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Diffstat (limited to 'kernel/printk/printk.c')
-rw-r--r--kernel/printk/printk.c175
1 files changed, 156 insertions, 19 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 60cdf6386763..eea6dbc2d8cf 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -26,7 +26,6 @@
#include <linux/nmi.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
-#include <linux/interrupt.h> /* For in_interrupt() */
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/security.h>
@@ -48,7 +47,7 @@
#include <linux/uio.h>
#include <asm/uaccess.h>
-#include <asm-generic/sections.h>
+#include <asm/sections.h>
#define CREATE_TRACE_POINTS
#include <trace/events/printk.h>
@@ -86,6 +85,111 @@ static struct lockdep_map console_lock_dep_map = {
};
#endif
+enum devkmsg_log_bits {
+ __DEVKMSG_LOG_BIT_ON = 0,
+ __DEVKMSG_LOG_BIT_OFF,
+ __DEVKMSG_LOG_BIT_LOCK,
+};
+
+enum devkmsg_log_masks {
+ DEVKMSG_LOG_MASK_ON = BIT(__DEVKMSG_LOG_BIT_ON),
+ DEVKMSG_LOG_MASK_OFF = BIT(__DEVKMSG_LOG_BIT_OFF),
+ DEVKMSG_LOG_MASK_LOCK = BIT(__DEVKMSG_LOG_BIT_LOCK),
+};
+
+/* Keep both the 'on' and 'off' bits clear, i.e. ratelimit by default: */
+#define DEVKMSG_LOG_MASK_DEFAULT 0
+
+static unsigned int __read_mostly devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
+
+static int __control_devkmsg(char *str)
+{
+ if (!str)
+ return -EINVAL;
+
+ if (!strncmp(str, "on", 2)) {
+ devkmsg_log = DEVKMSG_LOG_MASK_ON;
+ return 2;
+ } else if (!strncmp(str, "off", 3)) {
+ devkmsg_log = DEVKMSG_LOG_MASK_OFF;
+ return 3;
+ } else if (!strncmp(str, "ratelimit", 9)) {
+ devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT;
+ return 9;
+ }
+ return -EINVAL;
+}
+
+static int __init control_devkmsg(char *str)
+{
+ if (__control_devkmsg(str) < 0)
+ return 1;
+
+ /*
+ * Set sysctl string accordingly:
+ */
+ if (devkmsg_log == DEVKMSG_LOG_MASK_ON) {
+ memset(devkmsg_log_str, 0, DEVKMSG_STR_MAX_SIZE);
+ strncpy(devkmsg_log_str, "on", 2);
+ } else if (devkmsg_log == DEVKMSG_LOG_MASK_OFF) {
+ memset(devkmsg_log_str, 0, DEVKMSG_STR_MAX_SIZE);
+ strncpy(devkmsg_log_str, "off", 3);
+ }
+ /* else "ratelimit" which is set by default. */
+
+ /*
+ * Sysctl cannot change it anymore. The kernel command line setting of
+ * this parameter is to force the setting to be permanent throughout the
+ * runtime of the system. This is a precation measure against userspace
+ * trying to be a smarta** and attempting to change it up on us.
+ */
+ devkmsg_log |= DEVKMSG_LOG_MASK_LOCK;
+
+ return 0;
+}
+__setup("printk.devkmsg=", control_devkmsg);
+
+char devkmsg_log_str[DEVKMSG_STR_MAX_SIZE] = "ratelimit";
+
+int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ char old_str[DEVKMSG_STR_MAX_SIZE];
+ unsigned int old;
+ int err;
+
+ if (write) {
+ if (devkmsg_log & DEVKMSG_LOG_MASK_LOCK)
+ return -EINVAL;
+
+ old = devkmsg_log;
+ strncpy(old_str, devkmsg_log_str, DEVKMSG_STR_MAX_SIZE);
+ }
+
+ err = proc_dostring(table, write, buffer, lenp, ppos);
+ if (err)
+ return err;
+
+ if (write) {
+ err = __control_devkmsg(devkmsg_log_str);
+
+ /*
+ * Do not accept an unknown string OR a known string with
+ * trailing crap...
+ */
+ if (err < 0 || (err + 1 != *lenp)) {
+
+ /* ... and restore old setting. */
+ devkmsg_log = old;
+ strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE);
+
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
/*
* Number of registered extended console drivers.
*
@@ -614,6 +718,7 @@ struct devkmsg_user {
u64 seq;
u32 idx;
enum log_flags prev;
+ struct ratelimit_state rs;
struct mutex lock;
char buf[CONSOLE_EXT_LOG_MAX];
};
@@ -623,11 +728,24 @@ static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
char *buf, *line;
int level = default_message_loglevel;
int facility = 1; /* LOG_USER */
+ struct file *file = iocb->ki_filp;
+ struct devkmsg_user *user = file->private_data;
size_t len = iov_iter_count(from);
ssize_t ret = len;
- if (len > LOG_LINE_MAX)
+ if (!user || len > LOG_LINE_MAX)
return -EINVAL;
+
+ /* Ignore when user logging is disabled. */
+ if (devkmsg_log & DEVKMSG_LOG_MASK_OFF)
+ return len;
+
+ /* Ratelimit when not explicitly enabled. */
+ if (!(devkmsg_log & DEVKMSG_LOG_MASK_ON)) {
+ if (!___ratelimit(&user->rs, current->comm))
+ return ret;
+ }
+
buf = kmalloc(len+1, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
@@ -800,19 +918,24 @@ static int devkmsg_open(struct inode *inode, struct file *file)
struct devkmsg_user *user;
int err;
- /* write-only does not need any file context */
- if ((file->f_flags & O_ACCMODE) == O_WRONLY)
- return 0;
+ if (devkmsg_log & DEVKMSG_LOG_MASK_OFF)
+ return -EPERM;
- err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
- SYSLOG_FROM_READER);
- if (err)
- return err;
+ /* write-only does not need any file context */
+ if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
+ err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
+ SYSLOG_FROM_READER);
+ if (err)
+ return err;
+ }
user = kmalloc(sizeof(struct devkmsg_user), GFP_KERNEL);
if (!user)
return -ENOMEM;
+ ratelimit_default_init(&user->rs);
+ ratelimit_set_flags(&user->rs, RATELIMIT_MSG_ON_RELEASE);
+
mutex_init(&user->lock);
raw_spin_lock_irq(&logbuf_lock);
@@ -831,6 +954,8 @@ static int devkmsg_release(struct inode *inode, struct file *file)
if (!user)
return 0;
+ ratelimit_state_exit(&user->rs);
+
mutex_destroy(&user->lock);
kfree(user);
return 0;
@@ -986,6 +1111,11 @@ module_param(ignore_loglevel, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(ignore_loglevel,
"ignore loglevel setting (prints all kernel messages to the console)");
+static bool suppress_message_printing(int level)
+{
+ return (level >= console_loglevel && !ignore_loglevel);
+}
+
#ifdef CONFIG_BOOT_PRINTK_DELAY
static int boot_delay; /* msecs delay after each printk during bootup */
@@ -1015,7 +1145,7 @@ static void boot_delay_msec(int level)
unsigned long timeout;
if ((boot_delay == 0 || system_state != SYSTEM_BOOTING)
- || (level >= console_loglevel && !ignore_loglevel)) {
+ || suppress_message_printing(level)) {
return;
}
@@ -1439,8 +1569,6 @@ static void call_console_drivers(int level,
trace_console(text, len);
- if (level >= console_loglevel && !ignore_loglevel)
- return;
if (!console_drivers)
return;
@@ -1888,6 +2016,7 @@ static void call_console_drivers(int level,
static size_t msg_print_text(const struct printk_log *msg, enum log_flags prev,
bool syslog, char *buf, size_t size) { return 0; }
static size_t cont_print_text(char *text, size_t size) { return 0; }
+static bool suppress_message_printing(int level) { return false; }
/* Still needs to be defined for users */
DEFINE_PER_CPU(printk_func_t, printk_func);
@@ -2167,6 +2296,13 @@ static void console_cont_flush(char *text, size_t size)
if (!cont.len)
goto out;
+ if (suppress_message_printing(cont.level)) {
+ cont.cons = cont.len;
+ if (cont.flushed)
+ cont.len = 0;
+ goto out;
+ }
+
/*
* We still queue earlier records, likely because the console was
* busy. The earlier ones need to be printed before this one, we
@@ -2270,10 +2406,13 @@ skip:
break;
msg = log_from_idx(console_idx);
- if (msg->flags & LOG_NOCONS) {
+ level = msg->level;
+ if ((msg->flags & LOG_NOCONS) ||
+ suppress_message_printing(level)) {
/*
* Skip record we have buffered and already printed
- * directly to the console when we received it.
+ * directly to the console when we received it, and
+ * record that has level above the console loglevel.
*/
console_idx = log_next(console_idx);
console_seq++;
@@ -2287,7 +2426,6 @@ skip:
goto skip;
}
- level = msg->level;
len += msg_print_text(msg, console_prev, false,
text + len, sizeof(text) - len);
if (nr_ext_console_drivers) {
@@ -3177,9 +3315,8 @@ void show_regs_print_info(const char *log_lvl)
{
dump_stack_print_info(log_lvl);
- printk("%stask: %p ti: %p task.ti: %p\n",
- log_lvl, current, current_thread_info(),
- task_thread_info(current));
+ printk("%stask: %p task.stack: %p\n",
+ log_lvl, current, task_stack_page(current));
}
#endif