[PATCH 1/6] Keys: Sort out key quota system [try #3]

From: David Howells
Date: Tue Jun 20 2006 - 13:36:41 EST

From: David Howells <dhowells@xxxxxxxxxx>

The attached patch adds the ability for key creation to overrun the user's
quota in some circumstances - notably when a session keyring is created and
assigned to a process that didn't previously have one.

This means it's still possible to log in, should PAM require the creation of a
new session keyring, and fix an overburdened key quota.

Signed-Off-By: David Howells <dhowells@xxxxxxxxxx>
---

include/linux/key.h | 13 ++++++++++---
include/linux/security.h | 11 +++++++----
security/dummy.c | 3 ++-
security/keys/internal.h | 3 ++-
security/keys/key.c | 26 ++++++++++++++------------
security/keys/keyctl.c | 5 +++--
security/keys/keyring.c | 4 ++--
security/keys/process_keys.c | 24 +++++++++++++++++-------
security/keys/request_key.c | 36 +++++++++++++++++++++---------------
security/keys/request_key_auth.c | 2 +-
security/selinux/hooks.c | 9 ++++++---
11 files changed, 85 insertions(+), 51 deletions(-)

diff --git a/include/linux/key.h b/include/linux/key.h
index e81ebf9..e693e72 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -248,7 +248,14 @@ extern struct key *key_alloc(struct key_
const char *desc,
uid_t uid, gid_t gid,
struct task_struct *ctx,
- key_perm_t perm, int not_in_quota);
+ key_perm_t perm,
+ unsigned long flags);
+
+
+#define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
+#define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
+#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
+
extern int key_payload_reserve(struct key *key, size_t datalen);
extern int key_instantiate_and_link(struct key *key,
const void *data,
@@ -285,7 +292,7 @@ extern key_ref_t key_create_or_update(ke
const char *description,
const void *payload,
size_t plen,
- int not_in_quota);
+ unsigned long flags);

extern int key_update(key_ref_t key,
const void *payload,
@@ -299,7 +306,7 @@ extern int key_unlink(struct key *keyrin

extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
struct task_struct *ctx,
- int not_in_quota,
+ unsigned long flags,
struct key *dest);

extern int keyring_clear(struct key *keyring);
diff --git a/include/linux/security.h b/include/linux/security.h
index 383c320..d4aa1bf 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -853,6 +853,7 @@ #ifdef CONFIG_SECURITY
* Permit allocation of a key and assign security data. Note that key does
* not have a serial number assigned at this point.
* @key points to the key.
+ * @flags is the allocation flags
* Return 0 if permission is granted, -ve error otherwise.
* @key_free:
* Notification of destruction; free security data.
@@ -1313,7 +1314,7 @@ #endif /* CONFIG_SECURITY_NETWORK_XFRM *

/* key management security hooks */
#ifdef CONFIG_KEYS
- int (*key_alloc)(struct key *key, struct task_struct *tsk);
+ int (*key_alloc)(struct key *key, struct task_struct *tsk, unsigned long flags);
void (*key_free)(struct key *key);
int (*key_permission)(key_ref_t key_ref,
struct task_struct *context,
@@ -3009,9 +3010,10 @@ #endif /* CONFIG_SECURITY_NETWORK_XFRM *
#ifdef CONFIG_KEYS
#ifdef CONFIG_SECURITY
static inline int security_key_alloc(struct key *key,
- struct task_struct *tsk)
+ struct task_struct *tsk,
+ unsigned long flags)
{
- return security_ops->key_alloc(key, tsk);
+ return security_ops->key_alloc(key, tsk, flags);
}

static inline void security_key_free(struct key *key)
@@ -3029,7 +3031,8 @@ static inline int security_key_permissio
#else

static inline int security_key_alloc(struct key *key,
- struct task_struct *tsk)
+ struct task_struct *tsk,
+ unsigned long flags)
{
return 0;
}
diff --git a/security/dummy.c b/security/dummy.c
index c98d553..93a9180 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -860,7 +860,8 @@ static int dummy_setprocattr(struct task
}

#ifdef CONFIG_KEYS
-static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx)
+static inline int dummy_key_alloc(struct key *key, struct task_struct *ctx,
+ unsigned long flags)
{
return 0;
}
diff --git a/security/keys/internal.h b/security/keys/internal.h
index e066e60..3c2877f 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -99,7 +99,8 @@ extern int install_process_keyring(struc
extern struct key *request_key_and_link(struct key_type *type,
const char *description,
const char *callout_info,
- struct key *dest_keyring);
+ struct key *dest_keyring,
+ unsigned long flags);

/*
* request_key authorisation
diff --git a/security/keys/key.c b/security/keys/key.c
index 9ef9e5b..a9b6ca7 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -248,7 +248,7 @@ static inline void key_alloc_serial(stru
*/
struct key *key_alloc(struct key_type *type, const char *desc,
uid_t uid, gid_t gid, struct task_struct *ctx,
- key_perm_t perm, int not_in_quota)
+ key_perm_t perm, unsigned long flags)
{
struct key_user *user = NULL;
struct key *key;
@@ -269,12 +269,14 @@ struct key *key_alloc(struct key_type *t

/* check that the user's quota permits allocation of another key and
* its description */
- if (!not_in_quota) {
+ if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
spin_lock(&user->lock);
- if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
- user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
- )
- goto no_quota;
+ if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
+ if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
+ user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
+ )
+ goto no_quota;
+ }

user->qnkeys++;
user->qnbytes += quotalen;
@@ -308,7 +310,7 @@ struct key *key_alloc(struct key_type *t
key->payload.data = NULL;
key->security = NULL;

- if (!not_in_quota)
+ if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
key->flags |= 1 << KEY_FLAG_IN_QUOTA;

memset(&key->type_data, 0, sizeof(key->type_data));
@@ -318,7 +320,7 @@ #ifdef KEY_DEBUGGING
#endif

/* let the security module know about the key */
- ret = security_key_alloc(key, ctx);
+ ret = security_key_alloc(key, ctx, flags);
if (ret < 0)
goto security_error;

@@ -332,7 +334,7 @@ error:
security_error:
kfree(key->description);
kmem_cache_free(key_jar, key);
- if (!not_in_quota) {
+ if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
spin_lock(&user->lock);
user->qnkeys--;
user->qnbytes -= quotalen;
@@ -345,7 +347,7 @@ security_error:
no_memory_3:
kmem_cache_free(key_jar, key);
no_memory_2:
- if (!not_in_quota) {
+ if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
spin_lock(&user->lock);
user->qnkeys--;
user->qnbytes -= quotalen;
@@ -761,7 +763,7 @@ key_ref_t key_create_or_update(key_ref_t
const char *description,
const void *payload,
size_t plen,
- int not_in_quota)
+ unsigned long flags)
{
struct key_type *ktype;
struct key *keyring, *key = NULL;
@@ -822,7 +824,7 @@ key_ref_t key_create_or_update(key_ref_t

/* allocate a new key */
key = key_alloc(ktype, description, current->fsuid, current->fsgid,
- current, perm, not_in_quota);
+ current, perm, flags);
if (IS_ERR(key)) {
key_ref = ERR_PTR(PTR_ERR(key));
goto error_3;
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index ed71d86..d744585 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -102,7 +102,7 @@ asmlinkage long sys_add_key(const char _
/* create or update the requested key and add it to the target
* keyring */
key_ref = key_create_or_update(keyring_ref, type, description,
- payload, plen, 0);
+ payload, plen, KEY_ALLOC_IN_QUOTA);
if (!IS_ERR(key_ref)) {
ret = key_ref_to_ptr(key_ref)->serial;
key_ref_put(key_ref);
@@ -184,7 +184,8 @@ asmlinkage long sys_request_key(const ch

/* do the search */
key = request_key_and_link(ktype, description, callout_info,
- key_ref_to_ptr(dest_ref));
+ key_ref_to_ptr(dest_ref),
+ KEY_ALLOC_IN_QUOTA);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error5;
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 1357207..6c282bd 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -240,7 +240,7 @@ static long keyring_read(const struct ke
* allocate a keyring and link into the destination keyring
*/
struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
- struct task_struct *ctx, int not_in_quota,
+ struct task_struct *ctx, unsigned long flags,
struct key *dest)
{
struct key *keyring;
@@ -249,7 +249,7 @@ struct key *keyring_alloc(const char *de
keyring = key_alloc(&key_type_keyring, description,
uid, gid, ctx,
(KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
- not_in_quota);
+ flags);

if (!IS_ERR(keyring)) {
ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index e4eddbb..f5fbc37 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -77,7 +77,8 @@ int alloc_uid_keyring(struct user_struct
/* concoct a default session keyring */
sprintf(buf, "_uid_ses.%u", user->uid);

- session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx, 0, NULL);
+ session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
+ KEY_ALLOC_IN_QUOTA, NULL);
if (IS_ERR(session_keyring)) {
ret = PTR_ERR(session_keyring);
goto error;
@@ -87,8 +88,8 @@ int alloc_uid_keyring(struct user_struct
* keyring */
sprintf(buf, "_uid.%u", user->uid);

- uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx, 0,
- session_keyring);
+ uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
+ KEY_ALLOC_IN_QUOTA, session_keyring);
if (IS_ERR(uid_keyring)) {
key_put(session_keyring);
ret = PTR_ERR(uid_keyring);
@@ -144,7 +145,8 @@ int install_thread_keyring(struct task_s

sprintf(buf, "_tid.%u", tsk->pid);

- keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL);
+ keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+ KEY_ALLOC_QUOTA_OVERRUN, NULL);
if (IS_ERR(keyring)) {
ret = PTR_ERR(keyring);
goto error;
@@ -178,7 +180,8 @@ int install_process_keyring(struct task_
if (!tsk->signal->process_keyring) {
sprintf(buf, "_pid.%u", tsk->tgid);

- keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL);
+ keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+ KEY_ALLOC_QUOTA_OVERRUN, NULL);
if (IS_ERR(keyring)) {
ret = PTR_ERR(keyring);
goto error;
@@ -209,6 +212,7 @@ error:
static int install_session_keyring(struct task_struct *tsk,
struct key *keyring)
{
+ unsigned long flags;
struct key *old;
char buf[20];

@@ -218,7 +222,12 @@ static int install_session_keyring(struc
if (!keyring) {
sprintf(buf, "_ses.%u", tsk->tgid);

- keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk, 1, NULL);
+ flags = KEY_ALLOC_QUOTA_OVERRUN;
+ if (tsk->signal->session_keyring)
+ flags = KEY_ALLOC_IN_QUOTA;
+
+ keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+ flags, NULL);
if (IS_ERR(keyring))
return PTR_ERR(keyring);
}
@@ -729,7 +738,8 @@ long join_session_keyring(const char *na
keyring = find_keyring_by_name(name, 0);
if (PTR_ERR(keyring) == -ENOKEY) {
/* not found - try and create a new one */
- keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk, 0, NULL);
+ keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk,
+ KEY_ALLOC_IN_QUOTA, NULL);
if (IS_ERR(keyring)) {
ret = PTR_ERR(keyring);
goto error2;
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index eab66a0..58d1efd 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -48,8 +48,8 @@ static int call_sbin_request_key(struct
/* allocate a new session keyring */
sprintf(desc, "_req.%u", key->serial);

- keyring = keyring_alloc(desc, current->fsuid, current->fsgid,
- current, 1, NULL);
+ keyring = keyring_alloc(desc, current->fsuid, current->fsgid, current,
+ KEY_ALLOC_QUOTA_OVERRUN, NULL);
if (IS_ERR(keyring)) {
ret = PTR_ERR(keyring);
goto error_alloc;
@@ -126,7 +126,8 @@ error_alloc:
*/
static struct key *__request_key_construction(struct key_type *type,
const char *description,
- const char *callout_info)
+ const char *callout_info,
+ unsigned long flags)
{
request_key_actor_t actor;
struct key_construction cons;
@@ -134,12 +135,12 @@ static struct key *__request_key_constru
struct key *key, *authkey;
int ret, negated;

- kenter("%s,%s,%s", type->name, description, callout_info);
+ kenter("%s,%s,%s,%lx", type->name, description, callout_info, flags);

/* create a key and add it to the queue */
key = key_alloc(type, description,
- current->fsuid, current->fsgid,
- current, KEY_POS_ALL, 0);
+ current->fsuid, current->fsgid, current, KEY_POS_ALL,
+ flags);
if (IS_ERR(key))
goto alloc_failed;

@@ -258,15 +259,16 @@ alloc_failed:
static struct key *request_key_construction(struct key_type *type,
const char *description,
struct key_user *user,
- const char *callout_info)
+ const char *callout_info,
+ unsigned long flags)
{
struct key_construction *pcons;
struct key *key, *ckey;

DECLARE_WAITQUEUE(myself, current);

- kenter("%s,%s,{%d},%s",
- type->name, description, user->uid, callout_info);
+ kenter("%s,%s,{%d},%s,%lx",
+ type->name, description, user->uid, callout_info, flags);

/* see if there's such a key under construction already */
down_write(&key_construction_sem);
@@ -282,7 +284,8 @@ static struct key *request_key_construct
}

/* see about getting userspace to construct the key */
- key = __request_key_construction(type, description, callout_info);
+ key = __request_key_construction(type, description, callout_info,
+ flags);
error:
kleave(" = %p", key);
return key;
@@ -389,14 +392,15 @@ static void request_key_link(struct key
struct key *request_key_and_link(struct key_type *type,
const char *description,
const char *callout_info,
- struct key *dest_keyring)
+ struct key *dest_keyring,
+ unsigned long flags)
{
struct key_user *user;
struct key *key;
key_ref_t key_ref;

- kenter("%s,%s,%s,%p",
- type->name, description, callout_info, dest_keyring);
+ kenter("%s,%s,%s,%p,%lx",
+ type->name, description, callout_info, dest_keyring, flags);

/* search all the process keyrings for a key */
key_ref = search_process_keyrings(type, description, type->match,
@@ -429,7 +433,8 @@ struct key *request_key_and_link(struct
/* ask userspace (returns NULL if it waited on a key
* being constructed) */
key = request_key_construction(type, description,
- user, callout_info);
+ user, callout_info,
+ flags);
if (key)
break;

@@ -485,7 +490,8 @@ struct key *request_key(struct key_type
const char *description,
const char *callout_info)
{
- return request_key_and_link(type, description, callout_info, NULL);
+ return request_key_and_link(type, description, callout_info, NULL,
+ KEY_ALLOC_IN_QUOTA);

} /* end request_key() */

diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index cb9817c..cbf58a9 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -187,7 +187,7 @@ struct key *request_key_auth_new(struct
authkey = key_alloc(&key_type_request_key_auth, desc,
current->fsuid, current->fsgid, current,
KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
- KEY_USR_VIEW, 1);
+ KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
if (IS_ERR(authkey)) {
ret = PTR_ERR(authkey);
goto error_alloc;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 093efba..f80c74d 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4254,7 +4254,8 @@ static int selinux_setprocattr(struct ta

#ifdef CONFIG_KEYS

-static int selinux_key_alloc(struct key *k, struct task_struct *tsk)
+static int selinux_key_alloc(struct key *k, struct task_struct *tsk,
+ unsigned long flags)
{
struct task_security_struct *tsec = tsk->security;
struct key_security_struct *ksec;
@@ -4501,8 +4502,10 @@ static __init int selinux_init(void)

#ifdef CONFIG_KEYS
/* Add security information to initial keyrings */
- security_key_alloc(&root_user_keyring, current);
- security_key_alloc(&root_session_keyring, current);
+ security_key_alloc(&root_user_keyring, current,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ security_key_alloc(&root_session_keyring, current,
+ KEY_ALLOC_NOT_IN_QUOTA);
#endif

return 0;

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