linux-toradex.git/security/selinux/include/security.h, branch v5.6

selinux: treat atomic flags more carefully

2020-01-10T20:19:39+00:00

The disabled/enforcing/initialized flags are all accessed concurrently
by threads so use the appropriate accessors that ensure atomicity and
document that it is expected.

Use smp_load/acquire...() helpers (with memory barriers) for the
initialized flag, since it gates access to the rest of the state
structures.

Note that the disabled flag is currently not used for anything other
than avoiding double disable, but it will be used for bailing out of
hooks once security_delete_hooks() is removed.

Signed-off-by: Ondrej Mosnacek 
Acked-by: Stephen Smalley 
Reviewed-by: Kees Cook 
Reviewed-by: James Morris 
Signed-off-by: Paul Moore

selinux: randomize layout of key structures

2019-12-19T02:26:06+00:00

Randomize the layout of key selinux data structures.
Initially this is applied to the selinux_state, selinux_ss,
policydb, and task_security_struct data structures.

NB To test/use this mechanism, one must install the
necessary build-time dependencies, e.g. gcc-plugin-devel on Fedora,
and enable CONFIG_GCC_PLUGIN_RANDSTRUCT in the kernel configuration.

Signed-off-by: Stephen Smalley 
Reviewed-by: Kees Cook 
[PM: double semi-colon fixed]
Signed-off-by: Paul Moore

selinux: clean up selinux_enabled/disabled/enforcing_boot

2019-12-19T02:22:46+00:00

Rename selinux_enabled to selinux_enabled_boot to make it clear that
it only reflects whether SELinux was enabled at boot.  Replace the
references to it in the MAC_STATUS audit log in sel_write_enforce()
with hardcoded "1" values because this code is only reachable if SELinux
is enabled and does not change its value, and update the corresponding
MAC_STATUS audit log in sel_write_disable().  Stop clearing
selinux_enabled in selinux_disable() since it is not used outside of
initialization code that runs before selinux_disable() can be reached.
Mark both selinux_enabled_boot and selinux_enforcing_boot as __initdata
since they are only used in initialization code.

Wrap the disabled field in the struct selinux_state with
CONFIG_SECURITY_SELINUX_DISABLE since it is only used for
runtime disable.

Signed-off-by: Stephen Smalley 
Signed-off-by: Paul Moore

selinux: sidtab reverse lookup hash table

2019-12-09T21:14:51+00:00

This replaces the reverse table lookup and reverse cache with a
hashtable which improves cache-miss reverse-lookup times from
O(n) to O(1)* and maintains the same performance as a reverse
cache hit.

This reduces the time needed to add a new sidtab entry from ~500us
to 5us on a Pixel 3 when there are ~10,000 sidtab entries.

The implementation uses the kernel's generic hashtable API,
It uses the context's string represtation as the hash source,
and the kernels generic string hashing algorithm full_name_hash()
to reduce the string to a 32 bit value.

This change also maintains the improvement introduced in
commit ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve
performance") which removed the need to keep the current sidtab
locked during policy reload. It does however introduce periodic
locking of the target sidtab while converting the hashtable. Sidtab
entries are never modified or removed, so the context struct stored
in the sid_to_context tree can also be used for the context_to_sid
hashtable to reduce memory usage.

This bug was reported by:
- On the selinux bug tracker.
  BUG: kernel softlockup due to too many SIDs/contexts #37
  https://github.com/SELinuxProject/selinux-kernel/issues/37
- Jovana Knezevic on Android's bugtracker.
  Bug: 140252993
  "During multi-user performance testing, we create and remove users
  many times. selinux_android_restorecon_pkgdir goes from 1ms to over
  20ms after about 200 user creations and removals. Accumulated over
  ~280 packages, that adds a significant time to user creation,
  making perf benchmarks unreliable."

* Hashtable lookup is only O(1) when n < the number of buckets.

Signed-off-by: Jeff Vander Stoep 
Reported-by: Stephen Smalley 
Reported-by: Jovana Knezevic 
Reviewed-by: Stephen Smalley 
Tested-by: Stephen Smalley 
[PM: subj tweak, removed changelog from patch description]
Signed-off-by: Paul Moore

selinux: default_range glblub implementation

2019-10-07T23:01:35+00:00

A policy developer can now specify glblub as a default_range default and
the computed transition will be the intersection of the mls range of
the two contexts.

The glb (greatest lower bound) lub (lowest upper bound) of a range is calculated
as the greater of the low sensitivities and the lower of the high sensitivities
and the and of each category bitmap.

This can be used by MLS solution developers to compute a context that satisfies,
for example, the range of a network interface and the range of a user logging in.

Some examples are:

User Permitted Range | Network Device Label | Computed Label
---------------------|----------------------|----------------
s0-s1:c0.c12         | s0                   | s0
s0-s1:c0.c12         | s0-s1:c0.c1023       | s0-s1:c0.c12
s0-s4:c0.c512        | s1-s1:c0.c1023       | s1-s1:c0.c512
s0-s15:c0,c2         | s4-s6:c0.c128        | s4-s6:c0,c2
s0-s4                | s2-s6                | s2-s4
s0-s4                | s5-s8                | INVALID
s5-s8                | s0-s4                | INVALID

Signed-off-by: Joshua Brindle 
[PM: subject lines and checkpatch.pl fixes]
Signed-off-by: Paul Moore

selinux: try security xattr after genfs for kernfs filesystems

2019-03-21T01:53:04+00:00

Since kernfs supports the security xattr handlers, we can simply use
these to determine the inode's context, dropping the need to update it
from kernfs explicitly using a security_inode_notifysecctx() call.

We achieve this by setting a new sbsec flag SE_SBGENFS_XATTR to all
mounts that are known to use kernfs under the hood and then fetching the
xattrs after determining the fallback genfs sid in
inode_doinit_with_dentry() when this flag is set.

This will allow implementing full security xattr support in kernfs and
removing the ...notifysecctx() call in a subsequent patch.

Signed-off-by: Ondrej Mosnacek 
Acked-by: Stephen Smalley 
Acked-by: Casey Schaufler 
[PM: more manual merge fixups]
Signed-off-by: Paul Moore

Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2019-03-12T21:08:19+00:00

Pull vfs mount infrastructure updates from Al Viro:
 "The rest of core infrastructure; no new syscalls in that pile, but the
  old parts are switched to new infrastructure. At that point
  conversions of individual filesystems can happen independently; some
  are done here (afs, cgroup, procfs, etc.), there's also a large series
  outside of that pile dealing with NFS (quite a bit of option-parsing
  stuff is getting used there - it's one of the most convoluted
  filesystems in terms of mount-related logics), but NFS bits are the
  next cycle fodder.

  It got seriously simplified since the last cycle; documentation is
  probably the weakest bit at the moment - I considered dropping the
  commit introducing Documentation/filesystems/mount_api.txt (cutting
  the size increase by quarter ;-), but decided that it would be better
  to fix it up after -rc1 instead.

  That pile allows to do followup work in independent branches, which
  should make life much easier for the next cycle. fs/super.c size
  increase is unpleasant; there's a followup series that allows to
  shrink it considerably, but I decided to leave that until the next
  cycle"

* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
  afs: Use fs_context to pass parameters over automount
  afs: Add fs_context support
  vfs: Add some logging to the core users of the fs_context log
  vfs: Implement logging through fs_context
  vfs: Provide documentation for new mount API
  vfs: Remove kern_mount_data()
  hugetlbfs: Convert to fs_context
  cpuset: Use fs_context
  kernfs, sysfs, cgroup, intel_rdt: Support fs_context
  cgroup: store a reference to cgroup_ns into cgroup_fs_context
  cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper
  cgroup_do_mount(): massage calling conventions
  cgroup: stash cgroup_root reference into cgroup_fs_context
  cgroup2: switch to option-by-option parsing
  cgroup1: switch to option-by-option parsing
  cgroup: take options parsing into ->parse_monolithic()
  cgroup: fold cgroup1_mount() into cgroup1_get_tree()
  cgroup: start switching to fs_context
  ipc: Convert mqueue fs to fs_context
  proc: Add fs_context support to procfs
  ...

selinux: Implement the new mount API LSM hooks

2019-02-28T08:29:24+00:00

Implement the new mount API LSM hooks for SELinux.  At some point the old
hooks will need to be removed.

Signed-off-by: David Howells 
cc: Paul Moore 
cc: Stephen Smalley 
cc: selinux@tycho.nsa.gov
cc: linux-security-module@vger.kernel.org
Signed-off-by: Al Viro

selinux: log invalid contexts in AVCs

2019-01-25T22:31:14+00:00

In case a file has an invalid context set, in an AVC record generated
upon access to such file, the target context is always reported as
unlabeled. This patch adds new optional fields to the AVC record
(srawcon and trawcon) that report the actual context string if it
differs from the one reported in scontext/tcontext. This is useful for
diagnosing SELinux denials involving invalid contexts.

To trigger an AVC that illustrates this situation:

    # setenforce 0
    # touch /tmp/testfile
    # setfattr -n security.selinux -v system_u:object_r:banana_t:s0 /tmp/testfile
    # runcon system_u:system_r:sshd_t:s0 cat /tmp/testfile

AVC before:

type=AVC msg=audit(1547801083.248:11): avc:  denied  { open } for  pid=1149 comm="cat" path="/tmp/testfile" dev="tmpfs" ino=6608 scontext=system_u:system_r:sshd_t:s0 tcontext=system_u:object_r:unlabeled_t:s15:c0.c1023 tclass=file permissive=1

AVC after:

type=AVC msg=audit(1547801083.248:11): avc:  denied  { open } for  pid=1149 comm="cat" path="/tmp/testfile" dev="tmpfs" ino=6608 scontext=system_u:system_r:sshd_t:s0 tcontext=system_u:object_r:unlabeled_t:s15:c0.c1023 tclass=file permissive=1 trawcon=system_u:object_r:banana_t:s0

Note that it is also possible to encounter this situation with the
'scontext' field - e.g. when a new policy is loaded while a process is
running, whose context is not valid in the new policy.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1135683

Cc: Daniel Walsh 
Signed-off-by: Ondrej Mosnacek 
Reviewed-by: Stephen Smalley 
Signed-off-by: Paul Moore

selinux: make "selinux_policycap_names[]" const char *

2018-11-26T23:26:22+00:00

Those strings aren't written.

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Paul Moore