There is a permission discrepancy when consulting msq ipc object
metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl
command. The later does permission checks for the object vs S_IRUGO.
As such there can be cases where EACCESS is returned via syscall but the
info is displayed anyways in the procfs files.
While this might have security implications via info leaking (albeit no
writing to the msq metadata), this behavior goes way back and showing
all the objects regardless of the permissions was most likely an
overlook - so we are stuck with it. Furthermore, modifying either the
syscall or the procfs file can cause userspace programs to break (ie
ipcs). Some applications require getting the procfs info (without root
privileges) and can be rather slow in comparison with a syscall -- up to
500x in some reported cases for shm.
This patch introduces a new MSG_STAT_ANY command such that the msq ipc
object permissions are ignored, and only audited instead. In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.
Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reported-by: Robert Kettler <robert.kettler@outlook.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a permission discrepancy when consulting shm ipc object
metadata between /proc/sysvipc/sem (0444) and the SEM_STAT semctl
command. The later does permission checks for the object vs S_IRUGO.
As such there can be cases where EACCESS is returned via syscall but the
info is displayed anyways in the procfs files.
While this might have security implications via info leaking (albeit no
writing to the sma metadata), this behavior goes way back and showing
all the objects regardless of the permissions was most likely an
overlook - so we are stuck with it. Furthermore, modifying either the
syscall or the procfs file can cause userspace programs to break (ie
ipcs). Some applications require getting the procfs info (without root
privileges) and can be rather slow in comparison with a syscall -- up to
500x in some reported cases for shm.
This patch introduces a new SEM_STAT_ANY command such that the sem ipc
object permissions are ignored, and only audited instead. In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.
Link: http://lkml.kernel.org/r/20180215162458.10059-3-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reported-by: Robert Kettler <robert.kettler@outlook.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "sysvipc: introduce STAT_ANY commands", v2.
The following patches adds the discussed (see [1]) new command for shm
as well as for sems and msq as they are subject to the same
discrepancies for ipc object permission checks between the syscall and
via procfs. These new commands are justified in that (1) we are stuck
with this semantics as changing syscall and procfs can break userland;
and (2) some users can benefit from performance (for large amounts of
shm segments, for example) from not having to parse the procfs
interface.
Once merged, I will submit the necesary manpage updates. But I'm thinking
something like:
: diff --git a/man2/shmctl.2 b/man2/shmctl.2
: index 7bb503999941..bb00bbe21a57 100644
: --- a/man2/shmctl.2
: +++ b/man2/shmctl.2
: @@ -41,6 +41,7 @@
: .\" 2005-04-25, mtk -- noted aberrant Linux behavior w.r.t. new
: .\" attaches to a segment that has already been marked for deletion.
: .\" 2005-08-02, mtk: Added IPC_INFO, SHM_INFO, SHM_STAT descriptions.
: +.\" 2018-02-13, dbueso: Added SHM_STAT_ANY description.
: .\"
: .TH SHMCTL 2 2017-09-15 "Linux" "Linux Programmer's Manual"
: .SH NAME
: @@ -242,6 +243,18 @@ However, the
: argument is not a segment identifier, but instead an index into
: the kernel's internal array that maintains information about
: all shared memory segments on the system.
: +.TP
: +.BR SHM_STAT_ANY " (Linux-specific)"
: +Return a
: +.I shmid_ds
: +structure as for
: +.BR SHM_STAT .
: +However, the
: +.I shm_perm.mode
: +is not checked for read access for
: +.IR shmid ,
: +resembing the behaviour of
: +/proc/sysvipc/shm.
: .PP
: The caller can prevent or allow swapping of a shared
: memory segment with the following \fIcmd\fP values:
: @@ -287,7 +300,7 @@ operation returns the index of the highest used entry in the
: kernel's internal array recording information about all
: shared memory segments.
: (This information can be used with repeated
: -.B SHM_STAT
: +.B SHM_STAT/SHM_STAT_ANY
: operations to obtain information about all shared memory segments
: on the system.)
: A successful
: @@ -328,7 +341,7 @@ isn't accessible.
: \fIshmid\fP is not a valid identifier, or \fIcmd\fP
: is not a valid command.
: Or: for a
: -.B SHM_STAT
: +.B SHM_STAT/SHM_STAT_ANY
: operation, the index value specified in
: .I shmid
: referred to an array slot that is currently unused.
This patch (of 3):
There is a permission discrepancy when consulting shm ipc object metadata
between /proc/sysvipc/shm (0444) and the SHM_STAT shmctl command. The
later does permission checks for the object vs S_IRUGO. As such there can
be cases where EACCESS is returned via syscall but the info is displayed
anyways in the procfs files.
While this might have security implications via info leaking (albeit no
writing to the shm metadata), this behavior goes way back and showing all
the objects regardless of the permissions was most likely an overlook - so
we are stuck with it. Furthermore, modifying either the syscall or the
procfs file can cause userspace programs to break (ie ipcs). Some
applications require getting the procfs info (without root privileges) and
can be rather slow in comparison with a syscall -- up to 500x in some
reported cases.
This patch introduces a new SHM_STAT_ANY command such that the shm ipc
object permissions are ignored, and only audited instead. In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.
[1] https://lkml.org/lkml/2017/12/19/220
Link: http://lkml.kernel.org/r/20180215162458.10059-2-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Robert Kettler <robert.kettler@outlook.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull integrity updates from James Morris:
"A mixture of bug fixes, code cleanup, and continues to close
IMA-measurement, IMA-appraisal, and IMA-audit gaps.
Also note the addition of a new cred_getsecid LSM hook by Matthew
Garrett:
For IMA purposes, we want to be able to obtain the prepared secid
in the bprm structure before the credentials are committed. Add a
cred_getsecid hook that makes this possible.
which is used by a new CREDS_CHECK target in IMA:
In ima_bprm_check(), check with both the existing process
credentials and the credentials that will be committed when the new
process is started. This will not change behaviour unless the
system policy is extended to include CREDS_CHECK targets -
BPRM_CHECK will continue to check the same credentials that it did
previously"
* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
ima: Fallback to the builtin hash algorithm
ima: Add smackfs to the default appraise/measure list
evm: check for remount ro in progress before writing
ima: Improvements in ima_appraise_measurement()
ima: Simplify ima_eventsig_init()
integrity: Remove unused macro IMA_ACTION_RULE_FLAGS
ima: drop vla in ima_audit_measurement()
ima: Fix Kconfig to select TPM 2.0 CRB interface
evm: Constify *integrity_status_msg[]
evm: Move evm_hmac and evm_hash from evm_main.c to evm_crypto.c
fuse: define the filesystem as untrusted
ima: fail signature verification based on policy
ima: clear IMA_HASH
ima: re-evaluate files on privileged mounted filesystems
ima: fail file signature verification on non-init mounted filesystems
IMA: Support using new creds in appraisal policy
security: Add a cred_getsecid hook
Pull general security layer updates from James Morris:
- Convert security hooks from list to hlist, a nice cleanup, saving
about 50% of space, from Sargun Dhillon.
- Only pass the cred, not the secid, to kill_pid_info_as_cred and
security_task_kill (as the secid can be determined from the cred),
from Stephen Smalley.
- Close a potential race in kernel_read_file(), by making the file
unwritable before calling the LSM check (vs after), from Kees Cook.
* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
security: convert security hooks to use hlist
exec: Set file unwritable before LSM check
usb, signal, security: only pass the cred, not the secid, to kill_pid_info_as_cred and security_task_kill
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Merge tag 'selinux-pr-20180403' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull SELinux updates from Paul Moore:
"A bigger than usual pull request for SELinux, 13 patches (lucky!)
along with a scary looking diffstat.
Although if you look a bit closer, excluding the usual minor
tweaks/fixes, there are really only two significant changes in this
pull request: the addition of proper SELinux access controls for SCTP
and the encapsulation of a lot of internal SELinux state.
The SCTP changes are the result of a multi-month effort (maybe even a
year or longer?) between the SELinux folks and the SCTP folks to add
proper SELinux controls. A special thanks go to Richard for seeing
this through and keeping the effort moving forward.
The state encapsulation work is a bit of janitorial work that came out
of some early work on SELinux namespacing. The question of namespacing
is still an open one, but I believe there is some real value in the
encapsulation work so we've split that out and are now sending that up
to you"
* tag 'selinux-pr-20180403' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: wrap AVC state
selinux: wrap selinuxfs state
selinux: fix handling of uninitialized selinux state in get_bools/classes
selinux: Update SELinux SCTP documentation
selinux: Fix ltp test connect-syscall failure
selinux: rename the {is,set}_enforcing() functions
selinux: wrap global selinux state
selinux: fix typo in selinux_netlbl_sctp_sk_clone declaration
selinux: Add SCTP support
sctp: Add LSM hooks
sctp: Add ip option support
security: Add support for SCTP security hooks
netlabel: If PF_INET6, check sk_buff ip header version
For IMA purposes, we want to be able to obtain the prepared secid in the
bprm structure before the credentials are committed. Add a cred_getsecid
hook that makes this possible.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
All of the implementations of security hooks that take msg_queue only
access q_perm the struct kern_ipc_perm member. This means the
dependencies of the msg_queue security hooks can be simplified by
passing the kern_ipc_perm member of msg_queue.
Making this change will allow struct msg_queue to become private to
ipc/msg.c.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
All of the implementations of security hooks that take shmid_kernel only
access shm_perm the struct kern_ipc_perm member. This means the
dependencies of the shm security hooks can be simplified by passing
the kern_ipc_perm member of shmid_kernel..
Making this change will allow struct shmid_kernel to become private to ipc/shm.c.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
All of the implementations of security hooks that take sem_array only
access sem_perm the struct kern_ipc_perm member. This means the
dependencies of the sem security hooks can be simplified by passing
the kern_ipc_perm member of sem_array.
Making this change will allow struct sem and struct sem_array
to become private to ipc/sem.c.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Wrap the AVC state within the selinux_state structure and
pass it explicitly to all AVC functions. The AVC private state
is encapsulated in a selinux_avc structure that is referenced
from the selinux_state.
This change should have no effect on SELinux behavior or
APIs (userspace or LSM).
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
commit d178bc3a70 ("user namespace: usb:
make usb urbs user namespace aware (v2)") changed kill_pid_info_as_uid
to kill_pid_info_as_cred, saving and passing a cred structure instead of
uids. Since the secid can be obtained from the cred, drop the secid fields
from the usb_dev_state and async structures, and drop the secid argument to
kill_pid_info_as_cred. Replace the secid argument to security_task_kill
with the cred. Update SELinux, Smack, and AppArmor to use the cred, which
avoids the need for Smack and AppArmor to use a secid at all in this hook.
Further changes to Smack might still be required to take full advantage of
this change, since it should now be possible to perform capability
checking based on the supplied cred. The changes to Smack and AppArmor
have only been compile-tested.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
Define a selinux state structure (struct selinux_state) for
global SELinux state and pass it explicitly to all security server
functions. The public portion of the structure contains state
that is used throughout the SELinux code, such as the enforcing mode.
The structure also contains a pointer to a selinux_ss structure whose
definition is private to the security server and contains security
server specific state such as the policy database and SID table.
This change should have no effect on SELinux behavior or APIs
(userspace or LSM). It merely wraps SELinux state and passes it
explicitly as needed.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: minor fixups needed due to collisions with the SCTP patches]
Signed-off-by: Paul Moore <paul@paul-moore.com>
The SELinux SCTP implementation is explained in:
Documentation/security/SELinux-sctp.rst
Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Merge tag 'selinux-pr-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull SELinux updates from Paul Moore:
"Seven SELinux patches for v4.15, although five of the seven are small
build fixes and cleanups.
Of the remaining two patches, the only one worth really calling out is
Eric's fix for the SELinux filesystem xattr set/remove code; the other
patch simply converts the SELinux hash table implementation to use
kmem_cache.
Eric's setxattr/removexattr tweak converts SELinux back to calling the
commoncap implementations when the xattr is not SELinux related. The
immediate win is to fixup filesystem capabilities in user namespaces,
but it makes things a bit saner overall; more information in the
commit description"
* tag 'selinux-pr-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: remove extraneous initialization of slots_used and max_chain_len
selinux: remove redundant assignment to len
selinux: remove redundant assignment to str
selinux: fix build warning
selinux: fix build warning by removing the unused sid variable
selinux: Perform both commoncap and selinux xattr checks
selinux: Use kmem_cache for hashtab_node
Introduce a bpf object related check when sending and receiving files
through unix domain socket as well as binder. It checks if the receiving
process have privilege to read/write the bpf map or use the bpf program.
This check is necessary because the bpf maps and programs are using a
anonymous inode as their shared inode so the normal way of checking the
files and sockets when passing between processes cannot work properly on
eBPF object. This check only works when the BPF_SYSCALL is configured.
Signed-off-by: Chenbo Feng <fengc@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Implement the actual checks introduced to eBPF related syscalls. This
implementation use the security field inside bpf object to store a sid that
identify the bpf object. And when processes try to access the object,
selinux will check if processes have the right privileges. The creation
of eBPF object are also checked at the general bpf check hook and new
cmd introduced to eBPF domain can also be checked there.
Signed-off-by: Chenbo Feng <fengc@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
str is being assigned to an empty string but str is never being
read after that, so the assignment is redundant and can be removed.
Moving the declaration of str to a more localised block, cleans up
clang warning: "Value stored to 'str' is never read"
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This patch make selinux_task_prlimit() static since it is not used
anywhere else.
This fix the following build warning:
security/selinux/hooks.c:3981:5: warning: no previous prototype for 'selinux_task_prlimit' [-Wmissing-prototypes]
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This patch remove the unused variable sid
This fix the following build warning:
security/selinux/hooks.c:2921:6: warning: variable 'sid' set but not used [-Wunused-but-set-variable]
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
When selinux is loaded the relax permission checks for writing
security.capable are not honored. Which keeps file capabilities
from being used in user namespaces.
Stephen Smalley <sds@tycho.nsa.gov> writes:
> Originally SELinux called the cap functions directly since there was no
> stacking support in the infrastructure and one had to manually stack a
> secondary module internally. inode_setxattr and inode_removexattr
> however were special cases because the cap functions would check
> CAP_SYS_ADMIN for any non-capability attributes in the security.*
> namespace, and we don't want to impose that requirement on setting
> security.selinux. Thus, we inlined the capabilities logic into the
> selinux hook functions and adapted it appropriately.
Now that the permission checks in commoncap have evolved this
inlining of their contents has become a problem. So restructure
selinux_inode_removexattr, and selinux_inode_setxattr to call
both the corresponding cap_inode_ function and dentry_has_perm
when the attribute is not a selinux security xattr. This ensures
the policies of both commoncap and selinux are enforced.
This results in smack and selinux having the same basic structure
for setxattr and removexattr. Performing their own special permission
checks when it is their modules xattr being written to, and deferring
to commoncap when that is not the case. Then finally performing their
generic module policy on all xattr writes.
This structure is fine when you only consider stacking with the
commoncap lsm, but it becomes a problem if two lsms that don't want
the commoncap security checks on their own attributes need to be
stack. This means there will need to be updates in the future as lsm
stacking is improved, but at least now the structure between smack and
selinux is common making the code easier to refactor.
This change also has the effect that selinux_linux_setotherxattr becomes
unnecessary so it is removed.
Fixes: 8db6c34f1d ("Introduce v3 namespaced file capabilities")
Fixes: 7bbf0e052b76 ("[PATCH] selinux merge")
Historical Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Merge tag 'selinux-pr-20170831' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
"A relatively quiet period for SELinux, 11 patches with only two/three
having any substantive changes.
These noteworthy changes include another tweak to the NNP/nosuid
handling, per-file labeling for cgroups, and an object class fix for
AF_UNIX/SOCK_RAW sockets; the rest of the changes are minor tweaks or
administrative updates (Stephen's email update explains the file
explosion in the diffstat).
Everything passes the selinux-testsuite"
[ Also a couple of small patches from the security tree from Tetsuo
Handa for Tomoyo and LSM cleanup. The separation of security policy
updates wasn't all that clean - Linus ]
* tag 'selinux-pr-20170831' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: constify nf_hook_ops
selinux: allow per-file labeling for cgroupfs
lsm_audit: update my email address
selinux: update my email address
MAINTAINERS: update the NetLabel and Labeled Networking information
selinux: use GFP_NOWAIT in the AVC kmem_caches
selinux: Generalize support for NNP/nosuid SELinux domain transitions
selinux: genheaders should fail if too many permissions are defined
selinux: update the selinux info in MAINTAINERS
credits: update Paul Moore's info
selinux: Assign proper class to PF_UNIX/SOCK_RAW sockets
tomoyo: Update URLs in Documentation/admin-guide/LSM/tomoyo.rst
LSM: Remove security_task_create() hook.
running set*id processes. To do this, the bprm_secureexec LSM hook is
collapsed into the bprm_set_creds hook so the secureexec-ness of an exec
can be determined early enough to make decisions about rlimits and the
resulting memory layouts. Other logic acting on the secureexec-ness of an
exec is similarly consolidated. Capabilities needed some special handling,
but the refactoring removed other special handling, so that was a wash.
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Merge tag 'secureexec-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull secureexec update from Kees Cook:
"This series has the ultimate goal of providing a sane stack rlimit
when running set*id processes.
To do this, the bprm_secureexec LSM hook is collapsed into the
bprm_set_creds hook so the secureexec-ness of an exec can be
determined early enough to make decisions about rlimits and the
resulting memory layouts. Other logic acting on the secureexec-ness of
an exec is similarly consolidated. Capabilities needed some special
handling, but the refactoring removed other special handling, so that
was a wash"
* tag 'secureexec-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
exec: Consolidate pdeath_signal clearing
exec: Use sane stack rlimit under secureexec
exec: Consolidate dumpability logic
smack: Remove redundant pdeath_signal clearing
exec: Use secureexec for clearing pdeath_signal
exec: Use secureexec for setting dumpability
LSM: drop bprm_secureexec hook
commoncap: Move cap_elevated calculation into bprm_set_creds
commoncap: Refactor to remove bprm_secureexec hook
smack: Refactor to remove bprm_secureexec hook
selinux: Refactor to remove bprm_secureexec hook
apparmor: Refactor to remove bprm_secureexec hook
binfmt: Introduce secureexec flag
exec: Correct comments about "point of no return"
exec: Rename bprm->cred_prepared to called_set_creds
nf_hook_ops are not supposed to change at runtime. nf_register_net_hooks
and nf_unregister_net_hooks are working with const nf_hook_ops.
So mark the non-const nf_hook_ops structs as const.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This patch allows genfscon per-file labeling for cgroupfs. For instance,
this allows to label the "release_agent" file within each
cgroup mount and limit writes to it.
Signed-off-by: Antonio Murdaca <amurdaca@redhat.com>
[PM: subject line and merge tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Update my email address since epoch.ncsc.mil no longer exists.
MAINTAINERS and CREDITS are already correct.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
As systemd ramps up enabling NNP (NoNewPrivileges) for system services,
it is increasingly breaking SELinux domain transitions for those services
and their descendants. systemd enables NNP not only for services whose
unit files explicitly specify NoNewPrivileges=yes but also for services
whose unit files specify any of the following options in combination with
running without CAP_SYS_ADMIN (e.g. specifying User= or a
CapabilityBoundingSet= without CAP_SYS_ADMIN): SystemCallFilter=,
SystemCallArchitectures=, RestrictAddressFamilies=, RestrictNamespaces=,
PrivateDevices=, ProtectKernelTunables=, ProtectKernelModules=,
MemoryDenyWriteExecute=, or RestrictRealtime= as per the systemd.exec(5)
man page.
The end result is bad for the security of both SELinux-disabled and
SELinux-enabled systems. Packagers have to turn off these
options in the unit files to preserve SELinux domain transitions. For
users who choose to disable SELinux, this means that they miss out on
at least having the systemd-supported protections. For users who keep
SELinux enabled, they may still be missing out on some protections
because it isn't necessarily guaranteed that the SELinux policy for
that service provides the same protections in all cases.
commit 7b0d0b40cd ("selinux: Permit bounded transitions under
NO_NEW_PRIVS or NOSUID.") allowed bounded transitions under NNP in
order to support limited usage for sandboxing programs. However,
defining typebounds for all of the affected service domains
is impractical to implement in policy, since typebounds requires us
to ensure that each domain is allowed everything all of its descendant
domains are allowed, and this has to be repeated for the entire chain
of domain transitions. There is no way to clone all allow rules from
descendants to their ancestors in policy currently, and doing so would
be undesirable even if it were practical, as it requires leaking
permissions to objects and operations into ancestor domains that could
weaken their own security in order to allow them to the descendants
(e.g. if a descendant requires execmem permission, then so do all of
its ancestors; if a descendant requires execute permission to a file,
then so do all of its ancestors; if a descendant requires read to a
symbolic link or temporary file, then so do all of its ancestors...).
SELinux domains are intentionally not hierarchical / bounded in this
manner normally, and making them so would undermine their protections
and least privilege.
We have long had a similar tension with SELinux transitions and nosuid
mounts, albeit not as severe. Users often have had to choose between
retaining nosuid on a mount and allowing SELinux domain transitions on
files within those mounts. This likewise leads to unfortunate tradeoffs
in security.
Decouple NNP/nosuid from SELinux transitions, so that we don't have to
make a choice between them. Introduce a nnp_nosuid_transition policy
capability that enables transitions under NNP/nosuid to be based on
a permission (nnp_transition for NNP; nosuid_transition for nosuid)
between the old and new contexts in addition to the current support
for bounded transitions. Domain transitions can then be allowed in
policy without requiring the parent to be a strict superset of all of
its children.
With this change, systemd unit files can be left unmodified from upstream.
SELinux-disabled and SELinux-enabled users will benefit from retaining any
of the systemd-provided protections. SELinux policy will only need to
be adapted to enable the new policy capability and to allow the
new permissions between domain pairs as appropriate.
NB: Allowing nnp_transition between two contexts opens up the potential
for the old context to subvert the new context by installing seccomp
filters before the execve. Allowing nosuid_transition between two contexts
opens up the potential for a context transition to occur on a file from
an untrusted filesystem (e.g. removable media or remote filesystem). Use
with care.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
The SELinux bprm_secureexec hook can be merged with the bprm_set_creds
hook since it's dealing with the same information, and all of the details
are finalized during the first call to the bprm_set_creds hook via
prepare_binprm() (subsequent calls due to binfmt_script, etc, are ignored
via bprm->called_set_creds).
Here, the test can just happen at the end of the bprm_set_creds hook,
and the bprm_secureexec hook can be dropped.
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Tested-by: Paul Moore <paul@paul-moore.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
The cred_prepared bprm flag has a misleading name. It has nothing to do
with the bprm_prepare_cred hook, and actually tracks if bprm_set_creds has
been called. Rename this flag and improve its comment.
Cc: David Howells <dhowells@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
We no longer place these on a list so they can be const.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
For PF_UNIX, SOCK_RAW is synonymous with SOCK_DGRAM (cf.
net/unix/af_unix.c). This is a tad obscure, but libpcap uses it.
Signed-off-by: Luis Ressel <aranea@aixah.de>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Pull security layer updates from James Morris:
- a major update for AppArmor. From JJ:
* several bug fixes and cleanups
* the patch to add symlink support to securityfs that was floated
on the list earlier and the apparmorfs changes that make use of
securityfs symlinks
* it introduces the domain labeling base code that Ubuntu has been
carrying for several years, with several cleanups applied. And it
converts the current mediation over to using the domain labeling
base, which brings domain stacking support with it. This finally
will bring the base upstream code in line with Ubuntu and provide
a base to upstream the new feature work that Ubuntu carries.
* This does _not_ contain any of the newer apparmor mediation
features/controls (mount, signals, network, keys, ...) that
Ubuntu is currently carrying, all of which will be RFC'd on top
of this.
- Notable also is the Infiniband work in SELinux, and the new file:map
permission. From Paul:
"While we're down to 21 patches for v4.13 (it was 31 for v4.12),
the diffstat jumps up tremendously with over 2k of line changes.
Almost all of these changes are the SELinux/IB work done by
Daniel Jurgens; some other noteworthy changes include a NFS v4.2
labeling fix, a new file:map permission, and reporting of policy
capabilities on policy load"
There's also now genfscon labeling support for tracefs, which was
lost in v4.1 with the separation from debugfs.
- Smack incorporates a safer socket check in file_receive, and adds a
cap_capable call in privilege check.
- TPM as usual has a bunch of fixes and enhancements.
- Multiple calls to security_add_hooks() can now be made for the same
LSM, to allow LSMs to have hook declarations across multiple files.
- IMA now supports different "ima_appraise=" modes (eg. log, fix) from
the boot command line.
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (126 commits)
apparmor: put back designators in struct initialisers
seccomp: Switch from atomic_t to recount_t
seccomp: Adjust selftests to avoid double-join
seccomp: Clean up core dump logic
IMA: update IMA policy documentation to include pcr= option
ima: Log the same audit cause whenever a file has no signature
ima: Simplify policy_func_show.
integrity: Small code improvements
ima: fix get_binary_runtime_size()
ima: use ima_parse_buf() to parse template data
ima: use ima_parse_buf() to parse measurements headers
ima: introduce ima_parse_buf()
ima: Add cgroups2 to the defaults list
ima: use memdup_user_nul
ima: fix up #endif comments
IMA: Correct Kconfig dependencies for hash selection
ima: define is_ima_appraise_enabled()
ima: define Kconfig IMA_APPRAISE_BOOTPARAM option
ima: define a set of appraisal rules requiring file signatures
ima: extend the "ima_policy" boot command line to support multiple policies
...
In kernel version 4.1, tracefs was separated from debugfs into its
own filesystem. Prior to this split, files in
/sys/kernel/debug/tracing could be labeled during filesystem
creation using genfscon or later from userspace using setxattr. This
change re-enables support for genfscon labeling.
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This patch is based on a discussion generated by an earlier patch
from Tetsuo Handa:
* https://marc.info/?t=149035659300001&r=1&w=2
The double free problem involves the mnt_opts field of the
security_mnt_opts struct, selinux_parse_opts_str() frees the memory
on error, but doesn't set the field to NULL so if the caller later
attempts to call security_free_mnt_opts() we trigger the problem.
In order to play it safe we change selinux_parse_opts_str() to call
security_free_mnt_opts() on error instead of free'ing the memory
directly. This should ensure that everything is handled correctly,
regardless of what the caller may do.
Fixes: e000752989 ("LSM/SELinux: Interfaces to allow FS to control mount options")
Cc: stable@vger.kernel.org
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
When an NFSv4 client performs a mount operation, it first mounts the
NFSv4 root and then does path walk to the exported path and performs a
submount on that, cloning the security mount options from the root's
superblock to the submount's superblock in the process.
Unless the NFS server has an explicit fsid=0 export with the
"security_label" option, the NFSv4 root superblock will not have
SBLABEL_MNT set, and neither will the submount superblock after cloning
the security mount options. As a result, setxattr's of security labels
over NFSv4.2 will fail. In a similar fashion, NFSv4.2 mounts mounted
with the context= mount option will not show the correct labels because
the nfs_server->caps flags of the cloned superblock will still have
NFS_CAP_SECURITY_LABEL set.
Allowing the NFSv4 client to enable or disable SECURITY_LSM_NATIVE_LABELS
behavior will ensure that the SBLABEL_MNT flag has the correct value
when the client traverses from an exported path without the
"security_label" option to one with the "security_label" option and
vice versa. Similarly, checking to see if SECURITY_LSM_NATIVE_LABELS is
set upon return from security_sb_clone_mnt_opts() and clearing
NFS_CAP_SECURITY_LABEL if necessary will allow the correct labels to
be displayed for NFSv4.2 mounts mounted with the context= mount option.
Resolves: https://github.com/SELinuxProject/selinux-kernel/issues/35
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
Tested-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
It will allow us to remove the old netfilter hook api in the near future.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Paul Moore <paul@paul-moore.com>
It is likely that the SID for the same PKey will be requested many
times. To reduce the time to modify QPs and process MADs use a cache to
store PKey SIDs.
This code is heavily based on the "netif" and "netport" concept
originally developed by James Morris <jmorris@redhat.com> and Paul Moore
<paul@paul-moore.com> (see security/selinux/netif.c and
security/selinux/netport.c for more information)
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Add a type for Infiniband ports and an access vector for subnet
management packets. Implement the ib_port_smp hook to check that the
caller has permission to send and receive SMPs on the end port specified
by the device name and port. Add interface to query the SID for a IB
port, which walks the IB_PORT ocontexts to find an entry for the
given name and port.
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Add a type and access vector for PKeys. Implement the ib_pkey_access
hook to check that the caller has permission to access the PKey on the
given subnet prefix. Add an interface to get the PKey SID. Walk the PKey
ocontexts to find an entry for the given subnet prefix and pkey.
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Implement and attach hooks to allocate and free Infiniband object
security structures.
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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: Daniel Jurgens <danielj@mellanox.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
The check is already performed in ocontext_read() when the policy is
loaded. Removing the array also fixes the following warning when
building with clang:
security/selinux/hooks.c:338:20: error: variable 'labeling_behaviors'
is not needed and will not be emitted
[-Werror,-Wunneeded-internal-declaration]
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
open permission is currently only defined for files in the kernel
(COMMON_FILE_PERMS rather than COMMON_FILE_SOCK_PERMS). Construction of
an artificial test case that tries to open a socket via /proc/pid/fd will
generate a recvfrom avc denial because recvfrom and open happen to map to
the same permission bit in socket vs file classes.
open of a socket via /proc/pid/fd is not supported by the kernel regardless
and will ultimately return ENXIO. But we hit the permission check first and
can thus produce these odd/misleading denials. Omit the open check when
operating on a socket.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Add a map permission check on mmap so that we can distinguish memory mapped
access (since it has different implications for revocation). When a file
is opened and then read or written via syscalls like read(2)/write(2),
we revalidate access on each read/write operation via
selinux_file_permission() and therefore can revoke access if the
process context, the file context, or the policy changes in such a
manner that access is no longer allowed. When a file is opened and then
memory mapped via mmap(2) and then subsequently read or written directly
in memory, we presently have no way to revalidate or revoke access.
The purpose of a separate map permission check on mmap(2) is to permit
policy to prohibit memory mapping of specific files for which we need
to ensure that every access is revalidated, particularly useful for
scenarios where we expect the file to be relabeled at runtime in order
to reflect state changes (e.g. cross-domain solution, assured pipeline
without data copying).
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
SELinux uses CAP_MAC_ADMIN to control the ability to get or set a raw,
uninterpreted security context unknown to the currently loaded security
policy. When performing these checks, we only want to perform a base
capabilities check and a SELinux permission check. If any other
modules that implement a capable hook are stacked with SELinux, we do
not want to require them to also have to authorize CAP_MAC_ADMIN,
since it may have different implications for their security model.
Rework the CAP_MAC_ADMIN checks within SELinux to only invoke the
capabilities module and the SELinux permission checking.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This patch is a preparation for getting rid of task_create hook because
task_alloc hook which can do what task_create hook can do was revived.
Creating a new thread is unlikely prohibited by security policy, for
fork()/execve()/exit() is fundamental of how processes are managed in
Unix. If a program is known to create a new thread, it is likely that
permission to create a new thread is given to that program. Therefore,
a situation where security_task_create() returns an error is likely that
the program was exploited and lost control. Even if SELinux failed to
check permission to create a thread at security_task_create(), SELinux
can later check it at security_task_alloc(). Since the new thread is not
yet visible from the rest of the system, nobody can do bad things using
the new thread. What we waste will be limited to some initialization
steps such as dup_task_struct(), copy_creds() and audit_alloc() in
copy_process(). We can tolerate these overhead for unlikely situation.
Therefore, this patch changes SELinux to use task_alloc hook rather than
task_create hook so that we can remove task_create hook.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of
uninitialized memory in selinux_socket_bind():
==================================================================
BUG: KMSAN: use of unitialized memory
inter: 0
CPU: 3 PID: 1074 Comm: packet2 Tainted: G B 4.8.0-rc6+ #1916
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
0000000000000000 ffff8800882ffb08 ffffffff825759c8 ffff8800882ffa48
ffffffff818bf551 ffffffff85bab870 0000000000000092 ffffffff85bab550
0000000000000000 0000000000000092 00000000bb0009bb 0000000000000002
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff825759c8>] dump_stack+0x238/0x290 lib/dump_stack.c:51
[<ffffffff818bdee6>] kmsan_report+0x276/0x2e0 mm/kmsan/kmsan.c:1008
[<ffffffff818bf0fb>] __msan_warning+0x5b/0xb0 mm/kmsan/kmsan_instr.c:424
[<ffffffff822dae71>] selinux_socket_bind+0xf41/0x1080 security/selinux/hooks.c:4288
[<ffffffff8229357c>] security_socket_bind+0x1ec/0x240 security/security.c:1240
[<ffffffff84265d98>] SYSC_bind+0x358/0x5f0 net/socket.c:1366
[<ffffffff84265a22>] SyS_bind+0x82/0xa0 net/socket.c:1356
[<ffffffff81005678>] do_syscall_64+0x58/0x70 arch/x86/entry/common.c:292
[<ffffffff8518217c>] entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.o:?
chained origin: 00000000ba6009bb
[<ffffffff810bb7a7>] save_stack_trace+0x27/0x50 arch/x86/kernel/stacktrace.c:67
[< inline >] kmsan_save_stack_with_flags mm/kmsan/kmsan.c:322
[< inline >] kmsan_save_stack mm/kmsan/kmsan.c:337
[<ffffffff818bd2b8>] kmsan_internal_chain_origin+0x118/0x1e0 mm/kmsan/kmsan.c:530
[<ffffffff818bf033>] __msan_set_alloca_origin4+0xc3/0x130 mm/kmsan/kmsan_instr.c:380
[<ffffffff84265b69>] SYSC_bind+0x129/0x5f0 net/socket.c:1356
[<ffffffff84265a22>] SyS_bind+0x82/0xa0 net/socket.c:1356
[<ffffffff81005678>] do_syscall_64+0x58/0x70 arch/x86/entry/common.c:292
[<ffffffff8518217c>] return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.o:?
origin description: ----address@SYSC_bind (origin=00000000b8c00900)
==================================================================
(the line numbers are relative to 4.8-rc6, but the bug persists upstream)
, when I run the following program as root:
=======================================================
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(int argc, char *argv[]) {
struct sockaddr addr;
int size = 0;
if (argc > 1) {
size = atoi(argv[1]);
}
memset(&addr, 0, sizeof(addr));
int fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP);
bind(fd, &addr, size);
return 0;
}
=======================================================
(for different values of |size| other error reports are printed).
This happens because bind() unconditionally copies |size| bytes of
|addr| to the kernel, leaving the rest uninitialized. Then
security_socket_bind() reads the IP address bytes, including the
uninitialized ones, to determine the port, or e.g. pass them further to
sel_netnode_find(), which uses them to calculate a hash.
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
[PM: fixed some whitespace damage]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Mark all of the registration hooks as __ro_after_init (via the
__lsm_ro_after_init macro).
Signed-off-by: James Morris <james.l.morris@oracle.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Kees Cook <keescook@chromium.org>
Davidlohr Bueso
Linus Torvalds
Matthew Garrett
Eric W. Biederman
Stephen Smalley
Richard Haines
Paul Moore
Chenbo Feng
Colin Ian King
Corentin LABBE
Arvind Yadav
Antonio Murdaca
Kees Cook
Florian Westphal
Luis Ressel
Jeff Vander Stoep
Scott Mayhew
Daniel Jurgens
Matthias Kaehlcke
Tetsuo Handa
Alexander Potapenko
James Morris