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ac3b432839
module_layout manages different types of memory (text, data, rodata, etc.)
in one allocation, which is problematic for some reasons:
1. It is hard to enable CONFIG_STRICT_MODULE_RWX.
2. It is hard to use huge pages in modules (and not break strict rwx).
3. Many archs uses module_layout for arch-specific data, but it is not
obvious how these data are used (are they RO, RX, or RW?)
Improve the scenario by replacing 2 (or 3) module_layout per module with
up to 7 module_memory per module:
MOD_TEXT,
MOD_DATA,
MOD_RODATA,
MOD_RO_AFTER_INIT,
MOD_INIT_TEXT,
MOD_INIT_DATA,
MOD_INIT_RODATA,
and allocating them separately. This adds slightly more entries to
mod_tree (from up to 3 entries per module, to up to 7 entries per
module). However, this at most adds a small constant overhead to
__module_address(), which is expected to be fast.
Various archs use module_layout for different data. These data are put
into different module_memory based on their location in module_layout.
IOW, data that used to go with text is allocated with MOD_MEM_TYPE_TEXT;
data that used to go with data is allocated with MOD_MEM_TYPE_DATA, etc.
module_memory simplifies quite some of the module code. For example,
ARCH_WANTS_MODULES_DATA_IN_VMALLOC is a lot cleaner, as it just uses a
different allocator for the data. kernel/module/strict_rwx.c is also
much cleaner with module_memory.
Signed-off-by: Song Liu <song@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
// 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 module_set_memory(const struct module *mod, enum mod_mem_type type,
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int (*set_memory)(unsigned long start, int num_pages))
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{
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const struct module_memory *mod_mem = &mod->mem[type];
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set_vm_flush_reset_perms(mod_mem->base);
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set_memory((unsigned long)mod_mem->base, mod_mem->size >> PAGE_SHIFT);
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}
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/*
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* Since some arches are moving towards PAGE_KERNEL module allocations instead
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* of PAGE_KERNEL_EXEC, keep module_enable_x() independent of
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* CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
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* are strict.
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*/
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void module_enable_x(const struct module *mod)
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{
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for_class_mod_mem_type(type, text)
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module_set_memory(mod, type, set_memory_x);
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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 (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
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return;
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#ifdef CONFIG_STRICT_MODULE_RWX
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if (!rodata_enabled)
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return;
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#endif
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module_set_memory(mod, MOD_TEXT, set_memory_ro);
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module_set_memory(mod, MOD_INIT_TEXT, set_memory_ro);
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module_set_memory(mod, MOD_RODATA, set_memory_ro);
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module_set_memory(mod, MOD_INIT_RODATA, set_memory_ro);
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if (after_init)
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module_set_memory(mod, MOD_RO_AFTER_INIT, 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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if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
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return;
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for_class_mod_mem_type(type, data)
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module_set_memory(mod, type, 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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if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
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return 0;
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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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