linux-toradex.git/kernel/seccomp.c, branch v5.1-rc1

Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2019-03-07T19:44:01+00:00

Pull security subsystem updates from James Morris:

 - Extend LSM stacking to allow sharing of cred, file, ipc, inode, and
   task blobs. This paves the way for more full-featured LSMs to be
   merged, and is specifically aimed at LandLock and SARA LSMs. This
   work is from Casey and Kees.

 - There's a new LSM from Micah Morton: "SafeSetID gates the setid
   family of syscalls to restrict UID/GID transitions from a given
   UID/GID to only those approved by a system-wide whitelist." This
   feature is currently shipping in ChromeOS.

* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (62 commits)
  keys: fix missing __user in KEYCTL_PKEY_QUERY
  LSM: Update list of SECURITYFS users in Kconfig
  LSM: Ignore "security=" when "lsm=" is specified
  LSM: Update function documentation for cap_capable
  security: mark expected switch fall-throughs and add a missing break
  tomoyo: Bump version.
  LSM: fix return value check in safesetid_init_securityfs()
  LSM: SafeSetID: add selftest
  LSM: SafeSetID: remove unused include
  LSM: SafeSetID: 'depend' on CONFIG_SECURITY
  LSM: Add 'name' field for SafeSetID in DEFINE_LSM
  LSM: add SafeSetID module that gates setid calls
  LSM: add SafeSetID module that gates setid calls
  tomoyo: Allow multiple use_group lines.
  tomoyo: Coding style fix.
  tomoyo: Swicth from cred->security to task_struct->security.
  security: keys: annotate implicit fall throughs
  security: keys: annotate implicit fall throughs
  security: keys: annotate implicit fall through
  capabilities:: annotate implicit fall through
  ...

seccomp, bpf: disable preemption before calling into bpf prog

2019-02-21T23:14:19+00:00

All BPF programs must be called with preemption disabled.

Fixes: 568f196756ad ("bpf: check that BPF programs run with preemption disabled")
Reported-by: syzbot+8bf19ee2aa580de7a2a7@syzkaller.appspotmail.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann

Merge tag 'v5.0-rc3' into next-general

2019-01-22T22:33:10+00:00

Sync to Linux 5.0-rc3 to pull in the VFS changes which impacted a lot
of the LSM code.

seccomp: fix UAF in user-trap code

2019-01-15T17:43:12+00:00

On the failure path, we do an fput() of the listener fd if the filter fails
to install (e.g. because of a TSYNC race that's lost, or if the thread is
killed, etc.). fput() doesn't actually release the fd, it just ads it to a
work queue. Then the thread proceeds to free the filter, even though the
listener struct file has a reference to it.

To fix this, on the failure path let's set the private data to null, so we
know in ->release() to ignore the filter.

Reported-by: syzbot+981c26489b2d1c6316ba@syzkaller.appspotmail.com
Fixes: 6a21cc50f0c7 ("seccomp: add a return code to trap to userspace")
Signed-off-by: Tycho Andersen 
Acked-by: Kees Cook 
Signed-off-by: James Morris

LSM: generalize flag passing to security_capable

2019-01-10T22:16:06+00:00

This patch provides a general mechanism for passing flags to the
security_capable LSM hook. It replaces the specific 'audit' flag that is
used to tell security_capable whether it should log an audit message for
the given capability check. The reason for generalizing this flag
passing is so we can add an additional flag that signifies whether
security_capable is being called by a setid syscall (which is needed by
the proposed SafeSetID LSM).

Signed-off-by: Micah Morton 
Reviewed-by: Kees Cook 
Signed-off-by: James Morris

seccomp: fix poor type promotion

2018-12-14T00:49:01+00:00

sparse complains,

kernel/seccomp.c:1172:13: warning: incorrect type in assignment (different base types)
kernel/seccomp.c:1172:13:    expected restricted __poll_t [usertype] ret
kernel/seccomp.c:1172:13:    got int
kernel/seccomp.c:1173:13: warning: restricted __poll_t degrades to integer

Instead of assigning this to ret, since we don't use this anywhere, let's
just test it against 0 directly.

Signed-off-by: Tycho Andersen 
Reported-by: 0day robot 
Fixes: 6a21cc50f0c7 ("seccomp: add a return code to trap to userspace")
Signed-off-by: Kees Cook

seccomp: add a return code to trap to userspace

2018-12-12T00:28:41+00:00

This patch introduces a means for syscalls matched in seccomp to notify
some other task that a particular filter has been triggered.

The motivation for this is primarily for use with containers. For example,
if a container does an init_module(), we obviously don't want to load this
untrusted code, which may be compiled for the wrong version of the kernel
anyway. Instead, we could parse the module image, figure out which module
the container is trying to load and load it on the host.

As another example, containers cannot mount() in general since various
filesystems assume a trusted image. However, if an orchestrator knows that
e.g. a particular block device has not been exposed to a container for
writing, it want to allow the container to mount that block device (that
is, handle the mount for it).

This patch adds functionality that is already possible via at least two
other means that I know about, both of which involve ptrace(): first, one
could ptrace attach, and then iterate through syscalls via PTRACE_SYSCALL.
Unfortunately this is slow, so a faster version would be to install a
filter that does SECCOMP_RET_TRACE, which triggers a PTRACE_EVENT_SECCOMP.
Since ptrace allows only one tracer, if the container runtime is that
tracer, users inside the container (or outside) trying to debug it will not
be able to use ptrace, which is annoying. It also means that older
distributions based on Upstart cannot boot inside containers using ptrace,
since upstart itself uses ptrace to monitor services while starting.

The actual implementation of this is fairly small, although getting the
synchronization right was/is slightly complex.

Finally, it's worth noting that the classic seccomp TOCTOU of reading
memory data from the task still applies here, but can be avoided with
careful design of the userspace handler: if the userspace handler reads all
of the task memory that is necessary before applying its security policy,
the tracee's subsequent memory edits will not be read by the tracer.

Signed-off-by: Tycho Andersen 
CC: Kees Cook 
CC: Andy Lutomirski 
CC: Oleg Nesterov 
CC: Eric W. Biederman 
CC: "Serge E. Hallyn" 
Acked-by: Serge Hallyn 
CC: Christian Brauner 
CC: Tyler Hicks 
CC: Akihiro Suda 
Signed-off-by: Kees Cook

seccomp: switch system call argument type to void *

2018-12-12T00:28:41+00:00

The const qualifier causes problems for any code that wants to write to the
third argument of the seccomp syscall, as we will do in a future patch in
this series.

The third argument to the seccomp syscall is documented as void *, so
rather than just dropping the const, let's switch everything to use void *
as well.

I believe this is safe because of 1. the documentation above, 2. there's no
real type information exported about syscalls anywhere besides the man
pages.

Signed-off-by: Tycho Andersen 
CC: Kees Cook 
CC: Andy Lutomirski 
CC: Oleg Nesterov 
CC: Eric W. Biederman 
CC: "Serge E. Hallyn" 
Acked-by: Serge Hallyn 
CC: Christian Brauner 
CC: Tyler Hicks 
CC: Akihiro Suda 
Signed-off-by: Kees Cook

seccomp: hoist struct seccomp_data recalculation higher

2018-12-12T00:28:40+00:00

In the next patch, we're going to use the sd pointer passed to
__seccomp_filter() as the data to pass to userspace. Except that in some
cases (__seccomp_filter(SECCOMP_RET_TRACE), emulate_vsyscall(), every time
seccomp is inovked on power, etc.) the sd pointer will be NULL in order to
force seccomp to recompute the register data. Previously this recomputation
happened one level lower, in seccomp_run_filters(); this patch just moves
it up a level higher to __seccomp_filter().

Thanks Oleg for spotting this.

Signed-off-by: Tycho Andersen 
CC: Kees Cook 
CC: Andy Lutomirski 
CC: Oleg Nesterov 
CC: Eric W. Biederman 
CC: "Serge E. Hallyn" 
Acked-by: Serge Hallyn 
CC: Christian Brauner 
CC: Tyler Hicks 
CC: Akihiro Suda 
Signed-off-by: Kees Cook

Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2018-10-24T10:49:35+00:00

Pull security subsystem updates from James Morris:
 "In this patchset, there are a couple of minor updates, as well as some
  reworking of the LSM initialization code from Kees Cook (these prepare
  the way for ordered stackable LSMs, but are a valuable cleanup on
  their own)"

* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  LSM: Don't ignore initialization failures
  LSM: Provide init debugging infrastructure
  LSM: Record LSM name in struct lsm_info
  LSM: Convert security_initcall() into DEFINE_LSM()
  vmlinux.lds.h: Move LSM_TABLE into INIT_DATA
  LSM: Convert from initcall to struct lsm_info
  LSM: Remove initcall tracing
  LSM: Rename .security_initcall section to .lsm_info
  vmlinux.lds.h: Avoid copy/paste of security_init section
  LSM: Correctly announce start of LSM initialization
  security: fix LSM description location
  keys: Fix the use of the C++ keyword "private" in uapi/linux/keyctl.h
  seccomp: remove unnecessary unlikely()
  security: tomoyo: Fix obsolete function
  security/capabilities: remove check for -EINVAL