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From e74dd1d96753b0538192143adf58d04fcd3b242b Mon Sep 17 00:00:00 2001
From: Matthias Gerstner <mgerstner@suse.de>
Date: Fri, 14 Aug 2020 22:14:36 -0700
Subject: [PATCH] Correct multiple security issues that are present if the tcsd
is started by root instead of the tss user.
Patch fixes the following 3 CVEs:
CVE-2020-24332
If the tcsd daemon is started with root privileges,
the creation of the system.data file is prone to symlink attacks
CVE-2020-24330
If the tcsd daemon is started with root privileges,
it fails to drop the root gid after it is no longer needed
CVE-2020-24331
If the tcsd daemon is started with root privileges,
the tss user has read and write access to the /etc/tcsd.conf file
Authored-by: Matthias Gerstner <mgerstner@suse.de>
Signed-off-by: Debora Velarde Babb <debora@linux.ibm.com>
Upstream-Status: Backport
CVE: CVE-2020-24332
CVE: CVE-2020-24330
CVE: CVE-2020-24331
Signed-off-by: Armin Kuster <akuster@mvista.com>
---
src/tcs/ps/tcsps.c | 2 +-
src/tcsd/svrside.c | 1 +
src/tcsd/tcsd_conf.c | 10 +++++-----
3 files changed, 7 insertions(+), 6 deletions(-)
Index: git/src/tcs/ps/tcsps.c
===================================================================
--- git.orig/src/tcs/ps/tcsps.c
+++ git/src/tcs/ps/tcsps.c
@@ -72,7 +72,7 @@ get_file()
}
/* open and lock the file */
- system_ps_fd = open(tcsd_options.system_ps_file, O_CREAT|O_RDWR, 0600);
+ system_ps_fd = open(tcsd_options.system_ps_file, O_CREAT|O_RDWR|O_NOFOLLOW, 0600);
if (system_ps_fd < 0) {
LogError("system PS: open() of %s failed: %s",
tcsd_options.system_ps_file, strerror(errno));
Index: git/src/tcsd/svrside.c
===================================================================
--- git.orig/src/tcsd/svrside.c
+++ git/src/tcsd/svrside.c
@@ -473,6 +473,7 @@ main(int argc, char **argv)
}
return TCSERR(TSS_E_INTERNAL_ERROR);
}
+ setgid(pwd->pw_gid);
setuid(pwd->pw_uid);
#endif
#endif
Index: git/src/tcsd/tcsd_conf.c
===================================================================
--- git.orig/src/tcsd/tcsd_conf.c
+++ git/src/tcsd/tcsd_conf.c
@@ -743,7 +743,7 @@ conf_file_init(struct tcsd_config *conf)
#ifndef SOLARIS
struct group *grp;
struct passwd *pw;
- mode_t mode = (S_IRUSR|S_IWUSR);
+ mode_t mode = (S_IRUSR|S_IWUSR|S_IRGRP);
#endif /* SOLARIS */
TSS_RESULT result;
@@ -798,15 +798,15 @@ conf_file_init(struct tcsd_config *conf)
}
/* make sure user/group TSS owns the conf file */
- if (pw->pw_uid != stat_buf.st_uid || grp->gr_gid != stat_buf.st_gid) {
+ if (stat_buf.st_uid != 0 || grp->gr_gid != stat_buf.st_gid) {
LogError("TCSD config file (%s) must be user/group %s/%s", tcsd_config_file,
- TSS_USER_NAME, TSS_GROUP_NAME);
+ "root", TSS_GROUP_NAME);
return TCSERR(TSS_E_INTERNAL_ERROR);
}
- /* make sure only the tss user can manipulate the config file */
+ /* make sure only the tss user can read (but not manipulate) the config file */
if (((stat_buf.st_mode & 0777) ^ mode) != 0) {
- LogError("TCSD config file (%s) must be mode 0600", tcsd_config_file);
+ LogError("TCSD config file (%s) must be mode 0640", tcsd_config_file);
return TCSERR(TSS_E_INTERNAL_ERROR);
}
#endif /* SOLARIS */
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