The patch titled
Subject: kernel/kexec_file.c: use read-only sections in arch_kexec_apply_relocations*
has been removed from the -mm tree. Its filename was
kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx>
Subject: kernel/kexec_file.c: use read-only sections in arch_kexec_apply_relocations*
When the relocations are applied to the purgatory only the section the
relocations are applied to is writable. The other sections, i.e. the
symtab and .rel/.rela, are in read-only kexec_purgatory. Highlight this
by marking the corresponding variables as 'const'.
While at it also change the signatures of arch_kexec_apply_relocations* to
take section pointers instead of just the index of the relocation section.
This removes the second lookup and sanity check of the sections in arch
code.
Link: http://lkml.kernel.org/r/20180321112751.22196-6-prudo@xxxxxxxxxxxxxxxxxx
Signed-off-by: Philipp Rudo <prudo@xxxxxxxxxxxxxxxxxx>
Acked-by: Dave Young <dyoung@xxxxxxxxxx>
Cc: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/machine_kexec_64.c | 56 ++++++++----------------
include/linux/kexec.h | 13 +++--
kernel/kexec_file.c | 63 ++++++++++++++++++---------
3 files changed, 71 insertions(+), 61 deletions(-)
diff -puN arch/x86/kernel/machine_kexec_64.c~kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations arch/x86/kernel/machine_kexec_64.c
--- a/arch/x86/kernel/machine_kexec_64.c~kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations
+++ a/arch/x86/kernel/machine_kexec_64.c
@@ -382,52 +382,36 @@ void *arch_kexec_kernel_image_load(struc
/*
* Apply purgatory relocations.
*
- * ehdr: Pointer to elf headers
- * sechdrs: Pointer to section headers.
- * relsec: section index of SHT_RELA section.
+ * @pi: Purgatory to be relocated.
+ * @section: Section relocations applying to.
+ * @relsec: Section containing RELAs.
+ * @symtabsec: Corresponding symtab.
*
* TODO: Some of the code belongs to generic code. Move that in kexec.c.
*/
-int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
- Elf64_Shdr *sechdrs, unsigned int relsec)
+int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+ Elf_Shdr *section, const Elf_Shdr *relsec,
+ const Elf_Shdr *symtabsec)
{
unsigned int i;
Elf64_Rela *rel;
Elf64_Sym *sym;
void *location;
- Elf64_Shdr *section, *symtabsec;
unsigned long address, sec_base, value;
const char *strtab, *name, *shstrtab;
+ const Elf_Shdr *sechdrs;
- /*
- * ->sh_offset has been modified to keep the pointer to section
- * contents in memory
- */
- rel = (void *)sechdrs[relsec].sh_offset;
-
- /* Section to which relocations apply */
- section = &sechdrs[sechdrs[relsec].sh_info];
-
- pr_debug("Applying relocate section %u to %u\n", relsec,
- sechdrs[relsec].sh_info);
-
- /* Associated symbol table */
- symtabsec = &sechdrs[sechdrs[relsec].sh_link];
-
- /* String table */
- if (symtabsec->sh_link >= ehdr->e_shnum) {
- /* Invalid strtab section number */
- pr_err("Invalid string table section index %d\n",
- symtabsec->sh_link);
- return -ENOEXEC;
- }
+ /* String & section header string table */
+ sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
+ strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
+ shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
- strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
+ rel = (void *)pi->ehdr + relsec->sh_offset;
- /* section header string table */
- shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
+ pr_debug("Applying relocate section %s to %u\n",
+ shstrtab + relsec->sh_name, relsec->sh_info);
- for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
+ for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {
/*
* rel[i].r_offset contains byte offset from beginning
@@ -450,8 +434,8 @@ int arch_kexec_apply_relocations_add(con
* to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
* these respectively.
*/
- sym = (Elf64_Sym *)symtabsec->sh_offset +
- ELF64_R_SYM(rel[i].r_info);
+ sym = (void *)pi->ehdr + symtabsec->sh_offset;
+ sym += ELF64_R_SYM(rel[i].r_info);
if (sym->st_name)
name = strtab + sym->st_name;
@@ -474,12 +458,12 @@ int arch_kexec_apply_relocations_add(con
if (sym->st_shndx == SHN_ABS)
sec_base = 0;
- else if (sym->st_shndx >= ehdr->e_shnum) {
+ else if (sym->st_shndx >= pi->ehdr->e_shnum) {
pr_err("Invalid section %d for symbol %s\n",
sym->st_shndx, name);
return -ENOEXEC;
} else
- sec_base = sechdrs[sym->st_shndx].sh_addr;
+ sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
value = sym->st_value;
value += sec_base;
diff -puN include/linux/kexec.h~kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations include/linux/kexec.h
--- a/include/linux/kexec.h~kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations
+++ a/include/linux/kexec.h
@@ -171,6 +171,15 @@ struct kexec_buf {
bool top_down;
};
+int __weak arch_kexec_apply_relocations_add(struct purgatory_info *pi,
+ Elf_Shdr *section,
+ const Elf_Shdr *relsec,
+ const Elf_Shdr *symtab);
+int __weak arch_kexec_apply_relocations(struct purgatory_info *pi,
+ Elf_Shdr *section,
+ const Elf_Shdr *relsec,
+ const Elf_Shdr *symtab);
+
int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
int (*func)(struct resource *, void *));
extern int kexec_add_buffer(struct kexec_buf *kbuf);
@@ -304,10 +313,6 @@ int crash_shrink_memory(unsigned long ne
size_t crash_get_memory_size(void);
void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
-int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
- Elf_Shdr *sechdrs, unsigned int relsec);
-int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
- unsigned int relsec);
void arch_kexec_protect_crashkres(void);
void arch_kexec_unprotect_crashkres(void);
diff -puN kernel/kexec_file.c~kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations kernel/kexec_file.c
--- a/kernel/kexec_file.c~kexec_file-use-read-only-sections-in-arch_kexec_apply_relocations
+++ a/kernel/kexec_file.c
@@ -110,19 +110,35 @@ int __weak arch_kexec_kernel_verify_sig(
}
#endif
-/* Apply relocations of type RELA */
+/*
+ * arch_kexec_apply_relocations_add - apply relocations of type RELA
+ * @pi: Purgatory to be relocated.
+ * @section: Section relocations applying to.
+ * @relsec: Section containing RELAs.
+ * @symtab: Corresponding symtab.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
int __weak
-arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
- unsigned int relsec)
+arch_kexec_apply_relocations_add(struct purgatory_info *pi, Elf_Shdr *section,
+ const Elf_Shdr *relsec, const Elf_Shdr *symtab)
{
pr_err("RELA relocation unsupported.\n");
return -ENOEXEC;
}
-/* Apply relocations of type REL */
+/*
+ * arch_kexec_apply_relocations - apply relocations of type REL
+ * @pi: Purgatory to be relocated.
+ * @section: Section relocations applying to.
+ * @relsec: Section containing RELs.
+ * @symtab: Corresponding symtab.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
int __weak
-arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
- unsigned int relsec)
+arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section,
+ const Elf_Shdr *relsec, const Elf_Shdr *symtab)
{
pr_err("REL relocation unsupported.\n");
return -ENOEXEC;
@@ -879,14 +895,19 @@ static int kexec_apply_relocations(struc
{
int i, ret;
struct purgatory_info *pi = &image->purgatory_info;
- Elf_Shdr *sechdrs = pi->sechdrs;
+ const Elf_Shdr *sechdrs;
+
+ sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
- /* Apply relocations */
for (i = 0; i < pi->ehdr->e_shnum; i++) {
- Elf_Shdr *section, *symtab;
+ const Elf_Shdr *relsec;
+ const Elf_Shdr *symtab;
+ Elf_Shdr *section;
+
+ relsec = sechdrs + i;
- if (sechdrs[i].sh_type != SHT_RELA &&
- sechdrs[i].sh_type != SHT_REL)
+ if (relsec->sh_type != SHT_RELA &&
+ relsec->sh_type != SHT_REL)
continue;
/*
@@ -895,12 +916,12 @@ static int kexec_apply_relocations(struc
* symbol table. And ->sh_info contains section header
* index of section to which relocations apply.
*/
- if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
- sechdrs[i].sh_link >= pi->ehdr->e_shnum)
+ if (relsec->sh_info >= pi->ehdr->e_shnum ||
+ relsec->sh_link >= pi->ehdr->e_shnum)
return -ENOEXEC;
- section = &sechdrs[sechdrs[i].sh_info];
- symtab = &sechdrs[sechdrs[i].sh_link];
+ section = pi->sechdrs + relsec->sh_info;
+ symtab = sechdrs + relsec->sh_link;
if (!(section->sh_flags & SHF_ALLOC))
continue;
@@ -917,12 +938,12 @@ static int kexec_apply_relocations(struc
* Respective architecture needs to provide support for applying
* relocations of type SHT_RELA/SHT_REL.
*/
- if (sechdrs[i].sh_type == SHT_RELA)
- ret = arch_kexec_apply_relocations_add(pi->ehdr,
- sechdrs, i);
- else if (sechdrs[i].sh_type == SHT_REL)
- ret = arch_kexec_apply_relocations(pi->ehdr,
- sechdrs, i);
+ if (relsec->sh_type == SHT_RELA)
+ ret = arch_kexec_apply_relocations_add(pi, section,
+ relsec, symtab);
+ else if (relsec->sh_type == SHT_REL)
+ ret = arch_kexec_apply_relocations(pi, section,
+ relsec, symtab);
if (ret)
return ret;
}
_
Patches currently in -mm which might be from prudo@xxxxxxxxxxxxxxxxxx are
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