kernel/linux.git/security/keys/key.c, branch v3.18.62

KEYS: fix freeing uninitialized memory in key_update()

2017-06-14T10:54:17+00:00

commit 63a0b0509e700717a59f049ec6e4e04e903c7fe2 upstream. key_update() freed the key_preparsed_payload even if it was not initialized first. This would cause a crash if userspace called keyctl_update() on a key with type like "asymmetric" that has a ->preparse() method but not an ->update() method. Possibly it could even be triggered for other key types by racing with keyctl_setperm() to make the KEY_NEED_WRITE check fail (the permission was already checked, so normally it wouldn't fail there). Reproducer with key type "asymmetric", given a valid cert.der: keyctl new_session keyid=$(keyctl padd asymmetric desc @s < cert.der) keyctl setperm $keyid 0x3f000000 keyctl update $keyid data [ 150.686666] BUG: unable to handle kernel NULL pointer dereference at 0000000000000001 [ 150.687601] IP: asymmetric_key_free_kids+0x12/0x30 [ 150.688139] PGD 38a3d067 [ 150.688141] PUD 3b3de067 [ 150.688447] PMD 0 [ 150.688745] [ 150.689160] Oops: 0000 [#1] SMP [ 150.689455] Modules linked in: [ 150.689769] CPU: 1 PID: 2478 Comm: keyctl Not tainted 4.11.0-rc4-xfstests-00187-ga9f6b6b8cd2f #742 [ 150.690916] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 [ 150.692199] task: ffff88003b30c480 task.stack: ffffc90000350000 [ 150.692952] RIP: 0010:asymmetric_key_free_kids+0x12/0x30 [ 150.693556] RSP: 0018:ffffc90000353e58 EFLAGS: 00010202 [ 150.694142] RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000004 [ 150.694845] RDX: ffffffff81ee3920 RSI: ffff88003d4b0700 RDI: 0000000000000001 [ 150.697569] RBP: ffffc90000353e60 R08: ffff88003d5d2140 R09: 0000000000000000 [ 150.702483] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 150.707393] R13: 0000000000000004 R14: ffff880038a4d2d8 R15: 000000000040411f [ 150.709720] FS: 00007fcbcee35700(0000) GS:ffff88003fd00000(0000) knlGS:0000000000000000 [ 150.711504] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 150.712733] CR2: 0000000000000001 CR3: 0000000039eab000 CR4: 00000000003406e0 [ 150.714487] Call Trace: [ 150.714975] asymmetric_key_free_preparse+0x2f/0x40 [ 150.715907] key_update+0xf7/0x140 [ 150.716560] ? key_default_cmp+0x20/0x20 [ 150.717319] keyctl_update_key+0xb0/0xe0 [ 150.718066] SyS_keyctl+0x109/0x130 [ 150.718663] entry_SYSCALL_64_fastpath+0x1f/0xc2 [ 150.719440] RIP: 0033:0x7fcbce75ff19 [ 150.719926] RSP: 002b:00007ffd5d167088 EFLAGS: 00000206 ORIG_RAX: 00000000000000fa [ 150.720918] RAX: ffffffffffffffda RBX: 0000000000404d80 RCX: 00007fcbce75ff19 [ 150.721874] RDX: 00007ffd5d16785e RSI: 000000002866cd36 RDI: 0000000000000002 [ 150.722827] RBP: 0000000000000006 R08: 000000002866cd36 R09: 00007ffd5d16785e [ 150.723781] R10: 0000000000000004 R11: 0000000000000206 R12: 0000000000404d80 [ 150.724650] R13: 00007ffd5d16784d R14: 00007ffd5d167238 R15: 000000000040411f [ 150.725447] Code: 83 c4 08 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 85 ff 74 23 55 48 89 e5 53 48 89 fb <48> 8b 3f e8 06 21 c5 ff 48 8b 7b 08 e8 fd 20 c5 ff 48 89 df e8 [ 150.727489] RIP: asymmetric_key_free_kids+0x12/0x30 RSP: ffffc90000353e58 [ 150.728117] CR2: 0000000000000001 [ 150.728430] ---[ end trace f7f8fe1da2d5ae8d ]--- Fixes: 4d8c0250b841 ("KEYS: Call ->free_preparse() even after ->preparse() returns an error") Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

KEYS: potential uninitialized variable

2016-07-12T12:46:53+00:00

[ Upstream commit 38327424b40bcebe2de92d07312c89360ac9229a ] If __key_link_begin() failed then "edit" would be uninitialized. I've added a check to fix that. This allows a random user to crash the kernel, though it's quite difficult to achieve. There are three ways it can be done as the user would have to cause an error to occur in __key_link(): (1) Cause the kernel to run out of memory. In practice, this is difficult to achieve without ENOMEM cropping up elsewhere and aborting the attempt. (2) Revoke the destination keyring between the keyring ID being looked up and it being tested for revocation. In practice, this is difficult to time correctly because the KEYCTL_REJECT function can only be used from the request-key upcall process. Further, users can only make use of what's in /sbin/request-key.conf, though this does including a rejection debugging test - which means that the destination keyring has to be the caller's session keyring in practice. (3) Have just enough key quota available to create a key, a new session keyring for the upcall and a link in the session keyring, but not then sufficient quota to create a link in the nominated destination keyring so that it fails with EDQUOT. The bug can be triggered using option (3) above using something like the following: echo 80 >/proc/sys/kernel/keys/root_maxbytes keyctl request2 user debug:fred negate @t The above sets the quota to something much lower (80) to make the bug easier to trigger, but this is dependent on the system. Note also that the name of the keyring created contains a random number that may be between 1 and 10 characters in size, so may throw the test off by changing the amount of quota used. Assuming the failure occurs, something like the following will be seen: kfree_debugcheck: out of range ptr 6b6b6b6b6b6b6b68h ------------[ cut here ]------------ kernel BUG at ../mm/slab.c:2821! ... RIP: 0010:[] kfree_debugcheck+0x20/0x25 RSP: 0018:ffff8804014a7de8 EFLAGS: 00010092 RAX: 0000000000000034 RBX: 6b6b6b6b6b6b6b68 RCX: 0000000000000000 RDX: 0000000000040001 RSI: 00000000000000f6 RDI: 0000000000000300 RBP: ffff8804014a7df0 R08: 0000000000000001 R09: 0000000000000000 R10: ffff8804014a7e68 R11: 0000000000000054 R12: 0000000000000202 R13: ffffffff81318a66 R14: 0000000000000000 R15: 0000000000000001 ... Call Trace: kfree+0xde/0x1bc assoc_array_cancel_edit+0x1f/0x36 __key_link_end+0x55/0x63 key_reject_and_link+0x124/0x155 keyctl_reject_key+0xb6/0xe0 keyctl_negate_key+0x10/0x12 SyS_keyctl+0x9f/0xe7 do_syscall_64+0x63/0x13a entry_SYSCALL64_slow_path+0x25/0x25 Fixes: f70e2e06196a ('KEYS: Do preallocation for __key_link()') Signed-off-by: Dan Carpenter Signed-off-by: David Howells cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2014-10-12T14:13:55+00:00

Pull security subsystem updates from James Morris. Mostly ima, selinux, smack and key handling updates. * 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (65 commits) integrity: do zero padding of the key id KEYS: output last portion of fingerprint in /proc/keys KEYS: strip 'id:' from ca_keyid KEYS: use swapped SKID for performing partial matching KEYS: Restore partial ID matching functionality for asymmetric keys X.509: If available, use the raw subjKeyId to form the key description KEYS: handle error code encoded in pointer selinux: normalize audit log formatting selinux: cleanup error reporting in selinux_nlmsg_perm() KEYS: Check hex2bin()'s return when generating an asymmetric key ID ima: detect violations for mmaped files ima: fix race condition on ima_rdwr_violation_check and process_measurement ima: added ima_policy_flag variable ima: return an error code from ima_add_boot_aggregate() ima: provide 'ima_appraise=log' kernel option ima: move keyring initialization to ima_init() PKCS#7: Handle PKCS#7 messages that contain no X.509 certs PKCS#7: Better handling of unsupported crypto KEYS: Overhaul key identification when searching for asymmetric keys KEYS: Implement binary asymmetric key ID handling ...

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: Increase root_maxkeys and root_maxbytes sizes

2014-09-03T00:27:12+00:00

Now that NFS client uses the kernel key ring facility to store the NFSv4 id/gid mappings, the defaults for root_maxkeys and root_maxbytes need to be substantially increased. These values have been soak tested: https://bugzilla.redhat.com/show_bug.cgi?id=1033708#c73 Signed-off-by: Steve Dickson Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Call ->free_preparse() even after ->preparse() returns an error

2014-07-22T20:46:12+00:00

Call the ->free_preparse() key type op even after ->preparse() returns an error as it does cleaning up type stuff. Signed-off-by: David Howells Acked-by: Steve Dickson Acked-by: Jeff Layton Reviewed-by: Sage Weil

KEYS: Allow expiry time to be set when preparsing a key

2014-07-22T20:46:08+00:00

Allow a key type's preparsing routine to set the expiry time for a key. Signed-off-by: David Howells Acked-by: Steve Dickson Acked-by: Jeff Layton Reviewed-by: Sage Weil

KEYS: struct key_preparsed_payload should have two payload pointers

2014-07-22T20:46:02+00:00

struct key_preparsed_payload should have two payload pointers to correspond with those in struct key. Signed-off-by: David Howells Acked-by: Steve Dickson Acked-by: Jeff Layton Reviewed-by: Sage Weil

KEYS: Provide a generic instantiation function

2014-07-18T17:56:34+00:00

Provide a generic instantiation function for key types that use the preparse hook. This makes it easier to prereserve key quota before keyrings get locked to retain the new key. Signed-off-by: David Howells Acked-by: Steve Dickson Acked-by: Jeff Layton Reviewed-by: Sage Weil

KEYS: Move the flags representing required permission to linux/key.h

2014-03-14T17:44:49+00:00

Move the flags representing required permission to linux/key.h as the perm parameter of security_key_permission() is in terms of them - and not the permissions mask flags used in key->perm. Whilst we're at it: (1) Rename them to be KEY_NEED_xxx rather than KEY_xxx to avoid collisions with symbols in uapi/linux/input.h. (2) Don't use key_perm_t for a mask of required permissions, but rather limit it to the permissions mask attached to the key and arguments related directly to that. Signed-off-by: David Howells Tested-by: Dmitry Kasatkin