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Message-Id: <20180212100754.55121-18-prudo@linux.vnet.ibm.com>
Date: Mon, 12 Feb 2018 11:07:54 +0100
From: Philipp Rudo <prudo@...ux.vnet.ibm.com>
To: kexec@...ts.infradead.org, linux-s390@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Eric Biederman <ebiederm@...ssion.com>,
Vivek Goyal <vgoyal@...hat.com>,
Michael Ellerman <mpe@...erman.id.au>,
Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org
Subject: [PATCH 17/17] s390/kexec_file: Add ELF loader
Add an ELF loader for kexec_file. The main task here is to do proper sanity
checks on the ELF file. Basically all other functionality was already
implemented for the image loader.
Signed-off-by: Philipp Rudo <prudo@...ux.vnet.ibm.com>
---
arch/s390/include/asm/kexec.h | 1 +
arch/s390/kernel/Makefile | 2 +-
arch/s390/kernel/kexec_elf.c | 149 ++++++++++++++++++++++++++++++++++
arch/s390/kernel/machine_kexec_file.c | 1 +
4 files changed, 152 insertions(+), 1 deletion(-)
create mode 100644 arch/s390/kernel/kexec_elf.c
diff --git a/arch/s390/include/asm/kexec.h b/arch/s390/include/asm/kexec.h
index 532f5e4f198f..e450b82e2716 100644
--- a/arch/s390/include/asm/kexec.h
+++ b/arch/s390/include/asm/kexec.h
@@ -67,5 +67,6 @@ void kexec_file_update_kernel(struct kimage *iamge,
struct s390_load_data *data);
extern const struct kexec_file_ops s390_kexec_image_ops;
+extern const struct kexec_file_ops s390_kexec_elf_ops;
#endif /*_S390_KEXEC_H */
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 58a590709cc3..66d7b432c2a8 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -60,7 +60,7 @@ obj-y += debug.o irq.o ipl.o dis.o diag.o vdso.o als.o
obj-y += sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o
obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
-obj-y += machine_kexec_file.o kexec_image.o
+obj-y += machine_kexec_file.o kexec_image.o kexec_elf.o
extra-y += head.o head64.o vmlinux.lds
diff --git a/arch/s390/kernel/kexec_elf.c b/arch/s390/kernel/kexec_elf.c
new file mode 100644
index 000000000000..919ab2f1256f
--- /dev/null
+++ b/arch/s390/kernel/kexec_elf.c
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ELF loader for kexec_file_load system call.
+ *
+ * Copyright IBM Corp. 2018
+ *
+ * Author(s): Philipp Rudo <prudo@...ux.vnet.ibm.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/kexec.h>
+#include <asm/setup.h>
+
+static int kexec_file_add_elf_kernel(struct kimage *image,
+ struct s390_load_data *data,
+ char *kernel, unsigned long kernel_len)
+{
+ struct kexec_buf buf;
+ const Elf_Ehdr *ehdr;
+ const Elf_Phdr *phdr;
+ int i, ret;
+
+ ehdr = (Elf_Ehdr *)kernel;
+ buf.image = image;
+
+ phdr = (void *)ehdr + ehdr->e_phoff;
+ for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
+ if (phdr->p_type != PT_LOAD)
+ continue;
+
+ buf.buffer = kernel + phdr->p_offset;
+ buf.bufsz = phdr->p_filesz;
+
+ buf.mem = ALIGN(phdr->p_paddr, phdr->p_align);
+ buf.memsz = phdr->p_memsz;
+
+ if (phdr->p_paddr == 0) {
+ data->kernel_buf = buf.buffer;
+ data->memsz += STARTUP_NORMAL_OFFSET;
+
+ buf.buffer += STARTUP_NORMAL_OFFSET;
+ buf.bufsz -= STARTUP_NORMAL_OFFSET;
+
+ buf.mem += STARTUP_NORMAL_OFFSET;
+ buf.memsz -= STARTUP_NORMAL_OFFSET;
+ }
+
+ if (image->type == KEXEC_TYPE_CRASH)
+ buf.mem += crashk_res.start;
+
+ ret = kexec_add_buffer(&buf);
+ if (ret)
+ return ret;
+
+ data->memsz += buf.memsz;
+ }
+
+ return 0;
+}
+
+static void *s390_elf_load(struct kimage *image,
+ char *kernel, unsigned long kernel_len,
+ char *initrd, unsigned long initrd_len,
+ char *cmdline, unsigned long cmdline_len)
+{
+ struct s390_load_data data = {0};
+ const Elf_Ehdr *ehdr;
+ const Elf_Phdr *phdr;
+ size_t size;
+ int i, ret;
+
+ /* image->fobs->probe already checked for valid ELF magic number. */
+ ehdr = (Elf_Ehdr *)kernel;
+
+ if (ehdr->e_type != ET_EXEC ||
+ ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||
+ !elf_check_arch(ehdr))
+ return ERR_PTR(-EINVAL);
+
+ if (!ehdr->e_phnum || ehdr->e_phentsize != sizeof(Elf_Phdr))
+ return ERR_PTR(-EINVAL);
+
+ size = ehdr->e_ehsize + ehdr->e_phoff;
+ size += ehdr->e_phentsize * ehdr->e_phnum;
+ if (size > kernel_len)
+ return ERR_PTR(-EINVAL);
+
+ phdr = (void *)ehdr + ehdr->e_phoff;
+ size = ALIGN(size, phdr->p_align);
+ for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
+ if (phdr->p_type == PT_INTERP)
+ return ERR_PTR(-EINVAL);
+
+ if (phdr->p_offset > kernel_len)
+ return ERR_PTR(-EINVAL);
+
+ size += ALIGN(phdr->p_filesz, phdr->p_align);
+ }
+
+ if (size > kernel_len)
+ return ERR_PTR(-EINVAL);
+
+ ret = kexec_file_add_elf_kernel(image, &data, kernel, kernel_len);
+ if (ret)
+ return ERR_PTR(ret);
+
+ if (!data.memsz)
+ return ERR_PTR(-EINVAL);
+
+ if (initrd) {
+ ret = kexec_file_add_initrd(image, &data, initrd, initrd_len);
+ if (ret)
+ return ERR_PTR(ret);
+ }
+
+ ret = kexec_file_add_purgatory(image, &data);
+ if (ret)
+ return ERR_PTR(ret);
+
+ kexec_file_update_kernel(image, &data);
+
+ return NULL;
+}
+
+static int s390_elf_probe(const char *buf, unsigned long len)
+{
+ const Elf_Ehdr *ehdr;
+
+ if (len < sizeof(Elf_Ehdr))
+ return -ENOEXEC;
+
+ ehdr = (Elf_Ehdr *)buf;
+
+ /* Only check the ELF magic number here and do proper validity check
+ * in the loader. Any check here that fails would send the erroneous
+ * ELF file to the image loader that does not care what it gets.
+ * (Most likely) causing behavior not intended by the user.
+ */
+ if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
+ return -ENOEXEC;
+
+ return 0;
+}
+
+const struct kexec_file_ops s390_kexec_elf_ops = {
+ .probe = s390_elf_probe,
+ .load = s390_elf_load,
+};
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 050ceab746ec..8938e0eca4b0 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -12,6 +12,7 @@
#include <asm/setup.h>
const struct kexec_file_ops * const kexec_file_loaders[] = {
+ &s390_kexec_elf_ops,
&s390_kexec_image_ops,
NULL,
};
--
2.13.5
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