lkml.org 
[lkml]   [2020]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2] module: Harden STRICT_MODULE_RWX

We're very close to enforcing W^X memory, refuse to load modules that
violate this principle per construction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/module.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2044,9 +2044,29 @@ static void module_enable_x(const struct
frob_text(&mod->core_layout, set_memory_x);
frob_text(&mod->init_layout, set_memory_x);
}
+
+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_ARCH_HAS_STRICT_MODULE_RWX */
static void module_enable_nx(const struct module *mod) { }
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)
+{
+ return 0;
+}
#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */


@@ -3378,6 +3398,11 @@ static struct module *layout_and_allocat
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;

\
 
 \ /
  Last update: 2020-04-03 19:14    [W:0.469 / U:3.780 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site