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Partially fix problem with bad utmp entries when pututxline() fails

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Resolves: rhbz#1688848
This commit is contained in:
Ondřej Lysoněk 2019-08-05 14:14:50 +02:00
parent a0a47ca688
commit 6848e2e801
3 changed files with 165 additions and 1 deletions
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53
0001-Set-s_uwtmp_inserted-only-after-record-insertion-rem.patch Normal file
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@ -0,0 +1,53 @@
From 96698a525784ad91cb27b572dd5f871c183fdfa5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Lyson=C4=9Bk?= <olysonek@redhat.com>
Date: Sun, 28 Jul 2019 12:25:35 +0200
Subject: [PATCH 1/2] Set s_uwtmp_inserted only after record insertion/removal
pututxline() is the function that actually inserts the new record, so
setting 's_uwtmp_inserted' before calling pututxline() doesn't make
sense.
We'll need this change for other fixes.
---
sysdeputil.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sysdeputil.c b/sysdeputil.c
index 4fe56c2..bd1e8c9 100644
--- a/sysdeputil.c
+++ b/sysdeputil.c
@@ -1224,7 +1224,6 @@ vsf_insert_uwtmp(const struct mystr* p_user_str,
sizeof(s_utent.ut_line));
str_free(&line_str);
}
- s_uwtmp_inserted = 1;
s_utent.ut_type = USER_PROCESS;
s_utent.ut_pid = vsf_sysutil_getpid();
vsf_sysutil_strcpy(s_utent.ut_user, str_getbuf(p_user_str),
@@ -1235,6 +1234,7 @@ vsf_insert_uwtmp(const struct mystr* p_user_str,
setutxent();
(void) pututxline(&s_utent);
endutxent();
+ s_uwtmp_inserted = 1;
updwtmpx(WTMPX_FILE, &s_utent);
}
@@ -1245,7 +1245,6 @@ vsf_remove_uwtmp(void)
{
return;
}
- s_uwtmp_inserted = 0;
s_utent.ut_type = DEAD_PROCESS;
vsf_sysutil_memclr(s_utent.ut_user, sizeof(s_utent.ut_user));
vsf_sysutil_memclr(s_utent.ut_host, sizeof(s_utent.ut_host));
@@ -1253,6 +1252,7 @@ vsf_remove_uwtmp(void)
setutxent();
(void) pututxline(&s_utent);
endutxent();
+ s_uwtmp_inserted = 0;
s_utent.ut_tv.tv_sec = vsf_sysutil_get_time_sec();
updwtmpx(WTMPX_FILE, &s_utent);
}
--
2.20.1

105
0002-Repeat-pututxline-if-it-fails-with-EINTR.patch Normal file
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@ -0,0 +1,105 @@
From 896b3694ca062d747cd67e9e9ba246adb3fc706b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Lyson=C4=9Bk?= <olysonek@redhat.com>
Date: Mon, 5 Aug 2019 13:55:37 +0200
Subject: [PATCH 2/2] Repeat pututxline() if it fails with EINTR
This is a partial fix for rhbz#1688848. We cannot resolve it
completely until glibc bug rhbz#1734791 is fixed. See
https://bugzilla.redhat.com/show_bug.cgi?id=1688848#c13.
The maximum number of attempts is currently 2, which might seem
low. However setting it to 2 was a decision based on data - see
https://bugzilla.redhat.com/show_bug.cgi?id=1688848#c16.
Resolves: rhbz#1688848
---
sysdeputil.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 46 insertions(+), 7 deletions(-)
diff --git a/sysdeputil.c b/sysdeputil.c
index bd1e8c9..4fbcca7 100644
--- a/sysdeputil.c
+++ b/sysdeputil.c
@@ -1203,6 +1203,8 @@ void
vsf_insert_uwtmp(const struct mystr* p_user_str,
const struct mystr* p_host_str)
{
+ int attempts;
+
if (sizeof(s_utent.ut_line) < 16)
{
return;
@@ -1231,16 +1233,35 @@ vsf_insert_uwtmp(const struct mystr* p_user_str,
vsf_sysutil_strcpy(s_utent.ut_host, str_getbuf(p_host_str),
sizeof(s_utent.ut_host));
s_utent.ut_tv.tv_sec = vsf_sysutil_get_time_sec();
- setutxent();
- (void) pututxline(&s_utent);
- endutxent();
- s_uwtmp_inserted = 1;
+ for (attempts = 2; attempts > 0; --attempts)
+ {
+ struct utmpx* p_res;
+ setutxent();
+ p_res = pututxline(&s_utent);
+ /* For now we'll ignore errors other than EINTR and EAGAIN */
+ if (p_res != NULL || (errno != EINTR && errno != EAGAIN))
+ {
+ break;
+ }
+ }
+ if (attempts == 0)
+ {
+ /* This makes us skip pututxline() in vsf_remove_uwtmp() */
+ s_uwtmp_inserted = -1;
+ }
+ else
+ {
+ s_uwtmp_inserted = 1;
+ endutxent();
+ }
updwtmpx(WTMPX_FILE, &s_utent);
}
void
vsf_remove_uwtmp(void)
{
+ int attempts;
+
if (!s_uwtmp_inserted)
{
return;
@@ -1249,9 +1270,27 @@ vsf_remove_uwtmp(void)
vsf_sysutil_memclr(s_utent.ut_user, sizeof(s_utent.ut_user));
vsf_sysutil_memclr(s_utent.ut_host, sizeof(s_utent.ut_host));
s_utent.ut_tv.tv_sec = 0;
- setutxent();
- (void) pututxline(&s_utent);
- endutxent();
+ if (s_uwtmp_inserted == 1)
+ {
+ for (attempts = 2; attempts > 0; --attempts)
+ {
+ struct utmpx* p_res;
+ setutxent();
+ p_res = pututxline(&s_utent);
+ /* For now we'll ignore errors other than EINTR and EAGAIN */
+ if (p_res != NULL || (errno != EINTR && errno != EAGAIN))
+ {
+ break;
+ }
+ }
+ if (attempts != 0)
+ {
+ endutxent();
+ }
+ }
+ /* Set s_uwtmp_inserted to 0 regardless of the result of
+ * pututxline() to make sure we won't run this function twice.
+ */
s_uwtmp_inserted = 0;
s_utent.ut_tv.tv_sec = vsf_sysutil_get_time_sec();
updwtmpx(WTMPX_FILE, &s_utent);
--
2.20.1

8
vsftpd.spec
View File

@ -2,7 +2,7 @@
Name: vsftpd
Version: 3.0.3
Release: 31%{?dist}
Release: 32%{?dist}
Summary: Very Secure Ftp Daemon
# OpenSSL link exception
@ -89,6 +89,8 @@ Patch58: 0058-Make-the-max-number-of-bind-retries-tunable.patch
Patch59: 0059-Fix-SEGFAULT-when-running-in-a-container-as-PID-1.patch
Patch61: 0001-Move-closing-standard-FDs-after-listen.patch
Patch62: 0002-Prevent-recursion-in-bug.patch
Patch63: 0001-Set-s_uwtmp_inserted-only-after-record-insertion-rem.patch
Patch64: 0002-Repeat-pututxline-if-it-fails-with-EINTR.patch
%description
vsftpd is a Very Secure FTP daemon. It was written completely from
@ -157,6 +159,10 @@ mkdir -p $RPM_BUILD_ROOT/%{_var}/ftp/pub
%{_var}/ftp
%changelog
* Mon Aug 05 2019 Ondřej Lysoněk <olysonek@redhat.com> - 3.0.3-32
- Partially fix problem with bad utmp entries when pututxline() fails
- Resolves: rhbz#1688848
* Sat Aug 03 2019 Ondřej Lysoněk <olysonek@redhat.com> - 3.0.3-31
- Fix segfault when listen() returns an error
- Resolves: rhbz#1666380