| Message ID | 20240212213922.783301-11-surenb@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Memory allocation profiling | expand |
On Mon, Feb 12, 2024 at 01:38:56PM -0800, Suren Baghdasaryan wrote: > 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. > > 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> > --- > include/linux/codetag.h | 71 ++++++++++++++ > lib/Kconfig.debug | 4 + > lib/Makefile | 1 + > lib/codetag.c | 199 ++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 275 insertions(+) > create mode 100644 include/linux/codetag.h > create mode 100644 lib/codetag.c > > diff --git a/include/linux/codetag.h b/include/linux/codetag.h > new file mode 100644 > index 000000000000..a9d7adecc2a5 > --- /dev/null > +++ b/include/linux/codetag.h > @@ -0,0 +1,71 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * code tagging framework > + */ > +#ifndef _LINUX_CODETAG_H > +#define _LINUX_CODETAG_H > + > +#include <linux/types.h> > + > +struct codetag_iterator; > +struct codetag_type; > +struct seq_buf; > +struct module; > + > +/* > + * An instance of this structure is created in a special ELF section at every > + * code location being tagged. At runtime, the special section is treated as > + * an array of these. > + */ > +struct codetag { > + unsigned int flags; /* used in later patches */ > + unsigned int lineno; > + const char *modname; > + const char *function; > + const char *filename; > +} __aligned(8); > + > +union codetag_ref { > + struct codetag *ct; > +}; > + > +struct codetag_range { > + struct codetag *start; > + struct codetag *stop; > +}; > + > +struct codetag_module { > + struct module *mod; > + struct codetag_range range; > +}; > + > +struct codetag_type_desc { > + const char *section; > + size_t tag_size; > +}; > + > +struct codetag_iterator { > + struct codetag_type *cttype; > + struct codetag_module *cmod; > + unsigned long mod_id; > + struct codetag *ct; > +}; > + > +#define CODE_TAG_INIT { \ > + .modname = KBUILD_MODNAME, \ > + .function = __func__, \ > + .filename = __FILE__, \ > + .lineno = __LINE__, \ > + .flags = 0, \ > +} > + > +void codetag_lock_module_list(struct codetag_type *cttype, bool lock); > +struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype); > +struct codetag *codetag_next_ct(struct codetag_iterator *iter); > + > +void codetag_to_text(struct seq_buf *out, struct codetag *ct); > + > +struct codetag_type * > +codetag_register_type(const struct codetag_type_desc *desc); > + > +#endif /* _LINUX_CODETAG_H */ > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 975a07f9f1cc..0be2d00c3696 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -968,6 +968,10 @@ config DEBUG_STACKOVERFLOW > > If in doubt, say "N". > > +config CODE_TAGGING > + bool > + select KALLSYMS > + > source "lib/Kconfig.kasan" > source "lib/Kconfig.kfence" > source "lib/Kconfig.kmsan" > diff --git a/lib/Makefile b/lib/Makefile > index 6b09731d8e61..6b48b22fdfac 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -235,6 +235,7 @@ obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \ > of-reconfig-notifier-error-inject.o > obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o > > +obj-$(CONFIG_CODE_TAGGING) += codetag.o > lib-$(CONFIG_GENERIC_BUG) += bug.o > > obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o > diff --git a/lib/codetag.c b/lib/codetag.c > new file mode 100644 > index 000000000000..7708f8388e55 > --- /dev/null > +++ b/lib/codetag.c > @@ -0,0 +1,199 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +#include <linux/codetag.h> > +#include <linux/idr.h> > +#include <linux/kallsyms.h> > +#include <linux/module.h> > +#include <linux/seq_buf.h> > +#include <linux/slab.h> > + > +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; > +}; > + > +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) > +{ > + seq_buf_printf(out, "%s:%u module:%s func:%s", > + ct->filename, ct->lineno, > + ct->modname, ct->function); > +} Thank you for using seq_buf here! Also, will this need an EXPORT_SYMBOL_GPL()? > + > +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; > +} > + > +static void *get_symbol(struct module *mod, const char *prefix, const char *name) > +{ > + char buf[64]; Why is 64 enough? I was expecting KSYM_NAME_LEN here, but perhaps this is specialized enough to section names that it will not be a problem? If so, please document it clearly with a comment. > + int res; > + > + res = snprintf(buf, sizeof(buf), "%s%s", prefix, name); > + if (WARN_ON(res < 1 || res > sizeof(buf))) > + return NULL; Please use a seq_buf here instead of snprintf, which we're trying to get rid of. DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN); 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; > +} > + > +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; > +} > -- > 2.43.0.687.g38aa6559b0-goog >
On Mon, Feb 12, 2024 at 2:27 PM Kees Cook <keescook@chromium.org> wrote: > > On Mon, Feb 12, 2024 at 01:38:56PM -0800, Suren Baghdasaryan wrote: > > 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. > > > > 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> > > --- > > include/linux/codetag.h | 71 ++++++++++++++ > > lib/Kconfig.debug | 4 + > > lib/Makefile | 1 + > > lib/codetag.c | 199 ++++++++++++++++++++++++++++++++++++++++ > > 4 files changed, 275 insertions(+) > > create mode 100644 include/linux/codetag.h > > create mode 100644 lib/codetag.c > > > > diff --git a/include/linux/codetag.h b/include/linux/codetag.h > > new file mode 100644 > > index 000000000000..a9d7adecc2a5 > > --- /dev/null > > +++ b/include/linux/codetag.h > > @@ -0,0 +1,71 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > +/* > > + * code tagging framework > > + */ > > +#ifndef _LINUX_CODETAG_H > > +#define _LINUX_CODETAG_H > > + > > +#include <linux/types.h> > > + > > +struct codetag_iterator; > > +struct codetag_type; > > +struct seq_buf; > > +struct module; > > + > > +/* > > + * An instance of this structure is created in a special ELF section at every > > + * code location being tagged. At runtime, the special section is treated as > > + * an array of these. > > + */ > > +struct codetag { > > + unsigned int flags; /* used in later patches */ > > + unsigned int lineno; > > + const char *modname; > > + const char *function; > > + const char *filename; > > +} __aligned(8); > > + > > +union codetag_ref { > > + struct codetag *ct; > > +}; > > + > > +struct codetag_range { > > + struct codetag *start; > > + struct codetag *stop; > > +}; > > + > > +struct codetag_module { > > + struct module *mod; > > + struct codetag_range range; > > +}; > > + > > +struct codetag_type_desc { > > + const char *section; > > + size_t tag_size; > > +}; > > + > > +struct codetag_iterator { > > + struct codetag_type *cttype; > > + struct codetag_module *cmod; > > + unsigned long mod_id; > > + struct codetag *ct; > > +}; > > + > > +#define CODE_TAG_INIT { \ > > + .modname = KBUILD_MODNAME, \ > > + .function = __func__, \ > > + .filename = __FILE__, \ > > + .lineno = __LINE__, \ > > + .flags = 0, \ > > +} > > + > > +void codetag_lock_module_list(struct codetag_type *cttype, bool lock); > > +struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype); > > +struct codetag *codetag_next_ct(struct codetag_iterator *iter); > > + > > +void codetag_to_text(struct seq_buf *out, struct codetag *ct); > > + > > +struct codetag_type * > > +codetag_register_type(const struct codetag_type_desc *desc); > > + > > +#endif /* _LINUX_CODETAG_H */ > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 975a07f9f1cc..0be2d00c3696 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -968,6 +968,10 @@ config DEBUG_STACKOVERFLOW > > > > If in doubt, say "N". > > > > +config CODE_TAGGING > > + bool > > + select KALLSYMS > > + > > source "lib/Kconfig.kasan" > > source "lib/Kconfig.kfence" > > source "lib/Kconfig.kmsan" > > diff --git a/lib/Makefile b/lib/Makefile > > index 6b09731d8e61..6b48b22fdfac 100644 > > --- a/lib/Makefile > > +++ b/lib/Makefile > > @@ -235,6 +235,7 @@ obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \ > > of-reconfig-notifier-error-inject.o > > obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o > > > > +obj-$(CONFIG_CODE_TAGGING) += codetag.o > > lib-$(CONFIG_GENERIC_BUG) += bug.o > > > > obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o > > diff --git a/lib/codetag.c b/lib/codetag.c > > new file mode 100644 > > index 000000000000..7708f8388e55 > > --- /dev/null > > +++ b/lib/codetag.c > > @@ -0,0 +1,199 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +#include <linux/codetag.h> > > +#include <linux/idr.h> > > +#include <linux/kallsyms.h> > > +#include <linux/module.h> > > +#include <linux/seq_buf.h> > > +#include <linux/slab.h> > > + > > +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; > > +}; > > + > > +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) > > +{ > > + seq_buf_printf(out, "%s:%u module:%s func:%s", > > + ct->filename, ct->lineno, > > + ct->modname, ct->function); > > +} > > Thank you for using seq_buf here! > > Also, will this need an EXPORT_SYMBOL_GPL()? > > > + > > +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; > > +} > > + > > +static void *get_symbol(struct module *mod, const char *prefix, const char *name) > > +{ > > + char buf[64]; > > Why is 64 enough? I was expecting KSYM_NAME_LEN here, but perhaps this > is specialized enough to section names that it will not be a problem? This buffer is being used to hold the name of the section containing codetags appended with "__start_" or "__stop_" and the only current user is alloc_tag_init() which sets the section name to "alloc_tags". So, this buffer currently holds either "alloc_tags__start_" or "alloc_tags__stop_". When more codetag applications are added (like the ones we have shown in the original RFC [1]), there would be more section names. 64 was chosen as a big enough value to reasonably hold the section name with the suffix. But you are right, we should add a check for the section name size to ensure it always fits. Will add into my TODO list. [1] https://lore.kernel.org/all/20220830214919.53220-1-surenb@google.com/ > If so, please document it clearly with a comment. Will do. > > > + int res; > > + > > + res = snprintf(buf, sizeof(buf), "%s%s", prefix, name); > > + if (WARN_ON(res < 1 || res > sizeof(buf))) > > + return NULL; > > Please use a seq_buf here instead of snprintf, which we're trying to get > rid of. > > DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN); > char *buf; > > seq_buf_printf(sb, "%s%s", prefix, name); > if (seq_buf_has_overflowed(sb)) > return NULL; > > buf = seq_buf_str(sb); Will do. Thanks! > > > + > > + 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; > > +} > > + > > +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; > > +} > > -- > > 2.43.0.687.g38aa6559b0-goog > > > > -- > Kees Cook
On Mon, Feb 12, 2024 at 6:04 PM Suren Baghdasaryan <surenb@google.com> wrote: > > On Mon, Feb 12, 2024 at 2:27 PM Kees Cook <keescook@chromium.org> wrote: > > > > On Mon, Feb 12, 2024 at 01:38:56PM -0800, Suren Baghdasaryan wrote: > > > 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. > > > > > > 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> > > > --- > > > include/linux/codetag.h | 71 ++++++++++++++ > > > lib/Kconfig.debug | 4 + > > > lib/Makefile | 1 + > > > lib/codetag.c | 199 ++++++++++++++++++++++++++++++++++++++++ > > > 4 files changed, 275 insertions(+) > > > create mode 100644 include/linux/codetag.h > > > create mode 100644 lib/codetag.c > > > > > > diff --git a/include/linux/codetag.h b/include/linux/codetag.h > > > new file mode 100644 > > > index 000000000000..a9d7adecc2a5 > > > --- /dev/null > > > +++ b/include/linux/codetag.h > > > @@ -0,0 +1,71 @@ > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > +/* > > > + * code tagging framework > > > + */ > > > +#ifndef _LINUX_CODETAG_H > > > +#define _LINUX_CODETAG_H > > > + > > > +#include <linux/types.h> > > > + > > > +struct codetag_iterator; > > > +struct codetag_type; > > > +struct seq_buf; > > > +struct module; > > > + > > > +/* > > > + * An instance of this structure is created in a special ELF section at every > > > + * code location being tagged. At runtime, the special section is treated as > > > + * an array of these. > > > + */ > > > +struct codetag { > > > + unsigned int flags; /* used in later patches */ > > > + unsigned int lineno; > > > + const char *modname; > > > + const char *function; > > > + const char *filename; > > > +} __aligned(8); > > > + > > > +union codetag_ref { > > > + struct codetag *ct; > > > +}; > > > + > > > +struct codetag_range { > > > + struct codetag *start; > > > + struct codetag *stop; > > > +}; > > > + > > > +struct codetag_module { > > > + struct module *mod; > > > + struct codetag_range range; > > > +}; > > > + > > > +struct codetag_type_desc { > > > + const char *section; > > > + size_t tag_size; > > > +}; > > > + > > > +struct codetag_iterator { > > > + struct codetag_type *cttype; > > > + struct codetag_module *cmod; > > > + unsigned long mod_id; > > > + struct codetag *ct; > > > +}; > > > + > > > +#define CODE_TAG_INIT { \ > > > + .modname = KBUILD_MODNAME, \ > > > + .function = __func__, \ > > > + .filename = __FILE__, \ > > > + .lineno = __LINE__, \ > > > + .flags = 0, \ > > > +} > > > + > > > +void codetag_lock_module_list(struct codetag_type *cttype, bool lock); > > > +struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype); > > > +struct codetag *codetag_next_ct(struct codetag_iterator *iter); > > > + > > > +void codetag_to_text(struct seq_buf *out, struct codetag *ct); > > > + > > > +struct codetag_type * > > > +codetag_register_type(const struct codetag_type_desc *desc); > > > + > > > +#endif /* _LINUX_CODETAG_H */ > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > > index 975a07f9f1cc..0be2d00c3696 100644 > > > --- a/lib/Kconfig.debug > > > +++ b/lib/Kconfig.debug > > > @@ -968,6 +968,10 @@ config DEBUG_STACKOVERFLOW > > > > > > If in doubt, say "N". > > > > > > +config CODE_TAGGING > > > + bool > > > + select KALLSYMS > > > + > > > source "lib/Kconfig.kasan" > > > source "lib/Kconfig.kfence" > > > source "lib/Kconfig.kmsan" > > > diff --git a/lib/Makefile b/lib/Makefile > > > index 6b09731d8e61..6b48b22fdfac 100644 > > > --- a/lib/Makefile > > > +++ b/lib/Makefile > > > @@ -235,6 +235,7 @@ obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \ > > > of-reconfig-notifier-error-inject.o > > > obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o > > > > > > +obj-$(CONFIG_CODE_TAGGING) += codetag.o > > > lib-$(CONFIG_GENERIC_BUG) += bug.o > > > > > > obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o > > > diff --git a/lib/codetag.c b/lib/codetag.c > > > new file mode 100644 > > > index 000000000000..7708f8388e55 > > > --- /dev/null > > > +++ b/lib/codetag.c > > > @@ -0,0 +1,199 @@ > > > +// SPDX-License-Identifier: GPL-2.0-only > > > +#include <linux/codetag.h> > > > +#include <linux/idr.h> > > > +#include <linux/kallsyms.h> > > > +#include <linux/module.h> > > > +#include <linux/seq_buf.h> > > > +#include <linux/slab.h> > > > + > > > +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; > > > +}; > > > + > > > +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) > > > +{ > > > + seq_buf_printf(out, "%s:%u module:%s func:%s", > > > + ct->filename, ct->lineno, > > > + ct->modname, ct->function); > > > +} > > > > Thank you for using seq_buf here! > > > > Also, will this need an EXPORT_SYMBOL_GPL()? Missed this question. I don't think we need EXPORT_SYMBOL_GPL() here at least for now. Modules don't use these functions. The "alloc_tags" sections will be generated for each module at compile time but they themselves do not use it. > > > > > + > > > +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; > > > +} > > > + > > > +static void *get_symbol(struct module *mod, const char *prefix, const char *name) > > > +{ > > > + char buf[64]; > > > > Why is 64 enough? I was expecting KSYM_NAME_LEN here, but perhaps this > > is specialized enough to section names that it will not be a problem? > > This buffer is being used to hold the name of the section containing > codetags appended with "__start_" or "__stop_" and the only current > user is alloc_tag_init() which sets the section name to "alloc_tags". > So, this buffer currently holds either "alloc_tags__start_" or > "alloc_tags__stop_". When more codetag applications are added (like > the ones we have shown in the original RFC [1]), there would be more > section names. 64 was chosen as a big enough value to reasonably hold > the section name with the suffix. But you are right, we should add a > check for the section name size to ensure it always fits. Will add > into my TODO list. > > [1] https://lore.kernel.org/all/20220830214919.53220-1-surenb@google.com/ > > If so, please document it clearly with a comment. > > Will do. > > > > > > + int res; > > > + > > > + res = snprintf(buf, sizeof(buf), "%s%s", prefix, name); > > > + if (WARN_ON(res < 1 || res > sizeof(buf))) > > > + return NULL; > > > > Please use a seq_buf here instead of snprintf, which we're trying to get > > rid of. > > > > DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN); > > char *buf; > > > > seq_buf_printf(sb, "%s%s", prefix, name); > > if (seq_buf_has_overflowed(sb)) > > return NULL; > > > > buf = seq_buf_str(sb); > > Will do. Thanks! > > > > > > + > > > + 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; > > > +} > > > + > > > +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; > > > +} > > > -- > > > 2.43.0.687.g38aa6559b0-goog > > > > > > > -- > > Kees Cook
diff --git a/include/linux/codetag.h b/include/linux/codetag.h new file mode 100644 index 000000000000..a9d7adecc2a5 --- /dev/null +++ b/include/linux/codetag.h @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * code tagging framework + */ +#ifndef _LINUX_CODETAG_H +#define _LINUX_CODETAG_H + +#include <linux/types.h> + +struct codetag_iterator; +struct codetag_type; +struct seq_buf; +struct module; + +/* + * An instance of this structure is created in a special ELF section at every + * code location being tagged. At runtime, the special section is treated as + * an array of these. + */ +struct codetag { + unsigned int flags; /* used in later patches */ + unsigned int lineno; + const char *modname; + const char *function; + const char *filename; +} __aligned(8); + +union codetag_ref { + struct codetag *ct; +}; + +struct codetag_range { + struct codetag *start; + struct codetag *stop; +}; + +struct codetag_module { + struct module *mod; + struct codetag_range range; +}; + +struct codetag_type_desc { + const char *section; + size_t tag_size; +}; + +struct codetag_iterator { + struct codetag_type *cttype; + struct codetag_module *cmod; + unsigned long mod_id; + struct codetag *ct; +}; + +#define CODE_TAG_INIT { \ + .modname = KBUILD_MODNAME, \ + .function = __func__, \ + .filename = __FILE__, \ + .lineno = __LINE__, \ + .flags = 0, \ +} + +void codetag_lock_module_list(struct codetag_type *cttype, bool lock); +struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype); +struct codetag *codetag_next_ct(struct codetag_iterator *iter); + +void codetag_to_text(struct seq_buf *out, struct codetag *ct); + +struct codetag_type * +codetag_register_type(const struct codetag_type_desc *desc); + +#endif /* _LINUX_CODETAG_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 975a07f9f1cc..0be2d00c3696 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -968,6 +968,10 @@ config DEBUG_STACKOVERFLOW If in doubt, say "N". +config CODE_TAGGING + bool + select KALLSYMS + source "lib/Kconfig.kasan" source "lib/Kconfig.kfence" source "lib/Kconfig.kmsan" diff --git a/lib/Makefile b/lib/Makefile index 6b09731d8e61..6b48b22fdfac 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -235,6 +235,7 @@ obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \ of-reconfig-notifier-error-inject.o obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o +obj-$(CONFIG_CODE_TAGGING) += codetag.o lib-$(CONFIG_GENERIC_BUG) += bug.o obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o diff --git a/lib/codetag.c b/lib/codetag.c new file mode 100644 index 000000000000..7708f8388e55 --- /dev/null +++ b/lib/codetag.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/codetag.h> +#include <linux/idr.h> +#include <linux/kallsyms.h> +#include <linux/module.h> +#include <linux/seq_buf.h> +#include <linux/slab.h> + +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; +}; + +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) +{ + seq_buf_printf(out, "%s:%u module:%s func:%s", + ct->filename, ct->lineno, + ct->modname, 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; +} + +static void *get_symbol(struct module *mod, const char *prefix, const char *name) +{ + char buf[64]; + int res; + + res = snprintf(buf, sizeof(buf), "%s%s", prefix, name); + if (WARN_ON(res < 1 || res > sizeof(buf))) + return NULL; + + 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; +} + +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; +}