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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <158932282880.2885325.2688622278854566047.stgit@warthog.procyon.org.uk> To: Stephen Smalley Cc: dhowells@redhat.com, Jarkko Sakkinen , Paul Moore , Casey Schaufler , keyrings@vger.kernel.org, SElinux list , LSM List , linux-kernel Subject: [PATCH] keys: Move permissions checking decisions into the checking code MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3999876.1589475539.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 14 May 2020 17:58:59 +0100 Message-ID: <3999877.1589475539@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org How about this then? David --- commit fa37b6c7e2f86d16ede1e0e3cb73857152d51825 Author: David Howells Date: Thu May 14 17:48:55 2020 +0100 keys: Move permissions checking decisions into the checking code = Overhaul the permissions checking, moving the decisions of which permi= ts to request for what operation and what overrides to allow into the permis= sions checking functions in keyrings, SELinux and Smack. = To this end, the KEY_NEED_* constants are turned into an enum and expa= nded in number to cover operation types individually. = Note that some more tweaking is probably needed to separate kernel use= s, e.g. AFS using rxrpc keys, from direct userspace users. = Some overrides are available and this needs to be handled specially: = (1) KEY_FLAG_KEEP in key->flags - The key may not be deleted and/or t= hings may not be removed from the keyring. = (2) KEY_FLAG_ROOT_CAN_CLEAR in key->flags - The keyring can be cleare= d by CAP_SYS_ADMIN. = (3) KEY_FLAG_ROOT_CAN_INVAL in key->flags - The key can be invalidate= d by CAP_SYS_ADMIN. = (4) An appropriate auth token being set in cred->request_key_auth tha= t gives a process transient permission to view and instantiate a ke= y. This is used by the kernel to delegate instantiation to userspace= . = Note that this requires some tweaks to the testsuite as some of the er= ror codes change. = Signed-off-by: David Howells Reported-by: Stephen Smalley cc: Jarkko Sakkinen cc: Paul Moore cc: Stephen Smalley cc: Casey Schaufler cc: keyrings@vger.kernel.org cc: selinux@vger.kernel.org diff --git a/include/linux/key.h b/include/linux/key.h index b99b40db08fc..7fb00128c5ba 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -71,6 +71,34 @@ struct net; = #define KEY_PERM_UNDEF 0xffffffff = +/* + * The permissions required on a key that we're looking up. + */ +enum key_need_perm { + /* 0 is left undefined */ + KEY_NEED_ASSUME_AUTHORITY =3D 1, /* Want to assume instantiation authori= ty */ + KEY_NEED_CHOWN, /* Want to change key's ownership/group */ + KEY_NEED_DESCRIBE, /* Want to get a key's attributes */ + KEY_NEED_GET_SECURITY, /* Want to get a key's security label */ + KEY_NEED_INSTANTIATE, /* Want to instantiate a key */ + KEY_NEED_INVALIDATE, /* Want to invalidate key */ + KEY_NEED_JOIN, /* Want to set a keyring as the session keyring */ + KEY_NEED_KEYRING_ADD, /* Want to add a link to a keyring */ + KEY_NEED_KEYRING_CLEAR, /* Want to clear a keyring */ + KEY_NEED_KEYRING_DELETE, /* Want to remove a link from a keyring */ + KEY_NEED_LINK, /* Want to create a link to a key */ + KEY_NEED_READ, /* Want to read content to userspace */ + KEY_NEED_REVOKE, /* Want to revoke a key */ + KEY_NEED_SEARCH, /* Want to find a key in a search */ + KEY_NEED_SETPERM, /* Want to set the permissions mask */ + KEY_NEED_SET_RESTRICTION, /* Want to set a restriction on a keyring */ + KEY_NEED_SET_TIMEOUT, /* Want to set the expiration time on a key */ + KEY_NEED_UNLINK, /* Want to remove a link from a key */ + KEY_NEED_UPDATE, /* Want to update a key's payload */ + KEY_NEED_USE, /* Want to use a key (in kernel) */ + KEY_NEED_WATCH, /* Want to watch a key for events */ +}; + struct seq_file; struct user_struct; struct signal_struct; @@ -420,20 +448,9 @@ static inline key_serial_t key_serial(const struct ke= y *key) extern void key_set_timeout(struct key *, unsigned); = extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags, - key_perm_t perm); + enum key_need_perm need_perm); extern void key_free_user_ns(struct user_namespace *); = -/* - * The permissions required on a key that we're looking up. - */ -#define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */ -#define KEY_NEED_READ 0x02 /* Require permission to read content */ -#define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */ -#define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or= find (key) */ -#define KEY_NEED_LINK 0x10 /* Require permission to link */ -#define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes = */ -#define KEY_NEED_ALL 0x3f /* All the above permissions */ - static inline short key_read_state(const struct key *key) { /* Barrier versus mark_key_instantiated(). */ diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 733659613bf8..72debb96b002 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -357,7 +357,7 @@ LSM_HOOK(int, 0, key_alloc, struct key *key, const str= uct cred *cred, unsigned long flags) LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key) LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cr= ed, - unsigned perm) + enum key_need_perm need_perm, unsigned int flags) LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **_buffer) #endif /* CONFIG_KEYS */ = diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 3f1374cffb76..1cb01f6d2bed 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1102,6 +1102,14 @@ * @cred points to the credentials to provide the context against which t= o * evaluate the security data on the key. * @perm describes the combination of permissions required of this key. + * @flags indicates any special conditions set in the normal checks, such + * as: + * KEY_PERMISSION_USED_AUTH_OVERRIDE - A lack of permission was + * overridden by the presence of an instantiation authorisation + * token. + * KEY_PERMISSION_USED_SYSADMIN_OVERRIDE - A lack of permission was + * overridden by the presence of a KEY_FLAG_ROOT_CAN_xxx flag on + * the key an the success of a CAP_SYS_ADMIN check. * Return 0 if permission is granted, -ve error otherwise. * @key_getsecurity: * Get a textual representation of the security context attached to a key diff --git a/include/linux/security.h b/include/linux/security.h index e7914e4e0b02..a6a5fefcf4e0 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1762,13 +1762,17 @@ static inline int security_path_chroot(const struc= t path *path) } #endif /* CONFIG_SECURITY_PATH */ = +/* Flags for security_key_permission() */ +#define KEY_PERMISSION_USED_AUTH_OVERRIDE 0x01 /* Auth token overrode lac= k of permission */ +#define KEY_PERMISSION_USED_SYSADMIN_OVERRIDE 0x02 /* Sysadmin overrode l= ack of permission */ + #ifdef CONFIG_KEYS #ifdef CONFIG_SECURITY = int security_key_alloc(struct key *key, const struct cred *cred, unsigned= long flags); void security_key_free(struct key *key); -int security_key_permission(key_ref_t key_ref, - const struct cred *cred, unsigned perm); +int security_key_permission(key_ref_t key_ref, const struct cred *cred, + enum key_need_perm need_perm, unsigned int flags); int security_key_getsecurity(struct key *key, char **_buffer); = #else @@ -1786,7 +1790,8 @@ static inline void security_key_free(struct key *key= ) = static inline int security_key_permission(key_ref_t key_ref, const struct cred *cred, - unsigned perm) + enum key_need_perm need_perm, + unsigned int flags) { return 0; } diff --git a/security/keys/dh.c b/security/keys/dh.c index c4c629bb1c03..e43731d22310 100644 --- a/security/keys/dh.c +++ b/security/keys/dh.c @@ -22,10 +22,8 @@ static ssize_t dh_data_from_key(key_serial_t keyid, voi= d **data) ssize_t ret; = key_ref =3D lookup_user_key(keyid, 0, KEY_NEED_READ); - if (IS_ERR(key_ref)) { - ret =3D -ENOKEY; - goto error; - } + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = key =3D key_ref_to_ptr(key_ref); = @@ -52,7 +50,6 @@ static ssize_t dh_data_from_key(key_serial_t keyid, void= **data) } = key_put(key); -error: return ret; } = diff --git a/security/keys/internal.h b/security/keys/internal.h index 28e17f4f3328..d97cb9d98dc3 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -108,6 +108,14 @@ extern void __key_link_end(struct key *keyring, = extern key_ref_t find_key_to_update(key_ref_t keyring_ref, const struct keyring_index_key *index_key); +extern key_ref_t key_create_or_update_perm_checked(key_ref_t keyring_ref, + const char *type, + const char *description, + const void *payload, + size_t plen, + key_perm_t perm, + unsigned long flags); +extern int key_update_perm_checked(key_ref_t key_ref, const void *payload= , size_t plen); = extern struct key *keyring_search_instkey(struct key *keyring, key_serial_t target_id); @@ -165,9 +173,9 @@ extern struct key *request_key_and_link(struct key_typ= e *type, = extern bool lookup_user_key_possessed(const struct key *key, const struct key_match_data *match_data); -#define KEY_LOOKUP_CREATE 0x01 -#define KEY_LOOKUP_PARTIAL 0x02 -#define KEY_LOOKUP_FOR_UNLINK 0x04 +#define KEY_LOOKUP_CREATE 0x01 +#define KEY_LOOKUP_PARTIAL 0x02 +#define KEY_LOOKUP_AUTH_OVERRIDE 0x04 = extern long join_session_keyring(const char *name); extern void key_change_session_keyring(struct callback_head *twork); @@ -183,7 +191,7 @@ extern void key_gc_keytype(struct key_type *ktype); = extern int key_task_permission(const key_ref_t key_ref, const struct cred *cred, - key_perm_t perm); + enum key_need_perm need_perm); = static inline void notify_key(struct key *key, enum key_notification_subtype subtype, u32 aux) @@ -205,9 +213,10 @@ static inline void notify_key(struct key *key, /* * Check to see whether permission is granted to use a key in the desired= way. */ -static inline int key_permission(const key_ref_t key_ref, unsigned perm) +static inline int key_permission(const key_ref_t key_ref, + enum key_need_perm need_perm) { - return key_task_permission(key_ref, current_cred(), perm); + return key_task_permission(key_ref, current_cred(), need_perm); } = extern struct key_type key_type_request_key_auth; diff --git a/security/keys/key.c b/security/keys/key.c index e282c6179b21..d77d5dd61d42 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -755,7 +755,7 @@ static inline key_ref_t __key_update(key_ref_t key_ref= , int ret; = /* need write permission on the key to update it */ - ret =3D key_permission(key_ref, KEY_NEED_WRITE); + ret =3D key_permission(key_ref, KEY_NEED_UPDATE); if (ret < 0) goto error; = @@ -810,13 +810,13 @@ static inline key_ref_t __key_update(key_ref_t key_r= ef, * On success, the possession flag from the keyring ref will be tacked on= to * the key ref before it is returned. */ -key_ref_t key_create_or_update(key_ref_t keyring_ref, - const char *type, - const char *description, - const void *payload, - size_t plen, - key_perm_t perm, - unsigned long flags) +key_ref_t key_create_or_update_perm_checked(key_ref_t keyring_ref, + const char *type, + const char *description, + const void *payload, + size_t plen, + key_perm_t perm, + unsigned long flags) { struct keyring_index_key index_key =3D { .description =3D description, @@ -894,14 +894,6 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, } } = - /* if we're going to allocate a new key, we're going to have - * to modify the keyring */ - ret =3D key_permission(keyring_ref, KEY_NEED_WRITE); - if (ret < 0) { - key_ref =3D ERR_PTR(ret); - goto error_link_end; - } - /* if it's possible to update this type of key, search for an existing * key of the same type and description in the destination keyring and * update that instead if possible @@ -981,6 +973,27 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, = goto error_free_prep; } + +key_ref_t key_create_or_update(key_ref_t keyring_ref, + const char *type, + const char *description, + const void *payload, + size_t plen, + key_perm_t perm, + unsigned long flags) +{ + int ret; + + /* if we're going to allocate a new key, we're going to have + * to modify the keyring */ + ret =3D key_permission(keyring_ref, KEY_NEED_KEYRING_ADD); + if (ret < 0) + return ERR_PTR(ret); + + return key_create_or_update_perm_checked(keyring_ref, type, + description, payload, + plen, perm, flags); +} EXPORT_SYMBOL(key_create_or_update); = /** @@ -996,19 +1009,12 @@ EXPORT_SYMBOL(key_create_or_update); * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the = key * type does not support updating. The key type may return other errors. */ -int key_update(key_ref_t key_ref, const void *payload, size_t plen) +int key_update_perm_checked(key_ref_t key_ref, const void *payload, size_= t plen) { struct key_preparsed_payload prep; struct key *key =3D key_ref_to_ptr(key_ref); int ret; = - key_check(key); - - /* the key must be writable */ - ret =3D key_permission(key_ref, KEY_NEED_WRITE); - if (ret < 0) - return ret; - /* attempt to update it if supported */ if (!key->type->update) return -EOPNOTSUPP; @@ -1040,6 +1046,20 @@ int key_update(key_ref_t key_ref, const void *paylo= ad, size_t plen) key->type->free_preparse(&prep); return ret; } + +int key_update(key_ref_t key_ref, const void *payload, size_t plen) +{ + int ret; + + key_check(key_ref_to_ptr(key_ref)); + + /* the key must be writable */ + ret =3D key_permission(key_ref, KEY_NEED_UPDATE); + if (ret < 0) + return ret; + + return key_update_perm_checked(key_ref, payload, plen); +} EXPORT_SYMBOL(key_update); = /** diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 7d8de1c9a478..5e25b431a9b5 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -123,7 +123,8 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, } = /* find the target keyring (which must be writable) */ - keyring_ref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRIT= E); + keyring_ref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, + KEY_NEED_KEYRING_ADD); if (IS_ERR(keyring_ref)) { ret =3D PTR_ERR(keyring_ref); goto error3; @@ -131,9 +132,9 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, = /* create or update the requested key and add it to the target * keyring */ - key_ref =3D key_create_or_update(keyring_ref, type, description, - payload, plen, KEY_PERM_UNDEF, - KEY_ALLOC_IN_QUOTA); + key_ref =3D key_create_or_update_perm_checked(keyring_ref, type, descrip= tion, + payload, plen, KEY_PERM_UNDEF, + KEY_ALLOC_IN_QUOTA); if (!IS_ERR(key_ref)) { ret =3D key_ref_to_ptr(key_ref)->serial; key_ref_put(key_ref); @@ -207,7 +208,7 @@ SYSCALL_DEFINE4(request_key, const char __user *, _typ= e, dest_ref =3D NULL; if (destringid) { dest_ref =3D lookup_user_key(destringid, KEY_LOOKUP_CREATE, - KEY_NEED_WRITE); + KEY_NEED_KEYRING_ADD); if (IS_ERR(dest_ref)) { ret =3D PTR_ERR(dest_ref); goto error3; @@ -351,14 +352,14 @@ long keyctl_update_key(key_serial_t id, } = /* find the target key (which must be writable) */ - key_ref =3D lookup_user_key(id, 0, KEY_NEED_WRITE); + key_ref =3D lookup_user_key(id, 0, KEY_NEED_UPDATE); if (IS_ERR(key_ref)) { ret =3D PTR_ERR(key_ref); goto error2; } = /* update the key */ - ret =3D key_update(key_ref, payload, plen); + ret =3D key_update_perm_checked(key_ref, payload, plen); = key_ref_put(key_ref); error2: @@ -382,31 +383,14 @@ long keyctl_update_key(key_serial_t id, long keyctl_revoke_key(key_serial_t id) { key_ref_t key_ref; - struct key *key; - long ret; - - key_ref =3D lookup_user_key(id, 0, KEY_NEED_WRITE); - if (IS_ERR(key_ref)) { - ret =3D PTR_ERR(key_ref); - if (ret !=3D -EACCES) - goto error; - key_ref =3D lookup_user_key(id, 0, KEY_NEED_SETATTR); - if (IS_ERR(key_ref)) { - ret =3D PTR_ERR(key_ref); - goto error; - } - } = - key =3D key_ref_to_ptr(key_ref); - ret =3D 0; - if (test_bit(KEY_FLAG_KEEP, &key->flags)) - ret =3D -EPERM; - else - key_revoke(key); + key_ref =3D lookup_user_key(id, 0, KEY_NEED_REVOKE); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = + key_revoke(key_ref_to_ptr(key_ref)); key_ref_put(key_ref); -error: - return ret; + return 0; } = /* @@ -423,41 +407,16 @@ long keyctl_revoke_key(key_serial_t id) long keyctl_invalidate_key(key_serial_t id) { key_ref_t key_ref; - struct key *key; - long ret; = kenter("%d", id); = - key_ref =3D lookup_user_key(id, 0, KEY_NEED_SEARCH); - if (IS_ERR(key_ref)) { - ret =3D PTR_ERR(key_ref); - - /* Root is permitted to invalidate certain special keys */ - if (capable(CAP_SYS_ADMIN)) { - key_ref =3D lookup_user_key(id, 0, 0); - if (IS_ERR(key_ref)) - goto error; - if (test_bit(KEY_FLAG_ROOT_CAN_INVAL, - &key_ref_to_ptr(key_ref)->flags)) - goto invalidate; - goto error_put; - } - - goto error; - } + key_ref =3D lookup_user_key(id, 0, KEY_NEED_INVALIDATE); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = -invalidate: - key =3D key_ref_to_ptr(key_ref); - ret =3D 0; - if (test_bit(KEY_FLAG_KEEP, &key->flags)) - ret =3D -EPERM; - else - key_invalidate(key); -error_put: + key_invalidate(key_ref_to_ptr(key_ref)); key_ref_put(key_ref); -error: - kleave(" =3D %ld", ret); - return ret; + return 0; } = /* @@ -470,36 +429,15 @@ long keyctl_invalidate_key(key_serial_t id) long keyctl_keyring_clear(key_serial_t ringid) { key_ref_t keyring_ref; - struct key *keyring; long ret; = - keyring_ref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRIT= E); - if (IS_ERR(keyring_ref)) { - ret =3D PTR_ERR(keyring_ref); + keyring_ref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, + KEY_NEED_KEYRING_CLEAR); + if (IS_ERR(keyring_ref)) + return PTR_ERR(keyring_ref); = - /* Root is permitted to invalidate certain special keyrings */ - if (capable(CAP_SYS_ADMIN)) { - keyring_ref =3D lookup_user_key(ringid, 0, 0); - if (IS_ERR(keyring_ref)) - goto error; - if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR, - &key_ref_to_ptr(keyring_ref)->flags)) - goto clear; - goto error_put; - } - - goto error; - } - -clear: - keyring =3D key_ref_to_ptr(keyring_ref); - if (test_bit(KEY_FLAG_KEEP, &keyring->flags)) - ret =3D -EPERM; - else - ret =3D keyring_clear(keyring); -error_put: + ret =3D keyring_clear(key_ref_to_ptr(keyring_ref)); key_ref_put(keyring_ref); -error: return ret; } = @@ -519,7 +457,8 @@ long keyctl_keyring_link(key_serial_t id, key_serial_t= ringid) key_ref_t keyring_ref, key_ref; long ret; = - keyring_ref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRIT= E); + keyring_ref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, + KEY_NEED_KEYRING_ADD); if (IS_ERR(keyring_ref)) { ret =3D PTR_ERR(keyring_ref); goto error; @@ -554,28 +493,21 @@ long keyctl_keyring_link(key_serial_t id, key_serial= _t ringid) long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid) { key_ref_t keyring_ref, key_ref; - struct key *keyring, *key; long ret; = - keyring_ref =3D lookup_user_key(ringid, 0, KEY_NEED_WRITE); + keyring_ref =3D lookup_user_key(ringid, 0, KEY_NEED_KEYRING_DELETE); if (IS_ERR(keyring_ref)) { ret =3D PTR_ERR(keyring_ref); goto error; } = - key_ref =3D lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0); + key_ref =3D lookup_user_key(id, KEY_LOOKUP_PARTIAL, KEY_NEED_UNLINK); if (IS_ERR(key_ref)) { ret =3D PTR_ERR(key_ref); goto error2; } = - keyring =3D key_ref_to_ptr(keyring_ref); - key =3D key_ref_to_ptr(key_ref); - if (test_bit(KEY_FLAG_KEEP, &keyring->flags) && - test_bit(KEY_FLAG_KEEP, &key->flags)) - ret =3D -EPERM; - else - ret =3D key_unlink(keyring, key); + ret =3D key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref))= ; = key_ref_put(key_ref); error2: @@ -607,13 +539,13 @@ long keyctl_keyring_move(key_serial_t id, key_serial= _t from_ringid, if (IS_ERR(key_ref)) return PTR_ERR(key_ref); = - from_ref =3D lookup_user_key(from_ringid, 0, KEY_NEED_WRITE); + from_ref =3D lookup_user_key(from_ringid, 0, KEY_NEED_KEYRING_DELETE); if (IS_ERR(from_ref)) { ret =3D PTR_ERR(from_ref); goto error2; } = - to_ref =3D lookup_user_key(to_ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE)= ; + to_ref =3D lookup_user_key(to_ringid, KEY_LOOKUP_CREATE, KEY_NEED_KEYRIN= G_ADD); if (IS_ERR(to_ref)) { ret =3D PTR_ERR(to_ref); goto error3; @@ -647,33 +579,21 @@ long keyctl_describe_key(key_serial_t keyid, char __user *buffer, size_t buflen) { - struct key *key, *instkey; + struct key *key; key_ref_t key_ref; char *infobuf; long ret; int desclen, infolen; = - key_ref =3D lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW); - if (IS_ERR(key_ref)) { - /* viewing a key under construction is permitted if we have the - * authorisation token handy */ - if (PTR_ERR(key_ref) =3D=3D -EACCES) { - instkey =3D key_get_instantiation_authkey(keyid); - if (!IS_ERR(instkey)) { - key_put(instkey); - key_ref =3D lookup_user_key(keyid, - KEY_LOOKUP_PARTIAL, - 0); - if (!IS_ERR(key_ref)) - goto okay; - } - } - - ret =3D PTR_ERR(key_ref); - goto error; - } + /* Viewing a key under construction is permitted if we have the + * authorisation token handy. + */ + key_ref =3D lookup_user_key(keyid, + KEY_LOOKUP_PARTIAL | KEY_LOOKUP_AUTH_OVERRIDE, + KEY_NEED_DESCRIBE); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = -okay: key =3D key_ref_to_ptr(key_ref); desclen =3D strlen(key->description); = @@ -685,23 +605,21 @@ long keyctl_describe_key(key_serial_t keyid, from_kuid_munged(current_user_ns(), key->uid), from_kgid_munged(current_user_ns(), key->gid), key->perm); - if (!infobuf) - goto error2; - infolen =3D strlen(infobuf); - ret =3D infolen + desclen + 1; - - /* consider returning the data */ - if (buffer && buflen >=3D ret) { - if (copy_to_user(buffer, infobuf, infolen) !=3D 0 || - copy_to_user(buffer + infolen, key->description, - desclen + 1) !=3D 0) - ret =3D -EFAULT; - } + if (infobuf) { + infolen =3D strlen(infobuf); + ret =3D infolen + desclen + 1; + + /* consider returning the data */ + if (buffer && buflen >=3D ret) { + if (copy_to_user(buffer, infobuf, infolen) !=3D 0 || + copy_to_user(buffer + infolen, key->description, + desclen + 1) !=3D 0) + ret =3D -EFAULT; + } = - kfree(infobuf); -error2: + kfree(infobuf); + } key_ref_put(key_ref); -error: return ret; } = @@ -747,7 +665,7 @@ long keyctl_keyring_search(key_serial_t ringid, dest_ref =3D NULL; if (destringid) { dest_ref =3D lookup_user_key(destringid, KEY_LOOKUP_CREATE, - KEY_NEED_WRITE); + KEY_NEED_KEYRING_ADD); if (IS_ERR(dest_ref)) { ret =3D PTR_ERR(dest_ref); goto error3; @@ -817,9 +735,6 @@ static long __keyctl_read_key(struct key *key, char *b= uffer, size_t buflen) /* * Read a key's payload. * - * The key must either grant the caller Read permission, or it must grant= the - * caller Search permission when searched for from the process keyrings. - * * If successful, we place up to buflen bytes of data into the buffer, if= one * is provided, and return the amount of data that is available in the ke= y, * irrespective of how much we copied into the buffer. @@ -833,36 +748,11 @@ long keyctl_read_key(key_serial_t keyid, char __user= *buffer, size_t buflen) size_t key_data_len; = /* find the key first */ - key_ref =3D lookup_user_key(keyid, 0, 0); - if (IS_ERR(key_ref)) { - ret =3D -ENOKEY; - goto out; - } + key_ref =3D lookup_user_key(keyid, 0, KEY_NEED_READ); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = key =3D key_ref_to_ptr(key_ref); - - ret =3D key_read_state(key); - if (ret < 0) - goto key_put_out; /* Negatively instantiated */ - - /* see if we can read it directly */ - ret =3D key_permission(key_ref, KEY_NEED_READ); - if (ret =3D=3D 0) - goto can_read_key; - if (ret !=3D -EACCES) - goto key_put_out; - - /* we can't; see if it's searchable from this process's keyrings - * - we automatically take account of the fact that it may be - * dangling off an instantiation key - */ - if (!is_key_possessed(key_ref)) { - ret =3D -EACCES; - goto key_put_out; - } - - /* the key is probably readable - now try to read it */ -can_read_key: if (!key->type->read) { ret =3D -EOPNOTSUPP; goto key_put_out; @@ -929,18 +819,16 @@ long keyctl_read_key(key_serial_t keyid, char __user= *buffer, size_t buflen) = key_put_out: key_put(key); -out: return ret; } = /* * Change the ownership of a key * - * The key must grant the caller Setattr permission for this to work, tho= ugh - * the key need not be fully instantiated yet. For the UID to be changed= , or - * for the GID to be changed to a group the caller is not a member of, th= e - * caller must have sysadmin capability. If either uid or gid is -1 then= that - * attribute is not changed. + * The key need not be fully instantiated for this operation to be applie= d. + * For the UID to be changed, or for the GID to be changed to a group the + * caller is not a member of, the caller must have sysadmin capability. = If + * either uid or gid is -1 then that attribute is not changed. * * If the UID is to be changed, the new user must have sufficient quota t= o * accept the key. The quota deduction will be removed from the old user= to @@ -970,7 +858,7 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid= _t group) goto error; = key_ref =3D lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL, - KEY_NEED_SETATTR); + KEY_NEED_CHOWN); if (IS_ERR(key_ref)) { ret =3D PTR_ERR(key_ref); goto error; @@ -1062,9 +950,9 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gi= d_t group) /* * Change the permission mask on a key. * - * The key must grant the caller Setattr permission for this to work, tho= ugh - * the key need not be fully instantiated yet. If the caller does not ha= ve - * sysadmin capability, it may only change the permission on keys that it= owns. + * The key doesn't have to be fully instantiated yet for this to work. I= f the + * caller does not have sysadmin capability, it may only change the permi= ssion + * on keys that it owns. */ long keyctl_setperm_key(key_serial_t id, key_perm_t perm) { @@ -1077,7 +965,7 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t p= erm) goto error; = key_ref =3D lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL, - KEY_NEED_SETATTR); + KEY_NEED_SETPERM); if (IS_ERR(key_ref)) { ret =3D PTR_ERR(key_ref); goto error; @@ -1104,7 +992,7 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t p= erm) = /* * Get the destination keyring for instantiation and check that the calle= r has - * Write permission on it. + * permission to add a key to it. */ static long get_instantiation_keyring(key_serial_t ringid, struct request_key_auth *rka, @@ -1120,7 +1008,8 @@ static long get_instantiation_keyring(key_serial_t r= ingid, = /* if a specific keyring is nominated by ID, then use that */ if (ringid > 0) { - dkref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE); + dkref =3D lookup_user_key(ringid, KEY_LOOKUP_CREATE, + KEY_NEED_KEYRING_ADD); if (IS_ERR(dkref)) return PTR_ERR(dkref); *_dest_keyring =3D key_ref_to_ptr(dkref); @@ -1161,7 +1050,7 @@ static int keyctl_change_reqkey_auth(struct key *key= ) * Instantiate a key with the specified payload and link the key into the * destination keyring if one is given. * - * The caller must have the appropriate instantiation permit set for this= to + * The caller must have the appropriate instantiation token set for this = to * work (see keyctl_assume_authority). No other permissions are required= . * * If successful, 0 will be returned. @@ -1172,29 +1061,34 @@ long keyctl_instantiate_key_common(key_serial_t id= , { const struct cred *cred =3D current_cred(); struct request_key_auth *rka; - struct key *instkey, *dest_keyring; + struct key *key, *instkey, *dest_keyring; + key_ref_t kref; size_t plen =3D from ? iov_iter_count(from) : 0; void *payload; long ret; = kenter("%d,,%zu,%d", id, plen, ringid); = + if (plen > 1024 * 1024 - 1) + return -EINVAL; + if (!plen) from =3D NULL; = - ret =3D -EINVAL; - if (plen > 1024 * 1024 - 1) - goto error; - /* the appropriate instantiation authorisation key must have been * assumed before calling this */ - ret =3D -EPERM; instkey =3D cred->request_key_auth; if (!instkey) - goto error; + return -EPERM; + + kref =3D lookup_user_key(id, KEY_LOOKUP_PARTIAL, KEY_NEED_INSTANTIATE); + if (IS_ERR(kref)) + return PTR_ERR(kref); + key =3D key_ref_to_ptr(kref); = + ret =3D -EPERM; rka =3D instkey->payload.data[0]; - if (rka->target_key->serial !=3D id) + if (rka->target_key !=3D key) goto error; = /* pull the payload in if one was supplied */ @@ -1218,7 +1112,7 @@ long keyctl_instantiate_key_common(key_serial_t id, goto error2; = /* instantiate the key and link it into a keyring */ - ret =3D key_instantiate_and_link(rka->target_key, payload, plen, + ret =3D key_instantiate_and_link(key, payload, plen, dest_keyring, instkey); = key_put(dest_keyring); @@ -1234,6 +1128,7 @@ long keyctl_instantiate_key_common(key_serial_t id, kvfree(payload); } error: + key_put(key); return ret; } = @@ -1337,7 +1232,8 @@ long keyctl_reject_key(key_serial_t id, unsigned tim= eout, unsigned error, { const struct cred *cred =3D current_cred(); struct request_key_auth *rka; - struct key *instkey, *dest_keyring; + struct key *key, *instkey, *dest_keyring; + key_ref_t kref; long ret; = kenter("%d,%u,%u,%d", id, timeout, error, ringid); @@ -1353,13 +1249,18 @@ long keyctl_reject_key(key_serial_t id, unsigned t= imeout, unsigned error, = /* the appropriate instantiation authorisation key must have been * assumed before calling this */ - ret =3D -EPERM; instkey =3D cred->request_key_auth; if (!instkey) - goto error; + return -EPERM; + + kref =3D lookup_user_key(id, KEY_LOOKUP_PARTIAL, KEY_NEED_INSTANTIATE); + if (IS_ERR(kref)) + return PTR_ERR(kref); + key =3D key_ref_to_ptr(kref); = + ret =3D -EPERM; rka =3D instkey->payload.data[0]; - if (rka->target_key->serial !=3D id) + if (rka->target_key !=3D key) goto error; = /* find the destination keyring if present (which must also be @@ -1380,6 +1281,7 @@ long keyctl_reject_key(key_serial_t id, unsigned tim= eout, unsigned error, keyctl_change_reqkey_auth(NULL); = error: + key_put(key); return ret; } = @@ -1443,8 +1345,8 @@ long keyctl_set_reqkey_keyring(int reqkey_defl) /* * Set or clear the timeout on a key. * - * Either the key must grant the caller Setattr permission or else the ca= ller - * must hold an instantiation authorisation token for the key. + * Either the key must grant the caller permission or else the caller mus= t hold + * an instantiation authorisation token for the key. * * The timeout is either 0 to clear the timeout, or a number of seconds f= rom * the current time. The key and any links to the key will be automatica= lly @@ -1456,44 +1358,25 @@ long keyctl_set_reqkey_keyring(int reqkey_defl) */ long keyctl_set_timeout(key_serial_t id, unsigned timeout) { - struct key *key, *instkey; + struct key *key; key_ref_t key_ref; - long ret; - - key_ref =3D lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL, - KEY_NEED_SETATTR); - if (IS_ERR(key_ref)) { - /* setting the timeout on a key under construction is permitted - * if we have the authorisation token handy */ - if (PTR_ERR(key_ref) =3D=3D -EACCES) { - instkey =3D key_get_instantiation_authkey(id); - if (!IS_ERR(instkey)) { - key_put(instkey); - key_ref =3D lookup_user_key(id, - KEY_LOOKUP_PARTIAL, - 0); - if (!IS_ERR(key_ref)) - goto okay; - } - } = - ret =3D PTR_ERR(key_ref); - goto error; - } + /* Setting the timeout on a key under construction is permitted if we + * have the authorisation token handy + */ + key_ref =3D lookup_user_key(id, + KEY_LOOKUP_CREATE | + KEY_LOOKUP_PARTIAL | + KEY_LOOKUP_AUTH_OVERRIDE, + KEY_NEED_SET_TIMEOUT); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = -okay: key =3D key_ref_to_ptr(key_ref); - ret =3D 0; - if (test_bit(KEY_FLAG_KEEP, &key->flags)) { - ret =3D -EPERM; - } else { - key_set_timeout(key, timeout); - notify_key(key, NOTIFY_KEY_SETATTR, 0); - } + key_set_timeout(key, timeout); + notify_key(key, NOTIFY_KEY_SETATTR, 0); key_put(key); - -error: - return ret; + return 0; } = /* @@ -1562,27 +1445,17 @@ long keyctl_get_security(key_serial_t keyid, char __user *buffer, size_t buflen) { - struct key *key, *instkey; + struct key *key; key_ref_t key_ref; char *context; long ret; = - key_ref =3D lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW); - if (IS_ERR(key_ref)) { - if (PTR_ERR(key_ref) !=3D -EACCES) - return PTR_ERR(key_ref); - - /* viewing a key under construction is also permitted if we - * have the authorisation token handy */ - instkey =3D key_get_instantiation_authkey(keyid); - if (IS_ERR(instkey)) - return PTR_ERR(instkey); - key_put(instkey); - - key_ref =3D lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0); - if (IS_ERR(key_ref)) - return PTR_ERR(key_ref); - } + key_ref =3D lookup_user_key(keyid, + KEY_LOOKUP_PARTIAL | + KEY_LOOKUP_AUTH_OVERRIDE, + KEY_NEED_GET_SECURITY); + if (IS_ERR(key_ref)) + return PTR_ERR(key_ref); = key =3D key_ref_to_ptr(key_ref); ret =3D security_key_getsecurity(key, &context); @@ -1614,8 +1487,8 @@ long keyctl_get_security(key_serial_t keyid, * Attempt to install the calling process's session keyring on the proces= s's * parent process. * - * The keyring must exist and must grant the caller LINK permission, and = the - * parent process must be single-threaded and must have the same effectiv= e + * The keyring must exist and must grant the caller permission to join it= , and + * the parent process must be single-threaded and must have the same effe= ctive * ownership as this process and mustn't be SUID/SGID. * * The keyring will be emplaced on the parent when it next resumes usersp= ace. @@ -1631,7 +1504,7 @@ long keyctl_session_to_parent(void) struct cred *cred; int ret; = - keyring_r =3D lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK= ); + keyring_r =3D lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_JOIN= ); if (IS_ERR(keyring_r)) return PTR_ERR(keyring_r); = @@ -1733,7 +1606,7 @@ long keyctl_restrict_keyring(key_serial_t id, const = char __user *_type, char *restriction =3D NULL; long ret; = - key_ref =3D lookup_user_key(id, 0, KEY_NEED_SETATTR); + key_ref =3D lookup_user_key(id, 0, KEY_NEED_SET_RESTRICTION); if (IS_ERR(key_ref)) return PTR_ERR(key_ref); = @@ -1781,7 +1654,7 @@ long keyctl_watch_key(key_serial_t id, int watch_que= ue_fd, int watch_id) if (watch_id < -1 || watch_id > 0xff) return -EINVAL; = - key_ref =3D lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_VIEW); + key_ref =3D lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_WATCH); if (IS_ERR(key_ref)) return PTR_ERR(key_ref); key =3D key_ref_to_ptr(key_ref); diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c index 931d8dfb4a7f..aece0651eeae 100644 --- a/security/keys/keyctl_pkey.c +++ b/security/keys/keyctl_pkey.c @@ -77,7 +77,8 @@ static int keyctl_pkey_params_parse(struct kernel_pkey_p= arams *params) */ static int keyctl_pkey_params_get(key_serial_t id, const char __user *_info, - struct kernel_pkey_params *params) + struct kernel_pkey_params *params, + enum key_need_perm need_perm) { key_ref_t key_ref; void *p; @@ -95,7 +96,7 @@ static int keyctl_pkey_params_get(key_serial_t id, if (ret < 0) return ret; = - key_ref =3D lookup_user_key(id, 0, KEY_NEED_SEARCH); + key_ref =3D lookup_user_key(id, 0, need_perm); if (IS_ERR(key_ref)) return PTR_ERR(key_ref); params->key =3D key_ref_to_ptr(key_ref); @@ -113,7 +114,8 @@ static int keyctl_pkey_params_get(key_serial_t id, static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __use= r *_params, const char __user *_info, int op, - struct kernel_pkey_params *params) + struct kernel_pkey_params *params, + enum key_need_perm need_perm) { struct keyctl_pkey_params uparams; struct kernel_pkey_query info; @@ -125,7 +127,7 @@ static int keyctl_pkey_params_get_2(const struct keyct= l_pkey_params __user *_par if (copy_from_user(&uparams, _params, sizeof(uparams)) !=3D 0) return -EFAULT; = - ret =3D keyctl_pkey_params_get(uparams.key_id, _info, params); + ret =3D keyctl_pkey_params_get(uparams.key_id, _info, params, need_perm)= ; if (ret < 0) return ret; = @@ -168,7 +170,7 @@ long keyctl_pkey_query(key_serial_t id, = memset(¶ms, 0, sizeof(params)); = - ret =3D keyctl_pkey_params_get(id, _info, ¶ms); + ret =3D keyctl_pkey_params_get(id, _info, ¶ms, KEY_NEED_DESCRIBE); if (ret < 0) goto error; = @@ -213,7 +215,8 @@ long keyctl_pkey_e_d_s(int op, void *in, *out; long ret; = - ret =3D keyctl_pkey_params_get_2(_params, _info, op, ¶ms); + ret =3D keyctl_pkey_params_get_2(_params, _info, op, ¶ms, + KEY_NEED_USE); if (ret < 0) goto error_params; = @@ -289,7 +292,7 @@ long keyctl_pkey_verify(const struct keyctl_pkey_param= s __user *_params, long ret; = ret =3D keyctl_pkey_params_get_2(_params, _info, KEYCTL_PKEY_VERIFY, - ¶ms); + ¶ms, KEY_NEED_USE); if (ret < 0) goto error_params; = diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 14abfe765b7e..6199efbe19b4 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -1167,7 +1167,7 @@ struct key *find_keyring_by_name(const char *name, b= ool uid_keyring) continue; } else { if (key_permission(make_key_ref(keyring, 0), - KEY_NEED_SEARCH) < 0) + KEY_NEED_JOIN) < 0) continue; } = diff --git a/security/keys/permission.c b/security/keys/permission.c index 085f907b64ac..ba8d3b548bbc 100644 --- a/security/keys/permission.c +++ b/security/keys/permission.c @@ -7,13 +7,120 @@ = #include #include +#include #include "internal.h" = +/* + * Determine if we have sufficient permission to perform a check. + */ +static int check_key_permission(struct key *key, const struct cred *cred, + key_perm_t perms, enum key_need_perm need_perm) +{ + struct request_key_auth *rka; + + switch (need_perm) { + case KEY_NEED_ASSUME_AUTHORITY: + return 0; + + case KEY_NEED_DESCRIBE: + case KEY_NEED_GET_SECURITY: + if (perms & KEY_OTH_VIEW) + return 0; + goto check_auth_override; + + case KEY_NEED_CHOWN: + case KEY_NEED_SETPERM: + case KEY_NEED_SET_RESTRICTION: + return perms & KEY_OTH_SETATTR ? 0 : -EACCES; + + case KEY_NEED_INSTANTIATE: + goto check_auth_override; + + case KEY_NEED_INVALIDATE: + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + if (perms & KEY_OTH_SEARCH) + return 0; + if (test_bit(KEY_FLAG_ROOT_CAN_INVAL, &key->flags)) + goto check_sysadmin_override; + return -EACCES; + + case KEY_NEED_JOIN: + case KEY_NEED_LINK: + return perms & KEY_OTH_LINK ? 0 : -EACCES; + + case KEY_NEED_KEYRING_DELETE: + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + /* Fall through. */ + case KEY_NEED_KEYRING_ADD: + return perms & KEY_OTH_WRITE ? 0 : -EACCES; + + case KEY_NEED_KEYRING_CLEAR: + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + if (perms & KEY_OTH_WRITE) + return 0; + if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR, &key->flags)) + goto check_sysadmin_override; + return -EACCES; + + case KEY_NEED_READ: + return perms & (KEY_OTH_READ | KEY_OTH_SEARCH) ? 0 : -EACCES; + + case KEY_NEED_REVOKE: + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + return perms & (KEY_OTH_WRITE | KEY_OTH_SETATTR) ? 0 : -EACCES; + + case KEY_NEED_SEARCH: + return perms & KEY_OTH_SEARCH ? 0 : -EACCES; + + case KEY_NEED_SET_TIMEOUT: + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + if (perms & KEY_OTH_SETATTR) + return 0; + goto check_auth_override; + + case KEY_NEED_UNLINK: + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + return 0; + + case KEY_NEED_UPDATE: + return perms & KEY_OTH_WRITE ? 0 : -EACCES; + + case KEY_NEED_USE: + return perms & (KEY_OTH_READ | KEY_OTH_SEARCH) ? 0 : -EACCES; + + case KEY_NEED_WATCH: + return perms & KEY_OTH_VIEW ? 0 : -EACCES; + + default: + WARN_ON(1); + return -EACCES; + } + +check_auth_override: + if (!cred->request_key_auth) + return -EACCES; + rka =3D cred->request_key_auth->payload.data[0]; + if (rka->target_key !=3D key) + return -EACCES; + return KEY_PERMISSION_USED_AUTH_OVERRIDE; + +check_sysadmin_override: + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + return KEY_PERMISSION_USED_SYSADMIN_OVERRIDE; +} + /** * key_task_permission - Check a key can be used * @key_ref: The key to check. * @cred: The credentials to use. - * @perm: The permissions to check for. + * @need_perm: The permission required. * * Check to see whether permission is granted to use a key in the desired= way, * but permit the security modules to override. @@ -24,7 +131,7 @@ * permissions bits or the LSM check. */ int key_task_permission(const key_ref_t key_ref, const struct cred *cred, - unsigned perm) + enum key_need_perm need_perm) { struct key *key; key_perm_t kperm; @@ -57,20 +164,18 @@ int key_task_permission(const key_ref_t key_ref, cons= t struct cred *cred, kperm =3D key->perm; = use_these_perms: - /* use the top 8-bits of permissions for keys the caller possesses * - possessor permissions are additive with other permissions */ if (is_key_possessed(key_ref)) kperm |=3D key->perm >> 24; = - kperm =3D kperm & perm & KEY_NEED_ALL; - - if (kperm !=3D perm) - return -EACCES; + ret =3D check_key_permission(key, cred, kperm & KEY_OTH_ALL, need_perm); + if (ret < 0) + return ret; = - /* let LSM be the final arbiter */ - return security_key_permission(key_ref, cred, perm); + /* Let the LSMs be the final arbiter */ + return security_key_permission(key_ref, cred, need_perm, ret); } EXPORT_SYMBOL(key_task_permission); = diff --git a/security/keys/persistent.c b/security/keys/persistent.c index 97af230aa4b2..6131a1528680 100644 --- a/security/keys/persistent.c +++ b/security/keys/persistent.c @@ -151,7 +151,7 @@ long keyctl_get_persistent(uid_t _uid, key_serial_t de= stid) } = /* There must be a destination keyring */ - dest_ref =3D lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE); + dest_ref =3D lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_NEED_KEYRING= _ADD); if (IS_ERR(dest_ref)) return PTR_ERR(dest_ref); if (key_ref_to_ptr(dest_ref)->type !=3D &key_type_keyring) { diff --git a/security/keys/proc.c b/security/keys/proc.c index d0cde6685627..373e62556fa5 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -188,7 +188,7 @@ static int proc_keys_show(struct seq_file *m, void *v) } = /* check whether the current task is allowed to view the key */ - rc =3D key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW); + rc =3D key_task_permission(key_ref, ctx.cred, KEY_NEED_DESCRIBE); if (rc < 0) return 0; = diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index 09541de31f2f..e39d9033c34c 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -609,7 +609,7 @@ bool lookup_user_key_possessed(const struct key *key, * returned key reference. */ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags, - key_perm_t perm) + enum key_need_perm need_perm) { struct keyring_search_context ctx =3D { .match_data.cmp =3D lookup_user_key_possessed, @@ -773,35 +773,24 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned = long lflags, = /* 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 =3D 0; - goto error; - } + if (need_perm !=3D KEY_NEED_UNLINK) { + if (!(lflags & KEY_LOOKUP_PARTIAL)) { + ret =3D wait_for_key_construction(key, true); + if (ret < 0) + goto invalid_key; = - if (!(lflags & KEY_LOOKUP_PARTIAL)) { - ret =3D wait_for_key_construction(key, true); - switch (ret) { - case -ERESTARTSYS: - goto invalid_key; - default: - if (perm) + ret =3D -EIO; + if (key_read_state(key) =3D=3D KEY_IS_UNINSTANTIATED) + goto invalid_key; + } else { + ret =3D key_validate(key); + if (ret < 0) goto invalid_key; - case 0: - break; } - } else if (perm) { - ret =3D key_validate(key); - if (ret < 0) - goto invalid_key; } = - ret =3D -EIO; - if (!(lflags & KEY_LOOKUP_PARTIAL) && - key_read_state(key) =3D=3D KEY_IS_UNINSTANTIATED) - goto invalid_key; - /* check the permissions */ - ret =3D key_task_permission(key_ref, ctx.cred, perm); + ret =3D key_task_permission(key_ref, ctx.cred, need_perm); if (ret < 0) goto invalid_key; = diff --git a/security/keys/request_key.c b/security/keys/request_key.c index e1b9f1a80676..c835b7407a5f 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -332,10 +332,10 @@ static int construct_get_dest_keyring(struct key **_= dest_keyring) BUG(); } = - /* - * Require Write permission on the keyring. This is essential - * because the default keyring may be the session keyring, and - * joining a keyring only requires Search permission. + /* Require permission to add a link to the keyring. This is + * essential because the default keyring may be the session + * keyring, and joining a keyring only requires Search + * permission. * * However, this check is skipped for the "requestor keyring" so * that /sbin/request-key can itself use request_key() to add @@ -343,7 +343,7 @@ static int construct_get_dest_keyring(struct key **_de= st_keyring) */ if (dest_keyring && do_perm_check) { ret =3D key_permission(make_key_ref(dest_keyring, 1), - KEY_NEED_WRITE); + KEY_NEED_KEYRING_ADD); if (ret) { key_put(dest_keyring); return ret; diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_= auth.c index 41e9735006d0..588130b631b8 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -258,6 +258,7 @@ struct key *key_get_instantiation_authkey(key_serial_t= target_id) }; struct key *authkey; key_ref_t authkey_ref; + int ret; = ctx.index_key.desc_len =3D sprintf(description, "%x", target_id); = @@ -272,6 +273,12 @@ struct key *key_get_instantiation_authkey(key_serial_= t target_id) goto error; } = + ret =3D key_permission(authkey_ref, KEY_NEED_ASSUME_AUTHORITY); + if (ret < 0) { + key_ref_put(authkey_ref); + authkey =3D ERR_PTR(ret); + } + authkey =3D key_ref_to_ptr(authkey_ref); if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) { key_put(authkey); diff --git a/security/security.c b/security/security.c index c73334ab2882..e5e2200796f7 100644 --- a/security/security.c +++ b/security/security.c @@ -2398,10 +2398,10 @@ void security_key_free(struct key *key) call_void_hook(key_free, key); } = -int security_key_permission(key_ref_t key_ref, - const struct cred *cred, unsigned perm) +int security_key_permission(key_ref_t key_ref, const struct cred *cred, + enum key_need_perm need_perm, unsigned int flags) { - return call_int_hook(key_permission, 0, key_ref, cred, perm); + return call_int_hook(key_permission, 0, key_ref, cred, need_perm, flags)= ; } = int security_key_getsecurity(struct key *key, char **_buffer) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 0b4e32161b77..0761787dee13 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -91,6 +91,7 @@ #include #include #include +#include = #include "avc.h" #include "objsec.h" @@ -6539,27 +6540,144 @@ static void selinux_key_free(struct key *k) kfree(ksec); } = +/* + * Convert the requested KEY_NEED_* permit into an SELinux KEY__* permiss= ion. + * + * flags may also convey override flags such as + * KEY_PERMISSION_USED_AUTH/SYSADMIN_OVERRIDE to indicate when the main + * permission check overrode the permissions on the key. + * + * Returns the perms to check for in *_perm and *_perm2. If either perm = is + * present, then the operation is allowed. + */ +static int selinux_keyperm_to_av(struct key *key, const struct cred *cred= , + unsigned int need_perm, unsigned int flags, + u32 *_perm, u32 *_perm2) +{ + bool auth_can_override =3D false; /* See KEYCTL_ASSUME_AUTHORITY */ + bool sysadmin_can_override =3D false; + + switch (need_perm) { + case KEY_NEED_ASSUME_AUTHORITY: + return 0; + + case KEY_NEED_DESCRIBE: + case KEY_NEED_GET_SECURITY: + *_perm =3D KEY__VIEW; + auth_can_override =3D true; + break; + + case KEY_NEED_CHOWN: + case KEY_NEED_SETPERM: + case KEY_NEED_SET_RESTRICTION: + *_perm =3D KEY__SETATTR; + break; + + case KEY_NEED_INSTANTIATE: + auth_can_override =3D true; + break; + + case KEY_NEED_INVALIDATE: + *_perm =3D KEY__SEARCH; + if (test_bit(KEY_FLAG_ROOT_CAN_INVAL, &key->flags)) + sysadmin_can_override =3D true; + break; + + case KEY_NEED_JOIN: + case KEY_NEED_LINK: + *_perm =3D KEY__LINK; + break; + + case KEY_NEED_KEYRING_ADD: + case KEY_NEED_KEYRING_DELETE: + *_perm =3D KEY__WRITE; + break; + + case KEY_NEED_KEYRING_CLEAR: + *_perm =3D KEY__WRITE; + if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR, &key->flags)) + sysadmin_can_override =3D true; + break; + + case KEY_NEED_READ: + *_perm =3D KEY__READ; + break; + + case KEY_NEED_REVOKE: + *_perm =3D KEY__SETATTR; + *_perm2 =3D KEY__WRITE; + break; + + case KEY_NEED_SEARCH: + *_perm =3D KEY__SEARCH; + break; + + case KEY_NEED_SET_TIMEOUT: + *_perm =3D KEY__SETATTR; + auth_can_override =3D true; + break; + + case KEY_NEED_UNLINK: + return 0; /* Mustn't prevent this; KEY_FLAG_KEEP is already + * dealt with. */ + + case KEY_NEED_UPDATE: + *_perm =3D KEY__WRITE; + break; + + case KEY_NEED_USE: + *_perm =3D KEY__READ; + *_perm2 =3D KEY__SEARCH; + break; + + case KEY_NEED_WATCH: + *_perm =3D KEY__VIEW; + break; + + default: + WARN_ON(1); + return -EPERM; + } + + /* Just allow the operation if the process has an authorisation token. + * The presence of the token means that the kernel delegated + * instantiation of a key to the process - which is problematic if we + * then say that the process isn't allowed to get the description of + * the key or actually instantiate it. + */ + if (auth_can_override && cred->request_key_auth) { + struct request_key_auth *rka =3D + cred->request_key_auth->payload.data[0]; + if (rka->target_key =3D=3D key) + *_perm =3D 0; + } + + return 0; +} + static int selinux_key_permission(key_ref_t key_ref, const struct cred *cred, - unsigned perm) + enum key_need_perm need_perm, + unsigned int flags) { - struct key *key; - struct key_security_struct *ksec; - u32 sid; + struct key *key =3D key_ref_to_ptr(key_ref); + struct key_security_struct *ksec =3D key->security; + u32 sid, perm =3D 0, perm2 =3D 0; + int ret; = - /* if no specific permissions are requested, we skip the - permission check. No serious, additional covert channels - appear to be created. */ - if (perm =3D=3D 0) - return 0; + ret =3D selinux_keyperm_to_av(key, cred, need_perm, flags, &perm, &perm2= ); + if (ret < 0 || !perm) + return ret; = sid =3D cred_sid(cred); = - key =3D key_ref_to_ptr(key_ref); - ksec =3D key->security; + ret =3D avc_has_perm(&selinux_state, + sid, ksec->sid, SECCLASS_KEY, perm, NULL); + if (ret =3D=3D 0 || !perm2) + return ret; = return avc_has_perm(&selinux_state, - sid, ksec->sid, SECCLASS_KEY, perm, NULL); + sid, ksec->sid, SECCLASS_KEY, perm2, NULL); } = static int selinux_key_getsecurity(struct key *key, char **_buffer) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 8c61d175e195..ac9c93c48097 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4230,13 +4230,15 @@ static void smack_key_free(struct key *key) * smack_key_permission - Smack access on a key * @key_ref: gets to the object * @cred: the credentials to use - * @perm: requested key permissions + * @need_perm: requested key permission * * Return 0 if the task has read and write to the object, * an error code otherwise */ static int smack_key_permission(key_ref_t key_ref, - const struct cred *cred, unsigned perm) + const struct cred *cred, + enum key_need_perm need_perm, + unsigned int flags) { struct key *keyp; struct smk_audit_info ad; @@ -4244,12 +4246,6 @@ static int smack_key_permission(key_ref_t key_ref, int request =3D 0; int rc; = - /* - * Validate requested permissions - */ - if (perm & ~KEY_NEED_ALL) - return -EINVAL; - keyp =3D key_ref_to_ptr(key_ref); if (keyp =3D=3D NULL) return -EINVAL; @@ -4265,6 +4261,71 @@ static int smack_key_permission(key_ref_t key_ref, if (tkp =3D=3D NULL) return -EACCES; = + /* + * Validate requested permissions + */ + switch (need_perm) { + case KEY_NEED_ASSUME_AUTHORITY: + return 0; + + case KEY_NEED_DESCRIBE: + case KEY_NEED_GET_SECURITY: + request |=3D MAY_READ; + auth_can_override =3D true; + break; + + case KEY_NEED_CHOWN: + case KEY_NEED_INVALIDATE: + case KEY_NEED_JOIN: + case KEY_NEED_LINK: + case KEY_NEED_KEYRING_ADD: + case KEY_NEED_KEYRING_CLEAR: + case KEY_NEED_KEYRING_DELETE: + case KEY_NEED_REVOKE: + case KEY_NEED_SETPERM: + case KEY_NEED_SET_RESTRICTION: + case KEY_NEED_UPDATE: + request |=3D MAY_WRITE; + break; + + case KEY_NEED_INSTANTIATE: + auth_can_override =3D true; + break; + + case KEY_NEED_READ: + case KEY_NEED_SEARCH: + case KEY_NEED_USE: + case KEY_NEED_WATCH: + request |=3D MAY_READ; + break; + + case KEY_NEED_SET_TIMEOUT: + request |=3D MAY_WRITE; + auth_can_override =3D true; + break; + + case KEY_NEED_UNLINK: + return 0; /* Mustn't prevent this; KEY_FLAG_KEEP is already + * dealt with. */ + + default: + WARN_ON(1); + return -EINVAL; + } + + /* Just allow the operation if the process has an authorisation token. + * The presence of the token means that the kernel delegated + * instantiation of a key to the process - which is problematic if we + * then say that the process isn't allowed to get the description of + * the key or actually instantiate it. + */ + if (auth_can_override && cred->request_key_auth) { + struct request_key_auth *rka =3D + cred->request_key_auth->payload.data[0]; + if (rka->target_key =3D=3D key) + *_perm =3D 0; + } + if (smack_privileged_cred(CAP_MAC_OVERRIDE, cred)) return 0; = @@ -4273,10 +4334,6 @@ static int smack_key_permission(key_ref_t key_ref, ad.a.u.key_struct.key =3D keyp->serial; ad.a.u.key_struct.key_desc =3D keyp->description; #endif - if (perm & (KEY_NEED_READ | KEY_NEED_SEARCH | KEY_NEED_VIEW)) - request |=3D MAY_READ; - if (perm & (KEY_NEED_WRITE | KEY_NEED_LINK | KEY_NEED_SETATTR)) - request |=3D MAY_WRITE; rc =3D smk_access(tkp, keyp->security, request, &ad); rc =3D smk_bu_note("key access", tkp, keyp->security, request, rc); return rc;