lib: code tagging framework
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 <kent.overstreet@linux.dev> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Tested-by: Kees Cook <keescook@chromium.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Alice Ryhl <aliceryhl@google.com> Cc: Andreas Hindborg <a.hindborg@samsung.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Gary Guo <gary@garyguo.net> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wedson Almeida Filho <wedsonaf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Suren Baghdasaryan
Andrew Morton
parent
53ce720359
commit
916cc5167c
68
include/linux/codetag.h
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68
include/linux/codetag.h
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@ -0,0 +1,68 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* code tagging framework
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*/
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#ifndef _LINUX_CODETAG_H
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#define _LINUX_CODETAG_H
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#include <linux/types.h>
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struct codetag_iterator;
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struct codetag_type;
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struct codetag_module;
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struct seq_buf;
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struct module;
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/*
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* An instance of this structure is created in a special ELF section at every
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* code location being tagged. At runtime, the special section is treated as
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* an array of these.
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*/
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struct codetag {
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unsigned int flags; /* used in later patches */
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unsigned int lineno;
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const char *modname;
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const char *function;
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const char *filename;
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} __aligned(8);
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union codetag_ref {
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struct codetag *ct;
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};
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struct codetag_type_desc {
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const char *section;
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size_t tag_size;
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};
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struct codetag_iterator {
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struct codetag_type *cttype;
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struct codetag_module *cmod;
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unsigned long mod_id;
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struct codetag *ct;
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};
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#ifdef MODULE
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#define CT_MODULE_NAME KBUILD_MODNAME
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#else
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#define CT_MODULE_NAME NULL
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#endif
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#define CODE_TAG_INIT { \
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.modname = CT_MODULE_NAME, \
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.function = __func__, \
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.filename = __FILE__, \
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.lineno = __LINE__, \
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.flags = 0, \
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}
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void codetag_lock_module_list(struct codetag_type *cttype, bool lock);
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struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype);
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struct codetag *codetag_next_ct(struct codetag_iterator *iter);
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void codetag_to_text(struct seq_buf *out, struct codetag *ct);
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struct codetag_type *
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codetag_register_type(const struct codetag_type_desc *desc);
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#endif /* _LINUX_CODETAG_H */
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@ -968,6 +968,10 @@ config DEBUG_STACKOVERFLOW
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If in doubt, say "N".
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config CODE_TAGGING
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bool
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select KALLSYMS
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source "lib/Kconfig.kasan"
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source "lib/Kconfig.kfence"
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source "lib/Kconfig.kmsan"
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@ -233,6 +233,7 @@ obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \
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of-reconfig-notifier-error-inject.o
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obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
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obj-$(CONFIG_CODE_TAGGING) += codetag.o
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lib-$(CONFIG_GENERIC_BUG) += bug.o
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obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
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219
lib/codetag.c
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219
lib/codetag.c
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@ -0,0 +1,219 @@
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// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/codetag.h>
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#include <linux/idr.h>
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#include <linux/kallsyms.h>
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#include <linux/module.h>
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#include <linux/seq_buf.h>
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#include <linux/slab.h>
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struct codetag_type {
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struct list_head link;
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unsigned int count;
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struct idr mod_idr;
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struct rw_semaphore mod_lock; /* protects mod_idr */
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struct codetag_type_desc desc;
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};
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struct codetag_range {
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struct codetag *start;
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struct codetag *stop;
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};
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struct codetag_module {
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struct module *mod;
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struct codetag_range range;
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};
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static DEFINE_MUTEX(codetag_lock);
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static LIST_HEAD(codetag_types);
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void codetag_lock_module_list(struct codetag_type *cttype, bool lock)
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{
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if (lock)
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down_read(&cttype->mod_lock);
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else
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up_read(&cttype->mod_lock);
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}
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struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype)
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{
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struct codetag_iterator iter = {
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.cttype = cttype,
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.cmod = NULL,
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.mod_id = 0,
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.ct = NULL,
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};
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return iter;
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}
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static inline struct codetag *get_first_module_ct(struct codetag_module *cmod)
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{
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return cmod->range.start < cmod->range.stop ? cmod->range.start : NULL;
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}
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static inline
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struct codetag *get_next_module_ct(struct codetag_iterator *iter)
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{
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struct codetag *res = (struct codetag *)
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((char *)iter->ct + iter->cttype->desc.tag_size);
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return res < iter->cmod->range.stop ? res : NULL;
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}
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struct codetag *codetag_next_ct(struct codetag_iterator *iter)
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{
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struct codetag_type *cttype = iter->cttype;
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struct codetag_module *cmod;
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struct codetag *ct;
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lockdep_assert_held(&cttype->mod_lock);
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if (unlikely(idr_is_empty(&cttype->mod_idr)))
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return NULL;
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ct = NULL;
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while (true) {
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cmod = idr_find(&cttype->mod_idr, iter->mod_id);
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/* If module was removed move to the next one */
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if (!cmod)
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cmod = idr_get_next_ul(&cttype->mod_idr,
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&iter->mod_id);
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/* Exit if no more modules */
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if (!cmod)
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break;
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if (cmod != iter->cmod) {
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iter->cmod = cmod;
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ct = get_first_module_ct(cmod);
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} else
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ct = get_next_module_ct(iter);
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if (ct)
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break;
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iter->mod_id++;
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}
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iter->ct = ct;
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return ct;
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}
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void codetag_to_text(struct seq_buf *out, struct codetag *ct)
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{
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if (ct->modname)
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seq_buf_printf(out, "%s:%u [%s] func:%s",
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ct->filename, ct->lineno,
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ct->modname, ct->function);
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else
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seq_buf_printf(out, "%s:%u func:%s",
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ct->filename, ct->lineno, ct->function);
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}
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static inline size_t range_size(const struct codetag_type *cttype,
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const struct codetag_range *range)
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{
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return ((char *)range->stop - (char *)range->start) /
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cttype->desc.tag_size;
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}
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#ifdef CONFIG_MODULES
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static void *get_symbol(struct module *mod, const char *prefix, const char *name)
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{
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DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN);
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const char *buf;
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seq_buf_printf(&sb, "%s%s", prefix, name);
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if (seq_buf_has_overflowed(&sb))
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return NULL;
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buf = seq_buf_str(&sb);
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return mod ?
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(void *)find_kallsyms_symbol_value(mod, buf) :
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(void *)kallsyms_lookup_name(buf);
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}
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static struct codetag_range get_section_range(struct module *mod,
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const char *section)
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{
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return (struct codetag_range) {
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get_symbol(mod, "__start_", section),
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get_symbol(mod, "__stop_", section),
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};
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}
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static int codetag_module_init(struct codetag_type *cttype, struct module *mod)
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{
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struct codetag_range range;
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struct codetag_module *cmod;
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int err;
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range = get_section_range(mod, cttype->desc.section);
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if (!range.start || !range.stop) {
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pr_warn("Failed to load code tags of type %s from the module %s\n",
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cttype->desc.section,
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mod ? mod->name : "(built-in)");
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return -EINVAL;
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}
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/* Ignore empty ranges */
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if (range.start == range.stop)
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return 0;
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BUG_ON(range.start > range.stop);
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cmod = kmalloc(sizeof(*cmod), GFP_KERNEL);
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if (unlikely(!cmod))
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return -ENOMEM;
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cmod->mod = mod;
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cmod->range = range;
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down_write(&cttype->mod_lock);
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err = idr_alloc(&cttype->mod_idr, cmod, 0, 0, GFP_KERNEL);
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if (err >= 0)
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cttype->count += range_size(cttype, &range);
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up_write(&cttype->mod_lock);
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if (err < 0) {
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kfree(cmod);
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return err;
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}
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return 0;
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}
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#else /* CONFIG_MODULES */
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static int codetag_module_init(struct codetag_type *cttype, struct module *mod) { return 0; }
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#endif /* CONFIG_MODULES */
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struct codetag_type *
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codetag_register_type(const struct codetag_type_desc *desc)
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{
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struct codetag_type *cttype;
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int err;
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BUG_ON(desc->tag_size <= 0);
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cttype = kzalloc(sizeof(*cttype), GFP_KERNEL);
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if (unlikely(!cttype))
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return ERR_PTR(-ENOMEM);
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cttype->desc = *desc;
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idr_init(&cttype->mod_idr);
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init_rwsem(&cttype->mod_lock);
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err = codetag_module_init(cttype, NULL);
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if (unlikely(err)) {
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kfree(cttype);
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return ERR_PTR(err);
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}
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mutex_lock(&codetag_lock);
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list_add_tail(&cttype->link, &codetag_types);
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mutex_unlock(&codetag_lock);
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return cttype;
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}
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