[patch] pam_krb5-2.3.1-ccacheperms.patch

pam_krb5-2.3.1-ccacheperms.patch (text/plain), 7.67 KB, created by Robert Buchholz (RETIRED) on 2008-09-19 17:28:44 UTC

diff --git a/src/Makefile.am b/src/Makefile.am
index 61526e8..9b54f2a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -31,6 +31,8 @@ libpam_krb5_la_SOURCES = \
 	kuserok.c \
 	kuserok.h \
 	minikafs.h \
+	perms.c \
+	perms.h \
 	prompter.c \
 	prompter.h \
 	shmem.c \
@@ -106,6 +108,7 @@ harness_LDADD = \
 	map.lo \
 	initopts.lo \
 	options.lo \
+	perms.lo \
 	userinfo.lo \
 	sly.lo \
 	v4.lo \
@@ -119,6 +122,7 @@ harness_newpag_LDADD = \
 	pam_newpag.lo \
 	logstdio.lo \
 	options.lo \
+	perms.lo \
 	v4.lo \
 	v5.lo
 harness_newpag_LDADD += libpam_krb5.la @PAM_LIBS@ @KRB5_LIBS@ @KRB4_LIBS@ @KEYUTILS_LIBS@
diff --git a/src/perms.c b/src/perms.c
new file mode 100644
index 0000000..d999846
--- /dev/null
+++ b/src/perms.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2008 Red Hat, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, and the entire permission notice in its entirety,
+ *    including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior
+ *    written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of the
+ * GNU Lesser General Public License, in which case the provisions of the
+ * LGPL are required INSTEAD OF the above restrictions.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../config.h"
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "perms.h"
+
+struct _pam_krb5_perms {
+	uid_t ruid, euid;
+	gid_t rgid, egid;
+};
+
+struct _pam_krb5_perms *
+_pam_krb5_switch_perms(void)
+{
+	struct _pam_krb5_perms *ret;
+	ret = malloc(sizeof(*ret));
+	if (ret != NULL) {
+		ret->ruid = getuid();
+		ret->euid = geteuid();
+		ret->rgid = getgid();
+		ret->egid = getegid();
+		if (ret->ruid == ret->euid) {
+			ret->ruid = -1;
+			ret->euid = -1;
+		}
+		if (ret->rgid == ret->egid) {
+			ret->rgid = -1;
+			ret->egid = -1;
+		}
+		if (setregid(ret->egid, ret->rgid) == -1) {
+			free(ret);
+			ret = NULL;
+		} else {
+			if (setreuid(ret->euid, ret->ruid) == -1) {
+				setregid(ret->rgid, ret->egid);
+				free(ret);
+				ret = NULL;
+			}
+		}
+	}
+	return ret;
+}
+
+int
+_pam_krb5_restore_perms(struct _pam_krb5_perms *saved)
+{
+	int ret = -1;
+	if (saved != NULL) {
+		if ((setreuid(saved->ruid, saved->euid) == 0) &&
+		    (setregid(saved->rgid, saved->egid) == 0)) {
+			ret = 0;
+		}
+		free(saved);
+	}
+	return ret;
+}
diff --git a/src/perms.h b/src/perms.h
new file mode 100644
index 0000000..7aedb61
--- /dev/null
+++ b/src/perms.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2008 Red Hat, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, and the entire permission notice in its entirety,
+ *    including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior
+ *    written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of the
+ * GNU Lesser General Public License, in which case the provisions of the
+ * LGPL are required INSTEAD OF the above restrictions.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef pam_krb5_perms_h
+#define pam_krb5_perms_h
+
+struct _pam_krb5_perms;
+struct _pam_krb5_perms *_pam_krb5_switch_perms(void);
+int _pam_krb5_restore_perms(struct _pam_krb5_perms *saved);
+
+#endif
diff --git a/src/v5.c b/src/v5.c
index 87bf3b6..24ffbc6 100644
--- a/src/v5.c
+++ b/src/v5.c
@@ -66,6 +66,7 @@
 
 #include "conv.h"
 #include "log.h"
+#include "perms.h"
 #include "prompter.h"
 #include "stash.h"
 #include "userinfo.h"
@@ -833,6 +834,7 @@ v5_get_creds(krb5_context ctx,
 	const char *realm;
 	struct pam_message message;
 	struct _pam_krb5_prompter_data prompter_data;
+	struct _pam_krb5_perms *saved_perms;
 	krb5_principal service_principal;
 	krb5_creds tmpcreds;
 	krb5_ccache ccache;
@@ -884,20 +886,46 @@ v5_get_creds(krb5_context ctx,
 				      "from %s", krb5_cc_default_name(ctx));
 			}
 			memset(&ccache, 0, sizeof(ccache));
-			if (krb5_cc_default(ctx, &ccache) == 0) {
+			/* In case we're setuid/setgid, switch to the caller's
+			 * permissions. */
+			saved_perms = _pam_krb5_switch_perms();
+			if ((saved_perms != NULL) &&
+			    (krb5_cc_default(ctx, &ccache) == 0)) {
 				tmpcreds.client = userinfo->principal_name;
 				tmpcreds.server = service_principal;
 				i = krb5_cc_retrieve_cred(ctx, ccache, 0,
 							  &tmpcreds, creds);
 				/* FIXME: check if the creds are expired?
 				 * What's the right error code if we check, and
 				 * they are? */
 				memset(&tmpcreds, 0, sizeof(tmpcreds));
 				krb5_cc_close(ctx, ccache);
+				/* In case we're setuid/setgid, restore the
+				 * previous permissions. */
+				if (saved_perms != NULL) {
+					if (_pam_krb5_restore_perms(saved_perms) != 0) {
+						krb5_free_cred_contents(ctx, creds);
+						memset(creds, 0, sizeof(*creds));
+						krb5_free_principal(ctx, service_principal);
+						return PAM_SYSTEM_ERR;
+					}
+					saved_perms = NULL;
+				}
 			} else {
 				warn("error opening default ccache");
 				i = KRB5_CC_NOTFOUND;
 			}
+			/* In case we're setuid/setgid, switch back to the
+			 * previous permissions if we didn't already. */
+			if (saved_perms != NULL) {
+				if (_pam_krb5_restore_perms(saved_perms) != 0) {
+					krb5_free_cred_contents(ctx, creds);
+					memset(creds, 0, sizeof(*creds));
+					krb5_free_principal(ctx, service_principal);
+					return PAM_SYSTEM_ERR;
+				}
+				saved_perms = NULL;
+			}
 			krb5_free_principal(ctx, service_principal);
 		} else {
 			warn("error parsing TGT principal name (%s) "