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Keyrings fixes

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Merge tag 'keys-fixes-20170419' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull keyrings fixes from David Howells:

 (1) Disallow keyrings whose name begins with a '.' to be joined
     [CVE-2016-9604].

 (2) Change the name of the dead type to ".dead" to prevent user access
     [CVE-2017-6951].

 (3) Fix keyctl_set_reqkey_keyring() to not leak thread keyrings
     [CVE-2017-7472]

* tag 'keys-fixes-20170419' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  KEYS: fix keyctl_set_reqkey_keyring() to not leak thread keyrings
  KEYS: Change the name of the dead type to ".dead" to prevent user access
  KEYS: Disallow keyrings beginning with '.' to be joined as session keyrings
This commit is contained in:
Linus Torvalds 2017-04-20 11:12:51 -07:00
commit f205b5dc1c
3 changed files with 39 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
security/keys/gc.c
View File

@ -46,7 +46,7 @@ static unsigned long key_gc_flags;
* immediately unlinked.
*/
struct key_type key_type_dead = {
.name = "dead",
.name = ".dead",
};
/*

20
security/keys/keyctl.c
View File

@ -273,7 +273,8 @@ error:
* Create and join an anonymous session keyring or join a named session
* keyring, creating it if necessary. A named session keyring must have Search
* permission for it to be joined. Session keyrings without this permit will
* be skipped over.
* be skipped over. It is not permitted for userspace to create or join
* keyrings whose name begin with a dot.
*
* If successful, the ID of the joined session keyring will be returned.
*/
@ -290,12 +291,16 @@ long keyctl_join_session_keyring(const char __user *_name)
ret = PTR_ERR(name);
goto error;
}
ret = -EPERM;
if (name[0] == '.')
goto error_name;
}
/* join the session */
ret = join_session_keyring(name);
error_name:
kfree(name);
error:
return ret;
}
@ -1253,8 +1258,8 @@ error:
* Read or set the default keyring in which request_key() will cache keys and
* return the old setting.
*
* If a process keyring is specified then this will be created if it doesn't
* yet exist. The old setting will be returned if successful.
* If a thread or process keyring is specified then it will be created if it
* doesn't yet exist. The old setting will be returned if successful.
*/
long keyctl_set_reqkey_keyring(int reqkey_defl)
{
@ -1279,11 +1284,8 @@ long keyctl_set_reqkey_keyring(int reqkey_defl)
case KEY_REQKEY_DEFL_PROCESS_KEYRING:
ret = install_process_keyring_to_cred(new);
if (ret < 0) {
if (ret != -EEXIST)
goto error;
ret = 0;
}
if (ret < 0)
goto error;
goto set;
case KEY_REQKEY_DEFL_DEFAULT:

44
security/keys/process_keys.c
View File

@ -128,13 +128,18 @@ error:
}
/*
* Install a fresh thread keyring directly to new credentials. This keyring is
* allowed to overrun the quota.
* Install a thread keyring to the given credentials struct if it didn't have
* one already. This is allowed to overrun the quota.
*
* Return: 0 if a thread keyring is now present; -errno on failure.
*/
int install_thread_keyring_to_cred(struct cred *new)
{
struct key *keyring;
if (new->thread_keyring)
return 0;
keyring = keyring_alloc("_tid", new->uid, new->gid, new,
KEY_POS_ALL | KEY_USR_VIEW,
KEY_ALLOC_QUOTA_OVERRUN,
@ -147,7 +152,9 @@ int install_thread_keyring_to_cred(struct cred *new)
}
/*
* Install a fresh thread keyring, discarding the old one.
* Install a thread keyring to the current task if it didn't have one already.
*
* Return: 0 if a thread keyring is now present; -errno on failure.
*/
static int install_thread_keyring(void)
{
@ -158,8 +165,6 @@ static int install_thread_keyring(void)
if (!new)
return -ENOMEM;
BUG_ON(new->thread_keyring);
ret = install_thread_keyring_to_cred(new);
if (ret < 0) {
abort_creds(new);
@ -170,17 +175,17 @@ static int install_thread_keyring(void)
}
/*
* Install a process keyring directly to a credentials struct.
* Install a process keyring to the given credentials struct if it didn't have
* one already. This is allowed to overrun the quota.
*
* Returns -EEXIST if there was already a process keyring, 0 if one installed,
* and other value on any other error
* Return: 0 if a process keyring is now present; -errno on failure.
*/
int install_process_keyring_to_cred(struct cred *new)
{
struct key *keyring;
if (new->process_keyring)
return -EEXIST;
return 0;
keyring = keyring_alloc("_pid", new->uid, new->gid, new,
KEY_POS_ALL | KEY_USR_VIEW,
@ -194,11 +199,9 @@ int install_process_keyring_to_cred(struct cred *new)
}
/*
* Make sure a process keyring is installed for the current process. The
* existing process keyring is not replaced.
* Install a process keyring to the current task if it didn't have one already.
*
* Returns 0 if there is a process keyring by the end of this function, some
* error otherwise.
* Return: 0 if a process keyring is now present; -errno on failure.
*/
static int install_process_keyring(void)
{
@ -212,14 +215,18 @@ static int install_process_keyring(void)
ret = install_process_keyring_to_cred(new);
if (ret < 0) {
abort_creds(new);
return ret != -EEXIST ? ret : 0;
return ret;
}
return commit_creds(new);
}
/*
* Install a session keyring directly to a credentials struct.
* Install the given keyring as the session keyring of the given credentials
* struct, replacing the existing one if any. If the given keyring is NULL,
* then install a new anonymous session keyring.
*
* Return: 0 on success; -errno on failure.
*/
int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
{
@ -254,8 +261,11 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
}
/*
* Install a session keyring, discarding the old one. If a keyring is not
* supplied, an empty one is invented.
* Install the given keyring as the session keyring of the current task,
* replacing the existing one if any. If the given keyring is NULL, then
* install a new anonymous session keyring.
*
* Return: 0 on success; -errno on failure.
*/
static int install_session_keyring(struct key *keyring)
{