This enables "# cat cert.pem | keyctl padd asymmetric <keyring>"
Since prep->data is a "const void *" I didn't feel comfortable with
pem_decode() simply overwriting either the pointer or the contents
of the provided buffer. A secondary buffer is therefore allocated,
and then later freed by .free_preparse.
This compiles, but is otherwise untested. I'm interested in opinions
about this approach.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
crypto/asymmetric_keys/Makefile | 3
crypto/asymmetric_keys/asymmetric_type.c | 7 +
crypto/asymmetric_keys/pem.c | 185 ++++++++++++++++++++++++++++++
crypto/asymmetric_keys/pem.h | 8 +
crypto/asymmetric_keys/pkcs8_parser.c | 5 +
crypto/asymmetric_keys/x509_public_key.c | 5 +
include/linux/key-type.h | 2
7 files changed, 212 insertions(+), 3 deletions(-)
create mode 100644 crypto/asymmetric_keys/pem.c
create mode 100644 crypto/asymmetric_keys/pem.h
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 28b91adba2ae..1df8c976dd2f 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -8,7 +8,8 @@ obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += asymmetric_keys.o
asymmetric_keys-y := \
asymmetric_type.o \
restrict.o \
- signature.o
+ signature.o \
+ pem.o
obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
obj-$(CONFIG_ASYMMETRIC_TPM_KEY_SUBTYPE) += asym_tpm.o
diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index ad8af3d70ac0..f5d810c079b6 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -12,10 +12,12 @@
#include <linux/seq_file.h>
#include <linux/module.h>
#include <linux/slab.h>
+#include <linux/vmalloc.h>
#include <linux/ctype.h>
#include <keys/system_keyring.h>
#include <keys/user-type.h>
#include "asymmetric_keys.h"
+#include "pem.h"
MODULE_LICENSE("GPL");
@@ -378,6 +380,10 @@ static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
if (prep->datalen == 0)
return -EINVAL;
+ ret = pem_decode(prep);
+ if (ret < 0)
+ return ret;
+
down_read(&asymmetric_key_parsers_sem);
ret = -EBADMSG;
@@ -428,6 +434,7 @@ static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
}
asymmetric_key_free_kids(kids);
kfree(prep->description);
+ vfree(prep->decoded);
}
/*
diff --git a/crypto/asymmetric_keys/pem.c b/crypto/asymmetric_keys/pem.c
new file mode 100644
index 000000000000..b989fe7c1049
--- /dev/null
+++ b/crypto/asymmetric_keys/pem.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Unwrap a PEM-encoded asymmetric key. This implementation unwraps
+ * the interoperable text encoding format specified in RFC 7468.
+ *
+ * Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
+ *
+ * Copyright (c) 2021, Oracle and/or its affiliates.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/key-type.h>
+
+#include "pem.h"
+
+/* Encapsulation boundaries */
+#define PEM_EB_MARKER "-----"
+#define PEM_BEGIN_MARKER PEM_EB_MARKER "BEGIN"
+#define PEM_END_MARKER PEM_EB_MARKER "END"
+
+/*
+ * Unremarkable table-driven base64 decoder based on the public domain
+ * implementation provided at:
+ * https://en.wikibooks.org/wiki/Algorithm_Implementation/Miscellaneous/Base64
+ *
+ * XXX: Replace this implementation with one that handles EBCDIC input properly.
+ */
+
+#define WHITESPACE 253
+#define EQUALS 254
+#define INVALID 255
+
+static const u8 alphabet[] = {
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, WHITESPACE, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, 62, INVALID, INVALID, INVALID, 63,
+ 52, 53, 54, 55, 56, 57, 58, 59,
+ 60, 61, INVALID, INVALID, INVALID, EQUALS, INVALID, INVALID,
+ INVALID, 0, 1, 2, 3, 4, 5, 6,
+ 7, 8, 9, 10, 11, 12, 13, 14,
+ 15, 16, 17, 18, 19, 20, 21, 22,
+ 23, 24, 25, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, 26, 27, 28, 29, 30, 31, 32,
+ 33, 34, 35, 36, 37, 38, 39, 40,
+ 41, 42, 43, 44, 45, 46, 47, 48,
+ 49, 50, 51, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+ INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID, INVALID,
+};
+
+static bool base64decode(unsigned char *in, size_t inLen,
+ unsigned char *out, size_t *outLen)
+{
+ unsigned char *end = in + inLen;
+ char iter = 0;
+ uint32_t buf = 0;
+ size_t len = 0;
+
+ while (in < end) {
+ u8 c = alphabet[*in++];
+
+ switch (c) {
+ case WHITESPACE:
+ continue;
+ case INVALID:
+ return false;
+ case EQUALS:
+ in = end;
+ continue;
+ default:
+ buf = buf << 6 | c;
+ iter++;
+
+ if (iter == 4) {
+ if ((len += 3) > *outLen)
+ return false;
+ *(out++) = (buf >> 16) & 255;
+ *(out++) = (buf >> 8) & 255;
+ *(out++) = buf & 255;
+ buf = 0;
+ iter = 0;
+ }
+ }
+ }
+
+ if (iter == 3) {
+ if ((len += 2) > *outLen)
+ return false;
+ *(out++) = (buf >> 10) & 255;
+ *(out++) = (buf >> 2) & 255;
+ } else if (iter == 2) {
+ if (++len > *outLen)
+ return false;
+ *(out++) = (buf >> 4) & 255;
+ }
+
+ *outLen = len;
+ return true;
+}
+
+/**
+ * pem_decode - Attempt to decode a PEM-encoded data blob.
+ * @prep: Data content to examine
+ *
+ * Assumptions:
+ * - The input data buffer is not more than a few pages in size.
+ * - The input data buffer has already been vetted for proper
+ * kernel read access.
+ * - The input data buffer might not be NUL-terminated.
+ *
+ * PEM type labels are ignored. Subsequent parsing of the
+ * decoded message adequately identifies its content.
+ *
+ * On success, a pointer to a dynamically-allocated buffer
+ * containing the decoded content is returned. This buffer is
+ * vfree'd in the .free_preparse method.
+ *
+ * Return values:
+ * %1: @prep.decoded points to the decoded message
+ * %0: @prep did not contain a PEM-encoded message
+ *
+ * A negative errno is returned if an unexpected error has
+ * occurred (eg, memory exhaustion).
+ */
+int pem_decode(struct key_preparsed_payload *prep)
+{
+ const unsigned char *in = prep->data;
+ unsigned char *begin, *end, *out;
+ size_t outlen;
+
+ prep->decoded = NULL;
+ prep->decoded_len = 0;
+
+ /* Find the beginning encapsulation boundary */
+ begin = strnstr(in, PEM_BEGIN_MARKER, prep->datalen);
+ if (!begin)
+ goto out_not_pem;
+ begin = strnstr(begin, PEM_EB_MARKER, begin - in);
+ if (!begin)
+ goto out_not_pem;
+ begin += sizeof(PEM_EB_MARKER);
+
+ /* Find the ending encapsulation boundary */
+ end = strnstr(begin, PEM_END_MARKER, begin - in);
+ if (!end)
+ goto out_not_pem;
+ if (!strnstr(end, PEM_EB_MARKER, end - in))
+ goto out_not_pem;
+ end--;
+
+ /* Attempt to decode */
+ out = vmalloc(end - begin);
+ if (!out)
+ return -ENOMEM;
+ if (!base64decode(begin, end - begin, out, &outlen)) {
+ vfree(out);
+ goto out_not_pem;
+ }
+
+ prep->decoded = out;
+ prep->decoded_len = outlen;
+ return 1;
+
+out_not_pem:
+ return 0;
+}
diff --git a/crypto/asymmetric_keys/pem.h b/crypto/asymmetric_keys/pem.h
new file mode 100644
index 000000000000..51b9db517f94
--- /dev/null
+++ b/crypto/asymmetric_keys/pem.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASYMMETRIC_PEM_H
+#define __ASYMMETRIC_PEM_H
+
+int pem_decode(struct key_preparsed_payload *prep);
+
+#endif /* __ASYMMETRIC_PEM_H */
diff --git a/crypto/asymmetric_keys/pkcs8_parser.c b/crypto/asymmetric_keys/pkcs8_parser.c
index 105dcce27f71..b7ce76d3a767 100644
--- a/crypto/asymmetric_keys/pkcs8_parser.c
+++ b/crypto/asymmetric_keys/pkcs8_parser.c
@@ -137,7 +137,10 @@ static int pkcs8_key_preparse(struct key_preparsed_payload *prep)
{
struct public_key *pub;
- pub = pkcs8_parse(prep->data, prep->datalen);
+ if (prep->decoded)
+ pub = pkcs8_parse(prep->decoded, prep->decoded_len);
+ else
+ pub = pkcs8_parse(prep->data, prep->datalen);
if (IS_ERR(pub))
return PTR_ERR(pub);
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 3d45161b271a..d8b559ac6d7c 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -167,7 +167,10 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
char *desc = NULL, *p;
int ret;
- cert = x509_cert_parse(prep->data, prep->datalen);
+ if (prep->decoded)
+ cert = x509_cert_parse(prep->decoded, prep->decoded_len);
+ else
+ cert = x509_cert_parse(prep->data, prep->datalen);
if (IS_ERR(cert))
return PTR_ERR(cert);
diff --git a/include/linux/key-type.h b/include/linux/key-type.h
index 7d985a1dfe4a..1672f9599afa 100644
--- a/include/linux/key-type.h
+++ b/include/linux/key-type.h
@@ -34,6 +34,8 @@ struct key_preparsed_payload {
union key_payload payload; /* Proposed payload */
const void *data; /* Raw data */
size_t datalen; /* Raw datalen */
+ const void *decoded; /* PEM-decoded data */
+ size_t decoded_len; /* Length of PEM-decoded data */
size_t quotalen; /* Quota length for proposed payload */
time64_t expiry; /* Expiry time of key */
} __randomize_layout;
