diff options
Diffstat (limited to 'drivers/base')
-rw-r--r-- | drivers/base/devcoredump.c | 56 |
1 files changed, 48 insertions, 8 deletions
diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c index 96614b04544c..1bd120a0b084 100644 --- a/drivers/base/devcoredump.c +++ b/drivers/base/devcoredump.c @@ -31,6 +31,11 @@ #include <linux/fs.h> #include <linux/workqueue.h> +static struct class devcd_class; + +/* global disable flag, for security purposes */ +static bool devcd_disabled; + /* if data isn't read by userspace after 5 minutes then delete it */ #define DEVCD_TIMEOUT (HZ * 60 * 5) @@ -121,11 +126,51 @@ static const struct attribute_group *devcd_dev_groups[] = { &devcd_dev_group, NULL, }; +static int devcd_free(struct device *dev, void *data) +{ + struct devcd_entry *devcd = dev_to_devcd(dev); + + flush_delayed_work(&devcd->del_wk); + return 0; +} + +static ssize_t disabled_show(struct class *class, struct class_attribute *attr, + char *buf) +{ + return sprintf(buf, "%d\n", devcd_disabled); +} + +static ssize_t disabled_store(struct class *class, struct class_attribute *attr, + const char *buf, size_t count) +{ + long tmp = simple_strtol(buf, NULL, 10); + + /* + * This essentially makes the attribute write-once, since you can't + * go back to not having it disabled. This is intentional, it serves + * as a system lockdown feature. + */ + if (tmp != 1) + return -EINVAL; + + devcd_disabled = true; + + class_for_each_device(&devcd_class, NULL, NULL, devcd_free); + + return count; +} + +static struct class_attribute devcd_class_attrs[] = { + __ATTR_RW(disabled), + __ATTR_NULL +}; + static struct class devcd_class = { .name = "devcoredump", .owner = THIS_MODULE, .dev_release = devcd_dev_release, .dev_groups = devcd_dev_groups, + .class_attrs = devcd_class_attrs, }; static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count, @@ -192,6 +237,9 @@ void dev_coredumpm(struct device *dev, struct module *owner, struct devcd_entry *devcd; struct device *existing; + if (devcd_disabled) + goto free; + existing = class_find_device(&devcd_class, NULL, dev, devcd_match_failing); if (existing) { @@ -249,14 +297,6 @@ static int __init devcoredump_init(void) } __initcall(devcoredump_init); -static int devcd_free(struct device *dev, void *data) -{ - struct devcd_entry *devcd = dev_to_devcd(dev); - - flush_delayed_work(&devcd->del_wk); - return 0; -} - static void __exit devcoredump_exit(void) { class_for_each_device(&devcd_class, NULL, NULL, devcd_free); |