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  1. 06 4月, 2019 1 次提交
    • O
      selinux: do not override context on context mounts · e30e0b09
      由 Ondrej Mosnacek 提交于 
      [ Upstream commit 53e0c2aa9a59a48e3798ef193d573ade85aa80f5 ]

Ignore all selinux_inode_notifysecctx() calls on mounts with SBLABEL_MNT
flag unset. This is achived by returning -EOPNOTSUPP for this case in
selinux_inode_setsecurtity() (because that function should not be called
in such case anyway) and translating this error to 0 in
selinux_inode_notifysecctx().

This fixes behavior of kernfs-based filesystems when mounted with the
'context=' option. Before this patch, if a node's context had been
explicitly set to a non-default value and later the filesystem has been
remounted with the 'context=' option, then this node would show up as
having the manually-set context and not the mount-specified one.

Steps to reproduce:
    # mount -t cgroup2 cgroup2 /sys/fs/cgroup/unified
    # chcon unconfined_u:object_r:user_home_t:s0 /sys/fs/cgroup/unified/cgroup.stat
    # ls -lZ /sys/fs/cgroup/unified
    total 0
    -r--r--r--. 1 root root system_u:object_r:cgroup_t:s0        0 Dec 13 10:41 cgroup.controllers
    -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0        0 Dec 13 10:41 cgroup.max.depth
    -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0        0 Dec 13 10:41 cgroup.max.descendants
    -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0        0 Dec 13 10:41 cgroup.procs
    -r--r--r--. 1 root root unconfined_u:object_r:user_home_t:s0 0 Dec 13 10:41 cgroup.stat
    -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0        0 Dec 13 10:41 cgroup.subtree_control
    -rw-r--r--. 1 root root system_u:object_r:cgroup_t:s0        0 Dec 13 10:41 cgroup.threads
    # umount /sys/fs/cgroup/unified
    # mount -o context=system_u:object_r:tmpfs_t:s0 -t cgroup2 cgroup2 /sys/fs/cgroup/unified

Result before:
    # ls -lZ /sys/fs/cgroup/unified
    total 0
    -r--r--r--. 1 root root system_u:object_r:tmpfs_t:s0         0 Dec 13 10:41 cgroup.controllers
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0         0 Dec 13 10:41 cgroup.max.depth
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0         0 Dec 13 10:41 cgroup.max.descendants
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0         0 Dec 13 10:41 cgroup.procs
    -r--r--r--. 1 root root unconfined_u:object_r:user_home_t:s0 0 Dec 13 10:41 cgroup.stat
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0         0 Dec 13 10:41 cgroup.subtree_control
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0         0 Dec 13 10:41 cgroup.threads

Result after:
    # ls -lZ /sys/fs/cgroup/unified
    total 0
    -r--r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.controllers
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.max.depth
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.max.descendants
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.procs
    -r--r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.stat
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.subtree_control
    -rw-r--r--. 1 root root system_u:object_r:tmpfs_t:s0 0 Dec 13 10:41 cgroup.threads
Signed-off-by: NOndrej Mosnacek <omosnace@redhat.com>
Reviewed-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NPaul Moore <paul@paul-moore.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      e30e0b09
  3. 24 3月, 2019 2 次提交
  5. 26 1月, 2019 1 次提交
    • O
      selinux: always allow mounting submounts · 34ea589d
      由 Ondrej Mosnacek 提交于 
      [ Upstream commit 2cbdcb882f97a45f7475c67ac6257bbc16277dfe ]

If a superblock has the MS_SUBMOUNT flag set, we should always allow
mounting it. These mounts are done automatically by the kernel either as
part of mounting some parent mount (e.g. debugfs always mounts tracefs
under "tracing" for compatibility) or they are mounted automatically as
needed on subdirectory accesses (e.g. NFS crossmnt mounts). Since such
automounts are either an implicit consequence of the parent mount (which
is already checked) or they can happen during regular accesses (where it
doesn't make sense to check against the current task's context), the
mount permission check should be skipped for them.

Without this patch, attempts to access contents of an automounted
directory can cause unexpected SELinux denials.

In the current kernel tree, the MS_SUBMOUNT flag is set only via
vfs_submount(), which is called only from the following places:
 - AFS, when automounting special "symlinks" referencing other cells
 - CIFS, when automounting "referrals"
 - NFS, when automounting subtrees
 - debugfs, when automounting tracefs

In all cases the submounts are meant to be transparent to the user and
it makes sense that if mounting the master is allowed, then so should be
the automounts. Note that CAP_SYS_ADMIN capability checking is already
skipped for (SB_KERNMOUNT|SB_SUBMOUNT) in:
 - sget_userns() in fs/super.c:
	if (!(flags & (SB_KERNMOUNT|SB_SUBMOUNT)) &&
	    !(type->fs_flags & FS_USERNS_MOUNT) &&
	    !capable(CAP_SYS_ADMIN))
		return ERR_PTR(-EPERM);
 - sget() in fs/super.c:
        /* Ensure the requestor has permissions over the target filesystem */
        if (!(flags & (SB_KERNMOUNT|SB_SUBMOUNT)) && !ns_capable(user_ns, CAP_SYS_ADMIN))
                return ERR_PTR(-EPERM);

Verified internally on patched RHEL 7.6 with a reproducer using
NFS+httpd and selinux-tesuite.

Fixes: 93faccbb ("fs: Better permission checking for submounts")
Signed-off-by: NOndrej Mosnacek <omosnace@redhat.com>
Signed-off-by: NPaul Moore <paul@paul-moore.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      34ea589d
  7. 21 11月, 2018 1 次提交
  9. 14 11月, 2018 1 次提交
  11. 17 7月, 2018 1 次提交
  13. 12 7月, 2018 1 次提交
  15. 20 6月, 2018 1 次提交
  17. 16 6月, 2018 1 次提交
  19. 15 5月, 2018 4 次提交
  21. 14 5月, 2018 2 次提交
  23. 05 5月, 2018 1 次提交
  25. 04 5月, 2018 1 次提交
  27. 12 4月, 2018 3 次提交
    • D
      ipc/msg: introduce msgctl(MSG_STAT_ANY) · 23c8cec8
      由 Davidlohr Bueso 提交于 
      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.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Reported-by: NRobert 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      23c8cec8
    • D
      ipc/sem: introduce semctl(SEM_STAT_ANY) · a280d6dc
      由 Davidlohr Bueso 提交于 
      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.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Reported-by: NRobert 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a280d6dc
    • D
      ipc/shm: introduce shmctl(SHM_STAT_ANY) · c21a6970
      由 Davidlohr Bueso 提交于 
      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.netSigned-off-by: NDavidlohr Bueso <dbueso@suse.de>
Acked-by: NMichal 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c21a6970
  29. 28 3月, 2018 1 次提交
  31. 23 3月, 2018 4 次提交
  33. 21 3月, 2018 1 次提交
  35. 07 3月, 2018 1 次提交
  37. 03 3月, 2018 2 次提交
  39. 02 3月, 2018 1 次提交
    • S
      selinux: wrap global selinux state · aa8e712c
      由 Stephen Smalley 提交于 
      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: NStephen Smalley <sds@tycho.nsa.gov>
[PM: minor fixups needed due to collisions with the SCTP patches]
Signed-off-by: NPaul Moore <paul@paul-moore.com>
      aa8e712c
  41. 28 2月, 2018 1 次提交
  43. 27 2月, 2018 1 次提交
  45. 20 10月, 2017 2 次提交
  47. 17 10月, 2017 1 次提交
  49. 05 10月, 2017 2 次提交
  51. 04 10月, 2017 1 次提交
    • E
      selinux: Perform both commoncap and selinux xattr checks · 6b240306
      由 Eric W. Biederman 提交于 
      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: 8db6c34f ("Introduce v3 namespaced file capabilities")
Fixes: 7bbf0e052b76 ("[PATCH] selinux merge")
Historical Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.gitSigned-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: NSerge Hallyn <serge@hallyn.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NPaul Moore <paul@paul-moore.com>
      6b240306
  53. 29 8月, 2017 1 次提交