From 916cc5167cc6f81651f4460d9a35c939ad18ecff Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 21 Mar 2024 09:36:32 -0700 Subject: lib: code tagging framework MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add basic infrastructure to support code tagging which stores tag common information consisting of the module name, function, file name and line number. Provide functions to register a new code tag type and navigate between code tags. Link: https://lkml.kernel.org/r/20240321163705.3067592-11-surenb@google.com Co-developed-by: Kent Overstreet Signed-off-by: Kent Overstreet Signed-off-by: Suren Baghdasaryan Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Vlastimil Babka Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton --- lib/codetag.c | 219 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 219 insertions(+) create mode 100644 lib/codetag.c (limited to 'lib/codetag.c') diff --git a/lib/codetag.c b/lib/codetag.c new file mode 100644 index 000000000000..8b5b89ad508d --- /dev/null +++ b/lib/codetag.c @@ -0,0 +1,219 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include + +struct codetag_type { + struct list_head link; + unsigned int count; + struct idr mod_idr; + struct rw_semaphore mod_lock; /* protects mod_idr */ + struct codetag_type_desc desc; +}; + +struct codetag_range { + struct codetag *start; + struct codetag *stop; +}; + +struct codetag_module { + struct module *mod; + struct codetag_range range; +}; + +static DEFINE_MUTEX(codetag_lock); +static LIST_HEAD(codetag_types); + +void codetag_lock_module_list(struct codetag_type *cttype, bool lock) +{ + if (lock) + down_read(&cttype->mod_lock); + else + up_read(&cttype->mod_lock); +} + +struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype) +{ + struct codetag_iterator iter = { + .cttype = cttype, + .cmod = NULL, + .mod_id = 0, + .ct = NULL, + }; + + return iter; +} + +static inline struct codetag *get_first_module_ct(struct codetag_module *cmod) +{ + return cmod->range.start < cmod->range.stop ? cmod->range.start : NULL; +} + +static inline +struct codetag *get_next_module_ct(struct codetag_iterator *iter) +{ + struct codetag *res = (struct codetag *) + ((char *)iter->ct + iter->cttype->desc.tag_size); + + return res < iter->cmod->range.stop ? res : NULL; +} + +struct codetag *codetag_next_ct(struct codetag_iterator *iter) +{ + struct codetag_type *cttype = iter->cttype; + struct codetag_module *cmod; + struct codetag *ct; + + lockdep_assert_held(&cttype->mod_lock); + + if (unlikely(idr_is_empty(&cttype->mod_idr))) + return NULL; + + ct = NULL; + while (true) { + cmod = idr_find(&cttype->mod_idr, iter->mod_id); + + /* If module was removed move to the next one */ + if (!cmod) + cmod = idr_get_next_ul(&cttype->mod_idr, + &iter->mod_id); + + /* Exit if no more modules */ + if (!cmod) + break; + + if (cmod != iter->cmod) { + iter->cmod = cmod; + ct = get_first_module_ct(cmod); + } else + ct = get_next_module_ct(iter); + + if (ct) + break; + + iter->mod_id++; + } + + iter->ct = ct; + return ct; +} + +void codetag_to_text(struct seq_buf *out, struct codetag *ct) +{ + if (ct->modname) + seq_buf_printf(out, "%s:%u [%s] func:%s", + ct->filename, ct->lineno, + ct->modname, ct->function); + else + seq_buf_printf(out, "%s:%u func:%s", + ct->filename, ct->lineno, ct->function); +} + +static inline size_t range_size(const struct codetag_type *cttype, + const struct codetag_range *range) +{ + return ((char *)range->stop - (char *)range->start) / + cttype->desc.tag_size; +} + +#ifdef CONFIG_MODULES +static void *get_symbol(struct module *mod, const char *prefix, const char *name) +{ + DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN); + const char *buf; + + seq_buf_printf(&sb, "%s%s", prefix, name); + if (seq_buf_has_overflowed(&sb)) + return NULL; + + buf = seq_buf_str(&sb); + return mod ? + (void *)find_kallsyms_symbol_value(mod, buf) : + (void *)kallsyms_lookup_name(buf); +} + +static struct codetag_range get_section_range(struct module *mod, + const char *section) +{ + return (struct codetag_range) { + get_symbol(mod, "__start_", section), + get_symbol(mod, "__stop_", section), + }; +} + +static int codetag_module_init(struct codetag_type *cttype, struct module *mod) +{ + struct codetag_range range; + struct codetag_module *cmod; + int err; + + range = get_section_range(mod, cttype->desc.section); + if (!range.start || !range.stop) { + pr_warn("Failed to load code tags of type %s from the module %s\n", + cttype->desc.section, + mod ? mod->name : "(built-in)"); + return -EINVAL; + } + + /* Ignore empty ranges */ + if (range.start == range.stop) + return 0; + + BUG_ON(range.start > range.stop); + + cmod = kmalloc(sizeof(*cmod), GFP_KERNEL); + if (unlikely(!cmod)) + return -ENOMEM; + + cmod->mod = mod; + cmod->range = range; + + down_write(&cttype->mod_lock); + err = idr_alloc(&cttype->mod_idr, cmod, 0, 0, GFP_KERNEL); + if (err >= 0) + cttype->count += range_size(cttype, &range); + up_write(&cttype->mod_lock); + + if (err < 0) { + kfree(cmod); + return err; + } + + return 0; +} + +#else /* CONFIG_MODULES */ +static int codetag_module_init(struct codetag_type *cttype, struct module *mod) { return 0; } +#endif /* CONFIG_MODULES */ + +struct codetag_type * +codetag_register_type(const struct codetag_type_desc *desc) +{ + struct codetag_type *cttype; + int err; + + BUG_ON(desc->tag_size <= 0); + + cttype = kzalloc(sizeof(*cttype), GFP_KERNEL); + if (unlikely(!cttype)) + return ERR_PTR(-ENOMEM); + + cttype->desc = *desc; + idr_init(&cttype->mod_idr); + init_rwsem(&cttype->mod_lock); + + err = codetag_module_init(cttype, NULL); + if (unlikely(err)) { + kfree(cttype); + return ERR_PTR(err); + } + + mutex_lock(&codetag_lock); + list_add_tail(&cttype->link, &codetag_types); + mutex_unlock(&codetag_lock); + + return cttype; +} -- cgit v1.2.3 From a473573964e51dcb6efc182f773cd3924be4a184 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 21 Mar 2024 09:36:33 -0700 Subject: lib: code tagging module support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add support for code tagging from dynamically loaded modules. Link: https://lkml.kernel.org/r/20240321163705.3067592-12-surenb@google.com Signed-off-by: Suren Baghdasaryan Co-developed-by: Kent Overstreet Signed-off-by: Kent Overstreet Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Vlastimil Babka Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton --- lib/codetag.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 56 insertions(+), 2 deletions(-) (limited to 'lib/codetag.c') diff --git a/lib/codetag.c b/lib/codetag.c index 8b5b89ad508d..54d2828eba25 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -124,15 +124,20 @@ static void *get_symbol(struct module *mod, const char *prefix, const char *name { DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN); const char *buf; + void *ret; seq_buf_printf(&sb, "%s%s", prefix, name); if (seq_buf_has_overflowed(&sb)) return NULL; buf = seq_buf_str(&sb); - 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, @@ -173,8 +178,11 @@ 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) { @@ -185,6 +193,52 @@ static int codetag_module_init(struct codetag_type *cttype, struct module *mod) return 0; } +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); +} + #else /* CONFIG_MODULES */ static int codetag_module_init(struct codetag_type *cttype, struct module *mod) { return 0; } #endif /* CONFIG_MODULES */ -- cgit v1.2.3 From 47a92dfbe01f41bcbf359250ccb3caa589763abf Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 21 Mar 2024 09:36:34 -0700 Subject: lib: prevent module unloading if memory is not freed MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Skip freeing module's data section if there are non-zero allocation tags because otherwise, once these allocations are freed, the access to their code tag would cause UAF. Link: https://lkml.kernel.org/r/20240321163705.3067592-13-surenb@google.com Signed-off-by: Suren Baghdasaryan Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Kent Overstreet Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Vlastimil Babka Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton --- lib/codetag.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'lib/codetag.c') diff --git a/lib/codetag.c b/lib/codetag.c index 54d2828eba25..408062f722ce 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -5,6 +5,7 @@ #include #include #include +#include struct codetag_type { struct list_head link; @@ -206,12 +207,13 @@ void codetag_load_module(struct module *mod) mutex_unlock(&codetag_lock); } -void codetag_unload_module(struct module *mod) +bool codetag_unload_module(struct module *mod) { struct codetag_type *cttype; + bool unload_ok = true; if (!mod) - return; + return true; mutex_lock(&codetag_lock); list_for_each_entry(cttype, &codetag_types, link) { @@ -228,7 +230,8 @@ void codetag_unload_module(struct module *mod) } if (found) { if (cttype->desc.module_unload) - cttype->desc.module_unload(cttype, cmod); + if (!cttype->desc.module_unload(cttype, cmod)) + unload_ok = false; cttype->count -= range_size(cttype, &cmod->range); idr_remove(&cttype->mod_idr, mod_id); @@ -237,6 +240,8 @@ void codetag_unload_module(struct module *mod) up_write(&cttype->mod_lock); } mutex_unlock(&codetag_lock); + + return unload_ok; } #else /* CONFIG_MODULES */ -- cgit v1.2.3 From 1438d349d16b78d88f9e978a4a5496f078c8191b Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 21 Mar 2024 09:36:54 -0700 Subject: lib: add memory allocations report in show_mem() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Include allocations in show_mem reports. Link: https://lkml.kernel.org/r/20240321163705.3067592-33-surenb@google.com Signed-off-by: Kent Overstreet Signed-off-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton --- lib/codetag.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'lib/codetag.c') diff --git a/lib/codetag.c b/lib/codetag.c index 408062f722ce..5ace625f2328 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -36,6 +36,11 @@ void codetag_lock_module_list(struct codetag_type *cttype, bool lock) up_read(&cttype->mod_lock); } +bool codetag_trylock_module_list(struct codetag_type *cttype) +{ + return down_read_trylock(&cttype->mod_lock) != 0; +} + struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype) { struct codetag_iterator iter = { -- cgit v1.2.3