diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 7bb0ce3761332..4d079bf5564e5 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -10,177 +10,109 @@ * 2 of the Licence, or (at your option) any later version. */ +#include +#include +#include +#include #include #include #include +#include static enum lockdown_reason kernel_locked_down; +static struct mutex lockdown_mutex; -static const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { - [LOCKDOWN_NONE] = "none", - [LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading", - [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port", - [LOCKDOWN_EFI_TEST] = "/dev/efi_test access", - [LOCKDOWN_KEXEC] = "kexec of unsigned images", - [LOCKDOWN_HIBERNATION] = "hibernation", - [LOCKDOWN_PCI_ACCESS] = "direct PCI access", - [LOCKDOWN_IOPORT] = "raw io port access", - [LOCKDOWN_MSR] = "raw MSR access", - [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables", - [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", - [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", - [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", - [LOCKDOWN_MMIOTRACE] = "unsafe mmio", - [LOCKDOWN_DEBUGFS] = "debugfs access", - [LOCKDOWN_XMON_WR] = "xmon write access", - [LOCKDOWN_BPF_WRITE_USER] = "use of bpf to write user RAM", - [LOCKDOWN_INTEGRITY_MAX] = "integrity", - [LOCKDOWN_KCORE] = "/proc/kcore access", - [LOCKDOWN_KPROBES] = "use of kprobes", - [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM", - [LOCKDOWN_PERF] = "unsafe use of perf", - [LOCKDOWN_TRACEFS] = "use of tracefs", - [LOCKDOWN_XMON_RW] = "xmon read and write access", - [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", +/* Lockdown reason descriptions */ +static const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX + 1] = { + /* Reason descriptions */ }; -static const enum lockdown_reason lockdown_levels[] = {LOCKDOWN_NONE, - LOCKDOWN_INTEGRITY_MAX, - LOCKDOWN_CONFIDENTIALITY_MAX}; +static const enum lockdown_reason lockdown_levels[] = { + LOCKDOWN_NONE, + LOCKDOWN_INTEGRITY_MAX, + LOCKDOWN_CONFIDENTIALITY_MAX}; -/* - * Put the kernel into lock-down mode. - */ +/* Function to lock the kernel down */ static int lock_kernel_down(const char *where, enum lockdown_reason level) { - if (kernel_locked_down >= level) - return -EPERM; + int ret = -EPERM; + + mutex_lock(&lockdown_mutex); + + if (kernel_locked_down < level) { + kernel_locked_down = level; + pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n", where); + ret = 0; + } + + mutex_unlock(&lockdown_mutex); - kernel_locked_down = level; - pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n", - where); - return 0; + return ret; } +/* Function to handle lockdown parameter initialization */ static int __init lockdown_param(char *level) { - if (!level) - return -EINVAL; - - if (strcmp(level, "integrity") == 0) - lock_kernel_down("command line", LOCKDOWN_INTEGRITY_MAX); - else if (strcmp(level, "confidentiality") == 0) - lock_kernel_down("command line", LOCKDOWN_CONFIDENTIALITY_MAX); - else - return -EINVAL; - - return 0; + if (!level) + return -EINVAL; + + if (strcmp(level, "integrity") == 0) + return lock_kernel_down("command line", LOCKDOWN_INTEGRITY_MAX); + else if (strcmp(level, "confidentiality") == 0) + return lock_kernel_down("command line", LOCKDOWN_CONFIDENTIALITY_MAX); + else + return -EINVAL; } early_param("lockdown", lockdown_param); -/** - * lockdown_is_locked_down - Find out if the kernel is locked down - * @what: Tag to use in notice generated if lockdown is in effect - */ +/* Function to check if the kernel is locked down */ static int lockdown_is_locked_down(enum lockdown_reason what) { - if (WARN(what >= LOCKDOWN_CONFIDENTIALITY_MAX, - "Invalid lockdown reason")) - return -EPERM; - - if (kernel_locked_down >= what) { - if (lockdown_reasons[what]) - pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n", - current->comm, lockdown_reasons[what]); - return -EPERM; - } - - return 0; + int ret = 0; + + mutex_lock(&lockdown_mutex); + + if (what >= LOCKDOWN_CONFIDENTIALITY_MAX || kernel_locked_down >= what) + { + if (lockdown_reasons[what]) + pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n", + current->comm, lockdown_reasons[what]); + ret = -EPERM; + } + + mutex_unlock(&lockdown_mutex); + + return ret; } -static struct security_hook_list lockdown_hooks[] __lsm_ro_after_init = { - LSM_HOOK_INIT(locked_down, lockdown_is_locked_down), +/* File operations for the lockdown securityfs file */ +static const struct file_operations lockdown_ops = { + .read = lockdown_read, + .write = lockdown_write, }; +/* Initialize lockdown LSM */ static int __init lockdown_lsm_init(void) { + mutex_init(&lockdown_mutex); + #if defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_INTEGRITY) - lock_kernel_down("Kernel configuration", LOCKDOWN_INTEGRITY_MAX); + lock_kernel_down("Kernel configuration", LOCKDOWN_INTEGRITY_MAX); #elif defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY) - lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX); + lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX); #endif - security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks), - "lockdown"); - return 0; -} - -static ssize_t lockdown_read(struct file *filp, char __user *buf, size_t count, - loff_t *ppos) -{ - char temp[80]; - int i, offset = 0; - for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) { - enum lockdown_reason level = lockdown_levels[i]; - - if (lockdown_reasons[level]) { - const char *label = lockdown_reasons[level]; - - if (kernel_locked_down == level) - offset += sprintf(temp+offset, "[%s] ", label); - else - offset += sprintf(temp+offset, "%s ", label); - } - } - - /* Convert the last space to a newline if needed. */ - if (offset > 0) - temp[offset-1] = '\n'; - - return simple_read_from_buffer(buf, count, ppos, temp, strlen(temp)); + security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks), "lockdown"); + return 0; } -static ssize_t lockdown_write(struct file *file, const char __user *buf, - size_t n, loff_t *ppos) -{ - char *state; - int i, len, err = -EINVAL; - - state = memdup_user_nul(buf, n); - if (IS_ERR(state)) - return PTR_ERR(state); - - len = strlen(state); - if (len && state[len-1] == '\n') { - state[len-1] = '\0'; - len--; - } - - for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) { - enum lockdown_reason level = lockdown_levels[i]; - const char *label = lockdown_reasons[level]; - - if (label && !strcmp(state, label)) - err = lock_kernel_down("securityfs", level); - } - - kfree(state); - return err ? err : n; -} - -static const struct file_operations lockdown_ops = { - .read = lockdown_read, - .write = lockdown_write, -}; - static int __init lockdown_secfs_init(void) { - struct dentry *dentry; + struct dentry *dentry; - dentry = securityfs_create_file("lockdown", 0644, NULL, NULL, - &lockdown_ops); - return PTR_ERR_OR_ZERO(dentry); + dentry = securityfs_create_file("lockdown", 0644, NULL, NULL, &lockdown_ops); + return PTR_ERR_OR_ZERO(dentry); } core_initcall(lockdown_secfs_init); @@ -190,6 +122,6 @@ DEFINE_EARLY_LSM(lockdown) = { #else DEFINE_LSM(lockdown) = { #endif - .name = "lockdown", - .init = lockdown_lsm_init, + .name = "lockdown", + .init = lockdown_lsm_init, };