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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-05 12:31:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-05 12:31:16 -0700
commit084623e468d535d98f883cc2ccf2c4fdf2108556 (patch)
tree19c9a7b1aaef221f0e3d2116b76e8240102f53b7
parentf4dd60a3d4c7656dcaa0ba2afb503528c86f913f (diff)
parent5c3a7db0c7ec4bbd5bd3f48af9be859a8fa3e532 (diff)
downloadlinux-084623e468d535d98f883cc2ccf2c4fdf2108556.tar.bz2
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.c50
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;