[PATCH v2 13/39] lib: code tagging module support

Suren Baghdasaryan
2023-10-24T13:47:23Z

Add support for code tagging from dynamically loaded modules.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Co-developed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
include/linux/codetag.h | 12 +++++++++
kernel/module/main.c | 4 +++
lib/codetag.c | 58 +++++++++++++++++++++++++++++++++++++++--
3 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/include/linux/codetag.h b/include/linux/codetag.h
index a9d7adecc2a5..386733e89b31 100644
--- a/include/linux/codetag.h
+++ b/include/linux/codetag.h
@@ -42,6 +42,10 @@ struct codetag_module {
struct codetag_type_desc {
const char *section;
size_t tag_size;
+ void (*module_load)(struct codetag_type *cttype,
+ struct codetag_module *cmod);
+ void (*module_unload)(struct codetag_type *cttype,
+ struct codetag_module *cmod);
};

struct codetag_iterator {
@@ -68,4 +72,12 @@ void codetag_to_text(struct seq_buf *out, struct codetag *ct);
struct codetag_type *
codetag_register_type(const struct codetag_type_desc *desc);

+#ifdef CONFIG_CODE_TAGGING
+void codetag_load_module(struct module *mod);
+void codetag_unload_module(struct module *mod);
+#else
+static inline void codetag_load_module(struct module *mod) {}
+static inline void codetag_unload_module(struct module *mod) {}
+#endif
+
#endif /* _LINUX_CODETAG_H */
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 98fedfdb8db5..c0d3f562c7ab 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -56,6 +56,7 @@
#include <linux/dynamic_debug.h>
#include <linux/audit.h>
#include <linux/cfi.h>
+#include <linux/codetag.h>
#include <linux/debugfs.h>
#include <uapi/linux/module.h>
#include "internal.h"
@@ -1242,6 +1243,7 @@ static void free_module(struct module *mod)
{
trace_module_free(mod);

+ codetag_unload_module(mod);
mod_sysfs_teardown(mod);

/*
@@ -2975,6 +2977,8 @@ static int load_module(struct load_info *info, const char __user *uargs,
/* Get rid of temporary copy. */
free_copy(info, flags);

+ codetag_load_module(mod);
+
/* Done! */
trace_module_load(mod);

diff --git a/lib/codetag.c b/lib/codetag.c
index 7708f8388e55..4ea57fb37346 100644
--- a/lib/codetag.c
+++ b/lib/codetag.c
@@ -108,15 +108,20 @@ static inline size_t range_size(const struct codetag_type *cttype,
static void *get_symbol(struct module *mod, const char *prefix, const char *name)
{
char buf[64];
+ void *ret;
int res;

res = snprintf(buf, sizeof(buf), "%s%s", prefix, name);
if (WARN_ON(res < 1 || res > sizeof(buf)))
return NULL;

- return mod ?
+ preempt_disable();
+ ret = mod ?
(void *)find_kallsyms_symbol_value(mod, buf) :
(void *)kallsyms_lookup_name(buf);
+ preempt_enable();
+
+ return ret;
}

static struct codetag_range get_section_range(struct module *mod,
@@ -157,8 +162,11 @@ static int codetag_module_init(struct codetag_type *cttype, struct module *mod)

down_write(&cttype->mod_lock);
err = idr_alloc(&cttype->mod_idr, cmod, 0, 0, GFP_KERNEL);
- if (err >= 0)
+ if (err >= 0) {
cttype->count += range_size(cttype, &range);
+ if (cttype->desc.module_load)
+ cttype->desc.module_load(cttype, cmod);
+ }
up_write(&cttype->mod_lock);

if (err < 0) {
@@ -197,3 +205,49 @@ codetag_register_type(const struct codetag_type_desc *desc)

return cttype;
}
+
+void codetag_load_module(struct module *mod)
+{
+ struct codetag_type *cttype;
+
+ if (!mod)
+ return;
+
+ mutex_lock(&codetag_lock);
+ list_for_each_entry(cttype, &codetag_types, link)
+ codetag_module_init(cttype, mod);
+ mutex_unlock(&codetag_lock);
+}
+
+void codetag_unload_module(struct module *mod)
+{
+ struct codetag_type *cttype;
+
+ if (!mod)
+ return;
+
+ mutex_lock(&codetag_lock);
+ list_for_each_entry(cttype, &codetag_types, link) {
+ struct codetag_module *found = NULL;
+ struct codetag_module *cmod;
+ unsigned long mod_id, tmp;
+
+ down_write(&cttype->mod_lock);
+ idr_for_each_entry_ul(&cttype->mod_idr, cmod, tmp, mod_id) {
+ if (cmod->mod && cmod->mod == mod) {
+ found = cmod;
+ break;
+ }
+ }
+ if (found) {
+ if (cttype->desc.module_unload)
+ cttype->desc.module_unload(cttype, cmod);
+
+ cttype->count -= range_size(cttype, &cmod->range);
+ idr_remove(&cttype->mod_idr, mod_id);
+ kfree(cmod);
+ }
+ up_write(&cttype->mod_lock);
+ }
+ mutex_unlock(&codetag_lock);
+}
--
2.42.0.758.gaed0368e0e-goog