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authorLinus Torvalds <torvalds@linux-foundation.org>2017-04-20 11:12:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-04-20 11:12:51 -0700
commitf205b5dc1c9e62237ac6e21642724d8cbc85f7ee (patch)
tree73d32927586b80b6ceaaac8380b8ddd8c45024b7
parentf61143c45077df4fa78e2f1ba455a00bbe1d5b8c (diff)
parentc9f838d104fed6f2f61d68164712e3204bf5271b (diff)
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
-rw-r--r--security/keys/gc.c2
-rw-r--r--security/keys/keyctl.c20
-rw-r--r--security/keys/process_keys.c44
3 files changed, 39 insertions, 27 deletions
diff --git a/security/keys/gc.c b/security/keys/gc.c
index addf060399e0..9cb4fe4478a1 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -46,7 +46,7 @@ static unsigned long key_gc_flags;
* immediately unlinked.
*/
struct key_type key_type_dead = {
- .name = "dead",
+ .name = ".dead",
};
/*
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 52c34532c785..4ad3212adebe 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -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:
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index b6fdd22205b1..9139b18fc863 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -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)
{