diff options
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk.c | 170 |
1 files changed, 154 insertions, 16 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index d4de33934dac..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) { |