86 lines
2.5 KiB
C
86 lines
2.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Module strict rwx
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*
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* Copyright (C) 2015 Rusty Russell
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*/
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <linux/set_memory.h>
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#include "internal.h"
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static void frob_rodata(const struct module_layout *layout,
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int (*set_memory)(unsigned long start, int num_pages))
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{
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BUG_ON(!PAGE_ALIGNED(layout->base));
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BUG_ON(!PAGE_ALIGNED(layout->text_size));
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BUG_ON(!PAGE_ALIGNED(layout->ro_size));
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set_memory((unsigned long)layout->base + layout->text_size,
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(layout->ro_size - layout->text_size) >> PAGE_SHIFT);
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}
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static void frob_ro_after_init(const struct module_layout *layout,
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int (*set_memory)(unsigned long start, int num_pages))
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{
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BUG_ON(!PAGE_ALIGNED(layout->base));
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BUG_ON(!PAGE_ALIGNED(layout->ro_size));
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BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size));
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set_memory((unsigned long)layout->base + layout->ro_size,
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(layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT);
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}
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static void frob_writable_data(const struct module_layout *layout,
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int (*set_memory)(unsigned long start, int num_pages))
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{
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BUG_ON(!PAGE_ALIGNED(layout->base));
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BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size));
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BUG_ON(!PAGE_ALIGNED(layout->size));
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set_memory((unsigned long)layout->base + layout->ro_after_init_size,
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(layout->size - layout->ro_after_init_size) >> PAGE_SHIFT);
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}
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void module_enable_ro(const struct module *mod, bool after_init)
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{
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if (!rodata_enabled)
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return;
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set_vm_flush_reset_perms(mod->core_layout.base);
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set_vm_flush_reset_perms(mod->init_layout.base);
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frob_text(&mod->core_layout, set_memory_ro);
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frob_rodata(&mod->core_layout, set_memory_ro);
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frob_text(&mod->init_layout, set_memory_ro);
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frob_rodata(&mod->init_layout, set_memory_ro);
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if (after_init)
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frob_ro_after_init(&mod->core_layout, set_memory_ro);
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}
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void module_enable_nx(const struct module *mod)
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{
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frob_rodata(&mod->core_layout, set_memory_nx);
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frob_ro_after_init(&mod->core_layout, set_memory_nx);
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frob_writable_data(&mod->core_layout, set_memory_nx);
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frob_rodata(&mod->init_layout, set_memory_nx);
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frob_writable_data(&mod->init_layout, set_memory_nx);
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}
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int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
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char *secstrings, struct module *mod)
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{
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const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR;
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int i;
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for (i = 0; i < hdr->e_shnum; i++) {
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if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
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pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n",
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mod->name, secstrings + sechdrs[i].sh_name, i);
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return -ENOEXEC;
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}
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}
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return 0;
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}
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