openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 172 insertions, 0 deletions

diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h
new file mode 100644
index 000000000..01b5167fe
--- /dev/null
+++ b/security/selinux/include/avc.h
@@ -0,0 +1,172 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Access vector cache interface for object managers.
+ *
+ * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
+ */
+
+#ifndef _SELINUX_AVC_H_
+#define _SELINUX_AVC_H_
+
+#include <linux/stddef.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/kdev_t.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/audit.h>
+#include <linux/lsm_audit.h>
+#include <linux/in6.h>
+#include "flask.h"
+#include "av_permissions.h"
+#include "security.h"
+
+/*
+ * An entry in the AVC.
+ */
+struct avc_entry;
+
+struct task_struct;
+struct inode;
+struct sock;
+struct sk_buff;
+
+/*
+ * AVC statistics
+ */
+struct avc_cache_stats {
+	unsigned int lookups;
+	unsigned int misses;
+	unsigned int allocations;
+	unsigned int reclaims;
+	unsigned int frees;
+};
+
+/*
+ * We only need this data after we have decided to send an audit message.
+ */
+struct selinux_audit_data {
+	u32 ssid;
+	u32 tsid;
+	u16 tclass;
+	u32 requested;
+	u32 audited;
+	u32 denied;
+	int result;
+} __randomize_layout;
+
+/*
+ * AVC operations
+ */
+
+void __init avc_init(void);
+
+static inline u32 avc_audit_required(u32 requested, struct av_decision *avd,
+				     int result, u32 auditdeny, u32 *deniedp)
+{
+	u32 denied, audited;
+
+	if (avd->flags & AVD_FLAGS_NEVERAUDIT)
+		return 0;
+
+	denied = requested & ~avd->allowed;
+	if (unlikely(denied)) {
+		audited = denied & avd->auditdeny;
+		/*
+		 * auditdeny is TRICKY!  Setting a bit in
+		 * this field means that ANY denials should NOT be audited if
+		 * the policy contains an explicit dontaudit rule for that
+		 * permission.  Take notice that this is unrelated to the
+		 * actual permissions that were denied.  As an example lets
+		 * assume:
+		 *
+		 * denied == READ
+		 * avd.auditdeny & ACCESS == 0 (not set means explicit rule)
+		 * auditdeny & ACCESS == 1
+		 *
+		 * We will NOT audit the denial even though the denied
+		 * permission was READ and the auditdeny checks were for
+		 * ACCESS
+		 */
+		if (auditdeny && !(auditdeny & avd->auditdeny))
+			audited = 0;
+	} else if (result)
+		audited = denied = requested;
+	else
+		audited = requested & avd->auditallow;
+	*deniedp = denied;
+	return audited;
+}
+
+int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass, u32 requested, u32 audited,
+		   u32 denied, int result, struct common_audit_data *a);
+
+/**
+ * avc_audit - Audit the granting or denial of permissions.
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @requested: requested permissions
+ * @avd: access vector decisions
+ * @result: result from avc_has_perm_noaudit
+ * @a:  auxiliary audit data
+ *
+ * Audit the granting or denial of permissions in accordance
+ * with the policy.  This function is typically called by
+ * avc_has_perm() after a permission check, but can also be
+ * called directly by callers who use avc_has_perm_noaudit()
+ * in order to separate the permission check from the auditing.
+ * For example, this separation is useful when the permission check must
+ * be performed under a lock, to allow the lock to be released
+ * before calling the auditing code.
+ */
+static inline int avc_audit(u32 ssid, u32 tsid, u16 tclass, u32 requested,
+			    struct av_decision *avd, int result,
+			    struct common_audit_data *a)
+{
+	u32 audited, denied;
+	audited = avc_audit_required(requested, avd, result, 0, &denied);
+	if (likely(!audited))
+		return 0;
+	return slow_avc_audit(ssid, tsid, tclass, requested, audited, denied,
+			      result, a);
+}
+
+#define AVC_STRICT	   1 /* Ignore permissive mode. */
+#define AVC_EXTENDED_PERMS 2 /* update extended permissions */
+int avc_has_perm_noaudit(u32 ssid, u32 tsid, u16 tclass, u32 requested,
+			 unsigned int flags, struct av_decision *avd);
+
+int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, u32 requested,
+		 struct common_audit_data *auditdata);
+
+#define AVC_EXT_IOCTL	(1 << 0) /* Cache entry for an ioctl extended permission */
+#define AVC_EXT_NLMSG	(1 << 1) /* Cache entry for an nlmsg extended permission */
+int avc_has_extended_perms(u32 ssid, u32 tsid, u16 tclass, u32 requested,
+			   u8 driver, u8 base_perm, u8 perm,
+			   struct common_audit_data *ad);
+
+u32 avc_policy_seqno(void);
+
+#define AVC_CALLBACK_GRANT		1
+#define AVC_CALLBACK_TRY_REVOKE		2
+#define AVC_CALLBACK_REVOKE		4
+#define AVC_CALLBACK_RESET		8
+#define AVC_CALLBACK_AUDITALLOW_ENABLE	16
+#define AVC_CALLBACK_AUDITALLOW_DISABLE 32
+#define AVC_CALLBACK_AUDITDENY_ENABLE	64
+#define AVC_CALLBACK_AUDITDENY_DISABLE	128
+#define AVC_CALLBACK_ADD_XPERMS		256
+
+int avc_add_callback(int (*callback)(u32 event), u32 events);
+
+/* Exported to selinuxfs */
+int avc_get_hash_stats(char *page);
+unsigned int avc_get_cache_threshold(void);
+void avc_set_cache_threshold(unsigned int cache_threshold);
+
+#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
+DECLARE_PER_CPU(struct avc_cache_stats, avc_cache_stats);
+#endif
+
+#endif /* _SELINUX_AVC_H_ */