linux/security/keys, branch v4.4

KEYS: Fix race between read and revoke

2015-12-19T01:34:43Z

This fixes CVE-2015-7550. There's a race between keyctl_read() and keyctl_revoke(). If the revoke happens between keyctl_read() checking the validity of a key and the key's semaphore being taken, then the key type read method will see a revoked key. This causes a problem for the user-defined key type because it assumes in its read method that there will always be a payload in a non-revoked key and doesn't check for a NULL pointer. Fix this by making keyctl_read() check the validity of a key after taking semaphore instead of before. I think the bug was introduced with the original keyrings code. This was discovered by a multithreaded test program generated by syzkaller (http://github.com/google/syzkaller). Here's a cleaned up version: #include #include #include void *thr0(void *arg) { key_serial_t key = (unsigned long)arg; keyctl_revoke(key); return 0; } void *thr1(void *arg) { key_serial_t key = (unsigned long)arg; char buffer[16]; keyctl_read(key, buffer, 16); return 0; } int main() { key_serial_t key = add_key("user", "%", "foo", 3, KEY_SPEC_USER_KEYRING); pthread_t th[5]; pthread_create(&th[0], 0, thr0, (void *)(unsigned long)key); pthread_create(&th[1], 0, thr1, (void *)(unsigned long)key); pthread_create(&th[2], 0, thr0, (void *)(unsigned long)key); pthread_create(&th[3], 0, thr1, (void *)(unsigned long)key); pthread_join(th[0], 0); pthread_join(th[1], 0); pthread_join(th[2], 0); pthread_join(th[3], 0); return 0; } Build as: cc -o keyctl-race keyctl-race.c -lkeyutils -lpthread Run as: while keyctl-race; do :; done as it may need several iterations to crash the kernel. The crash can be summarised as: BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 IP: [] user_read+0x56/0xa3 ... Call Trace: [] keyctl_read_key+0xb6/0xd7 [] SyS_keyctl+0x83/0xe0 [] entry_SYSCALL_64_fastpath+0x12/0x6f Reported-by: Dmitry Vyukov Signed-off-by: David Howells Tested-by: Dmitry Vyukov Cc: stable@vger.kernel.org Signed-off-by: James Morris

KEYS: Fix handling of stored error in a negatively instantiated user key

2015-11-25T03:19:47Z

If a user key gets negatively instantiated, an error code is cached in the payload area. A negatively instantiated key may be then be positively instantiated by updating it with valid data. However, the ->update key type method must be aware that the error code may be there. The following may be used to trigger the bug in the user key type: keyctl request2 user user "" @u keyctl add user user "a" @u which manifests itself as: BUG: unable to handle kernel paging request at 00000000ffffff8a IP: [] __call_rcu.constprop.76+0x1f/0x280 kernel/rcu/tree.c:3046 PGD 7cc30067 PUD 0 Oops: 0002 [#1] SMP Modules linked in: CPU: 3 PID: 2644 Comm: a.out Not tainted 4.3.0+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003ddea700 ti: ffff88003dd88000 task.ti: ffff88003dd88000 RIP: 0010:[] [] __call_rcu.constprop.76+0x1f/0x280 [] __call_rcu.constprop.76+0x1f/0x280 kernel/rcu/tree.c:3046 RSP: 0018:ffff88003dd8bdb0 EFLAGS: 00010246 RAX: 00000000ffffff82 RBX: 0000000000000000 RCX: 0000000000000001 RDX: ffffffff81e3fe40 RSI: 0000000000000000 RDI: 00000000ffffff82 RBP: ffff88003dd8bde0 R08: ffff88007d2d2da0 R09: 0000000000000000 R10: 0000000000000000 R11: ffff88003e8073c0 R12: 00000000ffffff82 R13: ffff88003dd8be68 R14: ffff88007d027600 R15: ffff88003ddea700 FS: 0000000000b92880(0063) GS:ffff88007fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000ffffff8a CR3: 000000007cc5f000 CR4: 00000000000006e0 Stack: ffff88003dd8bdf0 ffffffff81160a8a 0000000000000000 00000000ffffff82 ffff88003dd8be68 ffff88007d027600 ffff88003dd8bdf0 ffffffff810a39e5 ffff88003dd8be20 ffffffff812a31ab ffff88007d027600 ffff88007d027620 Call Trace: [] kfree_call_rcu+0x15/0x20 kernel/rcu/tree.c:3136 [] user_update+0x8b/0xb0 security/keys/user_defined.c:129 [< inline >] __key_update security/keys/key.c:730 [] key_create_or_update+0x291/0x440 security/keys/key.c:908 [< inline >] SYSC_add_key security/keys/keyctl.c:125 [] SyS_add_key+0x101/0x1e0 security/keys/keyctl.c:60 [] entry_SYSCALL_64_fastpath+0x12/0x6a arch/x86/entry/entry_64.S:185 Note the error code (-ENOKEY) in EDX. A similar bug can be tripped by: keyctl request2 trusted user "" @u keyctl add trusted user "a" @u This should also affect encrypted keys - but that has to be correctly parameterised or it will fail with EINVAL before getting to the bit that will crashes. Reported-by: Dmitry Vyukov Signed-off-by: David Howells Acked-by: Mimi Zohar Signed-off-by: James Morris

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

2015-11-05T23:32:38Z

Pull security subsystem update from James Morris: "This is mostly maintenance updates across the subsystem, with a notable update for TPM 2.0, and addition of Jarkko Sakkinen as a maintainer of that" * 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (40 commits) apparmor: clarify CRYPTO dependency selinux: Use a kmem_cache for allocation struct file_security_struct selinux: ioctl_has_perm should be static selinux: use sprintf return value selinux: use kstrdup() in security_get_bools() selinux: use kmemdup in security_sid_to_context_core() selinux: remove pointless cast in selinux_inode_setsecurity() selinux: introduce security_context_str_to_sid selinux: do not check open perm on ftruncate call selinux: change CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE default KEYS: Merge the type-specific data with the payload data KEYS: Provide a script to extract a module signature KEYS: Provide a script to extract the sys cert list from a vmlinux file keys: Be more consistent in selection of union members used certs: add .gitignore to stop git nagging about x509_certificate_list KEYS: use kvfree() in add_key Smack: limited capability for changing process label TPM: remove unnecessary little endian conversion vTPM: support little endian guests char: Drop owner assignment from i2c_driver ...

KEYS: Merge the type-specific data with the payload data

2015-10-21T14:18:36Z

Merge the type-specific data with the payload data into one four-word chunk as it seems pointless to keep them separate. Use user_key_payload() for accessing the payloads of overloaded user-defined keys. Signed-off-by: David Howells cc: linux-cifs@vger.kernel.org cc: ecryptfs@vger.kernel.org cc: linux-ext4@vger.kernel.org cc: linux-f2fs-devel@lists.sourceforge.net cc: linux-nfs@vger.kernel.org cc: ceph-devel@vger.kernel.org cc: linux-ima-devel@lists.sourceforge.net

keys: Be more consistent in selection of union members used

2015-10-21T14:18:35Z

key->description and key->index_key.description are same because they are unioned. But, for readability, using same name for duplication and validation seems better. Signed-off-by: Insu Yun Signed-off-by: David Howells

KEYS: use kvfree() in add_key

2015-10-21T14:18:35Z

There is no need to make a flag to tell that this memory is allocated by kmalloc or vmalloc. Just use kvfree to free the memory. Signed-off-by: Geliang Tang Signed-off-by: David Howells

KEYS: Don't permit request_key() to construct a new keyring

2015-10-19T10:24:51Z

If request_key() is used to find a keyring, only do the search part - don't do the construction part if the keyring was not found by the search. We don't really want keyrings in the negative instantiated state since the rejected/negative instantiation error value in the payload is unioned with keyring metadata. Now the kernel gives an error: request_key("keyring", "#selinux,bdekeyring", "keyring", KEY_SPEC_USER_SESSION_KEYRING) = -1 EPERM (Operation not permitted) Signed-off-by: David Howells

keys, trusted: seal/unseal with TPM 2.0 chips

2015-10-18T23:01:22Z

Call tpm_seal_trusted() and tpm_unseal_trusted() for TPM 2.0 chips. We require explicit 'keyhandle=' option because there's no a fixed storage root key inside TPM2 chips. Signed-off-by: Jarkko Sakkinen Reviewed-by: Andreas Fuchs Tested-by: Mimi Zohar (on TPM 1.2) Tested-by: Chris J Arges Tested-by: Colin Ian King Tested-by: Kevin Strasser Signed-off-by: Peter Huewe

keys, trusted: move struct trusted_key_options to trusted-type.h

2015-10-18T23:01:21Z

Moved struct trusted_key_options to trustes-type.h so that the fields can be accessed from drivers/char/tpm. Signed-off-by: Jarkko Sakkinen Signed-off-by: Peter Huewe

KEYS: Fix crash when attempt to garbage collect an uninstantiated keyring

2015-10-15T16:21:37Z

The following sequence of commands: i=`keyctl add user a a @s` keyctl request2 keyring foo bar @t keyctl unlink $i @s tries to invoke an upcall to instantiate a keyring if one doesn't already exist by that name within the user's keyring set. However, if the upcall fails, the code sets keyring->type_data.reject_error to -ENOKEY or some other error code. When the key is garbage collected, the key destroy function is called unconditionally and keyring_destroy() uses list_empty() on keyring->type_data.link - which is in a union with reject_error. Subsequently, the kernel tries to unlink the keyring from the keyring names list - which oopses like this: BUG: unable to handle kernel paging request at 00000000ffffff8a IP: [] keyring_destroy+0x3d/0x88 ... Workqueue: events key_garbage_collector ... RIP: 0010:[] keyring_destroy+0x3d/0x88 RSP: 0018:ffff88003e2f3d30 EFLAGS: 00010203 RAX: 00000000ffffff82 RBX: ffff88003bf1a900 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 000000003bfc6901 RDI: ffffffff81a73a40 RBP: ffff88003e2f3d38 R08: 0000000000000152 R09: 0000000000000000 R10: ffff88003e2f3c18 R11: 000000000000865b R12: ffff88003bf1a900 R13: 0000000000000000 R14: ffff88003bf1a908 R15: ffff88003e2f4000 ... CR2: 00000000ffffff8a CR3: 000000003e3ec000 CR4: 00000000000006f0 ... Call Trace: [] key_gc_unused_keys.constprop.1+0x5d/0x10f [] key_garbage_collector+0x1fa/0x351 [] process_one_work+0x28e/0x547 [] worker_thread+0x26e/0x361 [] ? rescuer_thread+0x2a8/0x2a8 [] kthread+0xf3/0xfb [] ? kthread_create_on_node+0x1c2/0x1c2 [] ret_from_fork+0x3f/0x70 [] ? kthread_create_on_node+0x1c2/0x1c2 Note the value in RAX. This is a 32-bit representation of -ENOKEY. The solution is to only call ->destroy() if the key was successfully instantiated. Reported-by: Dmitry Vyukov Signed-off-by: David Howells Tested-by: Dmitry Vyukov