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Date: Wed, 11 May 2022 13:36:56 +0530
From: Maninder Singh <maninder1.s@...sung.com>
To: mcgrof@...nel.org, avimalin@...il.com, ast@...nel.org,
daniel@...earbox.net, andrii@...nel.org, kafai@...com,
songliubraving@...com, yhs@...com, john.fastabend@...il.com,
kpsingh@...nel.org, pmladek@...e.com, rostedt@...dmis.org,
senozhatsky@...omium.org, andriy.shevchenko@...ux.intel.com,
naveen.n.rao@...ux.ibm.com, davem@...emloft.net,
mhiramat@...nel.org, anil.s.keshavamurthy@...el.com,
linux@...musvillemoes.dk, akpm@...ux-foundation.org,
keescook@...omium.org
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
v.narang@...sung.com, Maninder Singh <maninder1.s@...sung.com>,
Onkarnath <onkarnath.1@...sung.com>
Subject: [PATCH 1/2] kallsyms: add kallsyms_show_value definition in all
cases
kallsyms_show_value return false if KALLSYMS is disabled,
but its usage is done by module.c also.
Thus when KALLSYMS is disabled, system will not print module
load address:
/ # insmod crash.ko
/ # lsmod
crash 12288 0 - Live 0x0000000000000000 (O)
After change (making definition generic)
============
/ # lsmod
crash 12288 0 - Live 0xffff800000ec0000 (O)
/ # cat /proc/modules
crash 12288 0 - Live 0xffff800000ec0000 (O)
/ #
BPF code has high dependency on kallsyms,
so bpf_dump_raw_ok check is not changed.
Co-developed-by: Onkarnath <onkarnath.1@...sung.com>
Signed-off-by: Onkarnath <onkarnath.1@...sung.com>
Signed-off-by: Maninder Singh <maninder1.s@...sung.com>
---
BPF logic is not changed and seems kprobe will work, rest kprobe
maintainer can comment if it can cause issue. Tested for modules data.
https://lkml.org/lkml/2022/4/13/326
include/linux/filter.h | 7 ++++++
include/linux/kallsyms.h | 10 +++-----
kernel/Makefile | 2 +-
kernel/kallsyms.c | 35 ---------------------------
kernel/kallsyms_tiny.c | 51 ++++++++++++++++++++++++++++++++++++++++
5 files changed, 62 insertions(+), 43 deletions(-)
create mode 100644 kernel/kallsyms_tiny.c
diff --git a/include/linux/filter.h b/include/linux/filter.h
index ed0c0ff42ad5..98c4365e726d 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -951,6 +951,7 @@ bool bpf_jit_needs_zext(void);
bool bpf_jit_supports_kfunc_call(void);
bool bpf_helper_changes_pkt_data(void *func);
+#ifdef CONFIG_KALLSYMS
static inline bool bpf_dump_raw_ok(const struct cred *cred)
{
/* Reconstruction of call-sites is dependent on kallsyms,
@@ -958,6 +959,12 @@ static inline bool bpf_dump_raw_ok(const struct cred *cred)
*/
return kallsyms_show_value(cred);
}
+#else
+static inline bool bpf_dump_raw_ok(const struct cred *cred)
+{
+ return false;
+}
+#endif
struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
const struct bpf_insn *patch, u32 len);
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index c24fa627ab6e..c5e63a217404 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -24,6 +24,9 @@
struct cred;
struct module;
+/* How and when do we show kallsyms values? */
+extern bool kallsyms_show_value(const struct cred *cred);
+
static inline int is_kernel_text(unsigned long addr)
{
if (__is_kernel_text(addr))
@@ -95,8 +98,6 @@ extern int sprint_kallsym_common(char *buffer, unsigned long address, int build_
int lookup_symbol_name(unsigned long addr, char *symname);
int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name);
-/* How and when do we show kallsyms values? */
-extern bool kallsyms_show_value(const struct cred *cred);
#else /* !CONFIG_KALLSYMS */
@@ -160,11 +161,6 @@ static inline int lookup_symbol_attrs(unsigned long addr, unsigned long *size, u
return -ERANGE;
}
-static inline bool kallsyms_show_value(const struct cred *cred)
-{
- return false;
-}
-
#endif /*CONFIG_KALLSYMS*/
static inline void print_ip_sym(const char *loglvl, unsigned long ip)
diff --git a/kernel/Makefile b/kernel/Makefile
index 318789c728d3..844ed3df95f6 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -10,7 +10,7 @@ obj-y = fork.o exec_domain.o panic.o \
extable.o params.o \
kthread.o sys_ni.o nsproxy.o \
notifier.o ksysfs.o cred.o reboot.o \
- async.o range.o smpboot.o ucount.o regset.o
+ async.o range.o smpboot.o ucount.o regset.o kallsyms_tiny.o
obj-$(CONFIG_USERMODE_DRIVER) += usermode_driver.o
obj-$(CONFIG_MODULES) += kmod.o
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 9a0d6cfca619..d818048cb9f7 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -819,41 +819,6 @@ static const struct seq_operations kallsyms_op = {
.show = s_show
};
-static inline int kallsyms_for_perf(void)
-{
-#ifdef CONFIG_PERF_EVENTS
- extern int sysctl_perf_event_paranoid;
- if (sysctl_perf_event_paranoid <= 1)
- return 1;
-#endif
- return 0;
-}
-
-/*
- * We show kallsyms information even to normal users if we've enabled
- * kernel profiling and are explicitly not paranoid (so kptr_restrict
- * is clear, and sysctl_perf_event_paranoid isn't set).
- *
- * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
- * block even that).
- */
-bool kallsyms_show_value(const struct cred *cred)
-{
- switch (kptr_restrict) {
- case 0:
- if (kallsyms_for_perf())
- return true;
- fallthrough;
- case 1:
- if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
- CAP_OPT_NOAUDIT) == 0)
- return true;
- fallthrough;
- default:
- return false;
- }
-}
-
static int kallsyms_open(struct inode *inode, struct file *file)
{
/*
diff --git a/kernel/kallsyms_tiny.c b/kernel/kallsyms_tiny.c
new file mode 100644
index 000000000000..96ad06836126
--- /dev/null
+++ b/kernel/kallsyms_tiny.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Samsung Electronics Co., Ltd
+ *
+ * Author:
+ * Maninder singh <maninder1.s@...sung.com>
+ * Onkarnath <onkarnath.1@...sung.com>
+ *
+ * A split of kernel/kallsyms.c
+ * Contains few generic definitions independent of CONFIG_KALLSYMS
+ * or defined under !CONFIG_KALLSYMS.
+ */
+
+#include <linux/kallsyms.h>
+#include <linux/security.h>
+
+static inline int kallsyms_for_perf(void)
+{
+#ifdef CONFIG_PERF_EVENTS
+ extern int sysctl_perf_event_paranoid;
+
+ if (sysctl_perf_event_paranoid <= 1)
+ return 1;
+#endif
+ return 0;
+}
+
+/*
+ * We show kallsyms information even to normal users if we've enabled
+ * kernel profiling and are explicitly not paranoid (so kptr_restrict
+ * is clear, and sysctl_perf_event_paranoid isn't set).
+ *
+ * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
+ * block even that).
+ */
+bool kallsyms_show_value(const struct cred *cred)
+{
+ switch (kptr_restrict) {
+ case 0:
+ if (kallsyms_for_perf())
+ return true;
+ fallthrough;
+ case 1:
+ if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
+ CAP_OPT_NOAUDIT) == 0)
+ return true;
+ fallthrough;
+ default:
+ return false;
+ }
+}
--
2.17.1
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