linux-stable.git/security, branch v3.16.78 Linux kernel stable tree keys: Fix missing null pointer check in request_key_auth_describe() 2019-11-22T15:57:27+00:00 Hillf Danton hdanton@sina.com 2019-09-02T12:37:29+00:00 3efd83051d52f492e5b6226fce58fcd35d0f372f commit d41a3effbb53b1bcea41e328d16a4d046a508381 upstream. If a request_key authentication token key gets revoked, there's a window in which request_key_auth_describe() can see it with a NULL payload - but it makes no check for this and something like the following oops may occur: BUG: Kernel NULL pointer dereference at 0x00000038 Faulting instruction address: 0xc0000000004ddf30 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [...] request_key_auth_describe+0x90/0xd0 LR [...] request_key_auth_describe+0x54/0xd0 Call Trace: [...] request_key_auth_describe+0x54/0xd0 (unreliable) [...] proc_keys_show+0x308/0x4c0 [...] seq_read+0x3d0/0x540 [...] proc_reg_read+0x90/0x110 [...] __vfs_read+0x3c/0x70 [...] vfs_read+0xb4/0x1b0 [...] ksys_read+0x7c/0x130 [...] system_call+0x5c/0x70 Fix this by checking for a NULL pointer when describing such a key. Also make the read routine check for a NULL pointer to be on the safe side. [DH: Modified to not take already-held rcu lock and modified to also check in the read routine] Fixes: 04c567d9313e ("[PATCH] Keys: Fix race between two instantiators of a key") Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by: Hillf Danton <hdanton@sina.com> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit d41a3effbb53b1bcea41e328d16a4d046a508381 upstream.

If a request_key authentication token key gets revoked, there's a window in
which request_key_auth_describe() can see it with a NULL payload - but it
makes no check for this and something like the following oops may occur:

	BUG: Kernel NULL pointer dereference at 0x00000038
	Faulting instruction address: 0xc0000000004ddf30
	Oops: Kernel access of bad area, sig: 11 [#1]
	...
	NIP [...] request_key_auth_describe+0x90/0xd0
	LR [...] request_key_auth_describe+0x54/0xd0
	Call Trace:
	[...] request_key_auth_describe+0x54/0xd0 (unreliable)
	[...] proc_keys_show+0x308/0x4c0
	[...] seq_read+0x3d0/0x540
	[...] proc_reg_read+0x90/0x110
	[...] __vfs_read+0x3c/0x70
	[...] vfs_read+0xb4/0x1b0
	[...] ksys_read+0x7c/0x130
	[...] system_call+0x5c/0x70

Fix this by checking for a NULL pointer when describing such a key.

Also make the read routine check for a NULL pointer to be on the safe side.

[DH: Modified to not take already-held rcu lock and modified to also check
 in the read routine]

Fixes: 04c567d9313e ("[PATCH] Keys: Fix race between two instantiators of a key")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
selinux: fix memory leak in policydb_init() 2019-11-22T15:57:09+00:00 Ondrej Mosnacek omosnace@redhat.com 2019-07-25T10:52:43+00:00 5e63515dadcf852203e6e71af670fb22249187ea commit 45385237f65aeee73641f1ef737d7273905a233f upstream. Since roles_init() adds some entries to the role hash table, we need to destroy also its keys/values on error, otherwise we get a memory leak in the error path. Reported-by: syzbot+fee3a14d4cdf92646287@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 45385237f65aeee73641f1ef737d7273905a233f upstream.

Since roles_init() adds some entries to the role hash table, we need to
destroy also its keys/values on error, otherwise we get a memory leak in
the error path.

Reported-by: syzbot+fee3a14d4cdf92646287@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
apparmor: enforce nullbyte at end of tag string 2019-10-05T15:20:01+00:00 Jann Horn jannh@google.com 2019-05-28T15:32:26+00:00 e17ce419721765aa3fbcd0a085a600b0f67c70ae commit 8404d7a674c49278607d19726e0acc0cae299357 upstream. A packed AppArmor policy contains null-terminated tag strings that are read by unpack_nameX(). However, unpack_nameX() uses string functions on them without ensuring that they are actually null-terminated, potentially leading to out-of-bounds accesses. Make sure that the tag string is null-terminated before passing it to strcmp(). Fixes: 736ec752d95e ("AppArmor: policy routines for loading and unpacking policy") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: John Johansen <john.johansen@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 8404d7a674c49278607d19726e0acc0cae299357 upstream.

A packed AppArmor policy contains null-terminated tag strings that are read
by unpack_nameX(). However, unpack_nameX() uses string functions on them
without ensuring that they are actually null-terminated, potentially
leading to out-of-bounds accesses.

Make sure that the tag string is null-terminated before passing it to
strcmp().

Fixes: 736ec752d95e ("AppArmor: policy routines for loading and unpacking policy")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
device_cgroup: fix RCU imbalance in error case 2019-08-13T11:38:47+00:00 Jann Horn jannh@google.com 2019-03-19T01:36:59+00:00 198f512652c375a22744e86dda97b46b5854e04f commit 0fcc4c8c044e117ac126ab6df4138ea9a67fa2a9 upstream. When dev_exception_add() returns an error (due to a failed memory allocation), make sure that we move the RCU preemption count back to where it was before we were called. We dropped the RCU read lock inside the loop body, so we can't just "break". sparse complains about this, too: $ make -s C=2 security/device_cgroup.o ./include/linux/rcupdate.h:647:9: warning: context imbalance in 'propagate_exception' - unexpected unlock Fixes: d591fb56618f ("device_cgroup: simplify cgroup tree walk in propagate_exception()") Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 0fcc4c8c044e117ac126ab6df4138ea9a67fa2a9 upstream.

When dev_exception_add() returns an error (due to a failed memory
allocation), make sure that we move the RCU preemption count back to where
it was before we were called. We dropped the RCU read lock inside the loop
body, so we can't just "break".

sparse complains about this, too:

$ make -s C=2 security/device_cgroup.o
./include/linux/rcupdate.h:647:9: warning: context imbalance in
'propagate_exception' - unexpected unlock

Fixes: d591fb56618f ("device_cgroup: simplify cgroup tree walk in propagate_exception()")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
selinux: avoid silent denials in permissive mode under RCU walk 2019-07-09T21:03:45+00:00 Stephen Smalley sds@tycho.nsa.gov 2018-12-12T15:10:55+00:00 cf1e870707687a674608836cb9947d033cd255f7 commit 3a28cff3bd4bf43f02be0c4e7933aebf3dc8197e upstream. commit 0dc1ba24f7fff6 ("SELINUX: Make selinux cache VFS RCU walks safe") results in no audit messages at all if in permissive mode because the cache is updated during the rcu walk and thus no denial occurs on the subsequent ref walk. Fix this by not updating the cache when performing a non-blocking permission check. This only affects search and symlink read checks during rcu walk. Fixes: 0dc1ba24f7fff6 ("SELINUX: Make selinux cache VFS RCU walks safe") Reported-by: BMK <bmktuwien@gmail.com> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Paul Moore <paul@paul-moore.com> [bwh: Backported to 3.16: - Add flags parameter to avc_update_node(), done upstream in commit fa1aa143ac4a "selinux: extended permissions for ioctls" - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 3a28cff3bd4bf43f02be0c4e7933aebf3dc8197e upstream.

commit 0dc1ba24f7fff6 ("SELINUX: Make selinux cache VFS RCU walks safe")
results in no audit messages at all if in permissive mode because the
cache is updated during the rcu walk and thus no denial occurs on
the subsequent ref walk.  Fix this by not updating the cache when
performing a non-blocking permission check.  This only affects search
and symlink read checks during rcu walk.

Fixes: 0dc1ba24f7fff6 ("SELINUX: Make selinux cache VFS RCU walks safe")
Reported-by: BMK <bmktuwien@gmail.com>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
[bwh: Backported to 3.16:
 - Add flags parameter to avc_update_node(), done upstream in commit
   fa1aa143ac4a "selinux: extended permissions for ioctls"
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
security/selinux: pass 'flags' arg to avc_audit() and avc_has_perm_flags() 2019-07-09T21:03:45+00:00 NeilBrown neilb@suse.de 2015-03-23T02:37:39+00:00 872dfecfaf15655f4c77b51d0077792df7c26bcb commit 7b20ea2579238f5e0da4bc93276c1b63c960c9ef upstream. This allows MAY_NOT_BLOCK to be passed, in RCU-walk mode, through the new avc_has_perm_flags() to avc_audit() and thence the slow_avc_audit. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [bwh: Backported to 3.16 as dependency of commit 3a28cff3bd4b "selinux: avoid silent denials in permissive mode under RCU walk"] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 7b20ea2579238f5e0da4bc93276c1b63c960c9ef upstream.

This allows MAY_NOT_BLOCK to be passed, in RCU-walk mode, through
the new avc_has_perm_flags() to avc_audit() and thence the slow_avc_audit.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.16 as dependency of commit 3a28cff3bd4b
 "selinux: avoid silent denials in permissive mode under RCU walk"]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
apparmor: provide userspace flag indicating binfmt_elf_mmap change 2019-05-02T20:42:07+00:00 John Johansen john.johansen@canonical.com 2017-01-16T08:42:43+00:00 a62ea6707949c2a49f8a4f62c5b5d4c1703451d3 commit 34c426acb75cc21bdf84685e106db0c1a3565057 upstream. Commit 9f834ec18def ("binfmt_elf: switch to new creds when switching to new mm") changed when the creds are installed by the binfmt_elf handler. This affects which creds are used to mmap the executable into the address space. Which can have an affect on apparmor policy. Add a flag to apparmor at /sys/kernel/security/apparmor/features/domain/fix_binfmt_elf_mmap to make it possible to detect this semantic change so that the userspace tools and the regression test suite can correctly deal with the change. BugLink: http://bugs.launchpad.net/bugs/1630069 Signed-off-by: John Johansen <john.johansen@canonical.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 34c426acb75cc21bdf84685e106db0c1a3565057 upstream.

Commit 9f834ec18def ("binfmt_elf: switch to new creds when switching to new mm")
changed when the creds are installed by the binfmt_elf handler. This
affects which creds are used to mmap the executable into the address
space. Which can have an affect on apparmor policy.

Add a flag to apparmor at
/sys/kernel/security/apparmor/features/domain/fix_binfmt_elf_mmap

to make it possible to detect this semantic change so that the userspace
tools and the regression test suite can correctly deal with the change.

BugLink: http://bugs.launchpad.net/bugs/1630069
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
KEYS: always initialize keyring_index_key::desc_len 2019-05-02T20:41:58+00:00 Eric Biggers ebiggers@google.com 2019-02-22T15:36:18+00:00 696bfa8c3d86e000b4a01fd391020e71d4fc1a9b commit ede0fa98a900e657d1fcd80b50920efc896c1a4c upstream. syzbot hit the 'BUG_ON(index_key->desc_len == 0);' in __key_link_begin() called from construct_alloc_key() during sys_request_key(), because the length of the key description was never calculated. The problem is that we rely on ->desc_len being initialized by search_process_keyrings(), specifically by search_nested_keyrings(). But, if the process isn't subscribed to any keyrings that never happens. Fix it by always initializing keyring_index_key::desc_len as soon as the description is set, like we already do in some places. The following program reproduces the BUG_ON() when it's run as root and no session keyring has been installed. If it doesn't work, try removing pam_keyinit.so from /etc/pam.d/login and rebooting. #include <stdlib.h> #include <unistd.h> #include <keyutils.h> int main(void) { int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING); keyctl_setperm(id, KEY_OTH_WRITE); setreuid(5000, 5000); request_key("user", "desc", "", id); } Reported-by: syzbot+ec24e95ea483de0a24da@syzkaller.appspotmail.com Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.morris@microsoft.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ede0fa98a900e657d1fcd80b50920efc896c1a4c upstream.

syzbot hit the 'BUG_ON(index_key->desc_len == 0);' in __key_link_begin()
called from construct_alloc_key() during sys_request_key(), because the
length of the key description was never calculated.

The problem is that we rely on ->desc_len being initialized by
search_process_keyrings(), specifically by search_nested_keyrings().
But, if the process isn't subscribed to any keyrings that never happens.

Fix it by always initializing keyring_index_key::desc_len as soon as the
description is set, like we already do in some places.

The following program reproduces the BUG_ON() when it's run as root and
no session keyring has been installed.  If it doesn't work, try removing
pam_keyinit.so from /etc/pam.d/login and rebooting.

    #include <stdlib.h>
    #include <unistd.h>
    #include <keyutils.h>

    int main(void)
    {
            int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);

            keyctl_setperm(id, KEY_OTH_WRITE);
            setreuid(5000, 5000);
            request_key("user", "desc", "", id);
    }

Reported-by: syzbot+ec24e95ea483de0a24da@syzkaller.appspotmail.com
Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
KEYS: restrict /proc/keys by credentials at open time 2019-05-02T20:41:58+00:00 Eric Biggers ebiggers@google.com 2017-09-18T18:38:29+00:00 1a844ebde7e7de0970d028faca990507e4287104 commit 4aa68e07d845562561f5e73c04aa521376e95252 upstream. When checking for permission to view keys whilst reading from /proc/keys, we should use the credentials with which the /proc/keys file was opened. This is because, in a classic type of exploit, it can be possible to bypass checks for the *current* credentials by passing the file descriptor to a suid program. Following commit 34dbbcdbf633 ("Make file credentials available to the seqfile interfaces") we can finally fix it. So let's do it. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 4aa68e07d845562561f5e73c04aa521376e95252 upstream.

When checking for permission to view keys whilst reading from
/proc/keys, we should use the credentials with which the /proc/keys file
was opened.  This is because, in a classic type of exploit, it can be
possible to bypass checks for the *current* credentials by passing the
file descriptor to a suid program.

Following commit 34dbbcdbf633 ("Make file credentials available to the
seqfile interfaces") we can finally fix it.  So let's do it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
KEYS: allow reaching the keys quotas exactly 2019-05-02T20:41:56+00:00 Eric Biggers ebiggers@google.com 2019-02-14T16:20:01+00:00 980e41e1b9db1a32b382efdd08c4b7c70b5dbd24 commit a08bf91ce28ed3ae7b6fef35d843fef8dc8c2cd9 upstream. If the sysctl 'kernel.keys.maxkeys' is set to some number n, then actually users can only add up to 'n - 1' keys. Likewise for 'kernel.keys.maxbytes' and the root_* versions of these sysctls. But these sysctls are apparently supposed to be *maximums*, as per their names and all documentation I could find -- the keyrings(7) man page, Documentation/security/keys/core.rst, and all the mentions of EDQUOT meaning that the key quota was *exceeded* (as opposed to reached). Thus, fix the code to allow reaching the quotas exactly. Fixes: 0b77f5bfb45c ("keys: make the keyring quotas controllable through /proc/sys") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.morris@microsoft.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a08bf91ce28ed3ae7b6fef35d843fef8dc8c2cd9 upstream.

If the sysctl 'kernel.keys.maxkeys' is set to some number n, then
actually users can only add up to 'n - 1' keys.  Likewise for
'kernel.keys.maxbytes' and the root_* versions of these sysctls.  But
these sysctls are apparently supposed to be *maximums*, as per their
names and all documentation I could find -- the keyrings(7) man page,
Documentation/security/keys/core.rst, and all the mentions of EDQUOT
meaning that the key quota was *exceeded* (as opposed to reached).

Thus, fix the code to allow reaching the quotas exactly.

Fixes: 0b77f5bfb45c ("keys: make the keyring quotas controllable through /proc/sys")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>