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-rw-r--r--Documentation/admin-guide/kernel-parameters.txt15
-rw-r--r--kernel/printk/printk.c28
-rw-r--r--kernel/printk/printk_ringbuffer.h2
-rw-r--r--kernel/printk/printk_safe.c16
-rw-r--r--lib/test_bitmap.c3
-rw-r--r--lib/test_printf.c12
-rw-r--r--lib/vsprintf.c36
-rw-r--r--tools/testing/selftests/kselftest_module.h18
8 files changed, 103 insertions, 27 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 52f8233f8bb8..8b5f717b8c8c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3293,6 +3293,21 @@
in certain environments such as networked servers or
real-time systems.
+ no_hash_pointers
+ Force pointers printed to the console or buffers to be
+ unhashed. By default, when a pointer is printed via %p
+ format string, that pointer is "hashed", i.e. obscured
+ by hashing the pointer value. This is a security feature
+ that hides actual kernel addresses from unprivileged
+ users, but it also makes debugging the kernel more
+ difficult since unequal pointers can no longer be
+ compared. However, if this command-line option is
+ specified, then all normal pointers will have their true
+ value printed. Pointers printed via %pK may still be
+ hashed. This option should only be specified when
+ debugging the kernel. Please do not use on production
+ kernels.
+
nohibernate [HIBERNATION] Disable hibernation and resume.
nohz= [KNL] Boottime enable/disable dynamic ticks
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5a95c688621f..575a34b88936 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -735,9 +735,9 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
logbuf_lock_irq();
}
- if (user->seq < prb_first_valid_seq(prb)) {
+ if (r->info->seq != user->seq) {
/* our last seen message is gone, return error and reset */
- user->seq = prb_first_valid_seq(prb);
+ user->seq = r->info->seq;
ret = -EPIPE;
logbuf_unlock_irq();
goto out;
@@ -812,6 +812,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
{
struct devkmsg_user *user = file->private_data;
+ struct printk_info info;
__poll_t ret = 0;
if (!user)
@@ -820,9 +821,9 @@ static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
poll_wait(file, &log_wait, wait);
logbuf_lock_irq();
- if (prb_read_valid(prb, user->seq, NULL)) {
+ if (prb_read_valid_info(prb, user->seq, &info, NULL)) {
/* return error when data has vanished underneath us */
- if (user->seq < prb_first_valid_seq(prb))
+ if (info.seq != user->seq)
ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
else
ret = EPOLLIN|EPOLLRDNORM;
@@ -1559,6 +1560,7 @@ static void syslog_clear(void)
int do_syslog(int type, char __user *buf, int len, int source)
{
+ struct printk_info info;
bool clear = false;
static int saved_console_loglevel = LOGLEVEL_DEFAULT;
int error;
@@ -1629,9 +1631,14 @@ int do_syslog(int type, char __user *buf, int len, int source)
/* Number of chars in the log buffer */
case SYSLOG_ACTION_SIZE_UNREAD:
logbuf_lock_irq();
- if (syslog_seq < prb_first_valid_seq(prb)) {
+ if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) {
+ /* No unread messages. */
+ logbuf_unlock_irq();
+ return 0;
+ }
+ if (info.seq != syslog_seq) {
/* messages are gone, move to first one */
- syslog_seq = prb_first_valid_seq(prb);
+ syslog_seq = info.seq;
syslog_partial = 0;
}
if (source == SYSLOG_FROM_PROC) {
@@ -1643,7 +1650,6 @@ int do_syslog(int type, char __user *buf, int len, int source)
error = prb_next_seq(prb) - syslog_seq;
} else {
bool time = syslog_partial ? syslog_time : printk_time;
- struct printk_info info;
unsigned int line_count;
u64 seq;
@@ -3429,9 +3435,11 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
goto out;
logbuf_lock_irqsave(flags);
- if (dumper->cur_seq < prb_first_valid_seq(prb)) {
- /* messages are gone, move to first available one */
- dumper->cur_seq = prb_first_valid_seq(prb);
+ if (prb_read_valid_info(prb, dumper->cur_seq, &info, NULL)) {
+ if (info.seq != dumper->cur_seq) {
+ /* messages are gone, move to first available one */
+ dumper->cur_seq = info.seq;
+ }
}
/* last entry */
diff --git a/kernel/printk/printk_ringbuffer.h b/kernel/printk/printk_ringbuffer.h
index 5dc9d022db07..73cc80e01cef 100644
--- a/kernel/printk/printk_ringbuffer.h
+++ b/kernel/printk/printk_ringbuffer.h
@@ -287,7 +287,7 @@ _DEFINE_PRINTKRB(name, descbits, avgtextbits, &_##name##_text[0])
/* Writer Interface */
/**
- * prb_rec_init_wd() - Initialize a buffer for writing records.
+ * prb_rec_init_wr() - Initialize a buffer for writing records.
*
* @r: The record to initialize.
* @text_buf_size: The needed text buffer size.
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index a0e6f746de6c..2e9e3ed7d63e 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -45,6 +45,8 @@ struct printk_safe_seq_buf {
static DEFINE_PER_CPU(struct printk_safe_seq_buf, safe_print_seq);
static DEFINE_PER_CPU(int, printk_context);
+static DEFINE_RAW_SPINLOCK(safe_read_lock);
+
#ifdef CONFIG_PRINTK_NMI
static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
#endif
@@ -180,8 +182,6 @@ static void report_message_lost(struct printk_safe_seq_buf *s)
*/
static void __printk_safe_flush(struct irq_work *work)
{
- static raw_spinlock_t read_lock =
- __RAW_SPIN_LOCK_INITIALIZER(read_lock);
struct printk_safe_seq_buf *s =
container_of(work, struct printk_safe_seq_buf, work);
unsigned long flags;
@@ -195,7 +195,7 @@ static void __printk_safe_flush(struct irq_work *work)
* different CPUs. This is especially important when printing
* a backtrace.
*/
- raw_spin_lock_irqsave(&read_lock, flags);
+ raw_spin_lock_irqsave(&safe_read_lock, flags);
i = 0;
more:
@@ -232,7 +232,7 @@ more:
out:
report_message_lost(s);
- raw_spin_unlock_irqrestore(&read_lock, flags);
+ raw_spin_unlock_irqrestore(&safe_read_lock, flags);
}
/**
@@ -278,6 +278,14 @@ void printk_safe_flush_on_panic(void)
raw_spin_lock_init(&logbuf_lock);
}
+ if (raw_spin_is_locked(&safe_read_lock)) {
+ if (num_online_cpus() > 1)
+ return;
+
+ debug_locks_off();
+ raw_spin_lock_init(&safe_read_lock);
+ }
+
printk_safe_flush();
}
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 4425a1dd4ef1..0ea0e8258f14 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -16,8 +16,7 @@
#include "../tools/testing/selftests/kselftest_module.h"
-static unsigned total_tests __initdata;
-static unsigned failed_tests __initdata;
+KSTM_MODULE_GLOBALS();
static char pbl_buffer[PAGE_SIZE] __initdata;
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 7d60f24240a4..95a2f82427c7 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -30,11 +30,13 @@
#define PAD_SIZE 16
#define FILL_CHAR '$'
-static unsigned total_tests __initdata;
-static unsigned failed_tests __initdata;
+KSTM_MODULE_GLOBALS();
+
static char *test_buffer __initdata;
static char *alloced_buffer __initdata;
+extern bool no_hash_pointers;
+
static int __printf(4, 0) __init
do_test(int bufsize, const char *expect, int elen,
const char *fmt, va_list ap)
@@ -301,6 +303,12 @@ plain(void)
{
int err;
+ if (no_hash_pointers) {
+ pr_warn("skipping plain 'p' tests");
+ skipped_tests += 2;
+ return;
+ }
+
err = plain_hash();
if (err) {
pr_warn("plain 'p' does not appear to be hashed\n");
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3b53c73580c5..41ddc353ebb8 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2090,6 +2090,32 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
return widen_string(buf, buf - buf_start, end, spec);
}
+/* Disable pointer hashing if requested */
+bool no_hash_pointers __ro_after_init;
+EXPORT_SYMBOL_GPL(no_hash_pointers);
+
+static int __init no_hash_pointers_enable(char *str)
+{
+ no_hash_pointers = true;
+
+ pr_warn("**********************************************************\n");
+ pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
+ pr_warn("** **\n");
+ pr_warn("** This system shows unhashed kernel memory addresses **\n");
+ pr_warn("** via the console, logs, and other interfaces. This **\n");
+ pr_warn("** might reduce the security of your system. **\n");
+ pr_warn("** **\n");
+ pr_warn("** If you see this message and you are not debugging **\n");
+ pr_warn("** the kernel, report this immediately to your system **\n");
+ pr_warn("** administrator! **\n");
+ pr_warn("** **\n");
+ pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n");
+ pr_warn("**********************************************************\n");
+
+ return 0;
+}
+early_param("no_hash_pointers", no_hash_pointers_enable);
+
/*
* Show a '%p' thing. A kernel extension is that the '%p' is followed
* by an extra set of alphanumeric characters that are extended format
@@ -2297,8 +2323,14 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
}
}
- /* default is to _not_ leak addresses, hash before printing */
- return ptr_to_id(buf, end, ptr, spec);
+ /*
+ * default is to _not_ leak addresses, so hash before printing,
+ * unless no_hash_pointers is specified on the command line.
+ */
+ if (unlikely(no_hash_pointers))
+ return pointer_string(buf, end, ptr, spec);
+ else
+ return ptr_to_id(buf, end, ptr, spec);
}
/*
diff --git a/tools/testing/selftests/kselftest_module.h b/tools/testing/selftests/kselftest_module.h
index e8eafaf0941a..e2ea41de3f35 100644
--- a/tools/testing/selftests/kselftest_module.h
+++ b/tools/testing/selftests/kselftest_module.h
@@ -11,7 +11,8 @@
#define KSTM_MODULE_GLOBALS() \
static unsigned int total_tests __initdata; \
-static unsigned int failed_tests __initdata
+static unsigned int failed_tests __initdata; \
+static unsigned int skipped_tests __initdata
#define KSTM_CHECK_ZERO(x) do { \
total_tests++; \
@@ -21,11 +22,16 @@ static unsigned int failed_tests __initdata
} \
} while (0)
-static inline int kstm_report(unsigned int total_tests, unsigned int failed_tests)
+static inline int kstm_report(unsigned int total_tests, unsigned int failed_tests,
+ unsigned int skipped_tests)
{
- if (failed_tests == 0)
- pr_info("all %u tests passed\n", total_tests);
- else
+ if (failed_tests == 0) {
+ if (skipped_tests) {
+ pr_info("skipped %u tests\n", skipped_tests);
+ pr_info("remaining %u tests passed\n", total_tests);
+ } else
+ pr_info("all %u tests passed\n", total_tests);
+ } else
pr_warn("failed %u out of %u tests\n", failed_tests, total_tests);
return failed_tests ? -EINVAL : 0;
@@ -36,7 +42,7 @@ static int __init __module##_init(void) \
{ \
pr_info("loaded.\n"); \
selftest(); \
- return kstm_report(total_tests, failed_tests); \
+ return kstm_report(total_tests, failed_tests, skipped_tests); \
} \
static void __exit __module##_exit(void) \
{ \
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-24 15:20:48 +0000