[PATCH 1/1] x86/kexec: UKI support

[Jan Hendrik Farr <kernel@jfarr.cc>]

make the kernel accept UKIs (Unified Kernel Images) for kexec_file_load.

UKIs contain the kernel bzImage, initrd, and cmdline all packaged up as
one EFI application. The main advantage of this is that the whole
combination is signed together as a package for secure boot.

This implementation parses the UKI and passes the bzImage, initrd, and
cmdline to the normal bzImage loader.

Signed-off-by: Jan Hendrik Farr <kernel@jfarr.cc>
---
 arch/x86/include/asm/kexec-uki.h       |   7 ++
 arch/x86/include/asm/parse_pefile.h    |  32 +++++++
 arch/x86/kernel/Makefile               |   2 +
 arch/x86/kernel/kexec-uki.c            | 113 +++++++++++++++++++++++++
 arch/x86/kernel/machine_kexec_64.c     |   2 +
 arch/x86/kernel/parse_pefile.c         | 110 ++++++++++++++++++++++++
 crypto/asymmetric_keys/mscode_parser.c |   2 +-
 crypto/asymmetric_keys/verify_pefile.c | 110 +++---------------------
 crypto/asymmetric_keys/verify_pefile.h |  16 ----
 9 files changed, 278 insertions(+), 116 deletions(-)
 create mode 100644 arch/x86/include/asm/kexec-uki.h
 create mode 100644 arch/x86/include/asm/parse_pefile.h
 create mode 100644 arch/x86/kernel/kexec-uki.c
 create mode 100644 arch/x86/kernel/parse_pefile.c

diff --git a/arch/x86/include/asm/kexec-uki.h b/arch/x86/include/asm/kexec-uki.h
new file mode 100644
index 000000000000..87fd2c6fb091
--- /dev/null
+++ b/arch/x86/include/asm/kexec-uki.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_KEXEC_UKI_H
+#define _ASM_KEXEC_UKI_H
+
+extern const struct kexec_file_ops kexec_uki_ops;
+
+#endif  /* _ASM_KEXEC_UKI_H */
diff --git a/arch/x86/include/asm/parse_pefile.h b/arch/x86/include/asm/parse_pefile.h
new file mode 100644
index 000000000000..c29f8c98ee66
--- /dev/null
+++ b/arch/x86/include/asm/parse_pefile.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+ *
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _ASM_PARSE_PEFILE_H
+#define _ASM_PARSE_PEFILE_H
+
+#include <linux/pe.h>
+
+struct pefile_context {
+	unsigned	header_size;
+	unsigned	image_checksum_offset;
+	unsigned	cert_dirent_offset;
+	unsigned	n_data_dirents;
+	unsigned	n_sections;
+	unsigned	certs_size;
+	unsigned	sig_offset;
+	unsigned	sig_len;
+	const struct section_header *secs;
+
+	/* PKCS#7 MS Individual Code Signing content */
+	const void	*digest;		/* Digest */
+	unsigned	digest_len;		/* Digest length */
+	const char	*digest_algo;		/* Digest algorithm */
+};
+int pefile_parse_binary(const void *pebuf, unsigned int pelen,
+			       struct pefile_context *ctx);
+
+#endif // _ASM_PARSE_PEFILE_H
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 3269a0e23d3a..8a37a977bf72 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -101,6 +101,8 @@ obj-$(CONFIG_CRASH_CORE)	+= crash_core_$(BITS).o
 obj-$(CONFIG_KEXEC_CORE)	+= machine_kexec_$(BITS).o
 obj-$(CONFIG_KEXEC_CORE)	+= relocate_kernel_$(BITS).o crash.o
 obj-$(CONFIG_KEXEC_FILE)	+= kexec-bzimage64.o
+obj-$(CONFIG_KEXEC_FILE)	+= kexec-uki.o
+obj-$(CONFIG_KEXEC_FILE)	+= parse_pefile.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump_$(BITS).o
 obj-y				+= kprobes/
 obj-$(CONFIG_MODULES)		+= module.o
diff --git a/arch/x86/kernel/kexec-uki.c b/arch/x86/kernel/kexec-uki.c
new file mode 100644
index 000000000000..9275196a6b71
--- /dev/null
+++ b/arch/x86/kernel/kexec-uki.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kexec UKI loader
+ *
+ * Copyright (C) 2023 Jan Hendrik Farr
+ *
+ * Authors:
+ *      Jan Hendrik Farr <kernel@jfarr.cc>
+ */
+
+#define pr_fmt(fmt)	"kexec-uki: " fmt
+
+#include <linux/kernel.h>
+#include "linux/pe.h"
+#include <linux/kexec.h>
+#include <linux/err.h>
+
+#include <asm/kexec-uki.h>
+#include <asm/kexec-bzimage64.h>
+#include <asm/parse_pefile.h>
+
+static int find_section(struct pefile_context *ctx, const char *name,
+			const struct section_header **sec)
+{
+	for (int i = 0; i < ctx->n_sections; i++) {
+		const struct section_header *cur_sec = &ctx->secs[i];
+
+		if (!strncmp(cur_sec->name, name, ARRAY_SIZE(cur_sec->name))) {
+			*sec = cur_sec;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int uki_probe(const char *buf, unsigned long len)
+{
+	int ret = -ENOEXEC;
+	struct pefile_context pe_ctx;
+
+	int r = pefile_parse_binary(buf, len, &pe_ctx);
+
+	if (r) {
+		pr_info("Not a UKI. Not a valid PE file\n");
+		return ret;
+	}
+
+	const struct section_header *_;
+
+	if (find_section(&pe_ctx, ".linux", &_) ||
+	    find_section(&pe_ctx, ".initrd", &_) ||
+	    find_section(&pe_ctx, ".cmdline", &_)) {
+		pr_info("Not a UKI. Missing .linux, .initrd, or .cmdline\n");
+		return ret;
+	}
+
+
+	pr_info("It's a UKI\n");
+	return 0;
+}
+
+static void *uki_load(struct kimage *image, char *kernel,
+		      unsigned long kernel_len, char *initrd,
+		      unsigned long initrd_len, char *cmdline,
+		      unsigned long cmdline_len)
+{
+	struct pefile_context pe_ctx;
+	int r = pefile_parse_binary(kernel, kernel_len, &pe_ctx);
+
+	if (r)
+		return ERR_PTR(r);
+
+	pr_debug("pefile_parse_binary return %d, number of sections: %d\n",
+		 r, pe_ctx.n_sections);
+
+	const struct section_header *sec_linux, *sec_initrd, *sec_cmdline;
+	int r_linux = find_section(&pe_ctx, ".linux", &sec_linux);
+	int r_initrd = find_section(&pe_ctx, ".initrd", &sec_initrd);
+	int r_cmdline = find_section(&pe_ctx, ".cmdline", &sec_cmdline);
+
+	if (r_linux || r_initrd || r_cmdline)
+		return ERR_PTR(-EINVAL);
+
+	void *ret = kexec_bzImage64_ops.load(
+		image,
+		kernel + sec_linux->data_addr,
+		sec_linux->raw_data_size,
+		kernel + sec_initrd->data_addr,
+		sec_initrd->raw_data_size,
+		kernel + sec_cmdline->data_addr,
+		sec_cmdline->raw_data_size
+	);
+
+	if (IS_ERR(ret))
+		pr_warn("bzImage64_load error\n");
+
+	return ret;
+}
+
+static int uki_cleanup(void *loader_data)
+{
+	return kexec_bzImage64_ops.cleanup(loader_data);
+}
+
+const struct kexec_file_ops kexec_uki_ops = {
+	.probe = uki_probe,
+	.load = uki_load,
+	.cleanup = uki_cleanup,
+#ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
+	.verify_sig = kexec_kernel_verify_pe_sig,
+#endif
+};
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 1a3e2c05a8a5..072f5aac52b9 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -25,6 +25,7 @@
 #include <asm/io_apic.h>
 #include <asm/debugreg.h>
 #include <asm/kexec-bzimage64.h>
+#include <asm/kexec-uki.h>
 #include <asm/setup.h>
 #include <asm/set_memory.h>
 #include <asm/cpu.h>
@@ -81,6 +82,7 @@ static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { retu
 #ifdef CONFIG_KEXEC_FILE
 const struct kexec_file_ops * const kexec_file_loaders[] = {
 		&kexec_bzImage64_ops,
+		&kexec_uki_ops,
 		NULL
 };
 #endif
diff --git a/arch/x86/kernel/parse_pefile.c b/arch/x86/kernel/parse_pefile.c
new file mode 100644
index 000000000000..7737c94a1848
--- /dev/null
+++ b/arch/x86/kernel/parse_pefile.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Parse a PE binary
+ *
+ * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2023 Jan Hendrik Farr
+ *
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <asm/parse_pefile.h>
+#include <linux/err.h>
+
+#define pr_fmt(fmt)	"parse_pefile: " fmt
+#include <linux/module.h>
+/*
+ * Parse a PE binary.
+ */
+int pefile_parse_binary(const void *pebuf, unsigned int pelen,
+			       struct pefile_context *ctx)
+{
+	const struct mz_hdr *mz = pebuf;
+	const struct pe_hdr *pe;
+	const struct pe32_opt_hdr *pe32;
+	const struct pe32plus_opt_hdr *pe64;
+	const struct data_directory *ddir;
+	const struct data_dirent *dde;
+	const struct section_header *secs, *sec;
+	size_t cursor, datalen = pelen;
+
+
+#define chkaddr(base, x, s)						\
+	do {								\
+		if ((x) < base || (s) >= datalen || (x) > datalen - (s)) \
+			return -ELIBBAD;				\
+	} while (0)
+
+	chkaddr(0, 0, sizeof(*mz));
+	if (mz->magic != MZ_MAGIC)
+		return -ELIBBAD;
+	cursor = sizeof(*mz);
+
+	chkaddr(cursor, mz->peaddr, sizeof(*pe));
+	pe = pebuf + mz->peaddr;
+	if (pe->magic != PE_MAGIC)
+		return -ELIBBAD;
+	cursor = mz->peaddr + sizeof(*pe);
+
+	chkaddr(0, cursor, sizeof(pe32->magic));
+	pe32 = pebuf + cursor;
+	pe64 = pebuf + cursor;
+
+	switch (pe32->magic) {
+	case PE_OPT_MAGIC_PE32:
+		chkaddr(0, cursor, sizeof(*pe32));
+		ctx->image_checksum_offset =
+			(unsigned long)&pe32->csum - (unsigned long)pebuf;
+		ctx->header_size = pe32->header_size;
+		cursor += sizeof(*pe32);
+		ctx->n_data_dirents = pe32->data_dirs;
+		break;
+
+	case PE_OPT_MAGIC_PE32PLUS:
+		chkaddr(0, cursor, sizeof(*pe64));
+		ctx->image_checksum_offset =
+			(unsigned long)&pe64->csum - (unsigned long)pebuf;
+		ctx->header_size = pe64->header_size;
+		cursor += sizeof(*pe64);
+		ctx->n_data_dirents = pe64->data_dirs;
+		break;
+
+	default:
+		pr_warn("Unknown PEOPT magic = %04hx\n", pe32->magic);
+		return -ELIBBAD;
+	}
+
+	pr_debug("checksum @ %x\n", ctx->image_checksum_offset);
+	pr_debug("header size = %x\n", ctx->header_size);
+
+	if (cursor >= ctx->header_size || ctx->header_size >= datalen)
+		return -ELIBBAD;
+
+	if (ctx->n_data_dirents > (ctx->header_size - cursor) / sizeof(*dde))
+		return -ELIBBAD;
+
+	ddir = pebuf + cursor;
+	cursor += sizeof(*dde) * ctx->n_data_dirents;
+
+	ctx->cert_dirent_offset =
+		(unsigned long)&ddir->certs - (unsigned long)pebuf;
+	ctx->certs_size = ddir->certs.size;
+
+	if (ddir->certs.virtual_address && ddir->certs.size) {
+
+		chkaddr(ctx->header_size, ddir->certs.virtual_address,
+			ddir->certs.size);
+		ctx->sig_offset = ddir->certs.virtual_address;
+		ctx->sig_len = ddir->certs.size;
+		pr_debug("cert = %x @%x [%*ph]\n",
+			 ctx->sig_len, ctx->sig_offset,
+			 ctx->sig_len, pebuf + ctx->sig_offset);
+
+	}
+
+	ctx->n_sections = pe->sections;
+	if (ctx->n_sections > (ctx->header_size - cursor) / sizeof(*sec))
+		return -ELIBBAD;
+	ctx->secs = secs = pebuf + cursor;
+
+	return 0;
+}
diff --git a/crypto/asymmetric_keys/mscode_parser.c b/crypto/asymmetric_keys/mscode_parser.c
index 839591ad21ac..063b348bb4c3 100644
--- a/crypto/asymmetric_keys/mscode_parser.c
+++ b/crypto/asymmetric_keys/mscode_parser.c
@@ -11,7 +11,7 @@
 #include <linux/err.h>
 #include <linux/oid_registry.h>
 #include <crypto/pkcs7.h>
-#include "verify_pefile.h"
+#include <asm/parse_pefile.h>
 #include "mscode.asn1.h"
 
 /*
diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index f440767bd727..fbb319094c0a 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -14,106 +14,9 @@
 #include <linux/asn1.h>
 #include <linux/verification.h>
 #include <crypto/hash.h>
+#include <asm/parse_pefile.h>
 #include "verify_pefile.h"
 
-/*
- * Parse a PE binary.
- */
-static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
-			       struct pefile_context *ctx)
-{
-	const struct mz_hdr *mz = pebuf;
-	const struct pe_hdr *pe;
-	const struct pe32_opt_hdr *pe32;
-	const struct pe32plus_opt_hdr *pe64;
-	const struct data_directory *ddir;
-	const struct data_dirent *dde;
-	const struct section_header *secs, *sec;
-	size_t cursor, datalen = pelen;
-
-	kenter("");
-
-#define chkaddr(base, x, s)						\
-	do {								\
-		if ((x) < base || (s) >= datalen || (x) > datalen - (s)) \
-			return -ELIBBAD;				\
-	} while (0)
-
-	chkaddr(0, 0, sizeof(*mz));
-	if (mz->magic != MZ_MAGIC)
-		return -ELIBBAD;
-	cursor = sizeof(*mz);
-
-	chkaddr(cursor, mz->peaddr, sizeof(*pe));
-	pe = pebuf + mz->peaddr;
-	if (pe->magic != PE_MAGIC)
-		return -ELIBBAD;
-	cursor = mz->peaddr + sizeof(*pe);
-
-	chkaddr(0, cursor, sizeof(pe32->magic));
-	pe32 = pebuf + cursor;
-	pe64 = pebuf + cursor;
-
-	switch (pe32->magic) {
-	case PE_OPT_MAGIC_PE32:
-		chkaddr(0, cursor, sizeof(*pe32));
-		ctx->image_checksum_offset =
-			(unsigned long)&pe32->csum - (unsigned long)pebuf;
-		ctx->header_size = pe32->header_size;
-		cursor += sizeof(*pe32);
-		ctx->n_data_dirents = pe32->data_dirs;
-		break;
-
-	case PE_OPT_MAGIC_PE32PLUS:
-		chkaddr(0, cursor, sizeof(*pe64));
-		ctx->image_checksum_offset =
-			(unsigned long)&pe64->csum - (unsigned long)pebuf;
-		ctx->header_size = pe64->header_size;
-		cursor += sizeof(*pe64);
-		ctx->n_data_dirents = pe64->data_dirs;
-		break;
-
-	default:
-		pr_warn("Unknown PEOPT magic = %04hx\n", pe32->magic);
-		return -ELIBBAD;
-	}
-
-	pr_debug("checksum @ %x\n", ctx->image_checksum_offset);
-	pr_debug("header size = %x\n", ctx->header_size);
-
-	if (cursor >= ctx->header_size || ctx->header_size >= datalen)
-		return -ELIBBAD;
-
-	if (ctx->n_data_dirents > (ctx->header_size - cursor) / sizeof(*dde))
-		return -ELIBBAD;
-
-	ddir = pebuf + cursor;
-	cursor += sizeof(*dde) * ctx->n_data_dirents;
-
-	ctx->cert_dirent_offset =
-		(unsigned long)&ddir->certs - (unsigned long)pebuf;
-	ctx->certs_size = ddir->certs.size;
-
-	if (!ddir->certs.virtual_address || !ddir->certs.size) {
-		pr_warn("Unsigned PE binary\n");
-		return -ENODATA;
-	}
-
-	chkaddr(ctx->header_size, ddir->certs.virtual_address,
-		ddir->certs.size);
-	ctx->sig_offset = ddir->certs.virtual_address;
-	ctx->sig_len = ddir->certs.size;
-	pr_debug("cert = %x @%x [%*ph]\n",
-		 ctx->sig_len, ctx->sig_offset,
-		 ctx->sig_len, pebuf + ctx->sig_offset);
-
-	ctx->n_sections = pe->sections;
-	if (ctx->n_sections > (ctx->header_size - cursor) / sizeof(*sec))
-		return -ELIBBAD;
-	ctx->secs = secs = pebuf + cursor;
-
-	return 0;
-}
 
 /*
  * Check and strip the PE wrapper from around the signature and check that the
@@ -431,6 +334,13 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen,
 	if (ret < 0)
 		return ret;
 
+	const struct data_dirent *certs = pebuf + ctx.cert_dirent_offset;
+
+	if (!certs->virtual_address || !certs->size) {
+		pr_warn("Unsigned PE binary\n");
+		return -ENODATA;
+	}
+
 	ret = pefile_strip_sig_wrapper(pebuf, &ctx);
 	if (ret < 0)
 		return ret;
@@ -439,8 +349,10 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen,
 				     pebuf + ctx.sig_offset, ctx.sig_len,
 				     trusted_keys, usage,
 				     mscode_parse, &ctx);
-	if (ret < 0)
+	if (ret < 0) {
+		pr_warn("invalid PE file signature\n");
 		goto error;
+	}
 
 	pr_debug("Digest: %u [%*ph]\n",
 		 ctx.digest_len, ctx.digest_len, ctx.digest);
diff --git a/crypto/asymmetric_keys/verify_pefile.h b/crypto/asymmetric_keys/verify_pefile.h
index e1628e100cde..5ab2f9a5b2ef 100644
--- a/crypto/asymmetric_keys/verify_pefile.h
+++ b/crypto/asymmetric_keys/verify_pefile.h
@@ -8,22 +8,6 @@
 #include <crypto/pkcs7.h>
 #include <crypto/hash_info.h>
 
-struct pefile_context {
-	unsigned	header_size;
-	unsigned	image_checksum_offset;
-	unsigned	cert_dirent_offset;
-	unsigned	n_data_dirents;
-	unsigned	n_sections;
-	unsigned	certs_size;
-	unsigned	sig_offset;
-	unsigned	sig_len;
-	const struct section_header *secs;
-
-	/* PKCS#7 MS Individual Code Signing content */
-	const void	*digest;		/* Digest */
-	unsigned	digest_len;		/* Digest length */
-	const char	*digest_algo;		/* Digest algorithm */
-};
 
 #define kenter(FMT, ...)					\
 	pr_devel("==> %s("FMT")\n", __func__, ##__VA_ARGS__)
-- 
2.40.1


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