pam_namespace: protect_dir(): use O_DIRECTORY to prevent local DoS

situations. CVE-2024-22365

Resolves: RHEL-21242

Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>

pam-1.3.1-namespace-protect-dir.patch

@@ -0,0 +1,58 @@
+From 031bb5a5d0d950253b68138b498dc93be69a64cb Mon Sep 17 00:00:00 2001
+From: Matthias Gerstner <matthias.gerstner@suse.de>
+Date: Wed, 27 Dec 2023 14:01:59 +0100
+Subject: [PATCH] pam_namespace: protect_dir(): use O_DIRECTORY to prevent
+ local DoS situations
+
+Without O_DIRECTORY the path crawling logic is subject to e.g. FIFOs
+being placed in user controlled directories, causing the PAM module to
+block indefinitely during `openat()`.
+
+Pass O_DIRECTORY to cause the `openat()` to fail if the path does not
+refer to a directory.
+
+With this the check whether the final path element is a directory
+becomes unnecessary, drop it.
+---
+ modules/pam_namespace/pam_namespace.c | 18 +-----------------
+ 1 file changed, 1 insertion(+), 17 deletions(-)
+
+diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c
+index 2528cff8..f72d6718 100644
+--- a/modules/pam_namespace/pam_namespace.c
++++ b/modules/pam_namespace/pam_namespace.c
+@@ -1201,7 +1201,7 @@ static int protect_dir(const char *path, mode_t mode, int do_mkdir,
+ 	int dfd = AT_FDCWD;
+ 	int dfd_next;
+ 	int save_errno;
+-	int flags = O_RDONLY;
++	int flags = O_RDONLY | O_DIRECTORY;
+ 	int rv = -1;
+ 	struct stat st;
+ 
+@@ -1255,22 +1255,6 @@ static int protect_dir(const char *path, mode_t mode, int do_mkdir,
+ 		rv = openat(dfd, dir, flags);
+ 	}
+ 
+-	if (rv != -1) {
+-		if (fstat(rv, &st) != 0) {
+-			save_errno = errno;
+-			close(rv);
+-			rv = -1;
+-			errno = save_errno;
+-			goto error;
+-		}
+-		if (!S_ISDIR(st.st_mode)) {
+-			close(rv);
+-			errno = ENOTDIR;
+-			rv = -1;
+-			goto error;
+-		}
+-	}
+-
+ 	if (flags & O_NOFOLLOW) {
+ 		/* we are inside user-owned dir - protect */
+ 		if (protect_mount(rv, p, idata) == -1) {
+-- 
+2.43.0
+

pam.spec

@@ -3,7 +3,7 @@
 Summary: An extensible library which provides authentication for applications
 Name: pam
 Version: 1.3.1
-Release: 32%{?dist}
+Release: 33%{?dist}
 # The library is BSD licensed with option to relicense as GPLv2+
 # - this option is redundant as the BSD license allows that anyway.
 # pam_timestamp, pam_loginuid, and pam_console modules are GPLv2+.
@@ -108,6 +108,8 @@ Patch67: pam-1.3.1-unix-default-rounds.patch
 Patch68: pam-1.3.1-faillock-create-tallydir.patch
 # https://github.com/linux-pam/linux-pam/commit/23393bef92c1e768eda329813d7af55481c6ca9f
 Patch69: pam-1.3.1-access-handle-hostnames.patch
+# https://github.com/linux-pam/linux-pam/commit/031bb5a5d0d950253b68138b498dc93be69a64cb
+Patch70: pam-1.3.1-namespace-protect-dir.patch
 
 %define _pamlibdir %{_libdir}
 %define _moduledir %{_libdir}/security
@@ -225,6 +227,7 @@ cp %{SOURCE18} .
 %patch67 -p1 -b .unix-default-rounds
 %patch68 -p1 -b .faillock-create-tallydir
 %patch69 -p1 -b .access-handle-hostnames
+%patch70 -p1 -b .namespace-protect-dir
 
 autoreconf -i
 
@@ -478,6 +481,10 @@ done
 %doc doc/specs/rfc86.0.txt
 
 %changelog
+* Mon Feb 12 2024 Iker Pedrosa <ipedrosa@redhat.com> - 1.3.1-33
+- pam_namespace: protect_dir(): use O_DIRECTORY to prevent local DoS
+  situations. CVE-2024-22365. Resolves: RHEL-21242
+
 * Fri Jan 26 2024 Iker Pedrosa <ipedrosa@redhat.com> - 1.3.1-32
 - pam_access: handle hostnames in access.conf. Resolves: RHEL-3374