Add a generic notificaiton mechanism in the LSM. Interested consumers
can register a callback with the LSM and security modules can produce
events.

Because access to Infiniband QPs are enforced in the setup phase of a
connection security should be enforced again if the policy changes.
Register infiniband devices for policy change notification and check all
QPs on that device when the notification is received.

Add a call to the notification mechanism from SELinux when the AVC
cache changes or setenforce is cleared.
Signed-off-by: NDaniel Jurgens <danielj@mellanox.com>
Acked-by: NJames Morris <james.l.morris@oracle.com>
Acked-by: NDoug Ledford <dledford@redhat.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>

Add new LSM hooks to allocate and free security contexts and check for
permission to access a PKey.

Allocate and free a security context when creating and destroying a QP.
This context is used for controlling access to PKeys.

When a request is made to modify a QP that changes the port, PKey index,
or alternate path, check that the QP has permission for the PKey in the
PKey table index on the subnet prefix of the port. If the QP is shared
make sure all handles to the QP also have access.

Store which port and PKey index a QP is using. After the reset to init
transition the user can modify the port, PKey index and alternate path
independently. So port and PKey settings changes can be a merge of the
previous settings and the new ones.

In order to maintain access control if there are PKey table or subnet
prefix change keep a list of all QPs are using each PKey index on
each port. If a change occurs all QPs using that device and port must
have access enforced for the new cache settings.

These changes add a transaction to the QP modify process. Association
with the old port and PKey index must be maintained if the modify fails,
and must be removed if it succeeds. Association with the new port and
PKey index must be established prior to the modify and removed if the
modify fails.

1. When a QP is modified to a particular Port, PKey index or alternate
   path insert that QP into the appropriate lists.

2. Check permission to access the new settings.

3. If step 2 grants access attempt to modify the QP.

4a. If steps 2 and 3 succeed remove any prior associations.

4b. If ether fails remove the new setting associations.

If a PKey table or subnet prefix changes walk the list of QPs and
check that they have permission. If not send the QP to the error state
and raise a fatal error event. If it's a shared QP make sure all the
QPs that share the real_qp have permission as well. If the QP that
owns a security structure is denied access the security structure is
marked as such and the QP is added to an error_list. Once the moving
the QP to error is complete the security structure mark is cleared.

Maintaining the lists correctly turns QP destroy into a transaction.
The hardware driver for the device frees the ib_qp structure, so while
the destroy is in progress the ib_qp pointer in the ib_qp_security
struct is undefined. When the destroy process begins the ib_qp_security
structure is marked as destroying. This prevents any action from being
taken on the QP pointer. After the QP is destroyed successfully it
could still listed on an error_list wait for it to be processed by that
flow before cleaning up the structure.

If the destroy fails the QPs port and PKey settings are reinserted into
the appropriate lists, the destroying flag is cleared, and access control
is enforced, in case there were any cache changes during the destroy
flow.

To keep the security changes isolated a new file is used to hold security
related functionality.
Signed-off-by: NDaniel Jurgens <danielj@mellanox.com>
Acked-by: NDoug Ledford <dledford@redhat.com>
[PM: merge fixup in ib_verbs.h and uverbs_cmd.c]
Signed-off-by: NPaul Moore <paul@paul-moore.com>

The commit d69dece5 ("LSM: Add /sys/kernel/security/lsm") extend
security_add_hooks() with a new parameter to register the LSM name,
which may be useful to make the list of currently loaded LSM available
to userspace. However, there is no clean way for an LSM to split its
hook declarations into multiple files, which may reduce the mess with
all the included files (needed for LSM hook argument types) and make the
source code easier to review and maintain.

This change allows an LSM to register multiple times its hook while
keeping a consistent list of LSM names as described in
Documentation/security/LSM.txt . The list reflects the order in which
checks are made. This patch only check for the last registered LSM. If
an LSM register multiple times its hooks, interleaved with other LSM
registrations (which should not happen), its name will still appear in
the same order that the hooks are called, hence multiple times.

To sum up, "capability,selinux,foo,foo" will be replaced with
"capability,selinux,foo", however "capability,foo,selinux,foo" will
remain as is.
Signed-off-by: NMickaël Salaün <mic@digikod.net>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

./lib/string.c:134: WARNING: Inline emphasis start-string without end-string.
./mm/filemap.c:522: WARNING: Inline interpreted text or phrase reference start-string without end-string.
./mm/filemap.c:1283: ERROR: Unexpected indentation.
./mm/filemap.c:3003: WARNING: Inline interpreted text or phrase reference start-string without end-string.
./mm/vmalloc.c:1544: WARNING: Inline emphasis start-string without end-string.
./mm/page_alloc.c:4245: ERROR: Unexpected indentation.
./ipc/util.c:676: ERROR: Unexpected indentation.
./drivers/pci/irq.c:35: WARNING: Block quote ends without a blank line; unexpected unindent.
./security/security.c:109: ERROR: Unexpected indentation.
./security/security.c:110: WARNING: Definition list ends without a blank line; unexpected unindent.
./block/genhd.c:275: WARNING: Inline strong start-string without end-string.
./block/genhd.c:283: WARNING: Inline strong start-string without end-string.
./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
./ipc/util.c:477: ERROR: Unknown target name: "s".
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

We switched from "struct task_struct"->security to "struct cred"->security
in Linux 2.6.29. But not all LSM modules were happy with that change.
TOMOYO LSM module is an example which want to use per "struct task_struct"
security blob, for TOMOYO's security context is defined based on "struct
task_struct" rather than "struct cred". AppArmor LSM module is another
example which want to use it, for AppArmor is currently abusing the cred
a little bit to store the change_hat and setexeccon info. Although
security_task_free() hook was revived in Linux 3.4 because Yama LSM module
wanted to release per "struct task_struct" security blob,
security_task_alloc() hook and "struct task_struct"->security field were
not revived. Nowadays, we are getting proposals of lightweight LSM modules
which want to use per "struct task_struct" security blob.

We are already allowing multiple concurrent LSM modules (up to one fully
armored module which uses "struct cred"->security field or exclusive hooks
like security_xfrm_state_pol_flow_match(), plus unlimited number of
lightweight modules which do not use "struct cred"->security nor exclusive
hooks) as long as they are built into the kernel. But this patch does not
implement variable length "struct task_struct"->security field which will
become needed when multiple LSM modules want to use "struct task_struct"->
security field. Although it won't be difficult to implement variable length
"struct task_struct"->security field, let's think about it after we merged
this patch.
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NJohn Johansen <john.johansen@canonical.com>
Acked-by: NSerge Hallyn <serge@hallyn.com>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Tested-by: NDjalal Harouni <tixxdz@gmail.com>
Acked-by: NJosé Bollo <jobol@nonadev.net>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: James Morris <james.l.morris@oracle.com>
Cc: José Bollo <jobol@nonadev.net>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

"struct security_hook_heads" is an array of "struct list_head"
where elements can be initialized just before registration.

There is no need to waste 350+ lines for initialization. Let's
initialize "struct security_hook_heads" just before registration.
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: James Morris <james.l.morris@oracle.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

Mark all of the registration hooks as __ro_after_init (via the
__lsm_ro_after_init macro).
Signed-off-by: NJames Morris <james.l.morris@oracle.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
Acked-by: NKees Cook <keescook@chromium.org>

When SELinux was first added to the kernel, a process could only get
and set its own resource limits via getrlimit(2) and setrlimit(2), so no
MAC checks were required for those operations, and thus no security hooks
were defined for them. Later, SELinux introduced a hook for setlimit(2)
with a check if the hard limit was being changed in order to be able to
rely on the hard limit value as a safe reset point upon context
transitions.

Later on, when prlimit(2) was added to the kernel with the ability to get
or set resource limits (hard or soft) of another process, LSM/SELinux was
not updated other than to pass the target process to the setrlimit hook.
This resulted in incomplete control over both getting and setting the
resource limits of another process.

Add a new security_task_prlimit() hook to the check_prlimit_permission()
function to provide complete mediation.  The hook is only called when
acting on another task, and only if the existing DAC/capability checks
would allow access.  Pass flags down to the hook to indicate whether the
prlimit(2) call will read, write, or both read and write the resource
limits of the target process.

The existing security_task_setrlimit() hook is left alone; it continues
to serve a purpose in supporting the ability to make decisions based on
the old and/or new resource limit values when setting limits.  This
is consistent with the DAC/capability logic, where
check_prlimit_permission() performs generic DAC/capability checks for
acting on another task, while do_prlimit() performs a capability check
based on a comparison of the old and new resource limits.  Fix the
inline documentation for the hook to match the code.

Implement the new hook for SELinux.  For setting resource limits, we
reuse the existing setrlimit permission.  Note that this does overload
the setrlimit permission to mean the ability to set the resource limit
(soft or hard) of another process or the ability to change one's own
hard limit.  For getting resource limits, a new getrlimit permission
is defined.  This was not originally defined since getrlimit(2) could
only be used to obtain a process' own limits.
Signed-off-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

I am still tired of having to find indirect ways to determine
what security modules are active on a system. I have added
/sys/kernel/security/lsm, which contains a comma separated
list of the active security modules. No more groping around
in /proc/filesystems or other clever hacks.

Unchanged from previous versions except for being updated
to the latest security next branch.
Signed-off-by: NCasey Schaufler <casey@schaufler-ca.com>
Acked-by: NJohn Johansen <john.johansen@canonical.com>
Acked-by: NPaul Moore <paul@paul-moore.com>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

As reported by yangshukui, a permission denial from security_task_wait()
can lead to a soft lockup in zap_pid_ns_processes() since it only expects
sys_wait4() to return 0 or -ECHILD. Further, security_task_wait() can
in general lead to zombies; in the absence of some way to automatically
reparent a child process upon a denial, the hook is not useful.  Remove
the security hook and its implementations in SELinux and Smack.  Smack
already removed its check from its hook.
Reported-by: Nyangshukui <yangshukui@huawei.com>
Signed-off-by: NStephen Smalley <sds@tycho.nsa.gov>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>

Processes can only alter their own security attributes via
/proc/pid/attr nodes.  This is presently enforced by each individual
security module and is also imposed by the Linux credentials
implementation, which only allows a task to alter its own credentials.
Move the check enforcing this restriction from the individual
security modules to proc_pid_attr_write() before calling the security hook,
and drop the unnecessary task argument to the security hook since it can
only ever be the current task.
Signed-off-by: NStephen Smalley <sds@tycho.nsa.gov>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Acked-by: NJohn Johansen <john.johansen@canonical.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>

During a new file creation we need to make sure new file is created with the
right label. New file is created in upper/ so effectively file should get
label as if task had created file in upper/.

We switched to mounter's creds for actual file creation. Also if there is a
whiteout present, then file will be created in work/ dir first and then
renamed in upper. In none of the cases file will be labeled as we want it to
be.

This patch introduces a new hook dentry_create_files_as(), which determines
the label/context dentry will get if it had been created by task in upper
and modify passed set of creds appropriately. Caller makes use of these new
creds for file creation.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
[PM: fix whitespace issues found with checkpatch.pl]
[PM: changes to use stat->mode in ovl_create_or_link()]
Signed-off-by: NPaul Moore <paul@paul-moore.com>

Provide a security hook which is called when xattrs of a file are being
copied up. This hook is called once for each xattr and LSM can return
0 if the security module wants the xattr to be copied up, 1 if the
security module wants the xattr to be discarded on the copy, -EOPNOTSUPP
if the security module does not handle/manage the xattr, or a -errno
upon an error.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
[PM: whitespace cleanup for checkpatch.pl]
Signed-off-by: NPaul Moore <paul@paul-moore.com>

Provide a security hook to label new file correctly when a file is copied
up from lower layer to upper layer of a overlay/union mount.

This hook can prepare a new set of creds which are suitable for new file
creation during copy up. Caller will use new creds to create file and then
revert back to old creds and release new creds.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
[PM: whitespace cleanup to appease checkpatch.pl]
Signed-off-by: NPaul Moore <paul@paul-moore.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Serge Hallyn pointed out that the current implementation of
security_inode_getsecurity() works if there is only one hook
provided for it, but will fail if there is more than one and
the attribute requested isn't supplied by the first module.
This isn't a problem today, since only SELinux and Smack
provide this hook and there is (currently) no way to enable
both of those modules at the same time. Serge, however, wants
to introduce a capability attribute and an inode_getsecurity
hook in the capability security module to handle it. This
addresses that upcoming problem, will be required for "extreme
stacking" and is just a better implementation.
Signed-off-by: NCasey Schaufler <casey@schaufler-ca.com>
Acked-by: NSerge Hallyn <serge@hallyn.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

security_settime() uses a timespec, which is not year 2038 safe
on 32bit systems. Thus this patch introduces the security_settime64()
function with timespec64 type. We also convert the cap_settime() helper
function to use the 64bit types.

This patch then moves security_settime() to the header file as an
inline helper function so that existing users can be iteratively
converted.

None of the existing hooks is using the timespec argument and therefor
the patch is not making any functional changes.

Cc: Serge Hallyn <serge.hallyn@canonical.com>,
Cc: James Morris <james.l.morris@oracle.com>,
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
Cc: Paul Moore <pmoore@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Kees Cook <keescook@chromium.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Reviewed-by: NJames Morris <james.l.morris@oracle.com>
Signed-off-by: NBaolin Wang <baolin.wang@linaro.org>
[jstultz: Reworded commit message]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This LSM enforces that kernel-loaded files (modules, firmware, etc)
must all come from the same filesystem, with the expectation that
such a filesystem is backed by a read-only device such as dm-verity
or CDROM. This allows systems that have a verified and/or unchangeable
filesystem to enforce module and firmware loading restrictions without
needing to sign the files individually.
Signed-off-by: NKees Cook <keescook@chromium.org>
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

The skb_owned_by hook was added with the commit ca10b9e9
("selinux: add a skb_owned_by() hook") and later removed
when said commit was reverted.

Later on, when switching to list of hooks, a field named
'skb_owned_by' was included into the security_hook_head struct,
but without any users nor caller.

This commit removes the said left-over field.

Fixes: b1d9e6b0 ("LSM: Switch to lists of hooks")
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Acked-by: NPaul Moore <pmoore@paul-moore.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... as well as unix_mknod() and may_o_create()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Replace copy_module_from_fd() with kernel_read_file_from_fd().

Although none of the upstreamed LSMs define a kernel_module_from_file
hook, IMA is called, based on policy, to prevent unsigned kernel modules
from being loaded by the original kernel module syscall and to
measure/appraise signed kernel modules.

The security function security_kernel_module_from_file() was called prior
to reading a kernel module.  Preventing unsigned kernel modules from being
loaded by the original kernel module syscall remains on the pre-read
kernel_read_file() security hook.  Instead of reading the kernel module
twice, once for measuring/appraising and again for loading the kernel
module, the signature validation is moved to the kernel_post_read_file()
security hook.

This patch removes the security_kernel_module_from_file() hook and security
call.
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>

The kernel_read_file security hook is called prior to reading the file
into memory.

Changelog v4+:
- export security_kernel_read_file()
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>

Replace the fw_read_file_contents with kernel_file_read_from_path().

Although none of the upstreamed LSMs define a kernel_fw_from_file hook,
IMA is called by the security function to prevent unsigned firmware from
being loaded and to measure/appraise signed firmware, based on policy.

Instead of reading the firmware twice, once for measuring/appraising the
firmware and again for reading the firmware contents into memory, the
kernel_post_read_file() security hook calculates the file hash based on
the in memory file buffer.  The firmware is read once.

This patch removes the LSM kernel_fw_from_file() hook and security call.

Changelog v4+:
- revert dropped buf->size assignment - reported by Sergey Senozhatsky
v3:
- remove kernel_fw_from_file hook
- use kernel_file_read_from_path() - requested by Luis
v2:
- reordered and squashed firmware patches
- fix MAX firmware size (Kees Cook)
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NLuis R. Rodriguez <mcgrof@kernel.org>

This patch defines a new IMA hook ima_post_read_file() for measuring
and appraising files read by the kernel. The caller loads the file into
memory before calling this function, which calculates the hash followed by
the normal IMA policy based processing.

Changelog v5:
- fail ima_post_read_file() if either file or buf is NULL
v3:
- rename ima_hash_and_process_file() to ima_post_read_file()

v1:
- split patch
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: NDmitry Kasatkin <dmitry.kasatkin@huawei.com>

To differentiate between the kernel_read_file() callers, this patch
defines a new enumeration named kernel_read_file_id and includes the
caller identifier as an argument.

Subsequent patches define READING_KEXEC_IMAGE, READING_KEXEC_INITRAMFS,
READING_FIRMWARE, READING_MODULE, and READING_POLICY.

Changelog v3:
- Replace the IMA specific enumeration with a generic one.
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>

For a while it was looked down upon to directly read files from Linux.
These days there exists a few mechanisms in the kernel that do just
this though to load a file into a local buffer.  There are minor but
important checks differences on each.  This patch set is the first
attempt at resolving some of these differences.

This patch introduces a common function for reading files from the kernel
with the corresponding security post-read hook and function.

Changelog v4+:
- export security_kernel_post_read_file() - Fengguang Wu
v3:
- additional bounds checking - Luis
v2:
- To simplify patch review, re-ordered patches
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: NLuis R. Rodriguez <mcgrof@suse.com>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>

Add a hook to invalidate an inode's security label when the cached
information becomes invalid.

Add the new hook in selinux: set a flag when a security label becomes
invalid.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: NJames Morris <james.l.morris@oracle.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NPaul Moore <pmoore@redhat.com>

Make the inode argument of the inode_getsecid hook non-const so that we
can use it to revalidate invalid security labels.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NPaul Moore <pmoore@redhat.com>

Make the inode argument of the inode_getsecurity hook non-const so that
we can use it to revalidate invalid security labels.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NPaul Moore <pmoore@redhat.com>

While in most cases commit b1d9e6b0 ("LSM: Switch to lists of hooks")
retained previous error returns, in three cases it altered them without
any explanation in the commit message. Restore all of them - in the
security_old_inode_init_security() case this led to reiserfs using
uninitialized data, sooner or later crashing the system (the only other
user of this function - ocfs2 - was unaffected afaict, since it passes
pre-initialized structures).
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NCasey Schaufler <casey@schaufler-ca.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

Now that minor LSMs can cleanly stack with major LSMs, remove the unneeded
config for Yama to be made to explicitly stack. Just selecting the main
Yama CONFIG will allow it to work, regardless of the major LSM. Since
distros using Yama are already forcing it to stack, this is effectively
a no-op change.

Additionally add MAINTAINERS entry.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

Today proc and sysfs do not contain any executable files.  Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.

Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.

Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.

The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.

This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.

Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc.  Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>