diff options
Diffstat (limited to 'kernel/module/strict_rwx.c')
-rw-r--r-- | kernel/module/strict_rwx.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c index 7949dfd449c2..43332b4416b0 100644 --- a/kernel/module/strict_rwx.c +++ b/kernel/module/strict_rwx.c @@ -11,6 +11,34 @@ #include <linux/set_memory.h> #include "internal.h" +/* + * LKM RO/NX protection: protect module's text/ro-data + * from modification and any data from execution. + * + * General layout of module is: + * [text] [read-only-data] [ro-after-init] [writable data] + * text_size -----^ ^ ^ ^ + * ro_size ------------------------| | | + * ro_after_init_size -----------------------------| | + * size -----------------------------------------------------------| + * + * These values are always page-aligned (as is base) when + * CONFIG_STRICT_MODULE_RWX is set. + */ + +/* + * Since some arches are moving towards PAGE_KERNEL module allocations instead + * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() independent of + * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we + * are strict. + */ +static void frob_text(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)) +{ + set_memory((unsigned long)layout->base, + PAGE_ALIGN(layout->text_size) >> PAGE_SHIFT); +} + static void frob_rodata(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { @@ -41,10 +69,24 @@ static void frob_writable_data(const struct module_layout *layout, (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); } +void module_enable_x(const struct module *mod) +{ + if (!PAGE_ALIGNED(mod->core_layout.base) || + !PAGE_ALIGNED(mod->init_layout.base)) + return; + + frob_text(&mod->core_layout, set_memory_x); + frob_text(&mod->init_layout, set_memory_x); +} + void module_enable_ro(const struct module *mod, bool after_init) { + if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) + return; +#ifdef CONFIG_STRICT_MODULE_RWX if (!rodata_enabled) return; +#endif set_vm_flush_reset_perms(mod->core_layout.base); set_vm_flush_reset_perms(mod->init_layout.base); @@ -60,6 +102,9 @@ void module_enable_ro(const struct module *mod, bool after_init) void module_enable_nx(const struct module *mod) { + if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) + return; + frob_rodata(&mod->core_layout, set_memory_nx); frob_ro_after_init(&mod->core_layout, set_memory_nx); frob_writable_data(&mod->core_layout, set_memory_nx); @@ -73,6 +118,9 @@ int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR; int i; + if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) + return 0; + for (i = 0; i < hdr->e_shnum; i++) { if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", |