[RFC 12/12] module: use aliases to find module on find_module_all()
From: Luis Chamberlain <mcgrof@kernel.org>
Date: 2023-03-11 05:18:30
Also in:
lkml
Subsystem:
module support, the rest · Maintainers:
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
Modules can have a series of aliases, but we don't currently use them to check if a module is already loaded. Part of this is because load_module() will stick to checking for already loaded modules using the actual module name, not an alias. Its however desriable to also check for aliases on find_module_all() for existing callers and future callers. The curent gain to using aliases on find_module_all() will simply be to be able to support unloading modules using the alias using the delete_module() syscall. You can debug this with dynamic debug: GRUB_CMDLINE_LINUX_DEFAULT="dyndbg=\"func module_process_aliases +p; func module_name_match +p; \" " Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- kernel/module/aliases.c | 17 +++++++++++++++++ kernel/module/internal.h | 5 +++++ kernel/module/main.c | 24 +++++++++++++++++++++++- 3 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/kernel/module/aliases.c b/kernel/module/aliases.c
index 2f30c9d4c765..69518bc5169a 100644
--- a/kernel/module/aliases.c
+++ b/kernel/module/aliases.c@@ -90,3 +90,20 @@ int module_process_aliases(struct module *mod, struct load_info *info) return -ENOMEM; } + +bool module_name_match_aliases(struct module *mod, const char *name, size_t len) +{ + unsigned int i; + const char *alias; + + for (i=0; i < mod->num_aliases; i++) { + alias = mod->aliases[i]; + if (strlen(alias) == len && !memcmp(alias, name, len)) { + pr_debug("module %s alias matched: alias[%u] = %s\n", + mod->name, i, alias); + return true; + } + } + + return false; +}
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 40bb80ed21e2..78aaad74f4ca 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h@@ -306,6 +306,7 @@ static inline int same_magic(const char *amagic, const char *bmagic, bool has_cr #ifdef CONFIG_MODULE_KERNEL_ALIAS void free_mod_aliases(struct module *mod); int module_process_aliases(struct module *mod, struct load_info *info); +bool module_name_match_aliases(struct module *mod, const char *name, size_t len); #else static void free_mod_aliases(struct module *mod) {
@@ -314,4 +315,8 @@ static int module_process_aliases(struct module *mod, struct load_info *info) { return 0; } +static bool module_name_match_aliases(struct module *mod, const char *name, size_t len) +{ + return false; +} #endif /* CONFIG_MODULE_KERNEL_ALIAS */
diff --git a/kernel/module/main.c b/kernel/module/main.c
index bc9202b60d55..cf044329da3c 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c@@ -338,6 +338,28 @@ bool find_symbol(struct find_symbol_arg *fsa) return false; } +static bool module_name_match(struct module *mod, const char *name, size_t len) +{ + unsigned int i; + const char *alias; + + if (strlen(mod->name) == len && !memcmp(mod->name, name, len)) + return true; + + return module_name_match_aliases(mod, name, len); + + for (i=0; i < mod->num_aliases; i++) { + alias = mod->aliases[i]; + if (strlen(alias) == len && !memcmp(alias, name, len)) { + pr_debug("module %s alias matched: alias[%u] = %s\n", + mod->name, i, alias); + return true; + } + } + + return false; +} + /* * Search for module by name: must hold module_mutex (or preempt disabled * for read-only access).
@@ -353,7 +375,7 @@ struct module *find_module_all(const char *name, size_t len, lockdep_is_held(&module_mutex)) { if (!even_unformed && mod->state == MODULE_STATE_UNFORMED) continue; - if (strlen(mod->name) == len && !memcmp(mod->name, name, len)) + if (module_name_match(mod, name, len)) return mod; } return NULL;
--
2.39.1