diff options
Diffstat (limited to 'kernel/kexec_core.c')
-rw-r--r-- | kernel/kexec_core.c | 94 |
1 files changed, 93 insertions, 1 deletions
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index b1cf259854ca..3d578c6fefee 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -921,10 +921,64 @@ int kimage_load_segment(struct kimage *image, return result; } +struct kexec_load_limit { + /* Mutex protects the limit count. */ + struct mutex mutex; + int limit; +}; + +static struct kexec_load_limit load_limit_reboot = { + .mutex = __MUTEX_INITIALIZER(load_limit_reboot.mutex), + .limit = -1, +}; + +static struct kexec_load_limit load_limit_panic = { + .mutex = __MUTEX_INITIALIZER(load_limit_panic.mutex), + .limit = -1, +}; + struct kimage *kexec_image; struct kimage *kexec_crash_image; -int kexec_load_disabled; +static int kexec_load_disabled; + #ifdef CONFIG_SYSCTL +static int kexec_limit_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + struct kexec_load_limit *limit = table->data; + int val; + struct ctl_table tmp = { + .data = &val, + .maxlen = sizeof(val), + .mode = table->mode, + }; + int ret; + + if (write) { + ret = proc_dointvec(&tmp, write, buffer, lenp, ppos); + if (ret) + return ret; + + if (val < 0) + return -EINVAL; + + mutex_lock(&limit->mutex); + if (limit->limit != -1 && val >= limit->limit) + ret = -EINVAL; + else + limit->limit = val; + mutex_unlock(&limit->mutex); + + return ret; + } + + mutex_lock(&limit->mutex); + val = limit->limit; + mutex_unlock(&limit->mutex); + + return proc_dointvec(&tmp, write, buffer, lenp, ppos); +} + static struct ctl_table kexec_core_sysctls[] = { { .procname = "kexec_load_disabled", @@ -936,6 +990,18 @@ static struct ctl_table kexec_core_sysctls[] = { .extra1 = SYSCTL_ONE, .extra2 = SYSCTL_ONE, }, + { + .procname = "kexec_load_limit_panic", + .data = &load_limit_panic, + .mode = 0644, + .proc_handler = kexec_limit_handler, + }, + { + .procname = "kexec_load_limit_reboot", + .data = &load_limit_reboot, + .mode = 0644, + .proc_handler = kexec_limit_handler, + }, { } }; @@ -947,6 +1013,32 @@ static int __init kexec_core_sysctl_init(void) late_initcall(kexec_core_sysctl_init); #endif +bool kexec_load_permitted(int kexec_image_type) +{ + struct kexec_load_limit *limit; + + /* + * Only the superuser can use the kexec syscall and if it has not + * been disabled. + */ + if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) + return false; + + /* Check limit counter and decrease it.*/ + limit = (kexec_image_type == KEXEC_TYPE_CRASH) ? + &load_limit_panic : &load_limit_reboot; + mutex_lock(&limit->mutex); + if (!limit->limit) { + mutex_unlock(&limit->mutex); + return false; + } + if (limit->limit != -1) + limit->limit--; + mutex_unlock(&limit->mutex); + + return true; +} + /* * No panic_cpu check version of crash_kexec(). This function is called * only when panic_cpu holds the current CPU number; this is the only CPU |