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, 156 insertions, 0 deletions

diff --git a/include/crypto/blake2b.h b/include/crypto/blake2b.h
new file mode 100644
index 000000000..3bc37fd10
--- /dev/null
+++ b/include/crypto/blake2b.h
@@ -0,0 +1,156 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+#ifndef _CRYPTO_BLAKE2B_H
+#define _CRYPTO_BLAKE2B_H
+
+#include <linux/bug.h>
+#include <linux/types.h>
+#include <linux/string.h>
+
+enum blake2b_lengths {
+	BLAKE2B_BLOCK_SIZE = 128,
+	BLAKE2B_HASH_SIZE = 64,
+	BLAKE2B_KEY_SIZE = 64,
+
+	BLAKE2B_160_HASH_SIZE = 20,
+	BLAKE2B_256_HASH_SIZE = 32,
+	BLAKE2B_384_HASH_SIZE = 48,
+	BLAKE2B_512_HASH_SIZE = 64,
+};
+
+/**
+ * struct blake2b_ctx - Context for hashing a message with BLAKE2b
+ * @h: compression function state
+ * @t: block counter
+ * @f: finalization indicator
+ * @buf: partial block buffer; 'buflen' bytes are valid
+ * @buflen: number of bytes buffered in @buf
+ * @outlen: length of output hash value in bytes, at most BLAKE2B_HASH_SIZE
+ */
+struct blake2b_ctx {
+	/* 'h', 't', and 'f' are used in assembly code, so keep them as-is. */
+	u64 h[8];
+	u64 t[2];
+	u64 f[2];
+	u8 buf[BLAKE2B_BLOCK_SIZE];
+	unsigned int buflen;
+	unsigned int outlen;
+};
+
+enum blake2b_iv {
+	BLAKE2B_IV0 = 0x6A09E667F3BCC908ULL,
+	BLAKE2B_IV1 = 0xBB67AE8584CAA73BULL,
+	BLAKE2B_IV2 = 0x3C6EF372FE94F82BULL,
+	BLAKE2B_IV3 = 0xA54FF53A5F1D36F1ULL,
+	BLAKE2B_IV4 = 0x510E527FADE682D1ULL,
+	BLAKE2B_IV5 = 0x9B05688C2B3E6C1FULL,
+	BLAKE2B_IV6 = 0x1F83D9ABFB41BD6BULL,
+	BLAKE2B_IV7 = 0x5BE0CD19137E2179ULL,
+};
+
+static inline void __blake2b_init(struct blake2b_ctx *ctx, size_t outlen,
+				  const void *key, size_t keylen)
+{
+	ctx->h[0] = BLAKE2B_IV0 ^ (0x01010000 | keylen << 8 | outlen);
+	ctx->h[1] = BLAKE2B_IV1;
+	ctx->h[2] = BLAKE2B_IV2;
+	ctx->h[3] = BLAKE2B_IV3;
+	ctx->h[4] = BLAKE2B_IV4;
+	ctx->h[5] = BLAKE2B_IV5;
+	ctx->h[6] = BLAKE2B_IV6;
+	ctx->h[7] = BLAKE2B_IV7;
+	ctx->t[0] = 0;
+	ctx->t[1] = 0;
+	ctx->f[0] = 0;
+	ctx->f[1] = 0;
+	ctx->buflen = 0;
+	ctx->outlen = outlen;
+	if (keylen) {
+		memcpy(ctx->buf, key, keylen);
+		memset(&ctx->buf[keylen], 0, BLAKE2B_BLOCK_SIZE - keylen);
+		ctx->buflen = BLAKE2B_BLOCK_SIZE;
+	}
+}
+
+/**
+ * blake2b_init() - Initialize a BLAKE2b context for a new message (unkeyed)
+ * @ctx: the context to initialize
+ * @outlen: length of output hash value in bytes, at most BLAKE2B_HASH_SIZE
+ *
+ * Context: Any context.
+ */
+static inline void blake2b_init(struct blake2b_ctx *ctx, size_t outlen)
+{
+	__blake2b_init(ctx, outlen, NULL, 0);
+}
+
+/**
+ * blake2b_init_key() - Initialize a BLAKE2b context for a new message (keyed)
+ * @ctx: the context to initialize
+ * @outlen: length of output hash value in bytes, at most BLAKE2B_HASH_SIZE
+ * @key: the key
+ * @keylen: the key length in bytes, at most BLAKE2B_KEY_SIZE
+ *
+ * Context: Any context.
+ */
+static inline void blake2b_init_key(struct blake2b_ctx *ctx, size_t outlen,
+				    const void *key, size_t keylen)
+{
+	WARN_ON(IS_ENABLED(DEBUG) && (!outlen || outlen > BLAKE2B_HASH_SIZE ||
+		!key || !keylen || keylen > BLAKE2B_KEY_SIZE));
+
+	__blake2b_init(ctx, outlen, key, keylen);
+}
+
+/**
+ * blake2b_update() - Update a BLAKE2b context with message data
+ * @ctx: the context to update; must have been initialized
+ * @in: the message data
+ * @inlen: the data length in bytes
+ *
+ * This can be called any number of times.
+ *
+ * Context: Any context.
+ */
+void blake2b_update(struct blake2b_ctx *ctx, const u8 *in, size_t inlen);
+
+/**
+ * blake2b_final() - Finish computing a BLAKE2b hash
+ * @ctx: the context to finalize; must have been initialized
+ * @out: (output) the resulting BLAKE2b hash.  Its length will be equal to the
+ *	 @outlen that was passed to blake2b_init() or blake2b_init_key().
+ *
+ * After finishing, this zeroizes @ctx.  So the caller does not need to do it.
+ *
+ * Context: Any context.
+ */
+void blake2b_final(struct blake2b_ctx *ctx, u8 *out);
+
+/**
+ * blake2b() - Compute BLAKE2b hash in one shot
+ * @key: the key, or NULL for an unkeyed hash
+ * @keylen: the key length in bytes (at most BLAKE2B_KEY_SIZE), or 0 for an
+ *	    unkeyed hash
+ * @in: the message data
+ * @inlen: the data length in bytes
+ * @out: (output) the resulting BLAKE2b hash, with length @outlen
+ * @outlen: length of output hash value in bytes, at most BLAKE2B_HASH_SIZE
+ *
+ * Context: Any context.
+ */
+static inline void blake2b(const u8 *key, size_t keylen,
+			   const u8 *in, size_t inlen,
+			   u8 *out, size_t outlen)
+{
+	struct blake2b_ctx ctx;
+
+	WARN_ON(IS_ENABLED(DEBUG) && ((!in && inlen > 0) || !out || !outlen ||
+		outlen > BLAKE2B_HASH_SIZE || keylen > BLAKE2B_KEY_SIZE ||
+		(!key && keylen)));
+
+	__blake2b_init(&ctx, outlen, key, keylen);
+	blake2b_update(&ctx, in, inlen);
+	blake2b_final(&ctx, out);
+}
+
+#endif /* _CRYPTO_BLAKE2B_H */