[PATCH bpf-next v3 3/5] error-injection: Separate error-injection from kprobe

Masami Hiramatsu
2018-01-10T10:18:05Z

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 <mhiramat@kernel.org>
---
Changes in v3:
- Fix a build error for asmlinkage on i386 by including compiler.h
- Fix "CONFIG_FUNCTION_ERROR_INJECT" typo.
- Separate CONFIG_MODULES dependent code
- Add CONFIG_KPROBES dependency for arch_deref_entry_point()
- Call error-injection init function in late_initcall stage.
- Fix read-side mutex lock
- Some cosmetic cleanups
---
arch/Kconfig | 2
arch/x86/Kconfig | 2
arch/x86/include/asm/error-injection.h | 13 ++
arch/x86/kernel/kprobes/core.c | 14 --
arch/x86/lib/Makefile | 1
arch/x86/lib/error-inject.c | 19 +++
fs/btrfs/disk-io.c | 2
fs/btrfs/free-space-cache.c | 2
include/asm-generic/error-injection.h | 20 +++
include/asm-generic/vmlinux.lds.h | 14 +-
include/linux/bpf.h | 12 --
include/linux/error-injection.h | 21 +++
include/linux/kprobes.h | 1
include/linux/module.h | 6 -
kernel/kprobes.c | 163 ------------------------
kernel/module.c | 8 +
kernel/trace/Kconfig | 2
kernel/trace/bpf_trace.c | 2
kernel/trace/trace_kprobe.c | 3
lib/Kconfig.debug | 4 +
lib/Makefile | 1
lib/error-inject.c | 213 ++++++++++++++++++++++++++++++++
22 files changed, 315 insertions(+), 210 deletions(-)
create mode 100644 arch/x86/include/asm/error-injection.h
create mode 100644 arch/x86/lib/error-inject.c
create mode 100644 include/asm-generic/error-injection.h
create mode 100644 include/linux/error-injection.h
create mode 100644 lib/error-inject.c

diff --git a/arch/Kconfig b/arch/Kconfig
index d3f4aaf9cb7a..97376accfb14 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -196,7 +196,7 @@ config HAVE_OPTPROBES
config HAVE_KPROBES_ON_FTRACE
bool

-config HAVE_KPROBE_OVERRIDE
+config HAVE_FUNCTION_ERROR_INJECTION
bool

config HAVE_NMI
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 45dc6233f2b9..366b19cb79b7 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -154,7 +154,7 @@ config X86
select HAVE_KERNEL_XZ
select HAVE_KPROBES
select HAVE_KPROBES_ON_FTRACE
- select HAVE_KPROBE_OVERRIDE
+ select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
select HAVE_KVM
select HAVE_LIVEPATCH if X86_64
diff --git a/arch/x86/include/asm/error-injection.h b/arch/x86/include/asm/error-injection.h
new file mode 100644
index 000000000000..47b7a1296245
--- /dev/null
+++ b/arch/x86/include/asm/error-injection.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ERROR_INJECTION_H
+#define _ASM_ERROR_INJECTION_H
+
+#include <linux/compiler.h>
+#include <linux/linkage.h>
+#include <asm/ptrace.h>
+#include <asm-generic/error-injection.h>
+
+asmlinkage void just_return_func(void);
+void override_function_with_return(struct pt_regs *regs);
+
+#endif /* _ASM_ERROR_INJECTION_H */
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index b02a377d5905..bd36f3c33cd0 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1183,17 +1183,3 @@ int arch_trampoline_kprobe(struct kprobe *p)
{
return 0;
}
-
-asmlinkage void override_func(void);
-asm(
- ".type override_func, @function\n"
- "override_func:\n"
- " ret\n"
- ".size override_func, .-override_func\n"
-);
-
-void arch_kprobe_override_function(struct pt_regs *regs)
-{
- regs->ip = (unsigned long)&override_func;
-}
-NOKPROBE_SYMBOL(arch_kprobe_override_function);
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 7b181b61170e..171377b83be1 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -26,6 +26,7 @@ lib-y += memcpy_$(BITS).o
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
+lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o

diff --git a/arch/x86/lib/error-inject.c b/arch/x86/lib/error-inject.c
new file mode 100644
index 000000000000..7b881d03d0dd
--- /dev/null
+++ b/arch/x86/lib/error-inject.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/error-injection.h>
+#include <linux/kprobes.h>
+
+asmlinkage void just_return_func(void);
+
+asm(
+ ".type just_return_func, @function\n"
+ "just_return_func:\n"
+ " ret\n"
+ ".size just_return_func, .-just_return_func\n"
+);
+
+void override_function_with_return(struct pt_regs *regs)
+{
+ regs->ip = (unsigned long)&just_return_func;
+}
+NOKPROBE_SYMBOL(override_function_with_return);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5da18ebc9222..5c540129ad81 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3124,7 +3124,7 @@ int open_ctree(struct super_block *sb,
goto fail_block_groups;
goto retry_root_backup;
}
-BPF_ALLOW_ERROR_INJECTION(open_ctree);
+ALLOW_ERROR_INJECTION(open_ctree);

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 fb1382893bfc..2a75e088b215 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;
}
-BPF_ALLOW_ERROR_INJECTION(io_ctl_init);
+ALLOW_ERROR_INJECTION(io_ctl_init);

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
new file mode 100644
index 000000000000..08352c9d9f97
--- /dev/null
+++ b/include/asm-generic/error-injection.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_ERROR_INJECTION_H
+#define _ASM_GENERIC_ERROR_INJECTION_H
+
+#if defined(__KERNEL__) && !defined(__ASSEMBLY__)
+#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 \
+ __attribute__((__section__("_error_injection_whitelist"))) \
+ _eil_addr_##fname = (unsigned long)fname;
+#else
+#define ALLOW_ERROR_INJECTION(fname)
+#endif
+#endif
+
+#endif /* _ASM_GENERIC_ERROR_INJECTION_H */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index a2e8582d094a..f2068cca5206 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -136,13 +136,13 @@
#define KPROBE_BLACKLIST()
#endif

-#ifdef CONFIG_BPF_KPROBE_OVERRIDE
-#define ERROR_INJECT_LIST() . = ALIGN(8); \
- VMLINUX_SYMBOL(__start_kprobe_error_inject_list) = .; \
- KEEP(*(_kprobe_error_inject_list)) \
- VMLINUX_SYMBOL(__stop_kprobe_error_inject_list) = .;
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+#define ERROR_INJECT_WHITELIST() . = ALIGN(8); \
+ VMLINUX_SYMBOL(__start_error_injection_whitelist) = .;\
+ KEEP(*(_error_injection_whitelist)) \
+ VMLINUX_SYMBOL(__stop_error_injection_whitelist) = .;
#else
-#define ERROR_INJECT_LIST()
+#define ERROR_INJECT_WHITELIST()
#endif

#ifdef CONFIG_EVENT_TRACING
@@ -573,7 +573,7 @@
FTRACE_EVENTS() \
TRACE_SYSCALLS() \
KPROBE_BLACKLIST() \
- ERROR_INJECT_LIST() \
+ ERROR_INJECT_WHITELIST() \
MEM_DISCARD(init.rodata) \
CLK_OF_TABLES() \
RESERVEDMEM_OF_TABLES() \
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 9e03046d1df2..ea865bb9f676 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -16,6 +16,7 @@
#include <linux/rbtree_latch.h>
#include <linux/numa.h>
#include <linux/wait.h>
+#include <linux/error-injection.h>

struct bpf_verifier_env;
struct perf_event;
@@ -593,15 +594,4 @@ extern const struct bpf_func_proto bpf_sock_map_update_proto;
void bpf_user_rnd_init_once(void);
u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);

-#if defined(__KERNEL__) && !defined(__ASSEMBLY__)
-#ifdef CONFIG_BPF_KPROBE_OVERRIDE
-#define BPF_ALLOW_ERROR_INJECTION(fname) \
-static unsigned long __used \
- __attribute__((__section__("_kprobe_error_inject_list"))) \
- _eil_addr_##fname = (unsigned long)fname;
-#else
-#define BPF_ALLOW_ERROR_INJECTION(fname)
-#endif
-#endif
-
#endif /* _LINUX_BPF_H */
diff --git a/include/linux/error-injection.h b/include/linux/error-injection.h
new file mode 100644
index 000000000000..130a67c50dac
--- /dev/null
+++ b/include/linux/error-injection.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_ERROR_INJECTION_H
+#define _LINUX_ERROR_INJECTION_H
+
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+
+#include <asm/error-injection.h>
+
+extern bool within_error_injection_list(unsigned long addr);
+
+#else /* !CONFIG_FUNCTION_ERROR_INJECTION */
+
+#include <asm-generic/error-injection.h>
+static inline bool within_error_injection_list(unsigned long addr)
+{
+ return false;
+}
+
+#endif
+
+#endif /* _LINUX_ERROR_INJECTION_H */
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 963fd364f3d6..9440a2fc8893 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -271,7 +271,6 @@ extern bool arch_kprobe_on_func_entry(unsigned long offset);
extern bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);

extern bool within_kprobe_blacklist(unsigned long addr);
-extern bool within_kprobe_error_injection_list(unsigned long addr);

struct kprobe_insn_cache {
struct mutex mutex;
diff --git a/include/linux/module.h b/include/linux/module.h
index 548fa09fa806..792e51d83bda 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -476,9 +476,9 @@ struct module {
unsigned int num_ctors;
#endif

-#ifdef CONFIG_BPF_KPROBE_OVERRIDE
- unsigned int num_kprobe_ei_funcs;
- unsigned long *kprobe_ei_funcs;
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+ unsigned int num_ei_funcs;
+ unsigned long *ei_funcs;
#endif
} ____cacheline_aligned __randomize_layout;
#ifndef MODULE_ARCH_INIT
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index b4aab48ad258..da2ccf142358 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -83,16 +83,6 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
return &(kretprobe_table_locks[hash].lock);
}

-/* List of symbols that can be overriden for error injection. */
-static LIST_HEAD(kprobe_error_injection_list);
-static DEFINE_MUTEX(kprobe_ei_mutex);
-struct kprobe_ei_entry {
- struct list_head list;
- unsigned long start_addr;
- unsigned long end_addr;
- void *priv;
-};
-
/* Blacklist -- list of struct kprobe_blacklist_entry */
static LIST_HEAD(kprobe_blacklist);

@@ -1404,17 +1394,6 @@ bool within_kprobe_blacklist(unsigned long addr)
return false;
}

-bool within_kprobe_error_injection_list(unsigned long addr)
-{
- struct kprobe_ei_entry *ent;
-
- list_for_each_entry(ent, &kprobe_error_injection_list, list) {
- if (addr >= ent->start_addr && addr < ent->end_addr)
- return true;
- }
- return false;
-}
-
/*
* If we have a symbol_name argument, look it up and add the offset field
* to it. This way, we can specify a relative address to a symbol.
@@ -2189,86 +2168,6 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
return 0;
}

-#ifdef CONFIG_BPF_KPROBE_OVERRIDE
-/* Markers of the _kprobe_error_inject_list section */
-extern unsigned long __start_kprobe_error_inject_list[];
-extern unsigned long __stop_kprobe_error_inject_list[];
-
-/*
- * Lookup and populate the kprobe_error_injection_list.
- *
- * For safety reasons we only allow certain functions to be overriden 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_kprobe_error_injection_list(unsigned long *start,
- unsigned long *end,
- void *priv)
-{
- unsigned long *iter;
- struct kprobe_ei_entry *ent;
- unsigned long entry, offset = 0, size = 0;
-
- mutex_lock(&kprobe_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, &kprobe_error_injection_list);
- }
- mutex_unlock(&kprobe_ei_mutex);
-}
-
-static void __init populate_kernel_kprobe_ei_list(void)
-{
- populate_kprobe_error_injection_list(__start_kprobe_error_inject_list,
- __stop_kprobe_error_inject_list,
- NULL);
-}
-
-static void module_load_kprobe_ei_list(struct module *mod)
-{
- if (!mod->num_kprobe_ei_funcs)
- return;
- populate_kprobe_error_injection_list(mod->kprobe_ei_funcs,
- mod->kprobe_ei_funcs +
- mod->num_kprobe_ei_funcs, mod);
-}
-
-static void module_unload_kprobe_ei_list(struct module *mod)
-{
- struct kprobe_ei_entry *ent, *n;
- if (!mod->num_kprobe_ei_funcs)
- return;
-
- mutex_lock(&kprobe_ei_mutex);
- list_for_each_entry_safe(ent, n, &kprobe_error_injection_list, list) {
- if (ent->priv == mod) {
- list_del_init(&ent->list);
- kfree(ent);
- }
- }
- mutex_unlock(&kprobe_ei_mutex);
-}
-#else
-static inline void __init populate_kernel_kprobe_ei_list(void) {}
-static inline void module_load_kprobe_ei_list(struct module *m) {}
-static inline void module_unload_kprobe_ei_list(struct module *m) {}
-#endif
-
/* Module notifier call back, checking kprobes on the module */
static int kprobes_module_callback(struct notifier_block *nb,
unsigned long val, void *data)
@@ -2279,11 +2178,6 @@ static int kprobes_module_callback(struct notifier_block *nb,
unsigned int i;
int checkcore = (val == MODULE_STATE_GOING);

- if (val == MODULE_STATE_COMING)
- module_load_kprobe_ei_list(mod);
- else if (val == MODULE_STATE_GOING)
- module_unload_kprobe_ei_list(mod);
-
if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
return NOTIFY_DONE;

@@ -2346,8 +2240,6 @@ static int __init init_kprobes(void)
pr_err("Please take care of using kprobes.\n");
}

- populate_kernel_kprobe_ei_list();
-
if (kretprobe_blacklist_size) {
/* lookup the function address from its name */
for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
@@ -2515,56 +2407,6 @@ static const struct file_operations debugfs_kprobe_blacklist_ops = {
.release = seq_release,
};

-/*
- * kprobes/error_injection_list -- shows which functions can be overriden for
- * error injection.
- * */
-static void *kprobe_ei_seq_start(struct seq_file *m, loff_t *pos)
-{
- mutex_lock(&kprobe_ei_mutex);
- return seq_list_start(&kprobe_error_injection_list, *pos);
-}
-
-static void kprobe_ei_seq_stop(struct seq_file *m, void *v)
-{
- mutex_unlock(&kprobe_ei_mutex);
-}
-
-static void *kprobe_ei_seq_next(struct seq_file *m, void *v, loff_t *pos)
-{
- return seq_list_next(v, &kprobe_error_injection_list, pos);
-}
-
-static int kprobe_ei_seq_show(struct seq_file *m, void *v)
-{
- char buffer[KSYM_SYMBOL_LEN];
- struct kprobe_ei_entry *ent =
- list_entry(v, struct kprobe_ei_entry, list);
-
- sprint_symbol(buffer, ent->start_addr);
- seq_printf(m, "%s\n", buffer);
- return 0;
-}
-
-static const struct seq_operations kprobe_ei_seq_ops = {
- .start = kprobe_ei_seq_start,
- .next = kprobe_ei_seq_next,
- .stop = kprobe_ei_seq_stop,
- .show = kprobe_ei_seq_show,
-};
-
-static int kprobe_ei_open(struct inode *inode, struct file *filp)
-{
- return seq_open(filp, &kprobe_ei_seq_ops);
-}
-
-static const struct file_operations debugfs_kprobe_ei_ops = {
- .open = kprobe_ei_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = seq_release,
-};
-
static void arm_all_kprobes(void)
{
struct hlist_head *head;
@@ -2706,11 +2548,6 @@ static int __init debugfs_kprobe_init(void)
if (!file)
goto error;

- file = debugfs_create_file("error_injection_list", 0444, dir, NULL,
- &debugfs_kprobe_ei_ops);
- if (!file)
- goto error;
-
return 0;

error:
diff --git a/kernel/module.c b/kernel/module.c
index bd695bfdc5c4..601494d4b7ea 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3118,10 +3118,10 @@ static int find_module_sections(struct module *mod, struct load_info *info)
sizeof(*mod->ftrace_callsites),
&mod->num_ftrace_callsites);
#endif
-#ifdef CONFIG_BPF_KPROBE_OVERRIDE
- mod->kprobe_ei_funcs = section_objs(info, "_kprobe_error_inject_list",
- sizeof(*mod->kprobe_ei_funcs),
- &mod->num_kprobe_ei_funcs);
+#ifdef CONFIG_FUNCTION_ERROR_INJECTION
+ mod->ei_funcs = section_objs(info, "_error_injection_whitelist",
+ sizeof(*mod->ei_funcs),
+ &mod->num_ei_funcs);
#endif
mod->extable = section_objs(info, "__ex_table",
sizeof(*mod->extable), &mod->num_exentries);
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 6400e1bf97c5..7114c885a78a 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -533,7 +533,7 @@ config FUNCTION_PROFILER
config BPF_KPROBE_OVERRIDE
bool "Enable BPF programs to override a kprobed function"
depends on BPF_EVENTS
- depends on HAVE_KPROBE_OVERRIDE
+ depends on FUNCTION_ERROR_INJECTION
default n
help
Allows BPF to override the execution of a probed function and
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 24ed6363e00f..460d5a899cef 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -84,7 +84,7 @@ EXPORT_SYMBOL_GPL(trace_call_bpf);
BPF_CALL_2(bpf_override_return, struct pt_regs *, regs, unsigned long, rc)
{
regs_set_return_value(regs, rc);
- arch_kprobe_override_function(regs);
+ override_function_with_return(regs);
return 0;
}

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index b8c90441bc87..1fad24acd444 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -21,6 +21,7 @@
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/rculist.h>
+#include <linux/error-injection.h>

#include "trace_probe.h"

@@ -107,7 +108,7 @@ bool trace_kprobe_error_injectable(struct trace_event_call *call)
} else {
addr = (unsigned long)tk->rp.kp.addr;
}
- return within_kprobe_error_injection_list(addr);
+ return within_error_injection_list(addr);
}

static int register_kprobe_event(struct trace_kprobe *tk);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 9d5b78aad4c5..2a33efdd1fea 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1500,6 +1500,10 @@ config FAULT_INJECTION
Provide fault-injection framework.
For more details, see Documentation/fault-injection/.

+config FUNCTION_ERROR_INJECTION
+ def_bool y
+ depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
+
config FAILSLAB
bool "Fault-injection capability for kmalloc"
depends on FAULT_INJECTION
diff --git a/lib/Makefile b/lib/Makefile
index a6c8529dd9b2..75ec13778cd8 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -149,6 +149,7 @@ obj-$(CONFIG_NETDEV_NOTIFIER_ERROR_INJECT) += netdev-notifier-error-inject.o
obj-$(CONFIG_MEMORY_NOTIFIER_ERROR_INJECT) += memory-notifier-error-inject.o
obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \
of-reconfig-notifier-error-inject.o
+obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

lib-$(CONFIG_GENERIC_BUG) += bug.o

diff --git a/lib/error-inject.c b/lib/error-inject.c
new file mode 100644
index 000000000000..ac9a371af719
--- /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 <linux/error-injection.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+/* 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 false;
+}
+
+/*
+ * 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);