linux-toradex.git/kernel/cred.c, branch Colibri_T30_LinuxImageV2.3Beta3_20141031

move RLIMIT_NPROC check from set_user() to do_execve_common()

2011-08-11T18:24:42+00:00

The patch http://lkml.org/lkml/2003/7/13/226 introduced an RLIMIT_NPROC
check in set_user() to check for NPROC exceeding via setuid() and
similar functions.

Before the check there was a possibility to greatly exceed the allowed
number of processes by an unprivileged user if the program relied on
rlimit only.  But the check created new security threat: many poorly
written programs simply don't check setuid() return code and believe it
cannot fail if executed with root privileges.  So, the check is removed
in this patch because of too often privilege escalations related to
buggy programs.

The NPROC can still be enforced in the common code flow of daemons
spawning user processes.  Most of daemons do fork()+setuid()+execve().
The check introduced in execve() (1) enforces the same limit as in
setuid() and (2) doesn't create similar security issues.

Neil Brown suggested to track what specific process has exceeded the
limit by setting PF_NPROC_EXCEEDED process flag.  With the change only
this process would fail on execve(), and other processes' execve()
behaviour is not changed.

Solar Designer suggested to re-check whether NPROC limit is still
exceeded at the moment of execve().  If the process was sleeping for
days between set*uid() and execve(), and the NPROC counter step down
under the limit, the defered execve() failure because NPROC limit was
exceeded days ago would be unexpected.  If the limit is not exceeded
anymore, we clear the flag on successful calls to execve() and fork().

The flag is also cleared on successful calls to set_user() as the limit
was exceeded for the previous user, not the current one.

Similar check was introduced in -ow patches (without the process flag).

v3 - clear PF_NPROC_EXCEEDED on successful calls to set_user().

Reviewed-by: James Morris 
Signed-off-by: Vasiliy Kulikov 
Acked-by: NeilBrown 
Signed-off-by: Linus Torvalds

Merge branch 'docs-move' of git://git.kernel.org/pub/scm/linux/kernel/git/rdunlap/linux-docs

2011-05-27T17:25:02+00:00

* 'docs-move' of git://git.kernel.org/pub/scm/linux/kernel/git/rdunlap/linux-docs:
  Create Documentation/security/, move LSM-, credentials-, and keys-related files from Documentation/   to Documentation/security/, add Documentation/security/00-INDEX, and update all occurrences of Documentation/   to Documentation/security/.

Create Documentation/security/,

2011-05-19T22:59:38+00:00

move LSM-, credentials-, and keys-related files from Documentation/
  to Documentation/security/,
add Documentation/security/00-INDEX, and
update all occurrences of Documentation/
  to Documentation/security/.

Merge branch 'master' into next

2011-05-19T08:51:57+00:00

Conflicts:
	include/linux/capability.h

Manually resolve merge conflict w/ thanks to Stephen Rothwell.

Signed-off-by: James Morris

Cache user_ns in struct cred

2011-05-13T18:45:33+00:00

If !CONFIG_USERNS, have current_user_ns() defined to (&init_user_ns).

Get rid of _current_user_ns.  This requires nsown_capable() to be
defined in capability.c rather than as static inline in capability.h,
so do that.

Request_key needs init_user_ns defined at current_user_ns if
!CONFIG_USERNS, so forward-declare that in cred.h if !CONFIG_USERNS
at current_user_ns() define.

Compile-tested with and without CONFIG_USERNS.

Signed-off-by: Serge E. Hallyn 
[ This makes a huge performance difference for acl_permission_check(),
  up to 30%.  And that is one of the hottest kernel functions for loads
  that are pathname-lookup heavy.  ]
Signed-off-by: Linus Torvalds

capabilities: delete all CAP_INIT macros

2011-04-04T00:31:16+00:00

The CAP_INIT macros of INH, BSET, and EFF made sense at one point in time,
but now days they aren't helping.  Just open code the logic in the
init_cred.

Signed-off-by: Eric Paris 
Acked-by: David Howells 
Signed-off-by: James Morris

userns: security: make capabilities relative to the user namespace

2011-03-24T02:47:02+00:00

- Introduce ns_capable to test for a capability in a non-default
  user namespace.
- Teach cap_capable to handle capabilities in a non-default
  user namespace.

The motivation is to get to the unprivileged creation of new
namespaces.  It looks like this gets us 90% of the way there, with
only potential uid confusion issues left.

I still need to handle getting all caps after creation but otherwise I
think I have a good starter patch that achieves all of your goals.

Changelog:
	11/05/2010: [serge] add apparmor
	12/14/2010: [serge] fix capabilities to created user namespaces
	Without this, if user serge creates a user_ns, he won't have
	capabilities to the user_ns he created.  THis is because we
	were first checking whether his effective caps had the caps
	he needed and returning -EPERM if not, and THEN checking whether
	he was the creator.  Reverse those checks.
	12/16/2010: [serge] security_real_capable needs ns argument in !security case
	01/11/2011: [serge] add task_ns_capable helper
	01/11/2011: [serge] add nsown_capable() helper per Bastian Blank suggestion
	02/16/2011: [serge] fix a logic bug: the root user is always creator of
		    init_user_ns, but should not always have capabilities to
		    it!  Fix the check in cap_capable().
	02/21/2011: Add the required user_ns parameter to security_capable,
		    fixing a compile failure.
	02/23/2011: Convert some macros to functions as per akpm comments.  Some
		    couldn't be converted because we can't easily forward-declare
		    them (they are inline if !SECURITY, extern if SECURITY).  Add
		    a current_user_ns function so we can use it in capability.h
		    without #including cred.h.  Move all forward declarations
		    together to the top of the #ifdef __KERNEL__ section, and use
		    kernel-doc format.
	02/23/2011: Per dhowells, clean up comment in cap_capable().
	02/23/2011: Per akpm, remove unreachable 'return -EPERM' in cap_capable.

(Original written and signed off by Eric;  latest, modified version
acked by him)

[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: export current_user_ns() for ecryptfs]
[serge.hallyn@canonical.com: remove unneeded extra argument in selinux's task_has_capability]
Signed-off-by: Eric W. Biederman 
Signed-off-by: Serge E. Hallyn 
Acked-by: "Eric W. Biederman" 
Acked-by: Daniel Lezcano 
Acked-by: David Howells 
Cc: James Morris 
Signed-off-by: Serge E. Hallyn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge commit 'v2.6.38-rc5' into core/locking

2011-02-16T12:33:41+00:00

Merge reason: pick up upstream fixes.

Signed-off-by: Ingo Molnar

CRED: Fix memory and refcount leaks upon security_prepare_creds() failure

2011-02-07T22:04:00+00:00

In prepare_kernel_cred() since 2.6.29, put_cred(new) is called without
assigning new->usage when security_prepare_creds() returned an error.  As a
result, memory for new and refcount for new->{user,group_info,tgcred} are
leaked because put_cred(new) won't call __put_cred() unless old->usage == 1.

Fix these leaks by assigning new->usage (and new->subscribers which was added
in 2.6.32) before calling security_prepare_creds().

Signed-off-by: Tetsuo Handa 
Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

CRED: Fix BUG() upon security_cred_alloc_blank() failure

2011-02-07T22:04:00+00:00

In cred_alloc_blank() since 2.6.32, abort_creds(new) is called with
new->security == NULL and new->magic == 0 when security_cred_alloc_blank()
returns an error.  As a result, BUG() will be triggered if SELinux is enabled
or CONFIG_DEBUG_CREDENTIALS=y.

If CONFIG_DEBUG_CREDENTIALS=y, BUG() is called from __invalid_creds() because
cred->magic == 0.  Failing that, BUG() is called from selinux_cred_free()
because selinux_cred_free() is not expecting cred->security == NULL.  This does
not affect smack_cred_free(), tomoyo_cred_free() or apparmor_cred_free().

Fix these bugs by

(1) Set new->magic before calling security_cred_alloc_blank().

(2) Handle null cred->security in creds_are_invalid() and selinux_cred_free().

Signed-off-by: Tetsuo Handa 
Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds