diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/keys/compat.c | 4 | ||||
| -rw-r--r-- | security/keys/internal.h | 3 | ||||
| -rw-r--r-- | security/keys/keyctl.c | 58 | ||||
| -rw-r--r-- | security/keys/keyring.c | 105 |
4 files changed, 170 insertions, 0 deletions
diff --git a/security/keys/compat.c b/security/keys/compat.c index 36c80bf5b89c..bb98f2b8dd7d 100644 --- a/security/keys/compat.c +++ b/security/keys/compat.c @@ -136,6 +136,10 @@ COMPAT_SYSCALL_DEFINE5(keyctl, u32, option, return keyctl_dh_compute(compat_ptr(arg2), compat_ptr(arg3), arg4, compat_ptr(arg5)); + case KEYCTL_RESTRICT_KEYRING: + return keyctl_restrict_keyring(arg2, compat_ptr(arg3), + compat_ptr(arg4)); + default: return -EOPNOTSUPP; } diff --git a/security/keys/internal.h b/security/keys/internal.h index 24762ae9a198..6ce016314897 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -252,6 +252,9 @@ struct iov_iter; extern long keyctl_instantiate_key_common(key_serial_t, struct iov_iter *, key_serial_t); +extern long keyctl_restrict_keyring(key_serial_t id, + const char __user *_type, + const char __user *_restriction); #ifdef CONFIG_PERSISTENT_KEYRINGS extern long keyctl_get_persistent(uid_t, key_serial_t); extern unsigned persistent_keyring_expiry; diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 52c34532c785..6ee2826a2d06 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1583,6 +1583,59 @@ error_keyring: } /* + * Apply a restriction to a given keyring. + * + * The caller must have Setattr permission to change keyring restrictions. + * + * The requested type name may be a NULL pointer to reject all attempts + * to link to the keyring. If _type is non-NULL, _restriction can be + * NULL or a pointer to a string describing the restriction. If _type is + * NULL, _restriction must also be NULL. + * + * Returns 0 if successful. + */ +long keyctl_restrict_keyring(key_serial_t id, const char __user *_type, + const char __user *_restriction) +{ + key_ref_t key_ref; + bool link_reject = !_type; + char type[32]; + char *restriction = NULL; + long ret; + + key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); + + if (_type) { + ret = key_get_type_from_user(type, _type, sizeof(type)); + if (ret < 0) + goto error; + } + + if (_restriction) { + if (!_type) { + ret = -EINVAL; + goto error; + } + + restriction = strndup_user(_restriction, PAGE_SIZE); + if (IS_ERR(restriction)) { + ret = PTR_ERR(restriction); + goto error; + } + } + + ret = keyring_restrict(key_ref, link_reject ? NULL : type, restriction); + kfree(restriction); + +error: + key_ref_put(key_ref); + + return ret; +} + +/* * The key control system call */ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3, @@ -1693,6 +1746,11 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3, (char __user *) arg3, (size_t) arg4, (void __user *) arg5); + case KEYCTL_RESTRICT_KEYRING: + return keyctl_restrict_keyring((key_serial_t) arg2, + (const char __user *) arg3, + (const char __user *) arg4); + default: return -EOPNOTSUPP; } diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 838334fec6ce..4d1678e4586f 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -947,6 +947,111 @@ key_ref_t keyring_search(key_ref_t keyring, } EXPORT_SYMBOL(keyring_search); +static struct key_restriction *keyring_restriction_alloc( + key_restrict_link_func_t check) +{ + struct key_restriction *keyres = + kzalloc(sizeof(struct key_restriction), GFP_KERNEL); + + if (!keyres) + return ERR_PTR(-ENOMEM); + + keyres->check = check; + + return keyres; +} + +/* + * Semaphore to serialise restriction setup to prevent reference count + * cycles through restriction key pointers. + */ +static DECLARE_RWSEM(keyring_serialise_restrict_sem); + +/* + * Check for restriction cycles that would prevent keyring garbage collection. + * keyring_serialise_restrict_sem must be held. + */ +static bool keyring_detect_restriction_cycle(const struct key *dest_keyring, + struct key_restriction *keyres) +{ + while (keyres && keyres->key && + keyres->key->type == &key_type_keyring) { + if (keyres->key == dest_keyring) + return true; + + keyres = keyres->key->restrict_link; + } + + return false; +} + +/** + * keyring_restrict - Look up and apply a restriction to a keyring + * + * @keyring: The keyring to be restricted + * @restriction: The restriction options to apply to the keyring + */ +int keyring_restrict(key_ref_t keyring_ref, const char *type, + const char *restriction) +{ + struct key *keyring; + struct key_type *restrict_type = NULL; + struct key_restriction *restrict_link; + int ret = 0; + + keyring = key_ref_to_ptr(keyring_ref); + key_check(keyring); + + if (keyring->type != &key_type_keyring) + return -ENOTDIR; + + if (!type) { + restrict_link = keyring_restriction_alloc(restrict_link_reject); + } else { + restrict_type = key_type_lookup(type); + + if (IS_ERR(restrict_type)) + return PTR_ERR(restrict_type); + + if (!restrict_type->lookup_restriction) { + ret = -ENOENT; + goto error; + } + + restrict_link = restrict_type->lookup_restriction(restriction); + } + + if (IS_ERR(restrict_link)) { + ret = PTR_ERR(restrict_link); + goto error; + } + + down_write(&keyring->sem); + down_write(&keyring_serialise_restrict_sem); + + if (keyring->restrict_link) + ret = -EEXIST; + else if (keyring_detect_restriction_cycle(keyring, restrict_link)) + ret = -EDEADLK; + else + keyring->restrict_link = restrict_link; + + up_write(&keyring_serialise_restrict_sem); + up_write(&keyring->sem); + + if (ret < 0) { + key_put(restrict_link->key); + kfree(restrict_link); + } + +error: + if (restrict_type) + key_type_put(restrict_type); + + return ret; +} +EXPORT_SYMBOL(keyring_restrict); + /* * Search the given keyring for a key that might be updated. * |