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, 84 insertions, 0 deletions

diff --git a/security/selinux/ss/conditional.h b/security/selinux/ss/conditional.h
new file mode 100644
index 000000000..468e98ad3
--- /dev/null
+++ b/security/selinux/ss/conditional.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Authors: Karl MacMillan <kmacmillan@tresys.com>
+ *          Frank Mayer <mayerf@tresys.com>
+ *          Copyright (C) 2003 - 2004 Tresys Technology, LLC
+ */
+
+#ifndef _CONDITIONAL_H_
+#define _CONDITIONAL_H_
+
+#include "avtab.h"
+#include "symtab.h"
+#include "policydb.h"
+#include "../include/conditional.h"
+
+#define COND_EXPR_MAXDEPTH 10
+
+/*
+ * A conditional expression is a list of operators and operands
+ * in reverse polish notation.
+ */
+struct cond_expr_node {
+#define COND_BOOL 1 /* plain bool */
+#define COND_NOT  2 /* !bool */
+#define COND_OR	  3 /* bool || bool */
+#define COND_AND  4 /* bool && bool */
+#define COND_XOR  5 /* bool ^ bool */
+#define COND_EQ	  6 /* bool == bool */
+#define COND_NEQ  7 /* bool != bool */
+#define COND_LAST COND_NEQ
+	u32 expr_type;
+	u32 boolean;
+};
+
+struct cond_expr {
+	struct cond_expr_node *nodes;
+	u32 len;
+};
+
+/*
+ * Each cond_node contains a list of rules to be enabled/disabled
+ * depending on the current value of the conditional expression. This
+ * struct is for that list.
+ */
+struct cond_av_list {
+	struct avtab_node **nodes;
+	u32 len;
+};
+
+/*
+ * A cond node represents a conditional block in a policy. It
+ * contains a conditional expression, the current state of the expression,
+ * two lists of rules to enable/disable depending on the value of the
+ * expression (the true list corresponds to if and the false list corresponds
+ * to else)..
+ */
+struct cond_node {
+	int cur_state;
+	struct cond_expr expr;
+	struct cond_av_list true_list;
+	struct cond_av_list false_list;
+};
+
+void cond_policydb_init(struct policydb *p);
+void cond_policydb_destroy(struct policydb *p);
+
+int cond_init_bool_indexes(struct policydb *p);
+int cond_destroy_bool(void *key, void *datum, void *p);
+
+int cond_index_bool(void *key, void *datum, void *datap);
+
+int cond_read_bool(struct policydb *p, struct symtab *s, struct policy_file *fp);
+int cond_read_list(struct policydb *p, struct policy_file *fp);
+int cond_write_bool(void *key, void *datum, void *ptr);
+int cond_write_list(struct policydb *p, struct policy_file *fp);
+
+void cond_compute_av(struct avtab *ctab, struct avtab_key *key,
+		     struct av_decision *avd, struct extended_perms *xperms);
+void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key,
+			 struct extended_perms_decision *xpermd);
+void evaluate_cond_nodes(struct policydb *p);
+void cond_policydb_destroy_dup(struct policydb *p);
+int cond_policydb_dup(struct policydb *new, const struct policydb *orig);
+
+#endif /* _CONDITIONAL_H_ */