The patch titled
Subject: maccess: allow architectures to provide kernel probing directly
has been added to the -mm tree. Its filename is
maccess-allow-architectures-to-provide-kernel-probing-directly.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/maccess-allow-architectures-to-provide-kernel-probing-directly.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/maccess-allow-architectures-to-provide-kernel-probing-directly.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Christoph Hellwig <hch@xxxxxx>
Subject: maccess: allow architectures to provide kernel probing directly
Provide alternative versions of probe_kernel_read, probe_kernel_write
and strncpy_from_kernel_unsafe that don't need set_fs magic, but instead
use arch hooks that are modelled after unsafe_{get,put}_user to access
kernel memory in an exception safe way.
Link: http://lkml.kernel.org/r/20200521152301.2587579-19-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/maccess.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 76 insertions(+)
--- a/mm/maccess.c~maccess-allow-architectures-to-provide-kernel-probing-directly
+++ a/mm/maccess.c
@@ -11,6 +11,81 @@ bool __weak probe_kernel_read_allowed(co
return true;
}
+#ifdef HAVE_GET_KERNEL_NOFAULT
+
+#define probe_kernel_read_loop(dst, src, len, type, err_label) \
+ while (len >= sizeof(type)) { \
+ __get_kernel_nofault(dst, src, type, err_label); \
+ dst += sizeof(type); \
+ src += sizeof(type); \
+ len -= sizeof(type); \
+ }
+
+long probe_kernel_read(void *dst, const void *src, size_t size)
+{
+ if (!probe_kernel_read_allowed(src, size))
+ return -EFAULT;
+
+ pagefault_disable();
+ probe_kernel_read_loop(dst, src, size, u64, Efault);
+ probe_kernel_read_loop(dst, src, size, u32, Efault);
+ probe_kernel_read_loop(dst, src, size, u16, Efault);
+ probe_kernel_read_loop(dst, src, size, u8, Efault);
+ pagefault_enable();
+ return 0;
+Efault:
+ pagefault_enable();
+ return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
+
+#define probe_kernel_write_loop(dst, src, len, type, err_label) \
+ while (len >= sizeof(type)) { \
+ __put_kernel_nofault(dst, src, type, err_label); \
+ dst += sizeof(type); \
+ src += sizeof(type); \
+ len -= sizeof(type); \
+ }
+
+long probe_kernel_write(void *dst, const void *src, size_t size)
+{
+ pagefault_disable();
+ probe_kernel_write_loop(dst, src, size, u64, Efault);
+ probe_kernel_write_loop(dst, src, size, u32, Efault);
+ probe_kernel_write_loop(dst, src, size, u16, Efault);
+ probe_kernel_write_loop(dst, src, size, u8, Efault);
+ pagefault_enable();
+ return 0;
+Efault:
+ pagefault_enable();
+ return -EFAULT;
+}
+
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
+{
+ const void *src = unsafe_addr;
+
+ if (unlikely(count <= 0))
+ return 0;
+ if (!probe_kernel_read_allowed(unsafe_addr, count))
+ return -EFAULT;
+
+ pagefault_disable();
+ do {
+ __get_kernel_nofault(dst, src, u8, Efault);
+ dst++;
+ src++;
+ } while (dst[-1] && src - unsafe_addr < count);
+ pagefault_enable();
+
+ dst[-1] = '\0';
+ return src - unsafe_addr;
+Efault:
+ pagefault_enable();
+ dst[-1] = '\0';
+ return -EFAULT;
+}
+#else /* HAVE_GET_KERNEL_NOFAULT */
/**
* probe_kernel_read(): safely attempt to read from kernel-space
* @dst: pointer to the buffer that shall take the data
@@ -113,6 +188,7 @@ long strncpy_from_kernel_nofault(char *d
return ret ? -EFAULT : src - unsafe_addr;
}
+#endif /* HAVE_GET_KERNEL_NOFAULT */
/**
* probe_user_read(): safely attempt to read from a user-space location
_
Patches currently in -mm which might be from hch@xxxxxx are
x86-hyperv-use-vmalloc_exec-for-the-hypercall-page.patch
x86-fix-vmap-arguments-in-map_irq_stack.patch
staging-android-ion-use-vmap-instead-of-vm_map_ram.patch
staging-media-ipu3-use-vmap-instead-of-reimplementing-it.patch
dma-mapping-use-vmap-insted-of-reimplementing-it.patch
powerpc-add-an-ioremap_phb-helper.patch
powerpc-remove-__ioremap_at-and-__iounmap_at.patch
mm-remove-__get_vm_area.patch
mm-unexport-unmap_kernel_range_noflush.patch
mm-rename-config_pgtable_mapping-to-config_zsmalloc_pgtable_mapping.patch
mm-only-allow-page-table-mappings-for-built-in-zsmalloc.patch
mm-pass-addr-as-unsigned-long-to-vb_free.patch
mm-remove-vmap_page_range_noflush-and-vunmap_page_range.patch
mm-rename-vmap_page_range-to-map_kernel_range.patch
mm-dont-return-the-number-of-pages-from-map_kernel_range_noflush.patch
mm-remove-map_vm_range.patch
mm-remove-unmap_vmap_area.patch
mm-remove-the-prot-argument-from-vm_map_ram.patch
mm-enforce-that-vmap-cant-map-pages-executable.patch
gpu-drm-remove-the-powerpc-hack-in-drm_legacy_sg_alloc.patch
mm-remove-the-pgprot-argument-to-__vmalloc.patch
mm-remove-the-prot-argument-to-__vmalloc_node.patch
mm-remove-both-instances-of-__vmalloc_node_flags.patch
mm-remove-__vmalloc_node_flags_caller.patch
mm-switch-the-test_vmalloc-module-to-use-__vmalloc_node.patch
mm-remove-vmalloc_user_node_flags.patch
arm64-use-__vmalloc_node-in-arch_alloc_vmap_stack.patch
powerpc-use-__vmalloc_node-in-alloc_vm_stack.patch
s390-use-__vmalloc_node-in-stack_alloc.patch
exec-simplify-the-copy_strings_kernel-calling-convention.patch
exec-open-code-copy_string_kernel.patch
amdgpu-a-null-mm-does-not-mean-a-thread-is-a-kthread.patch
kernel-move-use_mm-unuse_mm-to-kthreadc.patch
kernel-move-use_mm-unuse_mm-to-kthreadc-v2.patch
kernel-better-document-the-use_mm-unuse_mm-api-contract.patch
kernel-better-document-the-use_mm-unuse_mm-api-contract-v2.patch
kernel-set-user_ds-in-kthread_use_mm.patch
arm-fix-the-flush_icache_range-arguments-in-set_fiq_handler.patch
nds32-unexport-flush_icache_page.patch
powerpc-unexport-flush_icache_user_range.patch
unicore32-remove-flush_cache_user_range.patch
asm-generic-fix-the-inclusion-guards-for-cacheflushh.patch
asm-generic-dont-include-linux-mmh-in-cacheflushh.patch
asm-generic-dont-include-linux-mmh-in-cacheflushh-fix.patch
asm-generic-improve-the-flush_dcache_page-stub.patch
alpha-use-asm-generic-cacheflushh.patch
arm64-use-asm-generic-cacheflushh.patch
c6x-use-asm-generic-cacheflushh.patch
hexagon-use-asm-generic-cacheflushh.patch
ia64-use-asm-generic-cacheflushh.patch
microblaze-use-asm-generic-cacheflushh.patch
m68knommu-use-asm-generic-cacheflushh.patch
openrisc-use-asm-generic-cacheflushh.patch
powerpc-use-asm-generic-cacheflushh.patch
riscv-use-asm-generic-cacheflushh.patch
armsparcunicore32-remove-flush_icache_user_range.patch
mm-rename-flush_icache_user_range-to-flush_icache_user_page.patch
asm-generic-add-a-flush_icache_user_range-stub.patch
sh-implement-flush_icache_user_range.patch
xtensa-implement-flush_icache_user_range.patch
arm-rename-flush_cache_user_range-to-flush_icache_user_range.patch
m68k-implement-flush_icache_user_range.patch
exec-only-build-read_code-when-needed.patch
exec-use-flush_icache_user_range-in-read_code.patch
binfmt_flat-use-flush_icache_user_range.patch
nommu-use-flush_icache_user_range-in-brk-and-mmap.patch
module-move-the-set_fs-hack-for-flush_icache_range-to-m68k.patch
maccess-unexport-probe_kernel_write-and-probe_user_write.patch
maccess-remove-various-unused-weak-aliases.patch
maccess-remove-duplicate-kerneldoc-comments.patch
maccess-clarify-kerneldoc-comments.patch
maccess-update-the-top-of-file-comment.patch
maccess-rename-strncpy_from_unsafe_user-to-strncpy_from_user_nofault.patch
maccess-rename-strncpy_from_unsafe_strict-to-strncpy_from_kernel_nofault.patch
maccess-rename-strnlen_unsafe_user-to-strnlen_user_nofault.patch
maccess-remove-probe_read_common-and-probe_write_common.patch
maccess-unify-the-probe-kernel-arch-hooks.patch
bpf-factor-out-a-bpf_trace_copy_string-helper.patch
bpf-handle-the-compat-string-in-bpf_trace_copy_string-better.patch
bpf-rework-the-compat-kernel-probe-handling.patch
tracing-kprobes-handle-mixed-kernel-userspace-probes-better.patch
maccess-remove-strncpy_from_unsafe.patch
maccess-always-use-strict-semantics-for-probe_kernel_read.patch
maccess-move-user-access-routines-together.patch
maccess-allow-architectures-to-provide-kernel-probing-directly.patch
x86-use-non-set_fs-based-maccess-routines.patch
maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails.patch
