[GIT PULL] Bugfixes for the Keys subsystem

[James Morris]

Please pull these patches for the Keys subsystem, which fix:

- CVE-2017-7472
- CVE-2017-6951
- CVE-2016-9604


The following changes since commit f61143c45077df4fa78e2f1ba455a00bbe1d5b8c:

  Merge tag 'clk-fixes-for-linus' of 
git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux (2017-04-19 17:16:18 
-0700)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git 
for-linus

David Howells (2):
  KEYS: Disallow keyrings beginning with '.' to be joined as session 
keyrings
  KEYS: Change the name of the dead type to ".dead" to prevent user access

Eric Biggers (1):
  KEYS: fix keyctl_set_reqkey_keyring() to not leak thread keyrings

 security/keys/gc.c   |2 +-
 security/keys/keyctl.c   |   20 ++
 security/keys/process_keys.c |   44 +
 3 files changed, 39 insertions(+), 27 deletions(-)

---

commit b1be815668e2f0c6a1ebb9e5c27e3ae1bf4b9917
Author: Eric Biggers 
Date:   Wed Apr 19 17:13:02 2017 +0100

KEYS: fix keyctl_set_reqkey_keyring() to not leak thread keyrings

This fixes CVE-2017-7472.

Running the following program as an unprivileged user exhausts kernel
memory by leaking thread keyrings:

#include 

int main()
{
for (;;)

keyctl_set_reqkey_keyring(KEY_REQKEY_DEFL_THREAD_KEYRING);
}

Fix it by only creating a new thread keyring if there wasn't one before.
To make things more consistent, make install_thread_keyring_to_cred()
and install_process_keyring_to_cred() both return 0 if the corresponding
keyring is already present.

Fixes: d84f4f992cbd ("CRED: Inaugurate COW credentials")
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
Signed-off-by: James Morris 

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index ab082a2..4ad3212 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1258,8 +1258,8 @@ long keyctl_reject_key(key_serial_t id, unsigned timeout, 
unsigned 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)
 {
@@ -1284,11 +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:
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index b6fdd22..9139b18 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -128,13 +128,18 @@ int install_user_keyrings(void)
 }
 
 /*
- * 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 

[GIT PULL] Bugfixes for the Keys subsystem

[James Morris]

Please pull these patches for the Keys subsystem, which fix:

- CVE-2017-7472
- CVE-2017-6951
- CVE-2016-9604


The following changes since commit f61143c45077df4fa78e2f1ba455a00bbe1d5b8c:

  Merge tag 'clk-fixes-for-linus' of 
git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux (2017-04-19 17:16:18 
-0700)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git 
for-linus

David Howells (2):
  KEYS: Disallow keyrings beginning with '.' to be joined as session 
keyrings
  KEYS: Change the name of the dead type to ".dead" to prevent user access

Eric Biggers (1):
  KEYS: fix keyctl_set_reqkey_keyring() to not leak thread keyrings

 security/keys/gc.c   |2 +-
 security/keys/keyctl.c   |   20 ++
 security/keys/process_keys.c |   44 +
 3 files changed, 39 insertions(+), 27 deletions(-)

---

commit b1be815668e2f0c6a1ebb9e5c27e3ae1bf4b9917
Author: Eric Biggers 
Date:   Wed Apr 19 17:13:02 2017 +0100

KEYS: fix keyctl_set_reqkey_keyring() to not leak thread keyrings

This fixes CVE-2017-7472.

Running the following program as an unprivileged user exhausts kernel
memory by leaking thread keyrings:

#include 

int main()
{
for (;;)

keyctl_set_reqkey_keyring(KEY_REQKEY_DEFL_THREAD_KEYRING);
}

Fix it by only creating a new thread keyring if there wasn't one before.
To make things more consistent, make install_thread_keyring_to_cred()
and install_process_keyring_to_cred() both return 0 if the corresponding
keyring is already present.

Fixes: d84f4f992cbd ("CRED: Inaugurate COW credentials")
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
Signed-off-by: James Morris 

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index ab082a2..4ad3212 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1258,8 +1258,8 @@ long keyctl_reject_key(key_serial_t id, unsigned timeout, 
unsigned 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)
 {
@@ -1284,11 +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:
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index b6fdd22..9139b18 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -128,13 +128,18 @@ int install_user_keyrings(void)
 }
 
 /*
- * 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