ch, eof, fd;
int nl = FALSE;
@@ -527,6 +535,17 @@ replace_cmd() {
fprintf(stderr, "%s: Cannot allocate memory.\n", ProgramName);
return (-2);
}
+
+
+ /* Assumes Linux-style signal handlers (takes int, returns void) */
+ /* Signal handlers, to ensure we do not leave temp files in the
+ spool dir. We don't remove these on exiting this function;
+ but that's OK, we exit immediately afterwards anyway. */
+ signal(SIGHUP, sig_handler);
+ signal(SIGINT, sig_handler);
+ signal(SIGQUIT, sig_handler);
+ signal(SIGTSTP, SIG_IGN);
+
(void) snprintf(tn, MAX_FNAME, CRON_TAB("tmp.XXXXXX"));
fd = mkstemp(tn);
if (fd < 0) {
|
