[PATCHv6 03/13] kexec_file: Introduce routines to parse PE file

[Pingfan Liu <piliu@redhat.com>]

The incoming patches need to handle UEFI format image, which is in PE
format. Hence introducing some routines here.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Philipp Rudo <prudo@redhat.com>
To: kexec@lists.infradead.org
---
 kernel/Makefile         |  1 +
 kernel/kexec_internal.h |  3 ++
 kernel/kexec_uefi_app.c | 81 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 kernel/kexec_uefi_app.c

diff --git a/kernel/Makefile b/kernel/Makefile
index e83669841b8cc..f9e85c4a0622b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_CRASH_DUMP_KUNIT_TEST) += crash_core_test.o
 obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
 obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o
+obj-$(CONFIG_KEXEC_BPF) += kexec_uefi_app.o
 obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup/
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 228bb88c018bc..8e5e5c1237732 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -36,6 +36,9 @@ static inline void kexec_unlock(void)
 void kimage_file_post_load_cleanup(struct kimage *image);
 extern char kexec_purgatory[];
 extern size_t kexec_purgatory_size;
+extern bool pe_has_bpf_section(const char *file_buf, unsigned long pe_sz);
+extern int pe_get_section(const char *file_buf, const char *sect_name,
+		char **sect_start, unsigned long *sect_sz);
 #else /* CONFIG_KEXEC_FILE */
 static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
 #endif /* CONFIG_KEXEC_FILE */
diff --git a/kernel/kexec_uefi_app.c b/kernel/kexec_uefi_app.c
new file mode 100644
index 0000000000000..dbe6d76d47ffa
--- /dev/null
+++ b/kernel/kexec_uefi_app.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UEFI appilication file helpers
+ *
+ * Copyright (C) 2025, 2026 Red Hat, Inc
+ */
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/pe.h>
+#include <linux/string.h>
+#include "kexec_internal.h"
+
+/*
+ * The UEFI Terse Executable (TE) image has MZ header.
+ */
+static bool is_valid_pe(const char *kernel_buf, unsigned long kernel_len)
+{
+	struct mz_hdr *mz;
+	struct pe_hdr *pe;
+
+	if (!kernel_buf)
+		return false;
+	mz = (struct mz_hdr *)kernel_buf;
+	if (mz->magic != IMAGE_DOS_SIGNATURE)
+		return false;
+	pe = (struct pe_hdr *)(kernel_buf + mz->peaddr);
+	if (pe->magic != IMAGE_NT_SIGNATURE)
+		return false;
+	if (pe->opt_hdr_size == 0) {
+		pr_err("optional header is missing\n");
+		return false;
+	}
+	return true;
+}
+
+bool pe_has_bpf_section(const char *file_buf, unsigned long pe_sz)
+{
+	char *sect_start = NULL;
+	unsigned long sect_sz = 0;
+	int ret;
+
+	if (!is_valid_pe(file_buf, pe_sz))
+		return false;
+	ret = pe_get_section(file_buf, ".bpf", &sect_start, &sect_sz);
+	if (ret < 0)
+		return false;
+	return true;
+}
+
+int pe_get_section(const char *file_buf, const char *sect_name,
+		char **sect_start, unsigned long *sect_sz)
+{
+	struct pe_hdr *pe_hdr;
+	struct pe32plus_opt_hdr *opt_hdr;
+	struct section_header *sect_hdr;
+	int section_nr, i;
+	struct mz_hdr *mz = (struct mz_hdr *)file_buf;
+
+	*sect_start = NULL;
+	*sect_sz = 0;
+	pe_hdr = (struct pe_hdr *)(file_buf + mz->peaddr);
+	section_nr = pe_hdr->sections;
+	opt_hdr = (struct pe32plus_opt_hdr *)(file_buf + mz->peaddr +
+				sizeof(struct pe_hdr));
+	sect_hdr = (struct section_header *)((char *)opt_hdr +
+				pe_hdr->opt_hdr_size);
+
+	for (i = 0; i < section_nr; i++) {
+		if (strcmp(sect_hdr->name, sect_name) == 0) {
+			*sect_start = (char *)file_buf + sect_hdr->data_addr;
+			*sect_sz = sect_hdr->raw_data_size;
+			return 0;
+		}
+		sect_hdr++;
+	}
+
+	return -1;
+}
-- 
2.49.0