From 540adea3809f61115d2a1ea4ed6e627613452ba1 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Sat, 13 Jan 2018 02:55:03 +0900 Subject: error-injection: Separate error-injection from kprobe Since error-injection framework is not limited to be used by kprobes, nor bpf. Other kernel subsystems can use it freely for checking safeness of error-injection, e.g. livepatch, ftrace etc. So this separate error-injection framework from kprobes. Some differences has been made: - "kprobe" word is removed from any APIs/structures. - BPF_ALLOW_ERROR_INJECTION() is renamed to ALLOW_ERROR_INJECTION() since it is not limited for BPF too. - CONFIG_FUNCTION_ERROR_INJECTION is the config item of this feature. It is automatically enabled if the arch supports error injection feature for kprobe or ftrace etc. Signed-off-by: Masami Hiramatsu Reviewed-by: Josef Bacik Signed-off-by: Alexei Starovoitov --- lib/error-inject.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 213 insertions(+) create mode 100644 lib/error-inject.c (limited to 'lib/error-inject.c') diff --git a/lib/error-inject.c b/lib/error-inject.c new file mode 100644 index 000000000000..bccadcf3c981 --- /dev/null +++ b/lib/error-inject.c @@ -0,0 +1,213 @@ +// SPDX-License-Identifier: GPL-2.0 +// error-inject.c: Function-level error injection table +#include +#include +#include +#include +#include +#include +#include +#include + +/* Whitelist of symbols that can be overridden for error injection. */ +static LIST_HEAD(error_injection_list); +static DEFINE_MUTEX(ei_mutex); +struct ei_entry { + struct list_head list; + unsigned long start_addr; + unsigned long end_addr; + void *priv; +}; + +bool within_error_injection_list(unsigned long addr) +{ + struct ei_entry *ent; + bool ret = false; + + mutex_lock(&ei_mutex); + list_for_each_entry(ent, &error_injection_list, list) { + if (addr >= ent->start_addr && addr < ent->end_addr) { + ret = true; + break; + } + } + mutex_unlock(&ei_mutex); + return ret; +} + +/* + * Lookup and populate the error_injection_list. + * + * For safety reasons we only allow certain functions to be overridden with + * bpf_error_injection, so we need to populate the list of the symbols that have + * been marked as safe for overriding. + */ +static void populate_error_injection_list(unsigned long *start, + unsigned long *end, void *priv) +{ + unsigned long *iter; + struct ei_entry *ent; + unsigned long entry, offset = 0, size = 0; + + mutex_lock(&ei_mutex); + for (iter = start; iter < end; iter++) { + entry = arch_deref_entry_point((void *)*iter); + + if (!kernel_text_address(entry) || + !kallsyms_lookup_size_offset(entry, &size, &offset)) { + pr_err("Failed to find error inject entry at %p\n", + (void *)entry); + continue; + } + + ent = kmalloc(sizeof(*ent), GFP_KERNEL); + if (!ent) + break; + ent->start_addr = entry; + ent->end_addr = entry + size; + ent->priv = priv; + INIT_LIST_HEAD(&ent->list); + list_add_tail(&ent->list, &error_injection_list); + } + mutex_unlock(&ei_mutex); +} + +/* Markers of the _error_inject_whitelist section */ +extern unsigned long __start_error_injection_whitelist[]; +extern unsigned long __stop_error_injection_whitelist[]; + +static void __init populate_kernel_ei_list(void) +{ + populate_error_injection_list(__start_error_injection_whitelist, + __stop_error_injection_whitelist, + NULL); +} + +#ifdef CONFIG_MODULES +static void module_load_ei_list(struct module *mod) +{ + if (!mod->num_ei_funcs) + return; + + populate_error_injection_list(mod->ei_funcs, + mod->ei_funcs + mod->num_ei_funcs, mod); +} + +static void module_unload_ei_list(struct module *mod) +{ + struct ei_entry *ent, *n; + + if (!mod->num_ei_funcs) + return; + + mutex_lock(&ei_mutex); + list_for_each_entry_safe(ent, n, &error_injection_list, list) { + if (ent->priv == mod) { + list_del_init(&ent->list); + kfree(ent); + } + } + mutex_unlock(&ei_mutex); +} + +/* Module notifier call back, checking error injection table on the module */ +static int ei_module_callback(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct module *mod = data; + + if (val == MODULE_STATE_COMING) + module_load_ei_list(mod); + else if (val == MODULE_STATE_GOING) + module_unload_ei_list(mod); + + return NOTIFY_DONE; +} + +static struct notifier_block ei_module_nb = { + .notifier_call = ei_module_callback, + .priority = 0 +}; + +static __init int module_ei_init(void) +{ + return register_module_notifier(&ei_module_nb); +} +#else /* !CONFIG_MODULES */ +#define module_ei_init() (0) +#endif + +/* + * error_injection/whitelist -- shows which functions can be overridden for + * error injection. + */ +static void *ei_seq_start(struct seq_file *m, loff_t *pos) +{ + mutex_lock(&ei_mutex); + return seq_list_start(&error_injection_list, *pos); +} + +static void ei_seq_stop(struct seq_file *m, void *v) +{ + mutex_unlock(&ei_mutex); +} + +static void *ei_seq_next(struct seq_file *m, void *v, loff_t *pos) +{ + return seq_list_next(v, &error_injection_list, pos); +} + +static int ei_seq_show(struct seq_file *m, void *v) +{ + struct ei_entry *ent = list_entry(v, struct ei_entry, list); + + seq_printf(m, "%pf\n", (void *)ent->start_addr); + return 0; +} + +static const struct seq_operations ei_seq_ops = { + .start = ei_seq_start, + .next = ei_seq_next, + .stop = ei_seq_stop, + .show = ei_seq_show, +}; + +static int ei_open(struct inode *inode, struct file *filp) +{ + return seq_open(filp, &ei_seq_ops); +} + +static const struct file_operations debugfs_ei_ops = { + .open = ei_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + +static int __init ei_debugfs_init(void) +{ + struct dentry *dir, *file; + + dir = debugfs_create_dir("error_injection", NULL); + if (!dir) + return -ENOMEM; + + file = debugfs_create_file("list", 0444, dir, NULL, &debugfs_ei_ops); + if (!file) { + debugfs_remove(dir); + return -ENOMEM; + } + + return 0; +} + +static int __init init_error_injection(void) +{ + populate_kernel_ei_list(); + + if (!module_ei_init()) + ei_debugfs_init(); + + return 0; +} +late_initcall(init_error_injection); -- cgit v1.2.3-70-g09d2 From 663faf9f7beeaca4ad0176bb96c776eed9dad0c5 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Sat, 13 Jan 2018 02:55:33 +0900 Subject: error-injection: Add injectable error types Add injectable error types for each error-injectable function. One motivation of error injection test is to find software flaws, mistakes or mis-handlings of expectable errors. If we find such flaws by the test, that is a program bug, so we need to fix it. But if the tester miss input the error (e.g. just return success code without processing anything), it causes unexpected behavior even if the caller is correctly programmed to handle any errors. That is not what we want to test by error injection. To clarify what type of errors the caller must expect for each injectable function, this introduces injectable error types: - EI_ETYPE_NULL : means the function will return NULL if it fails. No ERR_PTR, just a NULL. - EI_ETYPE_ERRNO : means the function will return -ERRNO if it fails. - EI_ETYPE_ERRNO_NULL : means the function will return -ERRNO (ERR_PTR) or NULL. ALLOW_ERROR_INJECTION() macro is expanded to get one of NULL, ERRNO, ERRNO_NULL to record the error type for each function. e.g. ALLOW_ERROR_INJECTION(open_ctree, ERRNO) This error types are shown in debugfs as below. ==== / # cat /sys/kernel/debug/error_injection/list open_ctree [btrfs] ERRNO io_ctl_init [btrfs] ERRNO ==== Signed-off-by: Masami Hiramatsu Reviewed-by: Josef Bacik Signed-off-by: Alexei Starovoitov --- fs/btrfs/disk-io.c | 2 +- fs/btrfs/free-space-cache.c | 2 +- include/asm-generic/error-injection.h | 23 +++++++++++++++---- include/asm-generic/vmlinux.lds.h | 2 +- include/linux/error-injection.h | 6 +++++ include/linux/module.h | 3 ++- lib/error-inject.c | 43 +++++++++++++++++++++++++++++------ 7 files changed, 66 insertions(+), 15 deletions(-) (limited to 'lib/error-inject.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9798e21ebe9d..83e2349e1362 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3124,7 +3124,7 @@ recovery_tree_root: goto fail_block_groups; goto retry_root_backup; } -ALLOW_ERROR_INJECTION(open_ctree); +ALLOW_ERROR_INJECTION(open_ctree, ERRNO); static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate) { diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index ef847699031a..586bb06472bb 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -333,7 +333,7 @@ static int io_ctl_init(struct btrfs_io_ctl *io_ctl, struct inode *inode, return 0; } -ALLOW_ERROR_INJECTION(io_ctl_init); +ALLOW_ERROR_INJECTION(io_ctl_init, ERRNO); static void io_ctl_free(struct btrfs_io_ctl *io_ctl) { diff --git a/include/asm-generic/error-injection.h b/include/asm-generic/error-injection.h index 08352c9d9f97..296c65442f00 100644 --- a/include/asm-generic/error-injection.h +++ b/include/asm-generic/error-injection.h @@ -3,17 +3,32 @@ #define _ASM_GENERIC_ERROR_INJECTION_H #if defined(__KERNEL__) && !defined(__ASSEMBLY__) +enum { + EI_ETYPE_NONE, /* Dummy value for undefined case */ + EI_ETYPE_NULL, /* Return NULL if failure */ + EI_ETYPE_ERRNO, /* Return -ERRNO if failure */ + EI_ETYPE_ERRNO_NULL, /* Return -ERRNO or NULL if failure */ +}; + +struct error_injection_entry { + unsigned long addr; + int etype; +}; + #ifdef CONFIG_FUNCTION_ERROR_INJECTION /* * Whitelist ganerating macro. Specify functions which can be * error-injectable using this macro. */ -#define ALLOW_ERROR_INJECTION(fname) \ -static unsigned long __used \ +#define ALLOW_ERROR_INJECTION(fname, _etype) \ +static struct error_injection_entry __used \ __attribute__((__section__("_error_injection_whitelist"))) \ - _eil_addr_##fname = (unsigned long)fname; + _eil_addr_##fname = { \ + .addr = (unsigned long)fname, \ + .etype = EI_ETYPE_##_etype, \ + }; #else -#define ALLOW_ERROR_INJECTION(fname) +#define ALLOW_ERROR_INJECTION(fname, _etype) #endif #endif diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index f2068cca5206..ebe544e048cd 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -137,7 +137,7 @@ #endif #ifdef CONFIG_FUNCTION_ERROR_INJECTION -#define ERROR_INJECT_WHITELIST() . = ALIGN(8); \ +#define ERROR_INJECT_WHITELIST() STRUCT_ALIGN(); \ VMLINUX_SYMBOL(__start_error_injection_whitelist) = .;\ KEEP(*(_error_injection_whitelist)) \ VMLINUX_SYMBOL(__stop_error_injection_whitelist) = .; diff --git a/include/linux/error-injection.h b/include/linux/error-injection.h index 130a67c50dac..280c61ecbf20 100644 --- a/include/linux/error-injection.h +++ b/include/linux/error-injection.h @@ -7,6 +7,7 @@ #include extern bool within_error_injection_list(unsigned long addr); +extern int get_injectable_error_type(unsigned long addr); #else /* !CONFIG_FUNCTION_ERROR_INJECTION */ @@ -16,6 +17,11 @@ static inline bool within_error_injection_list(unsigned long addr) return false; } +static inline int get_injectable_error_type(unsigned long addr) +{ + return EI_ETYPE_NONE; +} + #endif #endif /* _LINUX_ERROR_INJECTION_H */ diff --git a/include/linux/module.h b/include/linux/module.h index 792e51d83bda..9642d3116718 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -19,6 +19,7 @@ #include #include #include +#include #include #include @@ -477,8 +478,8 @@ struct module { #endif #ifdef CONFIG_FUNCTION_ERROR_INJECTION + struct error_injection_entry *ei_funcs; unsigned int num_ei_funcs; - unsigned long *ei_funcs; #endif } ____cacheline_aligned __randomize_layout; #ifndef MODULE_ARCH_INIT diff --git a/lib/error-inject.c b/lib/error-inject.c index bccadcf3c981..c0d4600f4896 100644 --- a/lib/error-inject.c +++ b/lib/error-inject.c @@ -16,6 +16,7 @@ struct ei_entry { struct list_head list; unsigned long start_addr; unsigned long end_addr; + int etype; void *priv; }; @@ -35,6 +36,17 @@ bool within_error_injection_list(unsigned long addr) return ret; } +int get_injectable_error_type(unsigned long addr) +{ + struct ei_entry *ent; + + list_for_each_entry(ent, &error_injection_list, list) { + if (addr >= ent->start_addr && addr < ent->end_addr) + return ent->etype; + } + return EI_ETYPE_NONE; +} + /* * Lookup and populate the error_injection_list. * @@ -42,16 +54,17 @@ bool within_error_injection_list(unsigned long addr) * bpf_error_injection, so we need to populate the list of the symbols that have * been marked as safe for overriding. */ -static void populate_error_injection_list(unsigned long *start, - unsigned long *end, void *priv) +static void populate_error_injection_list(struct error_injection_entry *start, + struct error_injection_entry *end, + void *priv) { - unsigned long *iter; + struct error_injection_entry *iter; struct ei_entry *ent; unsigned long entry, offset = 0, size = 0; mutex_lock(&ei_mutex); for (iter = start; iter < end; iter++) { - entry = arch_deref_entry_point((void *)*iter); + entry = arch_deref_entry_point((void *)iter->addr); if (!kernel_text_address(entry) || !kallsyms_lookup_size_offset(entry, &size, &offset)) { @@ -65,6 +78,7 @@ static void populate_error_injection_list(unsigned long *start, break; ent->start_addr = entry; ent->end_addr = entry + size; + ent->etype = iter->etype; ent->priv = priv; INIT_LIST_HEAD(&ent->list); list_add_tail(&ent->list, &error_injection_list); @@ -73,8 +87,8 @@ static void populate_error_injection_list(unsigned long *start, } /* Markers of the _error_inject_whitelist section */ -extern unsigned long __start_error_injection_whitelist[]; -extern unsigned long __stop_error_injection_whitelist[]; +extern struct error_injection_entry __start_error_injection_whitelist[]; +extern struct error_injection_entry __stop_error_injection_whitelist[]; static void __init populate_kernel_ei_list(void) { @@ -157,11 +171,26 @@ static void *ei_seq_next(struct seq_file *m, void *v, loff_t *pos) return seq_list_next(v, &error_injection_list, pos); } +static const char *error_type_string(int etype) +{ + switch (etype) { + case EI_ETYPE_NULL: + return "NULL"; + case EI_ETYPE_ERRNO: + return "ERRNO"; + case EI_ETYPE_ERRNO_NULL: + return "ERRNO_NULL"; + default: + return "(unknown)"; + } +} + static int ei_seq_show(struct seq_file *m, void *v) { struct ei_entry *ent = list_entry(v, struct ei_entry, list); - seq_printf(m, "%pf\n", (void *)ent->start_addr); + seq_printf(m, "%pf\t%s\n", (void *)ent->start_addr, + error_type_string(ent->etype)); return 0; } -- cgit v1.2.3-70-g09d2