Commit message: KEYS: Fix race between read and revoke

This fixes CVE-2015-7550.

There's a race between keyctl_read() and keyctl_revoke().  If the revoke
happens between keyctl_read() checking the validity of a key and the key's
semaphore being taken, then the key type read method will see a revoked key.

This causes a problem for the user-defined key type because it assumes in
its read method that there will always be a payload in a non-revoked key
and doesn't check for a NULL pointer.

Fix this by making keyctl_read() check the validity of a key after taking
semaphore instead of before.

I think the bug was introduced with the original keyrings code.

This was discovered by a multithreaded test program generated by syzkaller
(http://github.com/google/syzkaller).  Here's a cleaned up version:

	#include <sys/types.h>
	#include <keyutils.h>
	#include <pthread.h>
	void *thr0(void *arg)
	{
		key_serial_t key = (unsigned long)arg;
		keyctl_revoke(key);
		return 0;
	}
	void *thr1(void *arg)
	{
		key_serial_t key = (unsigned long)arg;
		char buffer[16];
		keyctl_read(key, buffer, 16);
		return 0;
	}
	int main()
	{
		key_serial_t key = add_key("user", "%", "foo", 3, KEY_SPEC_USER_KEYRING);
		pthread_t th[5];
		pthread_create(&th[0], 0, thr0, (void *)(unsigned long)key);
		pthread_create(&th[1], 0, thr1, (void *)(unsigned long)key);
		pthread_create(&th[2], 0, thr0, (void *)(unsigned long)key);
		pthread_create(&th[3], 0, thr1, (void *)(unsigned long)key);
		pthread_join(th[0], 0);
		pthread_join(th[1], 0);
		pthread_join(th[2], 0);
		pthread_join(th[3], 0);
		return 0;
	}

Build as:

	cc -o keyctl-race keyctl-race.c -lkeyutils -lpthread

Run as:

	while keyctl-race; do :; done

as it may need several iterations to crash the kernel.  The crash can be
summarised as:

	BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
	IP: [<ffffffff81279b08>] user_read+0x56/0xa3
	...
	Call Trace:
	 [<ffffffff81276aa9>] keyctl_read_key+0xb6/0xd7
	 [<ffffffff81277815>] SyS_keyctl+0x83/0xe0
	 [<ffffffff815dbb97>] entry_SYSCALL_64_fastpath+0x12/0x6f

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>
CVE: CVE-2015-7550
CWE: CWE-362
Vulnerability description: The keyctl_read_key function in security/keys/keyctl.c in the Linux kernel before 4.3.4 does not properly use a semaphore, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via a crafted application that leverages a race condition between keyctl_revoke and keyctl_read calls.

Project: linux
File: keyctl.c

SYSCALL_DEFINE4(request_key, const char __user *, _type,
		const char __user *, _description,
		const char __user *, _callout_info,
		key_serial_t, destringid)
{
	struct key_type *ktype;
	struct key *key;
	key_ref_t dest_ref;
	size_t callout_len;
	char type[32], *description, *callout_info;
	long ret;

	/* pull the type into kernel space */
	ret = key_get_type_from_user(type, _type, sizeof(type));
	if (ret < 0)
		goto error;

	/* pull the description into kernel space */
	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
	if (IS_ERR(description)) {
		ret = PTR_ERR(description);
		goto error;
	}

	/* pull the callout info into kernel space */
	callout_info = NULL;
	callout_len = 0;
	if (_callout_info) {
		callout_info = strndup_user(_callout_info, PAGE_SIZE);
		if (IS_ERR(callout_info)) {
			ret = PTR_ERR(callout_info);
			goto error2;
		}
		callout_len = strlen(callout_info);
	}

	/* get the destination keyring if specified */
	dest_ref = NULL;
	if (destringid) {
		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
					   KEY_NEED_WRITE);
		if (IS_ERR(dest_ref)) {
			ret = PTR_ERR(dest_ref);
			goto error3;
		}
	}

	/* find the key type */
	ktype = key_type_lookup(type);
	if (IS_ERR(ktype)) {
		ret = PTR_ERR(ktype);
		goto error4;
	}

	/* do the search */
	key = request_key_and_link(ktype, description, callout_info,
				   callout_len, NULL, key_ref_to_ptr(dest_ref),
				   KEY_ALLOC_IN_QUOTA);
	if (IS_ERR(key)) {
		ret = PTR_ERR(key);
		goto error5;
	}

	/* wait for the key to finish being constructed */
	ret = wait_for_key_construction(key, 1);
	if (ret < 0)
		goto error6;

	ret = key->serial;

error6:
 	key_put(key);
error5:
	key_type_put(ktype);
error4:
	key_ref_put(dest_ref);
error3:
	kfree(callout_info);
error2:
	kfree(description);
error:
	return ret;
}

Project: linux
File: keyctl.c

SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
		unsigned long, arg4, unsigned long, arg5)
{
	switch (option) {
	case KEYCTL_GET_KEYRING_ID:
		return keyctl_get_keyring_ID((key_serial_t) arg2,
					     (int) arg3);

	case KEYCTL_JOIN_SESSION_KEYRING:
		return keyctl_join_session_keyring((const char __user *) arg2);

	case KEYCTL_UPDATE:
		return keyctl_update_key((key_serial_t) arg2,
					 (const void __user *) arg3,
					 (size_t) arg4);

	case KEYCTL_REVOKE:
		return keyctl_revoke_key((key_serial_t) arg2);

	case KEYCTL_DESCRIBE:
		return keyctl_describe_key((key_serial_t) arg2,
					   (char __user *) arg3,
					   (unsigned) arg4);

	case KEYCTL_CLEAR:
		return keyctl_keyring_clear((key_serial_t) arg2);

	case KEYCTL_LINK:
		return keyctl_keyring_link((key_serial_t) arg2,
					   (key_serial_t) arg3);

	case KEYCTL_UNLINK:
		return keyctl_keyring_unlink((key_serial_t) arg2,
					     (key_serial_t) arg3);

	case KEYCTL_SEARCH:
		return keyctl_keyring_search((key_serial_t) arg2,
					     (const char __user *) arg3,
					     (const char __user *) arg4,
					     (key_serial_t) arg5);

	case KEYCTL_READ:
		return keyctl_read_key((key_serial_t) arg2,
				       (char __user *) arg3,
				       (size_t) arg4);

	case KEYCTL_CHOWN:
		return keyctl_chown_key((key_serial_t) arg2,
					(uid_t) arg3,
					(gid_t) arg4);

	case KEYCTL_SETPERM:
		return keyctl_setperm_key((key_serial_t) arg2,
					  (key_perm_t) arg3);

	case KEYCTL_INSTANTIATE:
		return keyctl_instantiate_key((key_serial_t) arg2,
					      (const void __user *) arg3,
					      (size_t) arg4,
					      (key_serial_t) arg5);

	case KEYCTL_NEGATE:
		return keyctl_negate_key((key_serial_t) arg2,
					 (unsigned) arg3,
					 (key_serial_t) arg4);

	case KEYCTL_SET_REQKEY_KEYRING:
		return keyctl_set_reqkey_keyring(arg2);

	case KEYCTL_SET_TIMEOUT:
		return keyctl_set_timeout((key_serial_t) arg2,
					  (unsigned) arg3);

	case KEYCTL_ASSUME_AUTHORITY:
		return keyctl_assume_authority((key_serial_t) arg2);

	case KEYCTL_GET_SECURITY:
		return keyctl_get_security((key_serial_t) arg2,
					   (char __user *) arg3,
					   (size_t) arg4);

	case KEYCTL_SESSION_TO_PARENT:
		return keyctl_session_to_parent();

	case KEYCTL_REJECT:
		return keyctl_reject_key((key_serial_t) arg2,
					 (unsigned) arg3,
					 (unsigned) arg4,
					 (key_serial_t) arg5);

	case KEYCTL_INSTANTIATE_IOV:
		return keyctl_instantiate_key_iov(
			(key_serial_t) arg2,
			(const struct iovec __user *) arg3,
			(unsigned) arg4,
			(key_serial_t) arg5);

	case KEYCTL_INVALIDATE:
		return keyctl_invalidate_key((key_serial_t) arg2);

	case KEYCTL_GET_PERSISTENT:
		return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);

	default:
		return -EOPNOTSUPP;
	}
}

Project: linux
File: keyctl.c

static long get_instantiation_keyring(key_serial_t ringid,
				      struct request_key_auth *rka,
				      struct key **_dest_keyring)
{
	key_ref_t dkref;

	*_dest_keyring = NULL;

	/* just return a NULL pointer if we weren't asked to make a link */
	if (ringid == 0)
		return 0;

	/* if a specific keyring is nominated by ID, then use that */
	if (ringid > 0) {
		dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
		if (IS_ERR(dkref))
			return PTR_ERR(dkref);
		*_dest_keyring = key_ref_to_ptr(dkref);
		return 0;
	}

	if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
		return -EINVAL;

	/* otherwise specify the destination keyring recorded in the
	 * authorisation key (any KEY_SPEC_*_KEYRING) */
	if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
		*_dest_keyring = key_get(rka->dest_keyring);
		return 0;
	}

	return -ENOKEY;
}

Project: linux
File: keyctl.c

static int key_get_type_from_user(char *type,
				  const char __user *_type,
				  unsigned len)
{
	int ret;

	ret = strncpy_from_user(type, _type, len);
	if (ret < 0)
		return ret;
	if (ret == 0 || ret >= len)
		return -EINVAL;
	if (type[0] == '.')
		return -EPERM;
	type[len - 1] = '\0';
	return 0;
}

Project: linux
File: keyctl.c

long keyctl_assume_authority(key_serial_t id)
{
	struct key *authkey;
	long ret;

	/* special key IDs aren't permitted */
	ret = -EINVAL;
	if (id < 0)
		goto error;

	/* we divest ourselves of authority if given an ID of 0 */
	if (id == 0) {
		ret = keyctl_change_reqkey_auth(NULL);
		goto error;
	}

	/* attempt to assume the authority temporarily granted to us whilst we
	 * instantiate the specified key
	 * - the authorisation key must be in the current task's keyrings
	 *   somewhere
	 */
	authkey = key_get_instantiation_authkey(id);
	if (IS_ERR(authkey)) {
		ret = PTR_ERR(authkey);
		goto error;
	}

	ret = keyctl_change_reqkey_auth(authkey);
	if (ret < 0)
		goto error;
	key_put(authkey);

	ret = authkey->serial;
error:
	return ret;
}

Project: linux
File: keyctl.c

static int keyctl_change_reqkey_auth(struct key *key)
{
	struct cred *new;

	new = prepare_creds();
	if (!new)
		return -ENOMEM;

	key_put(new->request_key_auth);
	new->request_key_auth = key_get(key);

	return commit_creds(new);
}

Project: linux
File: keyctl.c

long keyctl_describe_key(key_serial_t keyid,
			 char __user *buffer,
			 size_t buflen)
{
	struct key *key, *instkey;
	key_ref_t key_ref;
	char *infobuf;
	long ret;
	int desclen, infolen;

	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
	if (IS_ERR(key_ref)) {
		/* viewing a key under construction is permitted if we have the
		 * authorisation token handy */
		if (PTR_ERR(key_ref) == -EACCES) {
			instkey = key_get_instantiation_authkey(keyid);
			if (!IS_ERR(instkey)) {
				key_put(instkey);
				key_ref = lookup_user_key(keyid,
							  KEY_LOOKUP_PARTIAL,
							  0);
				if (!IS_ERR(key_ref))
					goto okay;
			}
		}

		ret = PTR_ERR(key_ref);
		goto error;
	}

okay:
	key = key_ref_to_ptr(key_ref);
	desclen = strlen(key->description);

	/* calculate how much information we're going to return */
	ret = -ENOMEM;
	infobuf = kasprintf(GFP_KERNEL,
			    "%s;%d;%d;%08x;",
			    key->type->name,
			    from_kuid_munged(current_user_ns(), key->uid),
			    from_kgid_munged(current_user_ns(), key->gid),
			    key->perm);
	if (!infobuf)
		goto error2;
	infolen = strlen(infobuf);
	ret = infolen + desclen + 1;

	/* consider returning the data */
	if (buffer && buflen >= ret) {
		if (copy_to_user(buffer, infobuf, infolen) != 0 ||
		    copy_to_user(buffer + infolen, key->description,
				 desclen + 1) != 0)
			ret = -EFAULT;
	}

	kfree(infobuf);
error2:
	key_ref_put(key_ref);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_get_keyring_ID(key_serial_t id, int create)
{
	key_ref_t key_ref;
	unsigned long lflags;
	long ret;

	lflags = create ? KEY_LOOKUP_CREATE : 0;
	key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error;
	}

	ret = key_ref_to_ptr(key_ref)->serial;
	key_ref_put(key_ref);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_get_security(key_serial_t keyid,
			 char __user *buffer,
			 size_t buflen)
{
	struct key *key, *instkey;
	key_ref_t key_ref;
	char *context;
	long ret;

	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
	if (IS_ERR(key_ref)) {
		if (PTR_ERR(key_ref) != -EACCES)
			return PTR_ERR(key_ref);

		/* viewing a key under construction is also permitted if we
		 * have the authorisation token handy */
		instkey = key_get_instantiation_authkey(keyid);
		if (IS_ERR(instkey))
			return PTR_ERR(instkey);
		key_put(instkey);

		key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
		if (IS_ERR(key_ref))
			return PTR_ERR(key_ref);
	}

	key = key_ref_to_ptr(key_ref);
	ret = security_key_getsecurity(key, &context);
	if (ret == 0) {
		/* if no information was returned, give userspace an empty
		 * string */
		ret = 1;
		if (buffer && buflen > 0 &&
		    copy_to_user(buffer, "", 1) != 0)
			ret = -EFAULT;
	} else if (ret > 0) {
		/* return as much data as there's room for */
		if (buffer && buflen > 0) {
			if (buflen > ret)
				buflen = ret;

			if (copy_to_user(buffer, context, buflen) != 0)
				ret = -EFAULT;
		}

		kfree(context);
	}

	key_ref_put(key_ref);
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_instantiate_key(key_serial_t id,
			    const void __user *_payload,
			    size_t plen,
			    key_serial_t ringid)
{
	if (_payload && plen) {
		struct iovec iov;
		struct iov_iter from;
		int ret;

		ret = import_single_range(WRITE, (void __user *)_payload, plen,
					  &iov, &from);
		if (unlikely(ret))
			return ret;

		return keyctl_instantiate_key_common(id, &from, ringid);
	}

	return keyctl_instantiate_key_common(id, NULL, ringid);
}

Project: linux
File: keyctl.c

long keyctl_instantiate_key_common(key_serial_t id,
				   struct iov_iter *from,
				   key_serial_t ringid)
{
	const struct cred *cred = current_cred();
	struct request_key_auth *rka;
	struct key *instkey, *dest_keyring;
	size_t plen = from ? iov_iter_count(from) : 0;
	void *payload;
	long ret;

	kenter("%d,,%zu,%d", id, plen, ringid);

	if (!plen)
		from = NULL;

	ret = -EINVAL;
	if (plen > 1024 * 1024 - 1)
		goto error;

	/* the appropriate instantiation authorisation key must have been
	 * assumed before calling this */
	ret = -EPERM;
	instkey = cred->request_key_auth;
	if (!instkey)
		goto error;

	rka = instkey->payload.data[0];
	if (rka->target_key->serial != id)
		goto error;

	/* pull the payload in if one was supplied */
	payload = NULL;

	if (from) {
		ret = -ENOMEM;
		payload = kmalloc(plen, GFP_KERNEL);
		if (!payload) {
			if (plen <= PAGE_SIZE)
				goto error;
			payload = vmalloc(plen);
			if (!payload)
				goto error;
		}

		ret = -EFAULT;
		if (copy_from_iter(payload, plen, from) != plen)
			goto error2;
	}

	/* find the destination keyring amongst those belonging to the
	 * requesting task */
	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
	if (ret < 0)
		goto error2;

	/* instantiate the key and link it into a keyring */
	ret = key_instantiate_and_link(rka->target_key, payload, plen,
				       dest_keyring, instkey);

	key_put(dest_keyring);

	/* discard the assumed authority if it's just been disabled by
	 * instantiation of the key */
	if (ret == 0)
		keyctl_change_reqkey_auth(NULL);

error2:
	kvfree(payload);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_instantiate_key_iov(key_serial_t id,
				const struct iovec __user *_payload_iov,
				unsigned ioc,
				key_serial_t ringid)
{
	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
	struct iov_iter from;
	long ret;

	if (!_payload_iov)
		ioc = 0;

	ret = import_iovec(WRITE, _payload_iov, ioc,
				    ARRAY_SIZE(iovstack), &iov, &from);
	if (ret < 0)
		return ret;
	ret = keyctl_instantiate_key_common(id, &from, ringid);
	kfree(iov);
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_invalidate_key(key_serial_t id)
{
	key_ref_t key_ref;
	long ret;

	kenter("%d", id);

	key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);

		/* Root is permitted to invalidate certain special keys */
		if (capable(CAP_SYS_ADMIN)) {
			key_ref = lookup_user_key(id, 0, 0);
			if (IS_ERR(key_ref))
				goto error;
			if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
				     &key_ref_to_ptr(key_ref)->flags))
				goto invalidate;
			goto error_put;
		}

		goto error;
	}

invalidate:
	key_invalidate(key_ref_to_ptr(key_ref));
	ret = 0;
error_put:
	key_ref_put(key_ref);
error:
	kleave(" = %ld", ret);
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
{
	key_ref_t keyring_ref, key_ref;
	long ret;

	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error;
	}

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error2;
	}

	ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));

	key_ref_put(key_ref);
error2:
	key_ref_put(keyring_ref);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_keyring_search(key_serial_t ringid,
			   const char __user *_type,
			   const char __user *_description,
			   key_serial_t destringid)
{
	struct key_type *ktype;
	key_ref_t keyring_ref, key_ref, dest_ref;
	char type[32], *description;
	long ret;

	/* pull the type and description into kernel space */
	ret = key_get_type_from_user(type, _type, sizeof(type));
	if (ret < 0)
		goto error;

	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
	if (IS_ERR(description)) {
		ret = PTR_ERR(description);
		goto error;
	}

	/* get the keyring at which to begin the search */
	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error2;
	}

	/* get the destination keyring if specified */
	dest_ref = NULL;
	if (destringid) {
		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
					   KEY_NEED_WRITE);
		if (IS_ERR(dest_ref)) {
			ret = PTR_ERR(dest_ref);
			goto error3;
		}
	}

	/* find the key type */
	ktype = key_type_lookup(type);
	if (IS_ERR(ktype)) {
		ret = PTR_ERR(ktype);
		goto error4;
	}

	/* do the search */
	key_ref = keyring_search(keyring_ref, ktype, description);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);

		/* treat lack or presence of a negative key the same */
		if (ret == -EAGAIN)
			ret = -ENOKEY;
		goto error5;
	}

	/* link the resulting key to the destination keyring if we can */
	if (dest_ref) {
		ret = key_permission(key_ref, KEY_NEED_LINK);
		if (ret < 0)
			goto error6;

		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
		if (ret < 0)
			goto error6;
	}

	ret = key_ref_to_ptr(key_ref)->serial;

error6:
	key_ref_put(key_ref);
error5:
	key_type_put(ktype);
error4:
	key_ref_put(dest_ref);
error3:
	key_ref_put(keyring_ref);
error2:
	kfree(description);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
{
	key_ref_t keyring_ref, key_ref;
	long ret;

	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
	if (IS_ERR(keyring_ref)) {
		ret = PTR_ERR(keyring_ref);
		goto error;
	}

	key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error2;
	}

	ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));

	key_ref_put(key_ref);
error2:
	key_ref_put(keyring_ref);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
{
	return keyctl_reject_key(id, timeout, ENOKEY, ringid);
}

Project: linux
File: keyctl.c

long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
		       key_serial_t ringid)
{
	const struct cred *cred = current_cred();
	struct request_key_auth *rka;
	struct key *instkey, *dest_keyring;
	long ret;

	kenter("%d,%u,%u,%d", id, timeout, error, ringid);

	/* must be a valid error code and mustn't be a kernel special */
	if (error <= 0 ||
	    error >= MAX_ERRNO ||
	    error == ERESTARTSYS ||
	    error == ERESTARTNOINTR ||
	    error == ERESTARTNOHAND ||
	    error == ERESTART_RESTARTBLOCK)
		return -EINVAL;

	/* the appropriate instantiation authorisation key must have been
	 * assumed before calling this */
	ret = -EPERM;
	instkey = cred->request_key_auth;
	if (!instkey)
		goto error;

	rka = instkey->payload.data[0];
	if (rka->target_key->serial != id)
		goto error;

	/* find the destination keyring if present (which must also be
	 * writable) */
	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
	if (ret < 0)
		goto error;

	/* instantiate the key and link it into a keyring */
	ret = key_reject_and_link(rka->target_key, timeout, error,
				  dest_keyring, instkey);

	key_put(dest_keyring);

	/* discard the assumed authority if it's just been disabled by
	 * instantiation of the key */
	if (ret == 0)
		keyctl_change_reqkey_auth(NULL);

error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_revoke_key(key_serial_t id)
{
	key_ref_t key_ref;
	long ret;

	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		if (ret != -EACCES)
			goto error;
		key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
		if (IS_ERR(key_ref)) {
			ret = PTR_ERR(key_ref);
			goto error;
		}
	}

	key_revoke(key_ref_to_ptr(key_ref));
	ret = 0;

	key_ref_put(key_ref);
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_session_to_parent(void)
{
	struct task_struct *me, *parent;
	const struct cred *mycred, *pcred;
	struct callback_head *newwork, *oldwork;
	key_ref_t keyring_r;
	struct cred *cred;
	int ret;

	keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
	if (IS_ERR(keyring_r))
		return PTR_ERR(keyring_r);

	ret = -ENOMEM;

	/* our parent is going to need a new cred struct, a new tgcred struct
	 * and new security data, so we allocate them here to prevent ENOMEM in
	 * our parent */
	cred = cred_alloc_blank();
	if (!cred)
		goto error_keyring;
	newwork = &cred->rcu;

	cred->session_keyring = key_ref_to_ptr(keyring_r);
	keyring_r = NULL;
	init_task_work(newwork, key_change_session_keyring);

	me = current;
	rcu_read_lock();
	write_lock_irq(&tasklist_lock);

	ret = -EPERM;
	oldwork = NULL;
	parent = me->real_parent;

	/* the parent mustn't be init and mustn't be a kernel thread */
	if (parent->pid <= 1 || !parent->mm)
		goto unlock;

	/* the parent must be single threaded */
	if (!thread_group_empty(parent))
		goto unlock;

	/* the parent and the child must have different session keyrings or
	 * there's no point */
	mycred = current_cred();
	pcred = __task_cred(parent);
	if (mycred == pcred ||
	    mycred->session_keyring == pcred->session_keyring) {
		ret = 0;
		goto unlock;
	}

	/* the parent must have the same effective ownership and mustn't be
	 * SUID/SGID */
	if (!uid_eq(pcred->uid,	 mycred->euid) ||
	    !uid_eq(pcred->euid, mycred->euid) ||
	    !uid_eq(pcred->suid, mycred->euid) ||
	    !gid_eq(pcred->gid,	 mycred->egid) ||
	    !gid_eq(pcred->egid, mycred->egid) ||
	    !gid_eq(pcred->sgid, mycred->egid))
		goto unlock;

	/* the keyrings must have the same UID */
	if ((pcred->session_keyring &&
	     !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
	    !uid_eq(mycred->session_keyring->uid, mycred->euid))
		goto unlock;

	/* cancel an already pending keyring replacement */
	oldwork = task_work_cancel(parent, key_change_session_keyring);

	/* the replacement session keyring is applied just prior to userspace
	 * restarting */
	ret = task_work_add(parent, newwork, true);
	if (!ret)
		newwork = NULL;
unlock:
	write_unlock_irq(&tasklist_lock);
	rcu_read_unlock();
	if (oldwork)
		put_cred(container_of(oldwork, struct cred, rcu));
	if (newwork)
		put_cred(cred);
	return ret;

error_keyring:
	key_ref_put(keyring_r);
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_set_timeout(key_serial_t id, unsigned timeout)
{
	struct key *key, *instkey;
	key_ref_t key_ref;
	long ret;

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
				  KEY_NEED_SETATTR);
	if (IS_ERR(key_ref)) {
		/* setting the timeout on a key under construction is permitted
		 * if we have the authorisation token handy */
		if (PTR_ERR(key_ref) == -EACCES) {
			instkey = key_get_instantiation_authkey(id);
			if (!IS_ERR(instkey)) {
				key_put(instkey);
				key_ref = lookup_user_key(id,
							  KEY_LOOKUP_PARTIAL,
							  0);
				if (!IS_ERR(key_ref))
					goto okay;
			}
		}

		ret = PTR_ERR(key_ref);
		goto error;
	}

okay:
	key = key_ref_to_ptr(key_ref);
	key_set_timeout(key, timeout);
	key_put(key);

	ret = 0;
error:
	return ret;
}

Project: linux
File: keyctl.c

long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
{
	struct key *key;
	key_ref_t key_ref;
	long ret;

	ret = -EINVAL;
	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
		goto error;

	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
				  KEY_NEED_SETATTR);
	if (IS_ERR(key_ref)) {
		ret = PTR_ERR(key_ref);
		goto error;
	}

	key = key_ref_to_ptr(key_ref);

	/* make the changes with the locks held to prevent chown/chmod races */
	ret = -EACCES;
	down_write(&key->sem);

	/* if we're not the sysadmin, we can only change a key that we own */
	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
		key->perm = perm;
		ret = 0;
	}

	up_write(&key->sem);
	key_put(key);
error:
	return ret;
}