Commit Graph

42 Commits

Author SHA1 Message Date
Linus Torvalds 888d3c9f7f sysctl-6.4-rc1
This pull request goes with only a few sysctl moves from the
 kernel/sysctl.c file, the rest of the work has been put towards
 deprecating two API calls which incur recursion and prevent us
 from simplifying the registration process / saving memory per
 move. Most of the changes have been soaking on linux-next since
 v6.3-rc3.
 
 I've slowed down the kernel/sysctl.c moves due to Matthew Wilcox's
 feedback that we should see if we could *save* memory with these
 moves instead of incurring more memory. We currently incur more
 memory since when we move a syctl from kernel/sysclt.c out to its
 own file we end up having to add a new empty sysctl used to register
 it. To achieve saving memory we want to allow syctls to be passed
 without requiring the end element being empty, and just have our
 registration process rely on ARRAY_SIZE(). Without this, supporting
 both styles of sysctls would make the sysctl registration pretty
 brittle, hard to read and maintain as can be seen from Meng Tang's
 efforts to do just this [0]. Fortunately, in order to use ARRAY_SIZE()
 for all sysctl registrations also implies doing the work to deprecate
 two API calls which use recursion in order to support sysctl
 declarations with subdirectories.
 
 And so during this development cycle quite a bit of effort went into
 this deprecation effort. I've annotated the following two APIs are
 deprecated and in few kernel releases we should be good to remove them:
 
   * register_sysctl_table()
   * register_sysctl_paths()
 
 During this merge window we should be able to deprecate and unexport
 register_sysctl_paths(), we can probably do that towards the end
 of this merge window.
 
 Deprecating register_sysctl_table() will take a bit more time but
 this pull request goes with a few example of how to do this.
 
 As it turns out each of the conversions to move away from either of
 these two API calls *also* saves memory. And so long term, all these
 changes *will* prove to have saved a bit of memory on boot.
 
 The way I see it then is if remove a user of one deprecated call, it
 gives us enough savings to move one kernel/sysctl.c out from the
 generic arrays as we end up with about the same amount of bytes.
 
 Since deprecating register_sysctl_table() and register_sysctl_paths()
 does not require maintainer coordination except the final unexport
 you'll see quite a bit of these changes from other pull requests, I've
 just kept the stragglers after rc3.
 
 Most of these changes have been soaking on linux-next since around rc3.
 
 [0] https://lkml.kernel.org/r/ZAD+cpbrqlc5vmry@bombadil.infradead.org
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Merge tag 'sysctl-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "This only does a few sysctl moves from the kernel/sysctl.c file, the
  rest of the work has been put towards deprecating two API calls which
  incur recursion and prevent us from simplifying the registration
  process / saving memory per move. Most of the changes have been
  soaking on linux-next since v6.3-rc3.

  I've slowed down the kernel/sysctl.c moves due to Matthew Wilcox's
  feedback that we should see if we could *save* memory with these moves
  instead of incurring more memory. We currently incur more memory since
  when we move a syctl from kernel/sysclt.c out to its own file we end
  up having to add a new empty sysctl used to register it. To achieve
  saving memory we want to allow syctls to be passed without requiring
  the end element being empty, and just have our registration process
  rely on ARRAY_SIZE(). Without this, supporting both styles of sysctls
  would make the sysctl registration pretty brittle, hard to read and
  maintain as can be seen from Meng Tang's efforts to do just this [0].
  Fortunately, in order to use ARRAY_SIZE() for all sysctl registrations
  also implies doing the work to deprecate two API calls which use
  recursion in order to support sysctl declarations with subdirectories.

  And so during this development cycle quite a bit of effort went into
  this deprecation effort. I've annotated the following two APIs are
  deprecated and in few kernel releases we should be good to remove
  them:

   - register_sysctl_table()
   - register_sysctl_paths()

  During this merge window we should be able to deprecate and unexport
  register_sysctl_paths(), we can probably do that towards the end of
  this merge window.

  Deprecating register_sysctl_table() will take a bit more time but this
  pull request goes with a few example of how to do this.

  As it turns out each of the conversions to move away from either of
  these two API calls *also* saves memory. And so long term, all these
  changes *will* prove to have saved a bit of memory on boot.

  The way I see it then is if remove a user of one deprecated call, it
  gives us enough savings to move one kernel/sysctl.c out from the
  generic arrays as we end up with about the same amount of bytes.

  Since deprecating register_sysctl_table() and register_sysctl_paths()
  does not require maintainer coordination except the final unexport
  you'll see quite a bit of these changes from other pull requests, I've
  just kept the stragglers after rc3"

Link: https://lkml.kernel.org/r/ZAD+cpbrqlc5vmry@bombadil.infradead.org [0]

* tag 'sysctl-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (29 commits)
  fs: fix sysctls.c built
  mm: compaction: remove incorrect #ifdef checks
  mm: compaction: move compaction sysctl to its own file
  mm: memory-failure: Move memory failure sysctls to its own file
  arm: simplify two-level sysctl registration for ctl_isa_vars
  ia64: simplify one-level sysctl registration for kdump_ctl_table
  utsname: simplify one-level sysctl registration for uts_kern_table
  ntfs: simplfy one-level sysctl registration for ntfs_sysctls
  coda: simplify one-level sysctl registration for coda_table
  fs/cachefiles: simplify one-level sysctl registration for cachefiles_sysctls
  xfs: simplify two-level sysctl registration for xfs_table
  nfs: simplify two-level sysctl registration for nfs_cb_sysctls
  nfs: simplify two-level sysctl registration for nfs4_cb_sysctls
  lockd: simplify two-level sysctl registration for nlm_sysctls
  proc_sysctl: enhance documentation
  xen: simplify sysctl registration for balloon
  md: simplify sysctl registration
  hv: simplify sysctl registration
  scsi: simplify sysctl registration with register_sysctl()
  csky: simplify alignment sysctl registration
  ...
2023-04-27 16:52:33 -07:00
Luis Chamberlain 98cfeb8d54 yama: simplfy sysctls with register_sysctl()
register_sysctl_paths() is only need if you have directories with
entries, simplify this by using register_sysctl().

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-04-13 11:49:20 -07:00
Paul Moore f22f9aaf6c selinux: remove the runtime disable functionality
After working with the larger SELinux-based distros for several
years, we're finally at a place where we can disable the SELinux
runtime disable functionality.  The existing kernel deprecation
notice explains the functionality and why we want to remove it:

  The selinuxfs "disable" node allows SELinux to be disabled at
  runtime prior to a policy being loaded into the kernel.  If
  disabled via this mechanism, SELinux will remain disabled until
  the system is rebooted.

  The preferred method of disabling SELinux is via the "selinux=0"
  boot parameter, but the selinuxfs "disable" node was created to
  make it easier for systems with primitive bootloaders that did not
  allow for easy modification of the kernel command line.
  Unfortunately, allowing for SELinux to be disabled at runtime makes
  it difficult to secure the kernel's LSM hooks using the
  "__ro_after_init" feature.

It is that last sentence, mentioning the '__ro_after_init' hardening,
which is the real motivation for this change, and if you look at the
diffstat you'll see that the impact of this patch reaches across all
the different LSMs, helping prevent tampering at the LSM hook level.

From a SELinux perspective, it is important to note that if you
continue to disable SELinux via "/etc/selinux/config" it may appear
that SELinux is disabled, but it is simply in an uninitialized state.
If you load a policy with `load_policy -i`, you will see SELinux
come alive just as if you had loaded the policy during early-boot.

It is also worth noting that the "/sys/fs/selinux/disable" file is
always writable now, regardless of the Kconfig settings, but writing
to the file has no effect on the system, other than to display an
error on the console if a non-zero/true value is written.

Finally, in the several years where we have been working on
deprecating this functionality, there has only been one instance of
someone mentioning any user visible breakage.  In this particular
case it was an individual's kernel test system, and the workaround
documented in the deprecation notice ("selinux=0" on the kernel
command line) resolved the issue without problem.

Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2023-03-20 12:34:23 -04:00
Jens Axboe 91989c7078 task_work: cleanup notification modes
A previous commit changed the notification mode from true/false to an
int, allowing notify-no, notify-yes, or signal-notify. This was
backwards compatible in the sense that any existing true/false user
would translate to either 0 (on notification sent) or 1, the latter
which mapped to TWA_RESUME. TWA_SIGNAL was assigned a value of 2.

Clean this up properly, and define a proper enum for the notification
mode. Now we have:

- TWA_NONE. This is 0, same as before the original change, meaning no
  notification requested.
- TWA_RESUME. This is 1, same as before the original change, meaning
  that we use TIF_NOTIFY_RESUME.
- TWA_SIGNAL. This uses TIF_SIGPENDING/JOBCTL_TASK_WORK for the
  notification.

Clean up all the callers, switching their 0/1/false/true to using the
appropriate TWA_* mode for notifications.

Fixes: e91b481623 ("task_work: teach task_work_add() to do signal_wake_up()")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-17 15:05:30 -06:00
Christoph Hellwig 32927393dc sysctl: pass kernel pointers to ->proc_handler
Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-04-27 02:07:40 -04:00
Matteo Croce eec4844fae proc/sysctl: add shared variables for range check
In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range.  This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

    $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
    248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

    # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
    add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
    Data                                         old     new   delta
    sysctl_vals                                    -      12     +12
    __kstrtab_sysctl_vals                          -      12     +12
    max                                           14      10      -4
    int_max                                       16       -     -16
    one                                           68       -     -68
    zero                                         128      28    -100
    Total: Before=20583249, After=20583085, chg -0.00%

[mcroce@redhat.com: tipc: remove two unused variables]
  Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com
[akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c]
[arnd@arndb.de: proc/sysctl: make firmware loader table conditional]
  Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de
[akpm@linux-foundation.org: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 17:08:07 -07:00
Thomas Gleixner d2912cb15b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:55 +02:00
Thomas Gleixner ec8f24b7fa treewide: Add SPDX license identifier - Makefile/Kconfig
Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:46 +02:00
Jann Horn 1aa176ef5a Yama: mark local symbols as static
sparse complains that Yama defines functions and a variable as non-static
even though they don't exist in any header. Fix it by making them static.

Co-developed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Jann Horn <jannh@google.com>
[kees: merged similar static-ness fixes into a single patch]
Link: https://lkml.kernel.org/r/20190326230841.87834-1-jannh@google.com
Link: https://lkml.kernel.org/r/1553673018-19234-1-git-send-email-mojha@codeaurora.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
2019-03-28 10:02:29 -07:00
James Morris 9624d5c9c7 Linux 5.0-rc3
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Merge tag 'v5.0-rc3' into next-general

Sync to Linux 5.0-rc3 to pull in the VFS changes which impacted a lot
of the LSM code.
2019-01-22 14:33:10 -08:00
Kees Cook 9474f4e7cd Yama: Check for pid death before checking ancestry
It's possible that a pid has died before we take the rcu lock, in which
case we can't walk the ancestry list as it may be detached. Instead, check
for death first before doing the walk.

Reported-by: syzbot+a9ac39bf55329e206219@syzkaller.appspotmail.com
Fixes: 2d514487fa ("security: Yama LSM")
Cc: stable@vger.kernel.org
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
2019-01-16 12:00:56 -08:00
Kees Cook d6aed64b74 Yama: Initialize as ordered LSM
This converts Yama from being a direct "minor" LSM into an ordered LSM.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
2019-01-08 13:18:43 -08:00
Mike Rapoport 2ee0826085 pids: introduce find_get_task_by_vpid() helper
There are several functions that do find_task_by_vpid() followed by
get_task_struct().  We can use a helper function instead.

Link: http://lkml.kernel.org/r/1509602027-11337-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06 18:32:46 -08:00
Kees Cook 90bb766440 doc: ReSTify Yama.txt
Adjusts for ReST markup and moves under LSM admin guide.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-05-18 10:33:04 -06:00
James Morris ca97d939db security: mark LSM hooks as __ro_after_init
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>
2017-03-06 11:00:15 +11:00
Casey Schaufler d69dece5f5 LSM: Add /sys/kernel/security/lsm
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: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2017-01-19 13:18:29 +11:00
Josh Stone 50523a29d9 Yama: allow access for the current ptrace parent
Under ptrace_scope=1, it's possible to have a tracee that is already
ptrace-attached, but is no longer a direct descendant.  For instance, a
forking daemon will be re-parented to init, losing its ancestry to the
tracer that launched it.

The tracer can continue using ptrace in that state, but it will be
denied other accesses that check PTRACE_MODE_ATTACH, like process_vm_rw
and various procfs files.  There's no reason to prevent such access for
a tracer that already has ptrace control anyway.

This patch adds a case to ptracer_exception_found to allow access for
any task in the same thread group as the current ptrace parent.

Signed-off-by: Josh Stone <jistone@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-12-05 11:48:01 +11:00
Jann Horn dca6b41491 Yama: fix double-spinlock and user access in atomic context
Commit 8a56038c2a ("Yama: consolidate error reporting") causes lockups
when someone hits a Yama denial. Call chain:

process_vm_readv -> process_vm_rw -> process_vm_rw_core -> mm_access
-> ptrace_may_access
task_lock(...) is taken
__ptrace_may_access -> security_ptrace_access_check
-> yama_ptrace_access_check -> report_access -> kstrdup_quotable_cmdline
-> get_cmdline -> access_process_vm -> get_task_mm
task_lock(...) is taken again

task_lock(p) just calls spin_lock(&p->alloc_lock), so at this point,
spin_lock() is called on a lock that is already held by the current
process.

Also: Since the alloc_lock is a spinlock, sleeping inside
security_ptrace_access_check hooks is probably not allowed at all? So it's
not even possible to print the cmdline from in there because that might
involve paging in userspace memory.

It would be tempting to rewrite ptrace_may_access() to drop the alloc_lock
before calling the LSM, but even then, ptrace_may_access() itself might be
called from various contexts in which you're not allowed to sleep; for
example, as far as I understand, to be able to hold a reference to another
task, usually an RCU read lock will be taken (see e.g. kcmp() and
get_robust_list()), so that also prohibits sleeping. (And using e.g. FUSE,
a user can cause pagefault handling to take arbitrary amounts of time -
see https://bugs.chromium.org/p/project-zero/issues/detail?id=808.)

Therefore, AFAIK, in order to print the name of a process below
security_ptrace_access_check(), you'd have to either grab a reference to
the mm_struct and defer the access violation reporting or just use the
"comm" value that's stored in kernelspace and accessible without big
complications. (Or you could try to use some kind of atomic remote VM
access that fails if the memory isn't paged in, similar to
copy_from_user_inatomic(), and if necessary fall back to comm, but
that'd be kind of ugly because the comm/cmdline choice would look
pretty random to the user.)

Fix it by deferring reporting of the access violation until current
exits kernelspace the next time.

v2: Don't oops on PTRACE_TRACEME, call report_access under
task_lock(current). Also fix nonsensical comment. And don't use
GPF_ATOMIC for memory allocation with no locks held.
This patch is tested both for ptrace attach and ptrace traceme.

Fixes: 8a56038c2a ("Yama: consolidate error reporting")
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-05-26 09:56:18 +10:00
Sasha Levin 74f430cd0f Yama: use atomic allocations when reporting
Access reporting often happens from atomic contexes. Avoid
lockups when allocating memory for command lines.

Fixes: 8a56038c2a ("Yama: consolidate error reporting")
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
2016-05-04 10:54:05 -07:00
Kees Cook 8a56038c2a Yama: consolidate error reporting
Use a common error reporting function for Yama violation reports, and give
more detail into the process command lines.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-04-21 10:47:26 +10:00
Jann Horn 3dfb7d8cdb security: let security modules use PTRACE_MODE_* with bitmasks
It looks like smack and yama weren't aware that the ptrace mode
can have flags ORed into it - PTRACE_MODE_NOAUDIT until now, but
only for /proc/$pid/stat, and with the PTRACE_MODE_*CREDS patch,
all modes have flags ORed into them.

Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Kees Cook 730daa164e Yama: remove needless CONFIG_SECURITY_YAMA_STACKED
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: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-07-28 13:18:19 +10:00
Casey Schaufler b1d9e6b064 LSM: Switch to lists of hooks
Instead of using a vector of security operations
with explicit, special case stacking of the capability
and yama hooks use lists of hooks with capability and
yama hooks included as appropriate.

The security_operations structure is no longer required.
Instead, there is a union of the function pointers that
allows all the hooks lists to use a common mechanism for
list management while retaining typing. Each module
supplies an array describing the hooks it provides instead
of a sparsely populated security_operations structure.
The description includes the element that gets put on
the hook list, avoiding the issues surrounding individual
element allocation.

The method for registering security modules is changed to
reflect the information available. The method for removing
a module, currently only used by SELinux, has also changed.
It should be generic now, however if there are potential
race conditions based on ordering of hook removal that needs
to be addressed by the calling module.

The security hooks are called from the lists and the first
failure is returned.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-05-12 15:00:41 +10:00
Casey Schaufler e20b043a69 LSM: Add security module hook list heads
Add a list header for each security hook. They aren't used until
later in the patch series. They are grouped together in a structure
so that there doesn't need to be an external address for each.

Macro-ize the initialization of the security_operations
for each security module in anticipation of changing out
the security_operations structure.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-05-12 15:00:36 +10:00
Casey Schaufler 3c4ed7bdf5 LSM: Split security.h
The security.h header file serves two purposes,
interfaces for users of the security modules and
interfaces for security modules. Users of the
security modules don't need to know about what's
in the security_operations structure, so pull it
out into it's own header, lsm_hooks.h

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-05-12 15:00:16 +10:00
Stephen Smalley 44aa1d4413 security/yama: Remove unnecessary selects from Kconfig.
Yama selects SECURITYFS and SECURITY_PATH, but requires neither.
Remove them.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Kees Cook <keescook@chromium.org>
2015-02-27 16:53:10 -08:00
Kees Cook 41a4695ca4 Yama: do not modify global sysctl table entry
When the sysctl table is constified, we won't be able to directly modify
it. Instead, use a table copy that carries any needed changes.

Suggested-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Kees Cook <keescook@chromium.org>
2015-02-27 16:53:09 -08:00
Eric W. Biederman eddc0a3abf yama: Better permission check for ptraceme
Change the permission check for yama_ptrace_ptracee to the standard
ptrace permission check, testing if the traceer has CAP_SYS_PTRACE
in the tracees user namespace.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-03-26 13:17:58 -07:00
Linus Torvalds 6a2b60b17b Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace changes from Eric Biederman:
 "While small this set of changes is very significant with respect to
  containers in general and user namespaces in particular.  The user
  space interface is now complete.

  This set of changes adds support for unprivileged users to create user
  namespaces and as a user namespace root to create other namespaces.
  The tyranny of supporting suid root preventing unprivileged users from
  using cool new kernel features is broken.

  This set of changes completes the work on setns, adding support for
  the pid, user, mount namespaces.

  This set of changes includes a bunch of basic pid namespace
  cleanups/simplifications.  Of particular significance is the rework of
  the pid namespace cleanup so it no longer requires sending out
  tendrils into all kinds of unexpected cleanup paths for operation.  At
  least one case of broken error handling is fixed by this cleanup.

  The files under /proc/<pid>/ns/ have been converted from regular files
  to magic symlinks which prevents incorrect caching by the VFS,
  ensuring the files always refer to the namespace the process is
  currently using and ensuring that the ptrace_mayaccess permission
  checks are always applied.

  The files under /proc/<pid>/ns/ have been given stable inode numbers
  so it is now possible to see if different processes share the same
  namespaces.

  Through the David Miller's net tree are changes to relax many of the
  permission checks in the networking stack to allowing the user
  namespace root to usefully use the networking stack.  Similar changes
  for the mount namespace and the pid namespace are coming through my
  tree.

  Two small changes to add user namespace support were commited here adn
  in David Miller's -net tree so that I could complete the work on the
  /proc/<pid>/ns/ files in this tree.

  Work remains to make it safe to build user namespaces and 9p, afs,
  ceph, cifs, coda, gfs2, ncpfs, nfs, nfsd, ocfs2, and xfs so the
  Kconfig guard remains in place preventing that user namespaces from
  being built when any of those filesystems are enabled.

  Future design work remains to allow root users outside of the initial
  user namespace to mount more than just /proc and /sys."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (38 commits)
  proc: Usable inode numbers for the namespace file descriptors.
  proc: Fix the namespace inode permission checks.
  proc: Generalize proc inode allocation
  userns: Allow unprivilged mounts of proc and sysfs
  userns: For /proc/self/{uid,gid}_map derive the lower userns from the struct file
  procfs: Print task uids and gids in the userns that opened the proc file
  userns: Implement unshare of the user namespace
  userns: Implent proc namespace operations
  userns: Kill task_user_ns
  userns: Make create_new_namespaces take a user_ns parameter
  userns: Allow unprivileged use of setns.
  userns: Allow unprivileged users to create new namespaces
  userns: Allow setting a userns mapping to your current uid.
  userns: Allow chown and setgid preservation
  userns: Allow unprivileged users to create user namespaces.
  userns: Ignore suid and sgid on binaries if the uid or gid can not be mapped
  userns: fix return value on mntns_install() failure
  vfs: Allow unprivileged manipulation of the mount namespace.
  vfs: Only support slave subtrees across different user namespaces
  vfs: Add a user namespace reference from struct mnt_namespace
  ...
2012-12-17 15:44:47 -08:00
Kees Cook 235e752789 Yama: remove locking from delete path
Instead of locking the list during a delete, mark entries as invalid
and trigger a workqueue to clean them up. This lets us easily handle
task_free from interrupt context.

Signed-off-by: Kees Cook <keescook@chromium.org>
2012-11-20 10:32:08 -08:00
Kees Cook 93b69d437e Yama: add RCU to drop read locking
Stop using spinlocks in the read path. Add RCU list to handle the readers.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Acked-by: John Johansen <john.johansen@canonical.com>
2012-11-20 10:32:07 -08:00
Eric W. Biederman 4c44aaafa8 userns: Kill task_user_ns
The task_user_ns function hides the fact that it is getting the user
namespace from struct cred on the task.  struct cred may go away as
soon as the rcu lock is released.  This leads to a race where we
can dereference a stale user namespace pointer.

To make it obvious a struct cred is involved kill task_user_ns.

To kill the race modify the users of task_user_ns to only
reference the user namespace while the rcu lock is held.

Cc: Kees Cook <keescook@chromium.org>
Cc: James Morris <james.l.morris@oracle.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-11-20 04:17:44 -08:00
James Morris bf53083445 Linux 3.6-rc7
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Merge tag 'v3.6-rc7' into next

Linux 3.6-rc7

Requested by David Howells so he can merge his key susbsystem work into
my tree with requisite -linus changesets.
2012-09-28 13:37:32 +10:00
Kees Cook 2e4930eb7c Yama: handle 32-bit userspace prctl
When running a 64-bit kernel and receiving prctls from a 32-bit
userspace, the "-1" used as an unsigned long will end up being
misdetected. The kernel is looking for 0xffffffffffffffff instead of
0xffffffff. Since prctl lacks a distinct compat interface, Yama needs
to handle this translation itself. As such, support either value as
meaning PR_SET_PTRACER_ANY, to avoid breaking the ABI for 64-bit.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-09-08 01:06:14 +10:00
Kees Cook c6993e4ac0 security: allow Yama to be unconditionally stacked
Unconditionally call Yama when CONFIG_SECURITY_YAMA_STACKED is selected,
no matter what LSM module is primary.

Ubuntu and Chrome OS already carry patches to do this, and Fedora
has voiced interest in doing this as well. Instead of having multiple
distributions (or LSM authors) carrying these patches, just allow Yama
to be called unconditionally when selected by the new CONFIG.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-09-05 14:12:31 -07:00
Kees Cook 7612bfeecc Yama: access task_struct->comm directly
The core ptrace access checking routine holds a task lock, and when
reporting a failure, Yama takes a separate task lock. To avoid a
potential deadlock with two ptracers taking the opposite locks, do not
use get_task_comm() and just use ->comm directly since accuracy is not
important for the report.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
CC: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-08-17 20:40:38 +10:00
Kees Cook 9d8dad742a Yama: higher restrictions should block PTRACE_TRACEME
The higher ptrace restriction levels should be blocking even
PTRACE_TRACEME requests. The comments in the LSM documentation are
misleading about when the checks happen (the parent does not go through
security_ptrace_access_check() on a PTRACE_TRACEME call).

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org # 3.5.x and later
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-08-10 19:58:07 +10:00
Kees Cook 2cc8a71641 Yama: replace capable() with ns_capable()
When checking capabilities, the question we want to be asking is "does
current() have the capability in the child's namespace?"

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-05-15 10:27:57 +10:00
Dan Carpenter 08162e6a23 Yama: remove an unused variable
GCC complains that we don't use "one" any more after 389da25f93 "Yama:
add additional ptrace scopes".

security/yama/yama_lsm.c:322:12: warning: ?one? defined but not used
	[-Wunused-variable]

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-04-23 17:20:22 +10:00
Kees Cook 389da25f93 Yama: add additional ptrace scopes
This expands the available Yama ptrace restrictions to include two more
modes. Mode 2 requires CAP_SYS_PTRACE for PTRACE_ATTACH, and mode 3
completely disables PTRACE_ATTACH (and locks the sysctl).

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-04-19 13:39:56 +10:00
Kees Cook bf06189e4d Yama: add PR_SET_PTRACER_ANY
For a process to entirely disable Yama ptrace restrictions, it can use
the special PR_SET_PTRACER_ANY pid to indicate that any otherwise allowed
process may ptrace it. This is stronger than calling PR_SET_PTRACER with
pid "1" because it includes processes in external pid namespaces. This is
currently needed by the Chrome renderer, since its crash handler (Breakpad)
runs external to the renderer's pid namespace.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <jmorris@namei.org>
2012-02-16 10:25:18 +11:00
Kees Cook 2d514487fa security: Yama LSM
This adds the Yama Linux Security Module to collect DAC security
improvements (specifically just ptrace restrictions for now) that have
existed in various forms over the years and have been carried outside the
mainline kernel by other Linux distributions like Openwall and grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
2012-02-10 09:18:52 +11:00