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Fix timestamp handling in MDTM

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Resolves: rhbz#1567855
This commit is contained in:
Ondřej Lysoněk 2020-02-13 17:38:33 +01:00
parent f5375f041a
commit 9d90ef9e83
3 changed files with 214 additions and 1 deletions
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151
0001-Fix-timestamp-handling-in-MDTM.patch Normal file
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@ -0,0 +1,151 @@
From 6a4dc470e569df38b8a7ea09ee6aace3c73b7353 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Lyson=C4=9Bk?= <olysonek@redhat.com>
Date: Wed, 28 Mar 2018 09:06:34 +0200
Subject: [PATCH 1/2] Fix timestamp handling in MDTM
There were two problems with the timestamp handling with MDTM:
1. In vsf_sysutil_parse_time(), the `the_time.tm_isdst` attribute was
always set to 0, regardless of whether DST (daylight saving time)
is active on the given date or not.
This made glibc shift the timestamp when DST was in fact active on
the given date, in an attempt to correct the discrepancy between
the given timestamp and the `tm_isdst` attribute. The shifting
produced incorrect results however.
We fix this by setting `tm_isdst` to -1 to let glibc decide if DST
is active or not at the time of the timestamp. glibc won't touch
the timestamp then.
2. vsftpd used to record the offset from UTC of the current timezone
in the global variable `s_timezone`. This variable was then
subtracted from the variable `the_time` in vsf_sysutil_setmodtime()
when the config option use_localtime=NO was set. This was done to
compensate for the fact that mktime(), used in
vsf_sysutil_parse_time(), expects a timestamp expressed as local
time, whereas vsftpd is dealing with universal time.
However, this did not work in the case when the offset stored in
`s_timezone` did not match the timezone of the timestamp given to
mktime() - this happens when DST is active at the current time, but
DST is not active at the time of the timestamp, or vice versa.
We fix this by subtracting the real timezone offset directly in
vsf_sysutil_parse_time().
Note that the `tm_gmtoff` attribute, used in this fix, is a
BSD/glic extension. However, using `tm_gmtoff` seems like the
simplest solution and we need to make this work only with glibc
anyway.
The fix was tested in the following way. We checked that the timestamp
given to the MDTM command when setting modification time exactly
matches the timestamp received as response from MDTM when reading back
the modification time. Additionally, we checked that the modification
time was set correctly on the given file on disk.
These two checks were performed under various conditions - all the
combinations of DST/non-DST system time, DST/non-DST modification
time, use_localtime=YES/NO.
Note that (I think) this will still not work if the rules for when DST
is active change. For example, if DST is ever completely cancelled in
the Europe/Prague timezone, and vsftpd is dealing with a timestamp
from a time when DST was active, it will produce incorrect results. I
think we would need the full zone file to fix this, but the zone file
is hard to provide when we're chroot-ed.
Resolves: rhbz#1567855
---
postlogin.c | 5 +++--
sysutil.c | 17 ++++++++++-------
sysutil.h | 4 ++--
3 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/postlogin.c b/postlogin.c
index 7c749ef..8a3d9d2 100644
--- a/postlogin.c
+++ b/postlogin.c
@@ -1788,7 +1788,8 @@ handle_mdtm(struct vsf_session* p_sess)
if (do_write != 0)
{
str_split_char(&p_sess->ftp_arg_str, &s_filename_str, ' ');
- modtime = vsf_sysutil_parse_time(str_getbuf(&p_sess->ftp_arg_str));
+ modtime = vsf_sysutil_parse_time(
+ str_getbuf(&p_sess->ftp_arg_str), tunable_use_localtime);
str_copy(&p_sess->ftp_arg_str, &s_filename_str);
}
resolve_tilde(&p_sess->ftp_arg_str, p_sess);
@@ -1809,7 +1810,7 @@ handle_mdtm(struct vsf_session* p_sess)
else
{
retval = vsf_sysutil_setmodtime(
- str_getbuf(&p_sess->ftp_arg_str), modtime, tunable_use_localtime);
+ str_getbuf(&p_sess->ftp_arg_str), modtime);
if (retval != 0)
{
vsf_cmdio_write(p_sess, FTP_FILEFAIL,
diff --git a/sysutil.c b/sysutil.c
index e847650..66d4c5e 100644
--- a/sysutil.c
+++ b/sysutil.c
@@ -2819,11 +2819,13 @@ vsf_sysutil_syslog(const char* p_text, int severe)
}
long
-vsf_sysutil_parse_time(const char* p_text)
+vsf_sysutil_parse_time(const char* p_text, int is_localtime)
{
+ long res;
struct tm the_time;
unsigned int len = vsf_sysutil_strlen(p_text);
vsf_sysutil_memclr(&the_time, sizeof(the_time));
+ the_time.tm_isdst = -1;
if (len >= 8)
{
char yr[5];
@@ -2848,17 +2850,18 @@ vsf_sysutil_parse_time(const char* p_text)
the_time.tm_min = vsf_sysutil_atoi(mins);
the_time.tm_sec = vsf_sysutil_atoi(sec);
}
- return mktime(&the_time);
+ res = mktime(&the_time);
+ if (!is_localtime)
+ {
+ res += the_time.tm_gmtoff;
+ }
+ return res;
}
int
-vsf_sysutil_setmodtime(const char* p_file, long the_time, int is_localtime)
+vsf_sysutil_setmodtime(const char* p_file, long the_time)
{
struct utimbuf new_times;
- if (!is_localtime)
- {
- the_time -= s_timezone;
- }
vsf_sysutil_memclr(&new_times, sizeof(new_times));
new_times.actime = the_time;
new_times.modtime = the_time;
diff --git a/sysutil.h b/sysutil.h
index 7a59f13..b90f6ca 100644
--- a/sysutil.h
+++ b/sysutil.h
@@ -349,9 +349,9 @@ void vsf_sysutil_chroot(const char* p_root_path);
*/
long vsf_sysutil_get_time_sec(void);
long vsf_sysutil_get_time_usec(void);
-long vsf_sysutil_parse_time(const char* p_text);
+long vsf_sysutil_parse_time(const char* p_text, int is_localtime);
void vsf_sysutil_sleep(double seconds);
-int vsf_sysutil_setmodtime(const char* p_file, long the_time, int is_localtime);
+int vsf_sysutil_setmodtime(const char* p_file, long the_time);
/* Limits */
void vsf_sysutil_set_address_space_limit(unsigned long bytes);
--
2.24.1

56
0002-Drop-an-unused-global-variable.patch Normal file
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@ -0,0 +1,56 @@
From d0045e35674d64d166d17c3c079ae03e8c2e6361 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Lyson=C4=9Bk?= <olysonek@redhat.com>
Date: Thu, 13 Feb 2020 17:29:06 +0100
Subject: [PATCH 2/2] Drop an unused global variable
The global variable `s_timezone` is not used anymore, so we can drop
it.
---
sysutil.c | 17 +++--------------
1 file changed, 3 insertions(+), 14 deletions(-)
diff --git a/sysutil.c b/sysutil.c
index 66d4c5e..0ccf551 100644
--- a/sysutil.c
+++ b/sysutil.c
@@ -72,8 +72,6 @@ static struct timeval s_current_time;
static int s_current_pid = -1;
/* Exit function */
static exitfunc_t s_exit_func;
-/* Difference in timezone from GMT in seconds */
-static long s_timezone;
/* Our internal signal handling implementation details */
static struct vsf_sysutil_sig_details
@@ -2661,7 +2659,6 @@ char* vsf_sysutil_get_tz()
void
vsf_sysutil_tzset(void)
{
- int retval;
char *tz=NULL, tzbuf[sizeof("+HHMM!")];
time_t the_time = time(NULL);
struct tm* p_tm;
@@ -2681,17 +2678,9 @@ vsf_sysutil_tzset(void)
{
die("localtime");
}
- retval = strftime(tzbuf, sizeof(tzbuf), "%z", p_tm);
- tzbuf[sizeof(tzbuf) - 1] = '\0';
- if (retval == 5)
- {
- s_timezone = ((tzbuf[1] - '0') * 10 + (tzbuf[2] - '0')) * 60 * 60;
- s_timezone += ((tzbuf[3] - '0') * 10 + (tzbuf[4] - '0')) * 60;
- if (tzbuf[0] == '+')
- {
- s_timezone *= -1;
- }
- }
+ /* Not sure if the following call to strftime() has any desired side
+ effects, so I'm keeping it to be safe. */
+ (void) strftime(tzbuf, sizeof(tzbuf), "%z", p_tm);
/* Call in to the time subsystem again now that TZ is set, trying to force
* caching of the actual zoneinfo for the timezone.
*/
--
2.24.1

8
vsftpd.spec
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@ -2,7 +2,7 @@
Name: vsftpd
Version: 3.0.3
Release: 36%{?dist}
Release: 37%{?dist}
Summary: Very Secure Ftp Daemon
# OpenSSL link exception
@ -93,6 +93,8 @@ Patch63: 0001-Set-s_uwtmp_inserted-only-after-record-insertion-rem.patch
Patch64: 0002-Repeat-pututxline-if-it-fails-with-EINTR.patch
Patch65: 0001-Repeat-pututxline-until-it-succeeds-if-it-fails-with.patch
Patch66: 0001-Fix-assignment-of-an-enumerator-of-a-different-type.patch
Patch67: 0001-Fix-timestamp-handling-in-MDTM.patch
Patch68: 0002-Drop-an-unused-global-variable.patch
%description
vsftpd is a Very Secure FTP daemon. It was written completely from
@ -161,6 +163,10 @@ mkdir -p $RPM_BUILD_ROOT/%{_var}/ftp/pub
%{_var}/ftp
%changelog
* Thu Feb 13 2020 Ondřej Lysoněk <olysonek@redhat.com> - 3.0.3-37
- Fix timestamp handling in MDTM
- Resolves: rhbz#1567855
* Fri Feb 07 2020 Ondřej Lysoněk <olysonek@redhat.com> - 3.0.3-36
- Fix build with gcc 10
- Resolves: rhbz#1800239