2 files changed, 147 insertions, 3 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 2bb0c3085706..3daf2b3a09d2 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -330,6 +330,15 @@ struct mod_kallsyms {
         char *strtab;
 };
 
+#ifdef CONFIG_LIVEPATCH
+struct klp_modinfo {
+        Elf_Ehdr hdr;
+        Elf_Shdr *sechdrs;
+        char *secstrings;
+        unsigned int symndx;
+};
+#endif
+
 struct module {
         enum module_state state;
 
@@ -456,7 +465,11 @@ struct module {
 #endif
 
 #ifdef CONFIG_LIVEPATCH
+        bool klp; /* Is this a livepatch module? */
         bool klp_alive;
+
+        /* Elf information */
+        struct klp_modinfo *klp_info;
 #endif
 
 #ifdef CONFIG_MODULE_UNLOAD
@@ -630,6 +643,18 @@ static inline bool module_requested_async_probing(struct module *module)
         return module && module->async_probe_requested;
 }
 
+#ifdef CONFIG_LIVEPATCH
+static inline bool is_livepatch_module(struct module *mod)
+{
+        return mod->klp;
+}
+#else /* !CONFIG_LIVEPATCH */
+static inline bool is_livepatch_module(struct module *mod)
+{
+        return false;
+}
+#endif /* CONFIG_LIVEPATCH */
+
 #else /* !CONFIG_MODULES... */
 
 /* Given an address, look for it in the exception tables. */
diff --git a/kernel/module.c b/kernel/module.c
index 041200ca4a2d..5f71aa63ed2a 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1973,6 +1973,83 @@ static void module_enable_nx(const struct module *mod) { }
 static void module_disable_nx(const struct module *mod) { }
 #endif
 
+#ifdef CONFIG_LIVEPATCH
+/*
+ * Persist Elf information about a module. Copy the Elf header,
+ * section header table, section string table, and symtab section
+ * index from info to mod->klp_info.
+ */
+static int copy_module_elf(struct module *mod, struct load_info *info)
+{
+        unsigned int size, symndx;
+        int ret;
+
+        size = sizeof(*mod->klp_info);
+        mod->klp_info = kmalloc(size, GFP_KERNEL);
+        if (mod->klp_info == NULL)
+                return -ENOMEM;
+
+        /* Elf header */
+        size = sizeof(mod->klp_info->hdr);
+        memcpy(&mod->klp_info->hdr, info->hdr, size);
+
+        /* Elf section header table */
+        size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
+        mod->klp_info->sechdrs = kmalloc(size, GFP_KERNEL);
+        if (mod->klp_info->sechdrs == NULL) {
+                ret = -ENOMEM;
+                goto free_info;
+        }
+        memcpy(mod->klp_info->sechdrs, info->sechdrs, size);
+
+        /* Elf section name string table */
+        size = info->sechdrs[info->hdr->e_shstrndx].sh_size;
+        mod->klp_info->secstrings = kmalloc(size, GFP_KERNEL);
+        if (mod->klp_info->secstrings == NULL) {
+                ret = -ENOMEM;
+                goto free_sechdrs;
+        }
+        memcpy(mod->klp_info->secstrings, info->secstrings, size);
+
+        /* Elf symbol section index */
+        symndx = info->index.sym;
+        mod->klp_info->symndx = symndx;
+
+        /*
+         * For livepatch modules, core_kallsyms.symtab is a complete
+         * copy of the original symbol table. Adjust sh_addr to point
+         * to core_kallsyms.symtab since the copy of the symtab in module
+         * init memory is freed at the end of do_init_module().
+         */
+        mod->klp_info->sechdrs[symndx].sh_addr = \
+                (unsigned long) mod->core_kallsyms.symtab;
+
+        return 0;
+
+free_sechdrs:
+        kfree(mod->klp_info->sechdrs);
+free_info:
+        kfree(mod->klp_info);
+        return ret;
+}
+
+static void free_module_elf(struct module *mod)
+{
+        kfree(mod->klp_info->sechdrs);
+        kfree(mod->klp_info->secstrings);
+        kfree(mod->klp_info);
+}
+#else /* !CONFIG_LIVEPATCH */
+static int copy_module_elf(struct module *mod, struct load_info *info)
+{
+        return 0;
+}
+
+static void free_module_elf(struct module *mod)
+{
+}
+#endif /* CONFIG_LIVEPATCH */
+
 void __weak module_memfree(void *module_region)
 {
         vfree(module_region);
@@ -2011,6 +2088,9 @@ static void free_module(struct module *mod)
         /* Free any allocated parameters. */
         destroy_params(mod->kp, mod->num_kp);
 
+        if (is_livepatch_module(mod))
+                free_module_elf(mod);
+
         /* Now we can delete it from the lists */
         mutex_lock(&module_mutex);
         /* Unlink carefully: kallsyms could be walking list. */
@@ -2126,6 +2206,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info)
                                (long)sym[i].st_value);
                         break;
 
+                case SHN_LIVEPATCH:
+                        /* Livepatch symbols are resolved by livepatch */
+                        break;
+
                 case SHN_UNDEF:
                         ksym = resolve_symbol_wait(mod, info, name);
                         /* Ok if resolved.  */
@@ -2174,6 +2258,10 @@ static int apply_relocations(struct module *mod, const struct load_info *info)
                 if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC))
                         continue;
 
+                /* Livepatch relocation sections are applied by livepatch */
+                if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH)
+                        continue;
+
                 if (info->sechdrs[i].sh_type == SHT_REL)
                         err = apply_relocate(info->sechdrs, info->strtab,
                                              info->index.sym, i, mod);
@@ -2469,7 +2557,7 @@ static void layout_symtab(struct module *mod, struct load_info *info)
 
         /* Compute total space required for the core symbols' strtab. */
         for (ndst = i = 0; i < nsrc; i++) {
-                if (i == 0 ||
+                if (i == 0 || is_livepatch_module(mod) ||
                     is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
                                    info->index.pcpu)) {
                         strtab_size += strlen(&info->strtab[src[i].st_name])+1;
@@ -2528,7 +2616,7 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
         mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs;
         src = mod->kallsyms->symtab;
         for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) {
-                if (i == 0 ||
+                if (i == 0 || is_livepatch_module(mod) ||
                     is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
                                    info->index.pcpu)) {
                         dst[ndst] = src[i];
@@ -2667,6 +2755,26 @@ static int copy_chunked_from_user(void *dst, const void __user *usrc, unsigned l
         return 0;
 }
 
+#ifdef CONFIG_LIVEPATCH
+static int find_livepatch_modinfo(struct module *mod, struct load_info *info)
+{
+        mod->klp = get_modinfo(info, "livepatch") ? true : false;
+
+        return 0;
+}
+#else /* !CONFIG_LIVEPATCH */
+static int find_livepatch_modinfo(struct module *mod, struct load_info *info)
+{
+        if (get_modinfo(info, "livepatch")) {
+                pr_err("%s: module is marked as livepatch module, but livepatch support is disabled",
+                       mod->name);
+                return -ENOEXEC;
+        }
+
+        return 0;
+}
+#endif /* CONFIG_LIVEPATCH */
+
 /* Sets info->hdr and info->len. */
 static int copy_module_from_user(const void __user *umod, unsigned long len,
                                   struct load_info *info)
@@ -2821,6 +2929,10 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
                         "is unknown, you have been warned.\n", mod->name);
         }
 
+        err = find_livepatch_modinfo(mod, info);
+        if (err)
+                return err;
+
         /* Set up license info based on the info section */
         set_license(mod, get_modinfo(info, "license"));
 
@@ -3494,6 +3606,12 @@ static int load_module(struct load_info *info, const char __user *uargs,
         if (err < 0)
                 goto coming_cleanup;
 
+        if (is_livepatch_module(mod)) {
+                err = copy_module_elf(mod, info);
+                if (err < 0)
+                        goto sysfs_cleanup;
+        }
+
         /* Get rid of temporary copy. */
         free_copy(info);
 
@@ -3502,11 +3620,12 @@ static int load_module(struct load_info *info, const char __user *uargs,
 
         return do_init_module(mod);
 
+ sysfs_cleanup:
+        mod_sysfs_teardown(mod);
  coming_cleanup:
         blocking_notifier_call_chain(&module_notify_list,
                                      MODULE_STATE_GOING, mod);
         klp_module_going(mod);
-
  bug_cleanup:
         /* module_bug_cleanup needs module_mutex protection */
         mutex_lock(&module_mutex);