Use call_usermodehelper_setup() + call_usermodehelper_exec() instead of
calling call_usermodehelper_fns(). In case there's an OOM in this last
function the cleanup function may not be called - in this case we would
miss a call to key_put().
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull security subsystem update from James Morris:
"Just some minor updates across the subsystem"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
ima: eliminate passing d_name.name to process_measurement()
TPM: Retry SaveState command in suspend path
tpm/tpm_i2c_infineon: Add small comment about return value of __i2c_transfer
tpm/tpm_i2c_infineon.c: Add OF attributes type and name to the of_device_id table entries
tpm_i2c_stm_st33: Remove duplicate inclusion of header files
tpm: Add support for new Infineon I2C TPM (SLB 9645 TT 1.2 I2C)
char/tpm: Convert struct i2c_msg initialization to C99 format
drivers/char/tpm/tpm_ppi: use strlcpy instead of strncpy
tpm/tpm_i2c_stm_st33: formatting and white space changes
Smack: include magic.h in smackfs.c
selinux: make security_sb_clone_mnt_opts return an error on context mismatch
seccomp: allow BPF_XOR based ALU instructions.
Fix NULL pointer dereference in smack_inode_unlink() and smack_inode_rmdir()
Smack: add support for modification of existing rules
smack: SMACK_MAGIC to include/uapi/linux/magic.h
Smack: add missing support for transmute bit in smack_str_from_perm()
Smack: prevent revoke-subject from failing when unseen label is written to it
tomoyo: use DEFINE_SRCU() to define tomoyo_ss
tomoyo: use DEFINE_SRCU() to define tomoyo_ss
Pull cgroup updates from Tejun Heo:
- Fixes and a lot of cleanups. Locking cleanup is finally complete.
cgroup_mutex is no longer exposed to individual controlelrs which
used to cause nasty deadlock issues. Li fixed and cleaned up quite a
bit including long standing ones like racy cgroup_path().
- device cgroup now supports proper hierarchy thanks to Aristeu.
- perf_event cgroup now supports proper hierarchy.
- A new mount option "__DEVEL__sane_behavior" is added. As indicated
by the name, this option is to be used for development only at this
point and generates a warning message when used. Unfortunately,
cgroup interface currently has too many brekages and inconsistencies
to implement a consistent and unified hierarchy on top. The new flag
is used to collect the behavior changes which are necessary to
implement consistent unified hierarchy. It's likely that this flag
won't be used verbatim when it becomes ready but will be enabled
implicitly along with unified hierarchy.
The option currently disables some of broken behaviors in cgroup core
and also .use_hierarchy switch in memcg (will be routed through -mm),
which can be used to make very unusual hierarchy where nesting is
partially honored. It will also be used to implement hierarchy
support for blk-throttle which would be impossible otherwise without
introducing a full separate set of control knobs.
This is essentially versioning of interface which isn't very nice but
at this point I can't see any other options which would allow keeping
the interface the same while moving towards hierarchy behavior which
is at least somewhat sane. The planned unified hierarchy is likely
to require some level of adaptation from userland anyway, so I think
it'd be best to take the chance and update the interface such that
it's supportable in the long term.
Maintaining the existing interface does complicate cgroup core but
shouldn't put too much strain on individual controllers and I think
it'd be manageable for the foreseeable future. Maybe we'll be able
to drop it in a decade.
Fix up conflicts (including a semantic one adding a new #include to ppc
that was uncovered by header the file changes) as per Tejun.
* 'for-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (45 commits)
cpuset: fix compile warning when CONFIG_SMP=n
cpuset: fix cpu hotplug vs rebuild_sched_domains() race
cpuset: use rebuild_sched_domains() in cpuset_hotplug_workfn()
cgroup: restore the call to eventfd->poll()
cgroup: fix use-after-free when umounting cgroupfs
cgroup: fix broken file xattrs
devcg: remove parent_cgroup.
memcg: force use_hierarchy if sane_behavior
cgroup: remove cgrp->top_cgroup
cgroup: introduce sane_behavior mount option
move cgroupfs_root to include/linux/cgroup.h
cgroup: convert cgroupfs_root flag bits to masks and add CGRP_ prefix
cgroup: make cgroup_path() not print double slashes
Revert "cgroup: remove bind() method from cgroup_subsys."
perf: make perf_event cgroup hierarchical
cgroup: implement cgroup_is_descendant()
cgroup: make sure parent won't be destroyed before its children
cgroup: remove bind() method from cgroup_subsys.
devcg: remove broken_hierarchy tag
cgroup: remove cgroup_lock_is_held()
...
currently apparmor name parsing is only correctly handling
:<NS>:<profile>
but
:<NS>://<profile>
is also a valid form and what is exported to userspace.
Signed-off-by: John Johansen <john.johansen@canonical.com>
the exec file isn't processing its command arg. It should only set be
responding to a command of exec.
Also cleanup setprocattr some more while we are at it.
Signed-off-by: John Johansen <john.johansen@canonical.com>
smatch reports
error: potential NULL dereference 'ns'.
this can not actually occur because it relies on aa_split_fqname setting
both ns_name and name as null but ns_name will actually always have a
value in this case.
so remove the unnecessary if (ns_name) conditional that is resulting
in the false positive further down.
Signed-off-by: John Johansen <john.johansen@canonical.com>
The audit type table is missing a comma so that KILLED comes out as
KILLEDAUTO.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>
The top 8 bits of the base field have never been used, in fact can't
be used, by the current 'dfa16' format. However they will be used in the
future as flags, so mask them off when using base as an index value.
Note: the use of the top 8 bits, without masking is trapped by the verify
checks that base entries are within the size bounds.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
Move the free_profile fn ahead of aa_alloc_profile so it can be used
in aa_alloc_profile without a forward declaration.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
The sid is not going to be a direct property of a profile anymore, instead
it will be directly related to the label, and the profile will pickup
a label back reference.
For null-profiles replace the use of sid with a per namespace unique
id.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
Instead of limiting the setting of the processes limits to current,
relax this to tasks confined by the same profile, as the apparmor
controls for rlimits are at a profile level granularity.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>
The "permipc" command is unused and unfinished, remove it.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>
-ESTALE used to be incorrectly used to indicate a disconnected path, when
name lookup failed. This was fixed in commit e1b0e444 to correctly return
-EACCESS, but the error to failure message mapping was not correctly updated
to reflect this change.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>
When policy specifies a transition to a profile that is not currently
loaded, it result in exec being denied. However the failure is not being
audited correctly because the audit code is treating this as an allowed
permission and thus not reporting it.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-By: Steve Beattie <sbeattie@ubuntu.com>
Conflicts:
drivers/net/ethernet/emulex/benet/be_main.c
drivers/net/ethernet/intel/igb/igb_main.c
drivers/net/wireless/brcm80211/brcmsmac/mac80211_if.c
include/net/scm.h
net/batman-adv/routing.c
net/ipv4/tcp_input.c
The e{uid,gid} --> {uid,gid} credentials fix conflicted with the
cleanup in net-next to now pass cred structs around.
The be2net driver had a bug fix in 'net' that overlapped with the VLAN
interface changes by Patrick McHardy in net-next.
An IGB conflict existed because in 'net' the build_skb() support was
reverted, and in 'net-next' there was a comment style fix within that
code.
Several batman-adv conflicts were resolved by making sure that all
calls to batadv_is_my_mac() are changed to have a new bat_priv first
argument.
Eric Dumazet's TS ECR fix in TCP in 'net' conflicted with the F-RTO
rewrite in 'net-next', mostly overlapping changes.
Thanks to Stephen Rothwell and Antonio Quartulli for help with several
of these merge resolutions.
Signed-off-by: David S. Miller <davem@davemloft.net>
In devcgroup_css_alloc(), there is no longer need for parent_cgroup.
bd2953ebbb("devcg: propagate local changes down the hierarchy") made
the variable parent_cgroup redundant. This patch removes parent_cgroup
from devcgroup_css_alloc().
Signed-off-by: Rami Rosen <ramirose@gmail.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Passing a pointer to the dentry name, as a parameter to
process_measurement(), causes a race condition with rename() and
is unnecessary, as the dentry name is already accessible via the
file parameter.
In the normal case, we use the full pathname as provided by
brpm->filename, bprm->interp, or ima_d_path(). Only on ima_d_path()
failure, do we fallback to using the d_name.name, which points
either to external memory or d_iname.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Commit 90ba9b1986b5ac (tcp: tcp_make_synack() can use alloc_skb())
broke certain SELinux/NetLabel configurations by no longer correctly
assigning the sock to the outgoing SYNACK packet.
Cost of atomic operations on the LISTEN socket is quite big,
and we would like it to happen only if really needed.
This patch introduces a new security_ops->skb_owned_by() method,
that is a void operation unless selinux is active.
Reported-by: Miroslav Vadkerti <mvadkert@redhat.com>
Diagnosed-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-security-module@vger.kernel.org
Acked-by: James Morris <james.l.morris@oracle.com>
Tested-by: Paul Moore <pmoore@redhat.com>
Acked-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As reported for linux-next: Tree for Apr 2 (smack)
Add the required include for smackfs.c
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
I had the following problem reported a while back. If you mount the
same filesystem twice using NFSv4 with different contexts, then the
second context= option is ignored. For instance:
# mount server:/export /mnt/test1
# mount server:/export /mnt/test2 -o context=system_u:object_r:tmp_t:s0
# ls -dZ /mnt/test1
drwxrwxrwt. root root system_u:object_r:nfs_t:s0 /mnt/test1
# ls -dZ /mnt/test2
drwxrwxrwt. root root system_u:object_r:nfs_t:s0 /mnt/test2
When we call into SELinux to set the context of a "cloned" superblock,
it will currently just bail out when it notices that we're reusing an
existing superblock. Since the existing superblock is already set up and
presumably in use, we can't go overwriting its context with the one from
the "original" sb. Because of this, the second context= option in this
case cannot take effect.
This patch fixes this by turning security_sb_clone_mnt_opts into an int
return operation. When it finds that the "new" superblock that it has
been handed is already set up, it checks to see whether the contexts on
the old superblock match it. If it does, then it will just return
success, otherwise it'll return -EBUSY and emit a printk to tell the
admin why the second mount failed.
Note that this patch may cause casualties. The NFSv4 code relies on
being able to walk down to an export from the pseudoroot. If you mount
filesystems that are nested within one another with different contexts,
then this patch will make those mounts fail in new and "exciting" ways.
For instance, suppose that /export is a separate filesystem on the
server:
# mount server:/ /mnt/test1
# mount salusa:/export /mnt/test2 -o context=system_u:object_r:tmp_t:s0
mount.nfs: an incorrect mount option was specified
...with the printk in the ring buffer. Because we *might* eventually
walk down to /mnt/test1/export, the mount is denied due to this patch.
The second mount needs the pseudoroot superblock, but that's already
present with the wrong context.
OTOH, if we mount these in the reverse order, then both mounts work,
because the pseudoroot superblock created when mounting /export is
discarded once that mount is done. If we then however try to walk into
that directory, the automount fails for the similar reasons:
# cd /mnt/test1/scratch/
-bash: cd: /mnt/test1/scratch: Device or resource busy
The story I've gotten from the SELinux folks that I've talked to is that
this is desirable behavior. In SELinux-land, mounting the same data
under different contexts is wrong -- there can be only one.
Cc: Steve Dickson <steved@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Conflicts:
net/mac80211/sta_info.c
net/wireless/core.h
Two minor conflicts in wireless. Overlapping additions of extern
declarations in net/wireless/core.h and a bug fix overlapping with
the addition of a boolean parameter to __ieee80211_key_free().
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull userns fixes from Eric W Biederman:
"The bulk of the changes are fixing the worst consequences of the user
namespace design oversight in not considering what happens when one
namespace starts off as a clone of another namespace, as happens with
the mount namespace.
The rest of the changes are just plain bug fixes.
Many thanks to Andy Lutomirski for pointing out many of these issues."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
userns: Restrict when proc and sysfs can be mounted
ipc: Restrict mounting the mqueue filesystem
vfs: Carefully propogate mounts across user namespaces
vfs: Add a mount flag to lock read only bind mounts
userns: Don't allow creation if the user is chrooted
yama: Better permission check for ptraceme
pid: Handle the exit of a multi-threaded init.
scm: Require CAP_SYS_ADMIN over the current pidns to spoof pids.
Change the permission check for yama_ptrace_ptracee to the standard
ptrace permission check, testing if the traceer has CAP_SYS_PTRACE
in the tracees user namespace.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This patch makes exception changes to propagate down in hierarchy respecting
when possible local exceptions.
New exceptions allowing additional access to devices won't be propagated, but
it'll be possible to add an exception to access all of part of the newly
allowed device(s).
New exceptions disallowing access to devices will be propagated down and the
local group's exceptions will be revalidated for the new situation.
Example:
A
/ \
B
group behavior exceptions
A allow "b 8:* rwm", "c 116:1 rw"
B deny "c 1:3 rwm", "c 116:2 rwm", "b 3:* rwm"
If a new exception is added to group A:
# echo "c 116:* r" > A/devices.deny
it'll propagate down and after revalidating B's local exceptions, the exception
"c 116:2 rwm" will be removed.
In case parent's exceptions change and local exceptions are not allowed anymore,
they'll be deleted.
v7:
- do not allow behavior change when the cgroup has children
- update documentation
v6: fixed issues pointed by Serge Hallyn
- only copy parent's exceptions while propagating behavior if the local
behavior is different
- while propagating exceptions, do not clear and copy parent's: it'd be against
the premise we don't propagate access to more devices
v5: fixed issues pointed by Serge Hallyn
- updated documentation
- not propagating when an exception is written to devices.allow
- when propagating a new behavior, clean the local exceptions list if they're
for a different behavior
v4: fixed issues pointed by Tejun Heo
- separated function to walk the tree and collect valid propagation targets
v3: fixed issues pointed by Tejun Heo
- update documentation
- move css_online/css_offline changes to a new patch
- use cgroup_for_each_descendant_pre() instead of own descendant walk
- move exception_copy rework to a separared patch
- move exception_clean rework to a separated patch
v2: fixed issues pointed by Tejun Heo
- instead of keeping the local settings that won't apply anymore, remove them
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Allocate resources and change behavior only when online. This is needed in
order to determine if a node is suitable for hierarchy propagation or if it's
being removed.
Locking:
Both functions take devcgroup_mutex to make changes to device_cgroup structure.
Hierarchy propagation will also take devcgroup_mutex before walking the
tree while walking the tree itself is protected by rcu lock.
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently may_access() is only able to verify if an exception is valid for the
current cgroup, which has the same behavior. With hierarchy, it'll be also used
to verify if a cgroup local exception is valid towards its cgroup parent, which
might have different behavior.
v2:
- updated patch description
- rebased on top of a new patch to expand the may_access() logic to make it
more clear
- fixed argument description order in may_access()
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch fixes kernel Oops because of wrong common_audit_data type
in smack_inode_unlink() and smack_inode_rmdir().
When SMACK security module is enabled and SMACK logging is on (/smack/logging
is not zero) and you try to delete the file which
1) you cannot delete due to SMACK rules and logging of failures is on
or
2) you can delete and logging of success is on,
you will see following:
Unable to handle kernel NULL pointer dereference at virtual address 000002d7
[<...>] (strlen+0x0/0x28)
[<...>] (audit_log_untrustedstring+0x14/0x28)
[<...>] (common_lsm_audit+0x108/0x6ac)
[<...>] (smack_log+0xc4/0xe4)
[<...>] (smk_curacc+0x80/0x10c)
[<...>] (smack_inode_unlink+0x74/0x80)
[<...>] (security_inode_unlink+0x2c/0x30)
[<...>] (vfs_unlink+0x7c/0x100)
[<...>] (do_unlinkat+0x144/0x16c)
The function smack_inode_unlink() (and smack_inode_rmdir()) need
to log two structures of different types. First of all it does:
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
smk_ad_setfield_u_fs_path_dentry(&ad, dentry);
This will set common audit data type to LSM_AUDIT_DATA_DENTRY
and store dentry for auditing (by function smk_curacc(), which in turn calls
dump_common_audit_data(), which is actually uses provided data and logs it).
/*
* You need write access to the thing you're unlinking
*/
rc = smk_curacc(smk_of_inode(ip), MAY_WRITE, &ad);
if (rc == 0) {
/*
* You also need write access to the containing directory
*/
Then this function wants to log anoter data:
smk_ad_setfield_u_fs_path_dentry(&ad, NULL);
smk_ad_setfield_u_fs_inode(&ad, dir);
The function sets inode field, but don't change common_audit_data type.
rc = smk_curacc(smk_of_inode(dir), MAY_WRITE, &ad);
}
So the dump_common_audit() function incorrectly interprets inode structure
as dentry, and Oops will happen.
This patch reinitializes common_audit_data structures with correct type.
Also I removed unneeded
smk_ad_setfield_u_fs_path_dentry(&ad, NULL);
initialization, because both dentry and inode pointers are stored
in the same union.
Signed-off-by: Igor Zhbanov <i.zhbanov@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Rule modifications are enabled via /smack/change-rule. Format is as follows:
"Subject Object rwaxt rwaxt"
First two strings are subject and object labels up to 255 characters.
Third string contains permissions to enable.
Fourth string contains permissions to disable.
All unmentioned permissions will be left unchanged.
If no rule previously existed, it will be created.
Targeted for git://git.gitorious.org/smack-next/kernel.git
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
This fixes audit logs for granting or denial of permissions to show
information about transmute bit.
Targeted for git://git.gitorious.org/smack-next/kernel.git
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
Special file /smack/revoke-subject will silently accept labels that are not
present on the subject label list. Nothing has to be done for such labels,
as there are no rules for them to revoke.
Targeted for git://git.gitorious.org/smack-next/kernel.git
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
The call tree here is:
sk_clone_lock() <- takes bh_lock_sock(newsk);
xfrm_sk_clone_policy()
__xfrm_sk_clone_policy()
clone_policy() <- uses GFP_ATOMIC for allocations
security_xfrm_policy_clone()
security_ops->xfrm_policy_clone_security()
selinux_xfrm_policy_clone()
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>
DEFINE_STATIC_SRCU() defines srcu struct and do init at build time.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Looking at mm/process_vm_access.c:process_vm_rw() and comparing it to
compat_process_vm_rw() shows that the compatibility code requires an
explicit "access_ok()" check before calling
compat_rw_copy_check_uvector(). The same difference seems to appear when
we compare fs/read_write.c:do_readv_writev() to
fs/compat.c:compat_do_readv_writev().
This subtle difference between the compat and non-compat requirements
should probably be debated, as it seems to be error-prone. In fact,
there are two others sites that use this function in the Linux kernel,
and they both seem to get it wrong:
Now shifting our attention to fs/aio.c, we see that aio_setup_iocb()
also ends up calling compat_rw_copy_check_uvector() through
aio_setup_vectored_rw(). Unfortunately, the access_ok() check appears to
be missing. Same situation for
security/keys/compat.c:compat_keyctl_instantiate_key_iov().
I propose that we add the access_ok() check directly into
compat_rw_copy_check_uvector(), so callers don't have to worry about it,
and it therefore makes the compat call code similar to its non-compat
counterpart. Place the access_ok() check in the same location where
copy_from_user() can trigger a -EFAULT error in the non-compat code, so
the ABI behaviors are alike on both compat and non-compat.
While we are here, fix compat_do_readv_writev() so it checks for
compat_rw_copy_check_uvector() negative return values.
And also, fix a memory leak in compat_keyctl_instantiate_key_iov() error
handling.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This fixes CVE-2013-1792.
There is a race in install_user_keyrings() that can cause a NULL pointer
dereference when called concurrently for the same user if the uid and
uid-session keyrings are not yet created. It might be possible for an
unprivileged user to trigger this by calling keyctl() from userspace in
parallel immediately after logging in.
Assume that we have two threads both executing lookup_user_key(), both
looking for KEY_SPEC_USER_SESSION_KEYRING.
THREAD A THREAD B
=============================== ===============================
==>call install_user_keyrings();
if (!cred->user->session_keyring)
==>call install_user_keyrings()
...
user->uid_keyring = uid_keyring;
if (user->uid_keyring)
return 0;
<==
key = cred->user->session_keyring [== NULL]
user->session_keyring = session_keyring;
atomic_inc(&key->usage); [oops]
At the point thread A dereferences cred->user->session_keyring, thread B
hasn't updated user->session_keyring yet, but thread A assumes it is
populated because install_user_keyrings() returned ok.
The race window is really small but can be exploited if, for example,
thread B is interrupted or preempted after initializing uid_keyring, but
before doing setting session_keyring.
This couldn't be reproduced on a stock kernel. However, after placing
systemtap probe on 'user->session_keyring = session_keyring;' that
introduced some delay, the kernel could be crashed reliably.
Fix this by checking both pointers before deciding whether to return.
Alternatively, the test could be done away with entirely as it is checked
inside the mutex - but since the mutex is global, that may not be the best
way.
Signed-off-by: David Howells <dhowells@redhat.com>
Reported-by: Mateusz Guzik <mguzik@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Pull more VFS bits from Al Viro:
"Unfortunately, it looks like xattr series will have to wait until the
next cycle ;-/
This pile contains 9p cleanups and fixes (races in v9fs_fid_add()
etc), fixup for nommu breakage in shmem.c, several cleanups and a bit
more file_inode() work"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
constify path_get/path_put and fs_struct.c stuff
fix nommu breakage in shmem.c
cache the value of file_inode() in struct file
9p: if v9fs_fid_lookup() gets to asking server, it'd better have hashed dentry
9p: make sure ->lookup() adds fid to the right dentry
9p: untangle ->lookup() a bit
9p: double iput() in ->lookup() if d_materialise_unique() fails
9p: v9fs_fid_add() can't fail now
v9fs: get rid of v9fs_dentry
9p: turn fid->dlist into hlist
9p: don't bother with private lock in ->d_fsdata; dentry->d_lock will do just fine
more file_inode() open-coded instances
selinux: opened file can't have NULL or negative ->f_path.dentry
(In the meantime, the hlist traversal macros have changed, so this
required a semantic conflict fixup for the newly hlistified fid->dlist)
