diff options
| -rw-r--r-- | include/linux/key.h | 1 | ||||
| -rw-r--r-- | security/keys/keyring.c | 47 | ||||
| -rw-r--r-- | security/keys/process_keys.c | 2 |
3 files changed, 43 insertions, 7 deletions
diff --git a/include/linux/key.h b/include/linux/key.h index c505f83c9691..13c0dcd8ee48 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -136,6 +136,7 @@ struct key { time_t expiry; /* time at which key expires (or 0) */ time_t revoked_at; /* time at which key was revoked */ }; + time_t last_used_at; /* last time used for LRU keyring discard */ uid_t uid; gid_t gid; key_perm_t perm; /* access permissions */ diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 459b3cc347f2..89d02cfb00c2 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -30,6 +30,10 @@ (klist)->keys[index], \ rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) +#define MAX_KEYRING_LINKS \ + min_t(size_t, USHRT_MAX - 1, \ + ((PAGE_SIZE - sizeof(struct keyring_list)) / sizeof(struct key *))) + #define KEY_LINK_FIXQUOTA 1UL /* @@ -319,6 +323,8 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref, bool no_state_check) { struct { + /* Need a separate keylist pointer for RCU purposes */ + struct key *keyring; struct keyring_list *keylist; int kix; } stack[KEYRING_SEARCH_MAX_DEPTH]; @@ -451,6 +457,7 @@ ascend: continue; /* stack the current position */ + stack[sp].keyring = keyring; stack[sp].keylist = keylist; stack[sp].kix = kix; sp++; @@ -466,6 +473,7 @@ not_this_keyring: if (sp > 0) { /* resume the processing of a keyring higher up in the tree */ sp--; + keyring = stack[sp].keyring; keylist = stack[sp].keylist; kix = stack[sp].kix + 1; goto ascend; @@ -477,6 +485,10 @@ not_this_keyring: /* we found a viable match */ found: atomic_inc(&key->usage); + key->last_used_at = now.tv_sec; + keyring->last_used_at = now.tv_sec; + while (sp > 0) + stack[--sp].keyring->last_used_at = now.tv_sec; key_check(key); key_ref = make_key_ref(key, possessed); error_2: @@ -558,6 +570,8 @@ key_ref_t __keyring_search_one(key_ref_t keyring_ref, found: atomic_inc(&key->usage); + keyring->last_used_at = key->last_used_at = + current_kernel_time().tv_sec; rcu_read_unlock(); return make_key_ref(key, possessed); } @@ -611,6 +625,7 @@ struct key *find_keyring_by_name(const char *name, bool skip_perm_check) * (ie. it has a zero usage count) */ if (!atomic_inc_not_zero(&keyring->usage)) continue; + keyring->last_used_at = current_kernel_time().tv_sec; goto out; } } @@ -734,8 +749,9 @@ int __key_link_begin(struct key *keyring, const struct key_type *type, struct keyring_list *klist, *nklist; unsigned long prealloc; unsigned max; + time_t lowest_lru; size_t size; - int loop, ret; + int loop, lru, ret; kenter("%d,%s,%s,", key_serial(keyring), type->name, description); @@ -756,7 +772,9 @@ int __key_link_begin(struct key *keyring, const struct key_type *type, klist = rcu_dereference_locked_keyring(keyring); /* see if there's a matching key we can displace */ + lru = -1; if (klist && klist->nkeys > 0) { + lowest_lru = TIME_T_MAX; for (loop = klist->nkeys - 1; loop >= 0; loop--) { struct key *key = rcu_deref_link_locked(klist, loop, keyring); @@ -770,9 +788,23 @@ int __key_link_begin(struct key *keyring, const struct key_type *type, prealloc = 0; goto done; } + if (key->last_used_at < lowest_lru) { + lowest_lru = key->last_used_at; + lru = loop; + } } } + /* If the keyring is full then do an LRU discard */ + if (klist && + klist->nkeys == klist->maxkeys && + klist->maxkeys >= MAX_KEYRING_LINKS) { + kdebug("LRU discard %d\n", lru); + klist->delkey = lru; + prealloc = 0; + goto done; + } + /* check that we aren't going to overrun the user's quota */ ret = key_payload_reserve(keyring, keyring->datalen + KEYQUOTA_LINK_BYTES); @@ -786,15 +818,14 @@ int __key_link_begin(struct key *keyring, const struct key_type *type, } else { /* grow the key list */ max = 4; - if (klist) + if (klist) { max += klist->maxkeys; + if (max > MAX_KEYRING_LINKS) + max = MAX_KEYRING_LINKS; + BUG_ON(max <= klist->maxkeys); + } - ret = -ENFILE; - if (max > USHRT_MAX - 1) - goto error_quota; size = sizeof(*klist) + sizeof(struct key *) * max; - if (size > PAGE_SIZE) - goto error_quota; ret = -ENOMEM; nklist = kmalloc(size, GFP_KERNEL); @@ -873,6 +904,8 @@ void __key_link(struct key *keyring, struct key *key, klist = rcu_dereference_locked_keyring(keyring); atomic_inc(&key->usage); + keyring->last_used_at = key->last_used_at = + current_kernel_time().tv_sec; /* there's a matching key we can displace or an empty slot in a newly * allocated list we can fill */ diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index be7ecb2018dd..e137fcd7042c 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -732,6 +732,8 @@ try_again: if (ret < 0) goto invalid_key; + key->last_used_at = current_kernel_time().tv_sec; + error: put_cred(cred); return key_ref; |