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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-05 22:31:16 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-05 22:31:16 +0300 |
commit | 084623e468d535d98f883cc2ccf2c4fdf2108556 (patch) | |
tree | 19c9a7b1aaef221f0e3d2116b76e8240102f53b7 | |
parent | f4dd60a3d4c7656dcaa0ba2afb503528c86f913f (diff) | |
parent | 5c3a7db0c7ec4bbd5bd3f48af9be859a8fa3e532 (diff) | |
download | linux-084623e468d535d98f883cc2ccf2c4fdf2108556.tar.xz |
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
-rw-r--r-- | kernel/module.c | 50 |
1 files changed, 40 insertions, 10 deletions
diff --git a/kernel/module.c b/kernel/module.c index bca993c5f1bc..ef400c389f49 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1946,7 +1946,6 @@ static void mod_sysfs_teardown(struct module *mod) mod_sysfs_fini(mod); } -#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX /* * LKM RO/NX protection: protect module's text/ro-data * from modification and any data from execution. @@ -1960,6 +1959,14 @@ static void mod_sysfs_teardown(struct module *mod) * * 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, int (*set_memory)(unsigned long start, int num_pages)) { @@ -1969,6 +1976,15 @@ static void frob_text(const struct module_layout *layout, 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 static void frob_rodata(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) @@ -2026,20 +2042,29 @@ static void module_enable_nx(const struct module *mod) 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 */ static void module_enable_nx(const struct module *mod) { } static void module_enable_ro(const struct module *mod, bool after_init) {} -#endif /* CONFIG_STRICT_MODULE_RWX */ -static void module_enable_x(const struct module *mod) +static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) { - frob_text(&mod->core_layout, set_memory_x); - frob_text(&mod->init_layout, set_memory_x); + return 0; } -#else /* !CONFIG_ARCH_HAS_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 */ - +#endif /* CONFIG_STRICT_MODULE_RWX */ #ifdef CONFIG_LIVEPATCH /* @@ -3385,6 +3410,11 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) if (err < 0) 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. */ info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; |