kernel/linux.git/security/keys/keyring.c, branch v3.18.100

KEYS: return full count in keyring_read() if buffer is too small

2017-11-08T09:03:48+00:00

commit 3239b6f29bdfb4b0a2ba59df995fc9e6f4df7f1f upstream. Commit e645016abc80 ("KEYS: fix writing past end of user-supplied buffer in keyring_read()") made keyring_read() stop corrupting userspace memory when the user-supplied buffer is too small. However it also made the return value in that case be the short buffer size rather than the size required, yet keyctl_read() is actually documented to return the size required. Therefore, switch it over to the documented behavior. Note that for now we continue to have it fill the short buffer, since it did that before (pre-v3.13) and dump_key_tree_aux() in keyutils arguably relies on it. Fixes: e645016abc80 ("KEYS: fix writing past end of user-supplied buffer in keyring_read()") Reported-by: Ben Hutchings Signed-off-by: Eric Biggers Signed-off-by: David Howells Reviewed-by: James Morris Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

KEYS: prevent creating a different user's keyrings

2017-10-05T07:35:51+00:00

commit 237bbd29f7a049d310d907f4b2716a7feef9abf3 upstream. It was possible for an unprivileged user to create the user and user session keyrings for another user. For example: sudo -u '#3000' sh -c 'keyctl add keyring _uid.4000 "" @u keyctl add keyring _uid_ses.4000 "" @u sleep 15' & sleep 1 sudo -u '#4000' keyctl describe @u sudo -u '#4000' keyctl describe @us This is problematic because these "fake" keyrings won't have the right permissions. In particular, the user who created them first will own them and will have full access to them via the possessor permissions, which can be used to compromise the security of a user's keys: -4: alswrv-----v------------ 3000 0 keyring: _uid.4000 -5: alswrv-----v------------ 3000 0 keyring: _uid_ses.4000 Fix it by marking user and user session keyrings with a flag KEY_FLAG_UID_KEYRING. Then, when searching for a user or user session keyring by name, skip all keyrings that don't have the flag set. Fixes: 69664cf16af4 ("keys: don't generate user and user session keyrings unless they're accessed") Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman

KEYS: fix writing past end of user-supplied buffer in keyring_read()

2017-10-05T07:35:51+00:00

commit e645016abc803dafc75e4b8f6e4118f088900ffb upstream. Userspace can call keyctl_read() on a keyring to get the list of IDs of keys in the keyring. But if the user-supplied buffer is too small, the kernel would write the full list anyway --- which will corrupt whatever userspace memory happened to be past the end of the buffer. Fix it by only filling the space that is available. Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring") Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman

KEYS: ensure we free the assoc array edit if edit is valid

2015-08-04T18:28:38+00:00

[ Upstream commit HEAD ] commit ca4da5dd1f99fe9c59f1709fb43e818b18ad20e0 upstream. __key_link_end is not freeing the associated array edit structure and this leads to a 512 byte memory leak each time an identical existing key is added with add_key(). The reason the add_key() system call returns okay is that key_create_or_update() calls __key_link_begin() before checking to see whether it can update a key directly rather than adding/replacing - which it turns out it can. Thus __key_link() is not called through __key_instantiate_and_link() and __key_link_end() must cancel the edit. CVE-2015-1333 Signed-off-by: Colin Ian King Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman (cherry picked from commit c9cd9b18dac801040ada16562dc579d5ac366d75) Signed-off-by: Sasha Levin

KEYS: request_key() should reget expired keys rather than give EKEYEXPIRED

2014-12-01T22:52:53+00:00

Since the keyring facility can be viewed as a cache (at least in some applications), the local expiration time on the key should probably be viewed as a 'needs updating after this time' property rather than an absolute 'anyone now wanting to use this object is out of luck' property. Since request_key() is the main interface for the usage of keys, this should update or replace an expired key rather than issuing EKEYEXPIRED if the local expiration has been reached (ie. it should refresh the cache). For absolute conditions where refreshing the cache probably doesn't help, the key can be negatively instantiated using KEYCTL_REJECT_KEY with EKEYEXPIRED given as the error to issue. This will still cause request_key() to return EKEYEXPIRED as that was explicitly set. In the future, if the key type has an update op available, we might want to upcall with the expired key and allow the upcall to update it. We would pass a different operation name (the first column in /etc/request-key.conf) to the request-key program. request_key() returning EKEYEXPIRED is causing an NFS problem which Chuck Lever describes thusly: After about 10 minutes, my NFSv4 functional tests fail because the ownership of the test files goes to "-2". Looking at /proc/keys shows that the id_resolv keys that map to my test user ID have expired. The ownership problem persists until the expired keys are purged from the keyring, and fresh keys are obtained. I bisected the problem to 3.13 commit b2a4df200d57 ("KEYS: Expand the capacity of a keyring"). This commit inadvertantly changes the API contract of the internal function keyring_search_aux(). The root cause appears to be that b2a4df200d57 made "no state check" the default behavior. "No state check" means the keyring search iterator function skips checking the key's expiry timeout, and returns expired keys. request_key_and_link() depends on getting an -EAGAIN result code to know when to perform an upcall to refresh an expired key. This patch can be tested directly by: keyctl request2 user debug:fred a @s keyctl timeout %user:debug:fred 3 sleep 4 keyctl request2 user debug:fred a @s Without the patch, the last command gives error EKEYEXPIRED, but with the command it gives a new key. Reported-by: Carl Hetherington Reported-by: Chuck Lever Signed-off-by: David Howells Tested-by: Chuck Lever

KEYS: Simplify KEYRING_SEARCH_{NO,DO}_STATE_CHECK flags

2014-12-01T22:52:50+00:00

Simplify KEYRING_SEARCH_{NO,DO}_STATE_CHECK flags to be two variations of the same flag. They are effectively mutually exclusive and one or the other should be provided, but not both. Keyring cycle detection and key possession determination are the only things that set NO_STATE_CHECK, except that neither flag really does anything there because neither purpose makes use of the keyring_search_iterator() function, but rather provides their own. For cycle detection we definitely want to check inside of expired keyrings, just so that we don't create a cycle we can't get rid of. Revoked keyrings are cleared at revocation time and can't then be reused, so shouldn't be a problem either way. For possession determination, we *might* want to validate each keyring before searching it: do you possess a key that's hidden behind an expired or just plain inaccessible keyring? Currently, the answer is yes. Note that you cannot, however, possess a key behind a revoked keyring because they are cleared on revocation. keyring_search() sets DO_STATE_CHECK, which is correct. request_key_and_link() currently doesn't specify whether to check the key state or not - but it should set DO_STATE_CHECK. key_get_instantiation_authkey() also currently doesn't specify whether to check the key state or not - but it probably should also set DO_STATE_CHECK. Signed-off-by: David Howells Tested-by: Chuck Lever

KEYS: Make the key matching functions return bool

2014-09-16T16:36:08+00:00

Make the key matching functions pointed to by key_match_data::cmp return bool rather than int. Signed-off-by: David Howells Acked-by: Vivek Goyal

KEYS: Remove key_type::match in favour of overriding default by match_preparse

2014-09-16T16:36:06+00:00

A previous patch added a ->match_preparse() method to the key type. This is allowed to override the function called by the iteration algorithm. Therefore, we can just set a default that simply checks for an exact match of the key description with the original criterion data and allow match_preparse to override it as needed. The key_type::match op is then redundant and can be removed, as can the user_match() function. Signed-off-by: David Howells Acked-by: Vivek Goyal

KEYS: Preparse match data

2014-09-16T16:36:02+00:00

Preparse the match data. This provides several advantages: (1) The preparser can reject invalid criteria up front. (2) The preparser can convert the criteria to binary data if necessary (the asymmetric key type really wants to do binary comparison of the key IDs). (3) The preparser can set the type of search to be performed. This means that it's not then a one-off setting in the key type. (4) The preparser can set an appropriate comparator function. Signed-off-by: David Howells Acked-by: Vivek Goyal

KEYS: keyring: Provide key preparsing

2014-07-22T20:46:51+00:00

Provide key preparsing in the keyring so that we can make preparsing mandatory. For keyrings, however, only an empty payload is permitted. Signed-off-by: David Howells Acked-by: Steve Dickson Acked-by: Jeff Layton