Move the logic to mark special sections as read-only after module
initialization into a separate function, along other related code in
strict_rwx.c. Use a table with names of such sections to make it easier to
add more.
Signed-off-by: Petr Pavlu <petr.pavlu@xxxxxxxx>
---
kernel/module/internal.h | 2 ++
kernel/module/main.c | 18 +++---------------
kernel/module/strict_rwx.c | 33 +++++++++++++++++++++++++++++++++
3 files changed, 38 insertions(+), 15 deletions(-)
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 7e78f6a8e85e..c4c918d9b65e 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -333,6 +333,8 @@ int module_enable_text_rox(const struct module *mod);
int module_enforce_rwx_sections(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
const char *secstrings,
const struct module *mod);
+void module_mark_ro_after_init(const Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
+ const char *secstrings);
#ifdef CONFIG_MODULE_SIG
int module_sig_check(struct load_info *info, int flags);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 5399c182b3cb..12ca6c6d7efd 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2710,7 +2710,6 @@ core_param(module_blacklist, module_blacklist, charp, 0400);
static struct module *layout_and_allocate(struct load_info *info, int flags)
{
struct module *mod;
- unsigned int ndx;
int err;
/* Allow arches to frob section contents and sizes. */
@@ -2728,22 +2727,11 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;
/*
- * Mark ro_after_init section with SHF_RO_AFTER_INIT so that
- * layout_sections() can put it in the right place.
+ * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can
+ * put them in the right place.
* Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set.
*/
- ndx = find_sec(info, ".data..ro_after_init");
- if (ndx)
- info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT;
- /*
- * Mark the __jump_table section as ro_after_init as well: these data
- * structures are never modified, with the exception of entries that
- * refer to code in the __init section, which are annotated as such
- * at module load time.
- */
- ndx = find_sec(info, "__jump_table");
- if (ndx)
- info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT;
+ module_mark_ro_after_init(info->hdr, info->sechdrs, info->secstrings);
/*
* Determine total sizes, and put offsets in sh_entsize. For now
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index d1c43309bb25..598f89195336 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c
@@ -101,3 +101,36 @@ int module_enforce_rwx_sections(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
return 0;
}
+
+static const char *const ro_after_init[] = {
+ /*
+ * Section .data..ro_after_init holds data explicitly annotated by
+ * __ro_after_init.
+ */
+ ".data..ro_after_init",
+
+ /*
+ * Section __jump_table holds data structures that are never modified,
+ * with the exception of entries that refer to code in the __init
+ * section, which are marked as such at module load time.
+ */
+ "__jump_table",
+};
+
+void module_mark_ro_after_init(const Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
+ const char *secstrings)
+{
+ int i, j;
+
+ for (i = 1; i < hdr->e_shnum; i++) {
+ Elf_Shdr *shdr = &sechdrs[i];
+
+ for (j = 0; j < ARRAY_SIZE(ro_after_init); j++) {
+ if (strcmp(secstrings + shdr->sh_name,
+ ro_after_init[j]) == 0) {
+ shdr->sh_flags |= SHF_RO_AFTER_INIT;
+ break;
+ }
+ }
+ }
+}
--
2.43.0
