From d4f65b5d2497b2fd9c45f06b71deb4ab084a5b66 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 13 Sep 2012 13:06:29 +0100 Subject: KEYS: Add payload preparsing opportunity prior to key instantiate or update Give the key type the opportunity to preparse the payload prior to the instantiation and update routines being called. This is done with the provision of two new key type operations: int (*preparse)(struct key_preparsed_payload *prep); void (*free_preparse)(struct key_preparsed_payload *prep); If the first operation is present, then it is called before key creation (in the add/update case) or before the key semaphore is taken (in the update and instantiate cases). The second operation is called to clean up if the first was called. preparse() is given the opportunity to fill in the following structure: struct key_preparsed_payload { char *description; void *type_data[2]; void *payload; const void *data; size_t datalen; size_t quotalen; }; Before the preparser is called, the first three fields will have been cleared, the payload pointer and size will be stored in data and datalen and the default quota size from the key_type struct will be stored into quotalen. The preparser may parse the payload in any way it likes and may store data in the type_data[] and payload fields for use by the instantiate() and update() ops. The preparser may also propose a description for the key by attaching it as a string to the description field. This can be used by passing a NULL or "" description to the add_key() system call or the key_create_or_update() function. This cannot work with request_key() as that required the description to tell the upcall about the key to be created. This, for example permits keys that store PGP public keys to generate their own name from the user ID and public key fingerprint in the key. The instantiate() and update() operations are then modified to look like this: int (*instantiate)(struct key *key, struct key_preparsed_payload *prep); int (*update)(struct key *key, struct key_preparsed_payload *prep); and the new payload data is passed in *prep, whether or not it was preparsed. Signed-off-by: David Howells --- security/keys/key.c | 114 +++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 82 insertions(+), 32 deletions(-) (limited to 'security/keys/key.c') diff --git a/security/keys/key.c b/security/keys/key.c index 50d96d4e06f2..1d039af99f50 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -412,8 +412,7 @@ EXPORT_SYMBOL(key_payload_reserve); * key_construction_mutex. */ static int __key_instantiate_and_link(struct key *key, - const void *data, - size_t datalen, + struct key_preparsed_payload *prep, struct key *keyring, struct key *authkey, unsigned long *_prealloc) @@ -431,7 +430,7 @@ static int __key_instantiate_and_link(struct key *key, /* can't instantiate twice */ if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { /* instantiate the key */ - ret = key->type->instantiate(key, data, datalen); + ret = key->type->instantiate(key, prep); if (ret == 0) { /* mark the key as being instantiated */ @@ -482,22 +481,37 @@ int key_instantiate_and_link(struct key *key, struct key *keyring, struct key *authkey) { + struct key_preparsed_payload prep; unsigned long prealloc; int ret; + memset(&prep, 0, sizeof(prep)); + prep.data = data; + prep.datalen = datalen; + prep.quotalen = key->type->def_datalen; + if (key->type->preparse) { + ret = key->type->preparse(&prep); + if (ret < 0) + goto error; + } + if (keyring) { ret = __key_link_begin(keyring, key->type, key->description, &prealloc); if (ret < 0) - return ret; + goto error_free_preparse; } - ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey, + ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &prealloc); if (keyring) __key_link_end(keyring, key->type, prealloc); +error_free_preparse: + if (key->type->preparse) + key->type->free_preparse(&prep); +error: return ret; } @@ -706,7 +720,7 @@ void key_type_put(struct key_type *ktype) * if we get an error. */ static inline key_ref_t __key_update(key_ref_t key_ref, - const void *payload, size_t plen) + struct key_preparsed_payload *prep) { struct key *key = key_ref_to_ptr(key_ref); int ret; @@ -722,7 +736,7 @@ static inline key_ref_t __key_update(key_ref_t key_ref, down_write(&key->sem); - ret = key->type->update(key, payload, plen); + ret = key->type->update(key, prep); if (ret == 0) /* updating a negative key instantiates it */ clear_bit(KEY_FLAG_NEGATIVE, &key->flags); @@ -774,6 +788,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, unsigned long flags) { unsigned long prealloc; + struct key_preparsed_payload prep; const struct cred *cred = current_cred(); struct key_type *ktype; struct key *keyring, *key = NULL; @@ -789,8 +804,9 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, } key_ref = ERR_PTR(-EINVAL); - if (!ktype->match || !ktype->instantiate) - goto error_2; + if (!ktype->match || !ktype->instantiate || + (!description && !ktype->preparse)) + goto error_put_type; keyring = key_ref_to_ptr(keyring_ref); @@ -798,18 +814,37 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, key_ref = ERR_PTR(-ENOTDIR); if (keyring->type != &key_type_keyring) - goto error_2; + goto error_put_type; + + memset(&prep, 0, sizeof(prep)); + prep.data = payload; + prep.datalen = plen; + prep.quotalen = ktype->def_datalen; + if (ktype->preparse) { + ret = ktype->preparse(&prep); + if (ret < 0) { + key_ref = ERR_PTR(ret); + goto error_put_type; + } + if (!description) + description = prep.description; + key_ref = ERR_PTR(-EINVAL); + if (!description) + goto error_free_prep; + } ret = __key_link_begin(keyring, ktype, description, &prealloc); - if (ret < 0) - goto error_2; + if (ret < 0) { + key_ref = ERR_PTR(ret); + goto error_free_prep; + } /* if we're going to allocate a new key, we're going to have * to modify the keyring */ ret = key_permission(keyring_ref, KEY_WRITE); if (ret < 0) { key_ref = ERR_PTR(ret); - goto error_3; + goto error_link_end; } /* if it's possible to update this type of key, search for an existing @@ -840,25 +875,27 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, perm, flags); if (IS_ERR(key)) { key_ref = ERR_CAST(key); - goto error_3; + goto error_link_end; } /* instantiate it and link it into the target keyring */ - ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL, - &prealloc); + ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &prealloc); if (ret < 0) { key_put(key); key_ref = ERR_PTR(ret); - goto error_3; + goto error_link_end; } key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); - error_3: +error_link_end: __key_link_end(keyring, ktype, prealloc); - error_2: +error_free_prep: + if (ktype->preparse) + ktype->free_preparse(&prep); +error_put_type: key_type_put(ktype); - error: +error: return key_ref; found_matching_key: @@ -866,10 +903,9 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, * - we can drop the locks first as we have the key pinned */ __key_link_end(keyring, ktype, prealloc); - key_type_put(ktype); - key_ref = __key_update(key_ref, payload, plen); - goto error; + key_ref = __key_update(key_ref, &prep); + goto error_free_prep; } EXPORT_SYMBOL(key_create_or_update); @@ -888,6 +924,7 @@ EXPORT_SYMBOL(key_create_or_update); */ int key_update(key_ref_t key_ref, const void *payload, size_t plen) { + struct key_preparsed_payload prep; struct key *key = key_ref_to_ptr(key_ref); int ret; @@ -900,18 +937,31 @@ int key_update(key_ref_t key_ref, const void *payload, size_t plen) /* attempt to update it if supported */ ret = -EOPNOTSUPP; - if (key->type->update) { - down_write(&key->sem); - - ret = key->type->update(key, payload, plen); - if (ret == 0) - /* updating a negative key instantiates it */ - clear_bit(KEY_FLAG_NEGATIVE, &key->flags); + if (!key->type->update) + goto error; - up_write(&key->sem); + memset(&prep, 0, sizeof(prep)); + prep.data = payload; + prep.datalen = plen; + prep.quotalen = key->type->def_datalen; + if (key->type->preparse) { + ret = key->type->preparse(&prep); + if (ret < 0) + goto error; } - error: + down_write(&key->sem); + + ret = key->type->update(key, &prep); + if (ret == 0) + /* updating a negative key instantiates it */ + clear_bit(KEY_FLAG_NEGATIVE, &key->flags); + + up_write(&key->sem); + + if (key->type->preparse) + key->type->free_preparse(&prep); +error: return ret; } EXPORT_SYMBOL(key_update); -- cgit v1.2.3 From 96b5c8fea6c0861621051290d705ec2e971963f1 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 2 Oct 2012 19:24:56 +0100 Subject: KEYS: Reduce initial permissions on keys Reduce the initial permissions on new keys to grant the possessor everything, view permission only to the user (so the keys can be seen in /proc/keys) and nothing else. This gives the creator a chance to adjust the permissions mask before other processes can access the new key or create a link to it. To aid with this, keyring_alloc() now takes a permission argument rather than setting the permissions itself. The following permissions are now set: (1) The user and user-session keyrings grant the user that owns them full permissions and grant a possessor everything bar SETATTR. (2) The process and thread keyrings grant the possessor full permissions but only grant the user VIEW. This permits the user to see them in /proc/keys, but not to do anything with them. (3) Anonymous session keyrings grant the possessor full permissions, but only grant the user VIEW and READ. This means that the user can see them in /proc/keys and can list them, but nothing else. Possibly READ shouldn't be provided either. (4) Named session keyrings grant everything an anonymous session keyring does, plus they grant the user LINK permission. The whole point of named session keyrings is that others can also subscribe to them. Possibly this should be a separate permission to LINK. (5) The temporary session keyring created by call_sbin_request_key() gets the same permissions as an anonymous session keyring. (6) Keys created by add_key() get VIEW, SEARCH, LINK and SETATTR for the possessor, plus READ and/or WRITE if the key type supports them. The used only gets VIEW now. (7) Keys created by request_key() now get the same as those created by add_key(). Reported-by: Lennart Poettering Reported-by: Stef Walter Signed-off-by: David Howells --- include/linux/key.h | 1 + security/keys/key.c | 6 +++--- security/keys/keyring.c | 9 +++------ security/keys/process_keys.c | 26 +++++++++++++++++--------- security/keys/request_key.c | 11 ++++++++++- 5 files changed, 34 insertions(+), 19 deletions(-) (limited to 'security/keys/key.c') diff --git a/include/linux/key.h b/include/linux/key.h index cef3b315ba7c..890699815212 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -264,6 +264,7 @@ extern int key_unlink(struct key *keyring, extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, const struct cred *cred, + key_perm_t perm, unsigned long flags, struct key *dest); diff --git a/security/keys/key.c b/security/keys/key.c index 50d96d4e06f2..bebeca3a78e4 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -826,13 +826,13 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, /* if the client doesn't provide, decide on the permissions we want */ if (perm == KEY_PERM_UNDEF) { perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; - perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR; + perm |= KEY_USR_VIEW; if (ktype->read) - perm |= KEY_POS_READ | KEY_USR_READ; + perm |= KEY_POS_READ; if (ktype == &key_type_keyring || ktype->update) - perm |= KEY_USR_WRITE; + perm |= KEY_POS_WRITE; } /* allocate a new key */ diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 81e7852d281d..cf704a92083f 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -257,17 +257,14 @@ error: * Allocate a keyring and link into the destination keyring. */ struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, - const struct cred *cred, unsigned long flags, - struct key *dest) + const struct cred *cred, key_perm_t perm, + unsigned long flags, struct key *dest) { struct key *keyring; int ret; keyring = key_alloc(&key_type_keyring, description, - uid, gid, cred, - (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, - flags); - + uid, gid, cred, perm, flags); if (!IS_ERR(keyring)) { ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); if (ret < 0) { diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index 9de5dc598276..b58d93892740 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -46,9 +46,11 @@ int install_user_keyrings(void) struct user_struct *user; const struct cred *cred; struct key *uid_keyring, *session_keyring; + key_perm_t user_keyring_perm; char buf[20]; int ret; + user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL; cred = current_cred(); user = cred->user; @@ -72,8 +74,8 @@ int install_user_keyrings(void) uid_keyring = find_keyring_by_name(buf, true); if (IS_ERR(uid_keyring)) { uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, - cred, KEY_ALLOC_IN_QUOTA, - NULL); + cred, user_keyring_perm, + KEY_ALLOC_IN_QUOTA, NULL); if (IS_ERR(uid_keyring)) { ret = PTR_ERR(uid_keyring); goto error; @@ -88,7 +90,8 @@ int install_user_keyrings(void) if (IS_ERR(session_keyring)) { session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, - cred, KEY_ALLOC_IN_QUOTA, NULL); + cred, user_keyring_perm, + KEY_ALLOC_IN_QUOTA, NULL); if (IS_ERR(session_keyring)) { ret = PTR_ERR(session_keyring); goto error_release; @@ -129,6 +132,7 @@ int install_thread_keyring_to_cred(struct cred *new) struct key *keyring; keyring = keyring_alloc("_tid", new->uid, new->gid, new, + KEY_POS_ALL | KEY_USR_VIEW, KEY_ALLOC_QUOTA_OVERRUN, NULL); if (IS_ERR(keyring)) return PTR_ERR(keyring); @@ -173,8 +177,9 @@ int install_process_keyring_to_cred(struct cred *new) if (new->process_keyring) return -EEXIST; - keyring = keyring_alloc("_pid", new->uid, new->gid, - new, KEY_ALLOC_QUOTA_OVERRUN, NULL); + keyring = keyring_alloc("_pid", new->uid, new->gid, new, + KEY_POS_ALL | KEY_USR_VIEW, + KEY_ALLOC_QUOTA_OVERRUN, NULL); if (IS_ERR(keyring)) return PTR_ERR(keyring); @@ -223,8 +228,9 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring) if (cred->session_keyring) flags = KEY_ALLOC_IN_QUOTA; - keyring = keyring_alloc("_ses", cred->uid, cred->gid, - cred, flags, NULL); + keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred, + KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ, + flags, NULL); if (IS_ERR(keyring)) return PTR_ERR(keyring); } else { @@ -773,8 +779,10 @@ long join_session_keyring(const char *name) keyring = find_keyring_by_name(name, false); if (PTR_ERR(keyring) == -ENOKEY) { /* not found - try and create a new one */ - keyring = keyring_alloc(name, old->uid, old->gid, old, - KEY_ALLOC_IN_QUOTA, NULL); + keyring = keyring_alloc( + name, old->uid, old->gid, old, + KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK, + 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 275c4f9e4b8c..0ae3a2202771 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -126,6 +126,7 @@ static int call_sbin_request_key(struct key_construction *cons, cred = get_current_cred(); keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred, + KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ, KEY_ALLOC_QUOTA_OVERRUN, NULL); put_cred(cred); if (IS_ERR(keyring)) { @@ -347,6 +348,7 @@ static int construct_alloc_key(struct key_type *type, const struct cred *cred = current_cred(); unsigned long prealloc; struct key *key; + key_perm_t perm; key_ref_t key_ref; int ret; @@ -355,8 +357,15 @@ static int construct_alloc_key(struct key_type *type, *_key = NULL; mutex_lock(&user->cons_lock); + perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; + perm |= KEY_USR_VIEW; + if (type->read) + perm |= KEY_POS_READ; + if (type == &key_type_keyring || type->update) + perm |= KEY_POS_WRITE; + key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred, - KEY_POS_ALL, flags); + perm, flags); if (IS_ERR(key)) goto alloc_failed; -- cgit v1.2.3