[PATCH 4/5] x86/crash: pass the LUKS volume key to kdump kernel

[Coiby Xu]

1st kernel will build up the kernel command parameter luksvolumekey as
similar to elfcorehdr to pass the memory address of the stored info of
LUKS volume key to kdump kernel.

Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
---
 arch/x86/include/asm/crash.h      |  1 +
 arch/x86/kernel/crash.c           | 47 ++++++++++++++++++++++++++++++-
 arch/x86/kernel/kexec-bzimage64.c |  7 +++++
 include/linux/kexec.h             |  4 +++
 4 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/crash.h b/arch/x86/include/asm/crash.h
index 8b6bd63530dc..485f75dce2ca 100644
--- a/arch/x86/include/asm/crash.h
+++ b/arch/x86/include/asm/crash.h
@@ -4,6 +4,7 @@
 
 struct kimage;
 
+int crash_load_luks_volume_key(struct kimage *image);
 int crash_load_segments(struct kimage *image);
 int crash_setup_memmap_entries(struct kimage *image,
 		struct boot_params *params);
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index cdd92ab43cda..32d4a9e3badf 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -289,6 +289,7 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
 				 unsigned long long mend)
 {
 	unsigned long start, end;
+	int r;
 
 	cmem->ranges[0].start = mstart;
 	cmem->ranges[0].end = mend;
@@ -297,7 +298,19 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
 	/* Exclude elf header region */
 	start = image->elf_load_addr;
 	end = start + image->elf_headers_sz - 1;
-	return crash_exclude_mem_range(cmem, start, end);
+	r = crash_exclude_mem_range(cmem, start, end);
+
+	if (r)
+		return r;
+
+	/* Exclude LUKS volume key region */
+	if (image->luks_volume_key_addr) {
+		start = image->luks_volume_key_addr;
+		end = start + image->luks_volume_key_sz - 1;
+		return crash_exclude_mem_range(cmem, start, end);
+	}
+
+	return r;
 }
 
 /* Prepare memory map for crash dump kernel */
@@ -368,6 +381,38 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
 	return ret;
 }
 
+int crash_load_luks_volume_key(struct kimage *image)
+{
+	int ret;
+	struct kexec_buf kbuf = {
+		.image = image,
+		.buf_min = 0,
+		.buf_max = ULONG_MAX,
+		.top_down = false,
+		.random = true,
+	};
+
+	image->luks_volume_key_addr = 0;
+	ret = crash_pass_temp_luks_volume_key(&kbuf.buffer, &kbuf.bufsz);
+	if (ret)
+		return ret;
+
+	kbuf.memsz = kbuf.bufsz;
+	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
+	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
+	ret = kexec_add_buffer(&kbuf);
+	if (ret) {
+		vfree((void *)kbuf.buffer);
+		return ret;
+	}
+	image->luks_volume_key_addr = kbuf.mem;
+	image->luks_volume_key_sz = kbuf.bufsz;
+	pr_debug("Loaded LUKS volume key at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+		 image->luks_volume_key_addr, kbuf.bufsz, kbuf.bufsz);
+
+	return ret;
+}
+
 int crash_load_segments(struct kimage *image)
 {
 	int ret;
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index a61c12c01270..a859e9e5c876 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -76,6 +76,10 @@ static int setup_cmdline(struct kimage *image, struct boot_params *params,
 	if (image->type == KEXEC_TYPE_CRASH) {
 		len = sprintf(cmdline_ptr,
 			"elfcorehdr=0x%lx ", image->elf_load_addr);
+
+		if (image->luks_volume_key_addr != 0)
+			len += sprintf(cmdline_ptr + len,
+					"luksvolumekey=0x%lx ", image->luks_volume_key_addr);
 	}
 	memcpy(cmdline_ptr + len, cmdline, cmdline_len);
 	cmdline_len += len;
@@ -433,6 +437,9 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
 		ret = crash_load_segments(image);
 		if (ret)
 			return ERR_PTR(ret);
+		ret = crash_load_luks_volume_key(image);
+		if (ret)
+			pr_debug("Either no LUKS volume key or error to retrieve the LUKS volume key\n");
 	}
 
 	/*
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 5b2440444112..20d213076e46 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -374,6 +374,10 @@ struct kimage {
 	void *elf_headers;
 	unsigned long elf_headers_sz;
 	unsigned long elf_load_addr;
+
+	/* LUKS volume key buffer */
+	unsigned long luks_volume_key_addr;
+	unsigned long luks_volume_key_sz;
 };
 
 /* kexec interface functions */
-- 
2.40.1