[Buildroot] [git commit branch/2020.05.x] package/trousers: add upstream security fix

[Peter Korsgaard]

commit: https://git.buildroot.net/buildroot/commit/?id=0ff4b3ab56cd39ca8103130a113df3a36c2e4a7a
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2020.05.x

Fixes the following security issues:

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

For details, see the advisory:
https://www.openwall.com/lists/oss-security/2020/05/20/3

Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
(cherry picked from commit e71be18354391055a0a21e06a78aaade25ea62d0)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
 ...tiple-security-issues-that-are-present-if.patch | 90 ++++++++++++++++++++++
 package/trousers/trousers.mk                       |  3 +
 2 files changed, 93 insertions(+)

diff --git a/package/trousers/0003-Correct-multiple-security-issues-that-are-present-if.patch b/package/trousers/0003-Correct-multiple-security-issues-that-are-present-if.patch
new file mode 100644
index 0000000000..609245dad8
--- /dev/null
+++ b/package/trousers/0003-Correct-multiple-security-issues-that-are-present-if.patch
@@ -0,0 +1,90 @@
+From e74dd1d96753b0538192143adf58d04fcd3b242b Mon Sep 17 00:00:00 2001
+From: Matthias Gerstner <mgerstner at 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 at suse.de>
+Signed-off-by: Debora Velarde Babb <debora at linux.ibm.com>
+Signed-off-by: Peter Korsgaard <peter at korsgaard.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(-)
+
+diff --git a/src/tcs/ps/tcsps.c b/src/tcs/ps/tcsps.c
+index e47154b..85d45a9 100644
+--- a/src/tcs/ps/tcsps.c
++++ b/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));
+diff --git a/src/tcsd/svrside.c b/src/tcsd/svrside.c
+index 1ae1636..1c12ff3 100644
+--- a/src/tcsd/svrside.c
++++ b/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
+diff --git a/src/tcsd/tcsd_conf.c b/src/tcsd/tcsd_conf.c
+index a31503d..ea8ea13 100644
+--- a/src/tcsd/tcsd_conf.c
++++ b/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 */
+-- 
+2.20.1
+
diff --git a/package/trousers/trousers.mk b/package/trousers/trousers.mk
index 1d5364959c..5e6161ce4d 100644
--- a/package/trousers/trousers.mk
+++ b/package/trousers/trousers.mk
@@ -13,6 +13,9 @@ TROUSERS_INSTALL_STAGING = YES
 TROUSERS_AUTORECONF = YES
 TROUSERS_DEPENDENCIES = host-pkgconf openssl
 
+# 0003-Correct-multiple-security-issues-that-are-present-if.patch
+TROUSERS_IGNORE_CVES += CVE-2020-24330 CVE-2020-24331 CVE-2020-24332
+
 ifeq ($(BR2_PACKAGE_LIBICONV),y)
 TROUSERS_DEPENDENCIES += libiconv
 endif