Commit 084623e4 authored by Linus Torvalds's avatar Linus Torvalds

Merge tag 'modules-for-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

Pull module updates from Jessica Yu:

 - Harden CONFIG_STRICT_MODULE_RWX by rejecting any module that has
   SHF_WRITE|SHF_EXECINSTR sections

 - Remove and clean up nested #ifdefs, as it makes code hard to read

* tag 'modules-for-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: Harden STRICT_MODULE_RWX
  module: break nested ARCH_HAS_STRICT_MODULE_RWX and STRICT_MODULE_RWX #ifdefs
parents f4dd60a3 5c3a7db0
...@@ -1946,7 +1946,6 @@ static void mod_sysfs_teardown(struct module *mod) ...@@ -1946,7 +1946,6 @@ static void mod_sysfs_teardown(struct module *mod)
mod_sysfs_fini(mod); mod_sysfs_fini(mod);
} }
#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
/* /*
* LKM RO/NX protection: protect module's text/ro-data * LKM RO/NX protection: protect module's text/ro-data
* from modification and any data from execution. * from modification and any data from execution.
...@@ -1960,6 +1959,14 @@ static void mod_sysfs_teardown(struct module *mod) ...@@ -1960,6 +1959,14 @@ static void mod_sysfs_teardown(struct module *mod)
* *
* These values are always page-aligned (as is base) * These values are always page-aligned (as is base)
*/ */
/*
* Since some arches are moving towards PAGE_KERNEL module allocations instead
* of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() outside of the
* CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
* whether we are strict.
*/
#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
static void frob_text(const struct module_layout *layout, static void frob_text(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages)) int (*set_memory)(unsigned long start, int num_pages))
{ {
...@@ -1969,6 +1976,15 @@ static void frob_text(const struct module_layout *layout, ...@@ -1969,6 +1976,15 @@ static void frob_text(const struct module_layout *layout,
layout->text_size >> PAGE_SHIFT); layout->text_size >> PAGE_SHIFT);
} }
static void module_enable_x(const struct module *mod)
{
frob_text(&mod->core_layout, set_memory_x);
frob_text(&mod->init_layout, set_memory_x);
}
#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
static void module_enable_x(const struct module *mod) { }
#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
#ifdef CONFIG_STRICT_MODULE_RWX #ifdef CONFIG_STRICT_MODULE_RWX
static void frob_rodata(const struct module_layout *layout, static void frob_rodata(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages)) int (*set_memory)(unsigned long start, int num_pages))
...@@ -2026,20 +2042,29 @@ static void module_enable_nx(const struct module *mod) ...@@ -2026,20 +2042,29 @@ static void module_enable_nx(const struct module *mod)
frob_writable_data(&mod->init_layout, set_memory_nx); frob_writable_data(&mod->init_layout, set_memory_nx);
} }
static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *mod)
{
const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR;
int i;
for (i = 0; i < hdr->e_shnum; i++) {
if ((sechdrs[i].sh_flags & shf_wx) == shf_wx)
return -ENOEXEC;
}
return 0;
}
#else /* !CONFIG_STRICT_MODULE_RWX */ #else /* !CONFIG_STRICT_MODULE_RWX */
static void module_enable_nx(const struct module *mod) { } static void module_enable_nx(const struct module *mod) { }
static void module_enable_ro(const struct module *mod, bool after_init) {} static void module_enable_ro(const struct module *mod, bool after_init) {}
#endif /* CONFIG_STRICT_MODULE_RWX */ static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
static void module_enable_x(const struct module *mod) char *secstrings, struct module *mod)
{ {
frob_text(&mod->core_layout, set_memory_x); return 0;
frob_text(&mod->init_layout, set_memory_x);
} }
#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ #endif /* CONFIG_STRICT_MODULE_RWX */
static void module_enable_nx(const struct module *mod) { }
static void module_enable_x(const struct module *mod) { }
#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
#ifdef CONFIG_LIVEPATCH #ifdef CONFIG_LIVEPATCH
/* /*
...@@ -3385,6 +3410,11 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) ...@@ -3385,6 +3410,11 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
if (err < 0) if (err < 0)
return ERR_PTR(err); return ERR_PTR(err);
err = module_enforce_rwx_sections(info->hdr, info->sechdrs,
info->secstrings, info->mod);
if (err < 0)
return ERR_PTR(err);
/* We will do a special allocation for per-cpu sections later. */ /* We will do a special allocation for per-cpu sections later. */
info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;
......
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