KEYS: Deal with dead-type keys appropriately [try #6]

Allow keys for which the key type has been removed to be unlinked.  Currently
dead-type keys can only be disposed of by completely clearing the keyrings
that point to them.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/security/keys/internal.h b/security/keys/internal.h
index 9fb679c..a7252e7 100644 (file)
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -124,8 +124,11 @@ extern struct key *request_key_and_link(struct key_type *type,
                                        struct key *dest_keyring,
                                        unsigned long flags);
 
-extern key_ref_t lookup_user_key(key_serial_t id, int create, int partial,
+extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
                                 key_perm_t perm);
+#define KEY_LOOKUP_CREATE      0x01
+#define KEY_LOOKUP_PARTIAL     0x02
+#define KEY_LOOKUP_FOR_UNLINK  0x04
 
 extern long join_session_keyring(const char *name);
 

diff --git a/security/keys/key.c b/security/keys/key.c
index 4a1297d..3762d5b 100644 (file)
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -642,10 +642,8 @@ struct key *key_lookup(key_serial_t id)
        goto error;
 
  found:
-       /* pretend it doesn't exist if it's dead */
-       if (atomic_read(&key->usage) == 0 ||
-           test_bit(KEY_FLAG_DEAD, &key->flags) ||
-           key->type == &key_type_dead)
+       /* pretend it doesn't exist if it is awaiting deletion */
+       if (atomic_read(&key->usage) == 0)
                goto not_found;
 
        /* this races with key_put(), but that doesn't matter since key_put()

diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 7f09fb8..b85ace2 100644 (file)
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -103,7 +103,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type,
        }
 
        /* find the target keyring (which must be writable) */
-       keyring_ref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error3;
@@ -185,7 +185,8 @@ SYSCALL_DEFINE4(request_key, const char __user *, _type,
        /* get the destination keyring if specified */
        dest_ref = NULL;
        if (destringid) {
-               dest_ref = lookup_user_key(destringid, 1, 0, KEY_WRITE);
+               dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
+                                          KEY_WRITE);
                if (IS_ERR(dest_ref)) {
                        ret = PTR_ERR(dest_ref);
                        goto error3;
@@ -233,9 +234,11 @@ SYSCALL_DEFINE4(request_key, const char __user *, _type,
 long keyctl_get_keyring_ID(key_serial_t id, int create)
 {
        key_ref_t key_ref;
+       unsigned long lflags;
        long ret;
 
-       key_ref = lookup_user_key(id, create, 0, KEY_SEARCH);
+       lflags = create ? KEY_LOOKUP_CREATE : 0;
+       key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -309,7 +312,7 @@ long keyctl_update_key(key_serial_t id,
        }
 
        /* find the target key (which must be writable) */
-       key_ref = lookup_user_key(id, 0, 0, KEY_WRITE);
+       key_ref = lookup_user_key(id, 0, KEY_WRITE);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error2;
@@ -337,7 +340,7 @@ long keyctl_revoke_key(key_serial_t id)
        key_ref_t key_ref;
        long ret;
 
-       key_ref = lookup_user_key(id, 0, 0, KEY_WRITE);
+       key_ref = lookup_user_key(id, 0, KEY_WRITE);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -363,7 +366,7 @@ long keyctl_keyring_clear(key_serial_t ringid)
        key_ref_t keyring_ref;
        long ret;
 
-       keyring_ref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error;
@@ -389,13 +392,13 @@ 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, 1, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error;
        }
 
-       key_ref = lookup_user_key(id, 1, 0, KEY_LINK);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error2;
@@ -423,13 +426,13 @@ 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, 0, KEY_WRITE);
+       keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error;
        }
 
-       key_ref = lookup_user_key(id, 0, 0, 0);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error2;
@@ -465,7 +468,7 @@ long keyctl_describe_key(key_serial_t keyid,
        char *tmpbuf;
        long ret;
 
-       key_ref = lookup_user_key(keyid, 0, 1, KEY_VIEW);
+       key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
        if (IS_ERR(key_ref)) {
                /* viewing a key under construction is permitted if we have the
                 * authorisation token handy */
@@ -474,7 +477,8 @@ long keyctl_describe_key(key_serial_t keyid,
                        if (!IS_ERR(instkey)) {
                                key_put(instkey);
                                key_ref = lookup_user_key(keyid,
-                                                         0, 1, 0);
+                                                         KEY_LOOKUP_PARTIAL,
+                                                         0);
                                if (!IS_ERR(key_ref))
                                        goto okay;
                        }
@@ -558,7 +562,7 @@ long keyctl_keyring_search(key_serial_t ringid,
        }
 
        /* get the keyring at which to begin the search */
-       keyring_ref = lookup_user_key(ringid, 0, 0, KEY_SEARCH);
+       keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
        if (IS_ERR(keyring_ref)) {
                ret = PTR_ERR(keyring_ref);
                goto error2;
@@ -567,7 +571,8 @@ long keyctl_keyring_search(key_serial_t ringid,
        /* get the destination keyring if specified */
        dest_ref = NULL;
        if (destringid) {
-               dest_ref = lookup_user_key(destringid, 1, 0, KEY_WRITE);
+               dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
+                                          KEY_WRITE);
                if (IS_ERR(dest_ref)) {
                        ret = PTR_ERR(dest_ref);
                        goto error3;
@@ -637,7 +642,7 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
        long ret;
 
        /* find the key first */
-       key_ref = lookup_user_key(keyid, 0, 0, 0);
+       key_ref = lookup_user_key(keyid, 0, 0);
        if (IS_ERR(key_ref)) {
                ret = -ENOKEY;
                goto error;
@@ -700,7 +705,8 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
        if (uid == (uid_t) -1 && gid == (gid_t) -1)
                goto error;
 
-       key_ref = lookup_user_key(id, 1, 1, KEY_SETATTR);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
+                                 KEY_SETATTR);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -805,7 +811,8 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
        if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
                goto error;
 
-       key_ref = lookup_user_key(id, 1, 1, KEY_SETATTR);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
+                                 KEY_SETATTR);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -847,7 +854,7 @@ static long get_instantiation_keyring(key_serial_t ringid,
 
        /* if a specific keyring is nominated by ID, then use that */
        if (ringid > 0) {
-               dkref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
+               dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
                if (IS_ERR(dkref))
                        return PTR_ERR(dkref);
                *_dest_keyring = key_ref_to_ptr(dkref);
@@ -1083,7 +1090,8 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout)
        time_t expiry;
        long ret;
 
-       key_ref = lookup_user_key(id, 1, 1, KEY_SETATTR);
+       key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
+                                 KEY_SETATTR);
        if (IS_ERR(key_ref)) {
                ret = PTR_ERR(key_ref);
                goto error;
@@ -1170,7 +1178,7 @@ long keyctl_get_security(key_serial_t keyid,
        char *context;
        long ret;
 
-       key_ref = lookup_user_key(keyid, 0, 1, KEY_VIEW);
+       key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
        if (IS_ERR(key_ref)) {
                if (PTR_ERR(key_ref) != -EACCES)
                        return PTR_ERR(key_ref);
@@ -1182,7 +1190,7 @@ long keyctl_get_security(key_serial_t keyid,
                        return PTR_ERR(key_ref);
                key_put(instkey);
 
-               key_ref = lookup_user_key(keyid, 0, 1, 0);
+               key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
                if (IS_ERR(key_ref))
                        return PTR_ERR(key_ref);
        }

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index ed929af..4739cfb 100644 (file)
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -487,7 +487,7 @@ static int lookup_user_key_possessed(const struct key *key, const void *target)
  * - don't create special keyrings unless so requested
  * - partially constructed keys aren't found unless requested
  */
-key_ref_t lookup_user_key(key_serial_t id, int create, int partial,
+key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
                          key_perm_t perm)
 {
        struct request_key_auth *rka;
@@ -503,7 +503,7 @@ try_again:
        switch (id) {
        case KEY_SPEC_THREAD_KEYRING:
                if (!cred->thread_keyring) {
-                       if (!create)
+                       if (!(lflags & KEY_LOOKUP_CREATE))
                                goto error;
 
                        ret = install_thread_keyring();
@@ -521,7 +521,7 @@ try_again:
 
        case KEY_SPEC_PROCESS_KEYRING:
                if (!cred->tgcred->process_keyring) {
-                       if (!create)
+                       if (!(lflags & KEY_LOOKUP_CREATE))
                                goto error;
 
                        ret = install_process_keyring();
@@ -642,7 +642,14 @@ try_again:
                break;
        }
 
-       if (!partial) {
+       /* unlink does not use the nominated key in any way, so can skip all
+        * the permission checks as it is only concerned with the keyring */
+       if (lflags & KEY_LOOKUP_FOR_UNLINK) {
+               ret = 0;
+               goto error;
+       }
+
+       if (!(lflags & KEY_LOOKUP_PARTIAL)) {
                ret = wait_for_key_construction(key, true);
                switch (ret) {
                case -ERESTARTSYS:
@@ -660,7 +667,8 @@ try_again:
        }
 
        ret = -EIO;
-       if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
+       if (!(lflags & KEY_LOOKUP_PARTIAL) &&
+           !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
                goto invalid_key;
 
        /* check the permissions */