diff options
author | Kent Overstreet <kent.overstreet@linux.dev> | 2022-07-21 14:07:49 -0400 |
---|---|---|
committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-09-11 01:29:28 -0400 |
commit | b0f836cf2324fc5e2fba4a1cac7fa65a3bd741f1 (patch) | |
tree | 3af6105b6346ace233efc9f73b309153cae60dec /lib | |
parent | f70000d0b066a4d4562dbb270e4ab3f793d3c2a6 (diff) |
Code tagging based fault injection
This adds a new fault injection capability, based on code tagging.
To use, simply insert somewhere in your code
dynamic_fault("fault_class_name")
and check whether it returns true - if so, inject the error.
For example
if (dynamic_fault("init"))
return -EINVAL;
There's no need to define faults elsewhere, as with
include/linux/fault-injection.h. Faults show up in debugfs, under
/sys/kernel/debug/dynamic_faults, and can be selected based on
file/module/function/line number/class, and enabled permanently, or in
oneshot mode, or with a specified frequency.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Kconfig.debug | 6 | ||||
-rw-r--r-- | lib/Makefile | 2 | ||||
-rw-r--r-- | lib/dynamic_fault.c | 371 |
3 files changed, 379 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index e97527ef37e6..a19ec6fd7e8e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2036,6 +2036,12 @@ config FAULT_INJECTION_STACKTRACE_FILTER help Provide stacktrace filter for fault-injection capabilities +config CODETAG_FAULT_INJECTION + bool "Code tagging based fault injection" + select CODE_TAGGING + help + Dynamic fault injection based on code tagging + config ARCH_HAS_KCOV bool help diff --git a/lib/Makefile b/lib/Makefile index 7dc3a7216515..fb1d209398f7 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -229,6 +229,8 @@ obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o obj-$(CONFIG_CODE_TAGGING) += codetag.o obj-$(CONFIG_MEM_ALLOC_PROFILING) += alloc_tag.o +obj-$(CONFIG_CODETAG_FAULT_INJECTION) += dynamic_fault.o + lib-$(CONFIG_GENERIC_BUG) += bug.o obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o diff --git a/lib/dynamic_fault.c b/lib/dynamic_fault.c new file mode 100644 index 000000000000..c923743596d7 --- /dev/null +++ b/lib/dynamic_fault.c @@ -0,0 +1,371 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include <linux/ctype.h> +#include <linux/debugfs.h> +#include <linux/dynamic_fault.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/seq_buf.h> + +static struct codetag_type *cttype; + +bool __dynamic_fault_enabled(struct dfault *df) +{ + union dfault_state old, new; + unsigned int v = df->state.v; + bool ret; + + do { + old.v = new.v = v; + + if (new.enabled == DFAULT_disabled) + return false; + + ret = df->frequency + ? ++new.count >= df->frequency + : true; + if (ret) + new.count = 0; + if (ret && new.enabled == DFAULT_oneshot) + new.enabled = DFAULT_disabled; + } while ((v = cmpxchg(&df->state.v, old.v, new.v)) != old.v); + + if (ret) + pr_debug("returned true for %s:%u", df->tag.filename, df->tag.lineno); + + return ret; +} +EXPORT_SYMBOL(__dynamic_fault_enabled); + +static const char * const dfault_state_strs[] = { +#define x(n) #n, + DFAULT_STATES() +#undef x + NULL +}; + +static void dynamic_fault_to_text(struct seq_buf *out, struct dfault *df) +{ + codetag_to_text(out, &df->tag); + seq_buf_printf(out, "class:%s %s \"", df->class, + dfault_state_strs[df->state.enabled]); +} + +struct dfault_query { + struct codetag_query q; + + bool set_enabled:1; + unsigned int enabled:2; + + bool set_frequency:1; + unsigned int frequency; +}; + +/* + * Search the tables for _dfault's which match the given + * `query' and apply the `flags' and `mask' to them. Tells + * the user which dfault's were changed, or whether none + * were matched. + */ +static int dfault_change(struct dfault_query *query) +{ + struct codetag_iterator ct_iter = codetag_get_ct_iter(cttype); + struct codetag *ct; + unsigned int nfound = 0; + + codetag_lock_module_list(cttype, true); + + while ((ct = codetag_next_ct(&ct_iter))) { + struct dfault *df = container_of(ct, struct dfault, tag); + + if (!codetag_matches_query(&query->q, ct, ct_iter.cmod, df->class)) + continue; + + if (query->set_enabled && + query->enabled != df->state.enabled) { + if (query->enabled != DFAULT_disabled) + static_key_slow_inc(&df->enabled.key); + else if (df->state.enabled != DFAULT_disabled) + static_key_slow_dec(&df->enabled.key); + + df->state.enabled = query->enabled; + } + + if (query->set_frequency) + df->frequency = query->frequency; + + pr_debug("changed %s:%d [%s]%s #%d %s", + df->tag.filename, df->tag.lineno, df->tag.modname, + df->tag.function, query->q.cur_index, + dfault_state_strs[df->state.enabled]); + + nfound++; + } + + pr_debug("dfault: %u matches", nfound); + + codetag_lock_module_list(cttype, false); + + return nfound ? 0 : -ENOENT; +} + +#define DFAULT_TOKENS() \ + x(disable, 0) \ + x(enable, 0) \ + x(oneshot, 0) \ + x(frequency, 1) + +enum dfault_token { +#define x(name, nr_args) TOK_##name, + DFAULT_TOKENS() +#undef x +}; + +static const char * const dfault_token_strs[] = { +#define x(name, nr_args) #name, + DFAULT_TOKENS() +#undef x + NULL +}; + +static unsigned int dfault_token_nr_args[] = { +#define x(name, nr_args) nr_args, + DFAULT_TOKENS() +#undef x +}; + +static enum dfault_token str_to_token(const char *word, unsigned int nr_words) +{ + int tok = match_string(dfault_token_strs, ARRAY_SIZE(dfault_token_strs), word); + + if (tok < 0) { + pr_debug("unknown keyword \"%s\"", word); + return tok; + } + + if (nr_words < dfault_token_nr_args[tok]) { + pr_debug("insufficient arguments to \"%s\"", word); + return -EINVAL; + } + + return tok; +} + +static int dfault_parse_command(struct dfault_query *query, + enum dfault_token tok, + char *words[], size_t nr_words) +{ + unsigned int i = 0; + int ret; + + switch (tok) { + case TOK_disable: + query->set_enabled = true; + query->enabled = DFAULT_disabled; + break; + case TOK_enable: + query->set_enabled = true; + query->enabled = DFAULT_enabled; + break; + case TOK_oneshot: + query->set_enabled = true; + query->enabled = DFAULT_oneshot; + break; + case TOK_frequency: + query->set_frequency = 1; + ret = kstrtouint(words[i++], 10, &query->frequency); + if (ret) + return ret; + + if (!query->set_enabled) { + query->set_enabled = 1; + query->enabled = DFAULT_enabled; + } + break; + } + + return i; +} + +static int dynamic_fault_store(char *buf) +{ + struct dfault_query query = { NULL }; +#define MAXWORDS 9 + char *tok, *words[MAXWORDS]; + int ret, nr_words, i = 0; + + buf = codetag_query_parse(&query.q, buf); + if (IS_ERR(buf)) + return PTR_ERR(buf); + + while ((tok = strsep_no_empty(&buf, " \t\r\n"))) { + if (nr_words == ARRAY_SIZE(words)) + return -EINVAL; /* ran out of words[] before bytes */ + words[nr_words++] = tok; + } + + while (i < nr_words) { + const char *tok_str = words[i++]; + enum dfault_token tok = str_to_token(tok_str, nr_words - i); + + if (tok < 0) + return tok; + + ret = dfault_parse_command(&query, tok, words + i, nr_words - i); + if (ret < 0) + return ret; + + i += ret; + BUG_ON(i > nr_words); + } + + pr_debug("q->function=\"%s\" q->filename=\"%s\" " + "q->module=\"%s\" q->line=%u-%u\n q->index=%u-%u", + query.q.function, query.q.filename, query.q.module, + query.q.first_line, query.q.last_line, + query.q.first_index, query.q.last_index); + + ret = dfault_change(&query); + if (ret < 0) + return ret; + + return 0; +} + +struct dfault_iter { + struct codetag_iterator ct_iter; + + struct seq_buf buf; + char rawbuf[4096]; +}; + +static int dfault_open(struct inode *inode, struct file *file) +{ + struct dfault_iter *iter; + + iter = kzalloc(sizeof(*iter), GFP_KERNEL); + if (!iter) + return -ENOMEM; + + codetag_lock_module_list(cttype, true); + iter->ct_iter = codetag_get_ct_iter(cttype); + codetag_lock_module_list(cttype, false); + + file->private_data = iter; + seq_buf_init(&iter->buf, iter->rawbuf, sizeof(iter->rawbuf)); + return 0; +} + +static int dfault_release(struct inode *inode, struct file *file) +{ + struct dfault_iter *iter = file->private_data; + + kfree(iter); + return 0; +} + +struct user_buf { + char __user *buf; /* destination user buffer */ + size_t size; /* size of requested read */ + ssize_t ret; /* bytes read so far */ +}; + +static int flush_ubuf(struct user_buf *dst, struct seq_buf *src) +{ + if (src->len) { + size_t bytes = min_t(size_t, src->len, dst->size); + int err = copy_to_user(dst->buf, src->buffer, bytes); + + if (err) + return err; + + dst->ret += bytes; + dst->buf += bytes; + dst->size -= bytes; + src->len -= bytes; + memmove(src->buffer, src->buffer + bytes, src->len); + } + + return 0; +} + +static ssize_t dfault_read(struct file *file, char __user *ubuf, + size_t size, loff_t *ppos) +{ + struct dfault_iter *iter = file->private_data; + struct user_buf buf = { .buf = ubuf, .size = size }; + struct codetag *ct; + struct dfault *df; + int err; + + codetag_lock_module_list(iter->ct_iter.cttype, true); + while (1) { + err = flush_ubuf(&buf, &iter->buf); + if (err || !buf.size) + break; + + ct = codetag_next_ct(&iter->ct_iter); + if (!ct) + break; + + df = container_of(ct, struct dfault, tag); + dynamic_fault_to_text(&iter->buf, df); + seq_buf_putc(&iter->buf, '\n'); + } + codetag_lock_module_list(iter->ct_iter.cttype, false); + + return err ?: buf.ret; +} + +/* + * File_ops->write method for <debugfs>/dynamic_fault/conrol. Gathers the + * command text from userspace, parses and executes it. + */ +static ssize_t dfault_write(struct file *file, const char __user *ubuf, + size_t len, loff_t *offp) +{ + char tmpbuf[256]; + + if (len == 0) + return 0; + /* we don't check *offp -- multiple writes() are allowed */ + if (len > sizeof(tmpbuf)-1) + return -E2BIG; + if (copy_from_user(tmpbuf, ubuf, len)) + return -EFAULT; + tmpbuf[len] = '\0'; + pr_debug("read %zu bytes from userspace", len); + + dynamic_fault_store(tmpbuf); + + *offp += len; + return len; +} + +static const struct file_operations dfault_ops = { + .owner = THIS_MODULE, + .open = dfault_open, + .release = dfault_release, + .read = dfault_read, + .write = dfault_write +}; + +static int __init dynamic_fault_init(void) +{ + const struct codetag_type_desc desc = { + .section = "dynamic_fault_tags", + .tag_size = sizeof(struct dfault), + }; + struct dentry *debugfs_file; + + cttype = codetag_register_type(&desc); + if (IS_ERR_OR_NULL(cttype)) + return PTR_ERR(cttype); + + debugfs_file = debugfs_create_file("dynamic_faults", 0666, NULL, NULL, &dfault_ops); + if (IS_ERR(debugfs_file)) + return PTR_ERR(debugfs_file); + + return 0; +} +module_init(dynamic_fault_init); |