sysctl: add support for poll()

Adding support for poll() in sysctl fs allows userspace to receive
notifications of changes in sysctl entries.  This adds a infrastructure to
allow files in sysctl fs to be pollable and implements it for hostname and
domainname.

[akpm@linux-foundation.org: s/declare/define/ for definitions]
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Greg KH <gregkh@suse.de>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
prctl: use CAP_SYS_RESOURCE for PR_SET_MM option

CAP_SYS_ADMIN is already overloaded left and right, so to have more
fine-grained access control use CAP_SYS_RESOURCE here.

The CAP_SYS_RESOUCE is chosen because this prctl option allows a current
process to adjust some fields of memory map descriptor which rather
represents what the process owns: pointers to code, data, stack
segments, command line, auxiliary vector data and etc.

Suggested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
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>
prctl: add PR_{SET,GET}_CHILD_SUBREAPER to allow simple process supervision

Userspace service managers/supervisors need to track their started
services.  Many services daemonize by double-forking and get implicitly
re-parented to PID 1.  The service manager will no longer be able to
receive the SIGCHLD signals for them, and is no longer in charge of
reaping the children with wait().  All information about the children is
lost at the moment PID 1 cleans up the re-parented processes.

With this prctl, a service manager process can mark itself as a sort of
'sub-init', able to stay as the parent for all orphaned processes
created by the started services.  All SIGCHLD signals will be delivered
to the service manager.

Receiving SIGCHLD and doing wait() is in cases of a service-manager much
preferred over any possible asynchronous notification about specific
PIDs, because the service manager has full access to the child process
data in /proc and the PID can not be re-used until the wait(), the
service-manager itself is in charge of, has happened.

As a side effect, the relevant parent PID information does not get lost
by a double-fork, which results in a more elaborate process tree and
'ps' output:

before:
  # ps afx
  253 ?        Ss     0:00 /bin/dbus-daemon --system --nofork
  294 ?        Sl     0:00 /usr/libexec/polkit-1/polkitd
  328 ?        S      0:00 /usr/sbin/modem-manager
  608 ?        Sl     0:00 /usr/libexec/colord
  658 ?        Sl     0:00 /usr/libexec/upowerd
  819 ?        Sl     0:00 /usr/libexec/imsettings-daemon
  916 ?        Sl     0:00 /usr/libexec/udisks-daemon
  917 ?        S      0:00  \_ udisks-daemon: not polling any devices

after:
  # ps afx
  294 ?        Ss     0:00 /bin/dbus-daemon --system --nofork
  426 ?        Sl     0:00  \_ /usr/libexec/polkit-1/polkitd
  449 ?        S      0:00  \_ /usr/sbin/modem-manager
  635 ?        Sl     0:00  \_ /usr/libexec/colord
  705 ?        Sl     0:00  \_ /usr/libexec/upowerd
  959 ?        Sl     0:00  \_ /usr/libexec/udisks-daemon
  960 ?        S      0:00  |   \_ udisks-daemon: not polling any devices
  977 ?        Sl     0:00  \_ /usr/libexec/packagekitd

This prctl is orthogonal to PID namespaces.  PID namespaces are isolated
from each other, while a service management process usually requires the
services to live in the same namespace, to be able to talk to each
other.

Users of this will be the systemd per-user instance, which provides
init-like functionality for the user's login session and D-Bus, which
activates bus services on-demand.  Both need init-like capabilities to
be able to properly keep track of the services they start.

Many thanks to Oleg for several rounds of review and insights.

[akpm@linux-foundation.org: fix comment layout and spelling]
[akpm@linux-foundation.org: add lengthy code comment from Oleg]
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 userns: Remove unnecessary cast to struct user_struct when copying cr.

.ed->user.

In struct cred the user member is and has always been declared struct user_struct *user.
At most a constant struct cred will have a constant pointer to non-constant user_struct
so remove this unnecessary cast.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
userns: Convert setting and getting uid and gid system calls to use kuid and kgid

Convert setregid, setgid, setreuid, setuid,
setresuid, getresuid, setresgid, getresgid, setfsuid, setfsgid,
getuid, geteuid, getgid, getegid,
waitpid, waitid, wait4.

Convert userspace uids and gids into kuids and kgids before
being placed on struct cred.  Convert struct cred kuids and
kgids into userspace uids and gids when returning them.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids

Update the permission checks to use the new uid_eq and gid_eq helpers
and remove the now unnecessary user_ns equality comparison.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
userns: signal remove unnecessary map_cred_ns

map_cred_ns is a light wrapper around from_kuid with the order of the arguments
reversed.  Replace map_cred_ns with from_kuid and remove map_cred_ns.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
ARM: use set_current_blocked() and block_sigmask()

As described in e6fa16ab ("signal: sigprocmask() should do
retarget_shared_pending()") the modification of current->blocked is
incorrect as we need to check for shared signals we're about to block.

Also, use the new helper function introduced in commit 5e6292c0f28f
("signal: add block_sigmask() for adding sigmask to current->blocked")
which centralises the code for updating current->blocked after
successfully delivering a signal and reduces the amount of duplicate code
across architectures.  In the past some architectures got this code wrong,
so using this helper function should stop that from happening again.

Cc: Arnd Bergmann <arnd.bergmann@linaro.org>
Cc: Dave Martin <dave.martin@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arm: add elf.h to arch/arm/kernel/ptrace.c

It was implicitly getting it via an implicit presence of module.h
but when we clean that up, we'll get a bunch of lines like this:

arch/arm/kernel/ptrace.c:764: error: 'NT_PRSTATUS' undeclared here (not in a function)
arch/arm/kernel/ptrace.c:765: error: 'ELF_NGREG' undeclared here (not in a function)
arch/arm/kernel/ptrace.c:776: error: 'NT_PRFPREG' undeclared here (not in a function)

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Kernel: Audit Support For The ARM Platform

This patch provides functionality to audit system call events on the
ARM platform. The implementation was based off the structure of the
MIPS platform and information in this
(http://lists.fedoraproject.org/pipermail/arm/2009-October/000382.html)
mailing list thread. The required audit_syscall_exit and
audit_syscall_entry checks were added to ptrace using the standard
registers for system call values (r0 through r3). A thread information
flag was added for auditing (TIF_SYSCALL_AUDIT) and a meta-flag was
added (_TIF_SYSCALL_WORK) to simplify modifications to the syscall
entry/exit. Now, if either the TRACE flag is set or the AUDIT flag is
set, the syscall_trace function will be executed. The prober changes
were made to Kconfig to allow CONFIG_AUDITSYSCALL to be enabled.

Due to platform availability limitations, this patch was only tested
on the Android platform running the modified "android-goldfish-2.6.29"
kernel. A test compile was performed using Code Sourcery's
cross-compilation toolset and the current linux-3.0 stable kernel. The
changes compile without error. I'm hoping, due to the simple modifications,
the patch is "obviously correct".

Signed-off-by: Nathaniel Husted <nhusted@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Audit: push audit success and retcode into arch ptrace.h

The audit system previously expected arches calling to audit_syscall_exit to
supply as arguments if the syscall was a success and what the return code was.
Audit also provides a helper AUDITSC_RESULT which was supposed to simplify things
by converting from negative retcodes to an audit internal magic value stating
success or failure.  This helper was wrong and could indicate that a valid
pointer returned to userspace was a failed syscall.  The fix is to fix the
layering foolishness.  We now pass audit_syscall_exit a struct pt_reg and it
in turns calls back into arch code to collect the return value and to
determine if the syscall was a success or failure.  We also define a generic
is_syscall_success() macro which determines success/failure based on if the
value is < -MAX_ERRNO.  This works for arches like x86 which do not use a
separate mechanism to indicate syscall failure.

We make both the is_syscall_success() and regs_return_value() static inlines
instead of macros.  The reason is because the audit function must take a void*
for the regs.  (uml calls theirs struct uml_pt_regs instead of just struct
pt_regs so audit_syscall_exit can't take a struct pt_regs).  Since the audit
function takes a void* we need to use static inlines to cast it back to the
arch correct structure to dereference it.

The other major change is that on some arches, like ia64, MIPS and ppc, we
change regs_return_value() to give us the negative value on syscall failure.
THE only other user of this macro, kretprobe_example.c, won't notice and it
makes the value signed consistently for the audit functions across all archs.

In arch/sh/kernel/ptrace_64.c I see that we were using regs[9] in the old
audit code as the return value.  But the ptrace_64.h code defined the macro
regs_return_value() as regs[3].  I have no idea which one is correct, but this
patch now uses the regs_return_value() function, so it now uses regs[3].

For powerpc we previously used regs->result but now use the
regs_return_value() function which uses regs->gprs[3].  regs->gprs[3] is
always positive so the regs_return_value(), much like ia64 makes it negative
before calling the audit code when appropriate.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: H. Peter Anvin <hpa@zytor.com> [for x86 portion]
Acked-by: Tony Luck <tony.luck@intel.com> [for ia64]
Acked-by: Richard Weinberger <richard@nod.at> [for uml]
Acked-by: David S. Miller <davem@davemloft.net> [for sparc]
Acked-by: Ralf Baechle <ralf@linux-mips.org> [for mips]
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [for ppc]
audit: inline audit_syscall_entry to reduce burden on archs

Every arch calls:

if (unlikely(current->audit_context))
	audit_syscall_entry()

which requires knowledge about audit (the existance of audit_context) in
the arch code.  Just do it all in static inline in audit.h so that arch's
can remain blissfully ignorant.

Signed-off-by: Eric Paris <eparis@redhat.com>
audit: drop audit_set_macxattr as it doesn't do anything

unused.  deleted.

Signed-off-by: Eric Paris <eparis@redhat.com>
audit: remove audit_finish_fork as it can't be called

Audit entry,always rules are not allowed and are automatically changed in
exit,always rules in userspace.  The kernel refuses to load such rules.

Thus a task in the middle of a syscall (and thus in audit_finish_fork())
can only be in one of two states: AUDIT_BUILD_CONTEXT or AUDIT_DISABLED.
Since the current task cannot be in AUDIT_RECORD_CONTEXT we aren't every
going to actually use the code in audit_finish_fork() since it will
return without doing anything.  Thus drop the code.

Signed-off-by: Eric Paris <eparis@redhat.com>
audit: remove task argument to audit_set_loginuid

The function always deals with current.  Don't expose an option
pretending one can use it for something.  You can't.

Signed-off-by: Eric Paris <eparis@redhat.com>
constify path argument of audit_log_d_path()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
x86-64: Emulate legacy vsyscalls

There's a fair amount of code in the vsyscall page.  It contains
a syscall instruction (in the gettimeofday fallback) and who
knows what will happen if an exploit jumps into the middle of
some other code.

Reduce the risk by replacing the vsyscalls with short magic
incantations that cause the kernel to emulate the real
vsyscalls. These incantations are useless if entered in the
middle.

This causes vsyscalls to be a little more expensive than real
syscalls.  Fortunately sensible programs don't use them.
The only exception is time() which is still called by glibc
through the vsyscall - but calling time() millions of times
per second is not sensible. glibc has this fixed in the
development tree.

This patch is not perfect: the vread_tsc and vread_hpet
functions are still at a fixed address.  Fixing that might
involve making alternative patching work in the vDSO.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/e64e1b3c64858820d12c48fa739efbd1485e79d5.1307292171.git.luto@mit.edu
[ Removed the CONFIG option - it's simpler to just do it unconditionally. Tidied up the code as well. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Conflicts:

	arch/x86/include/asm/irq_vectors.h
	arch/x86/include/asm/traps.h
	arch/x86/include/asm/vsyscall.h
	arch/x86/kernel/Makefile
	arch/x86/kernel/vsyscall_64.c
	arch/x86/kernel/vsyscall_emu_64.S
seccomp: kill the seccomp_t typedef

Replaces the seccomp_t typedef with struct seccomp to match modern
kernel style.

Signed-off-by: Will Drewry <wad@chromium.org>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Eric Paris <eparis@redhat.com>

v18: rebase
...
v14: rebase/nochanges
v13: rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc
v12: rebase on to linux-next
v8-v11: no changes
v7: struct seccomp_struct -> struct seccomp
v6: original inclusion in this series.
Signed-off-by: James Morris <james.l.morris@oracle.com>