14 Aug, 2008
1 commit
-
Fix the setting of PF_SUPERPRIV by __capable() as it could corrupt the flags
the target process if that is not the current process and it is trying to
change its own flags in a different way at the same time.__capable() is using neither atomic ops nor locking to protect t->flags. This
patch removes __capable() and introduces has_capability() that doesn't set
PF_SUPERPRIV on the process being queried.This patch further splits security_ptrace() in two:
(1) security_ptrace_may_access(). This passes judgement on whether one
process may access another only (PTRACE_MODE_ATTACH for ptrace() and
PTRACE_MODE_READ for /proc), and takes a pointer to the child process.
current is the parent.(2) security_ptrace_traceme(). This passes judgement on PTRACE_TRACEME only,
and takes only a pointer to the parent process. current is the child.In Smack and commoncap, this uses has_capability() to determine whether
the parent will be permitted to use PTRACE_ATTACH if normal checks fail.
This does not set PF_SUPERPRIV.Two of the instances of __capable() actually only act on current, and so have
been changed to calls to capable().Of the places that were using __capable():
(1) The OOM killer calls __capable() thrice when weighing the killability of a
process. All of these now use has_capability().(2) cap_ptrace() and smack_ptrace() were using __capable() to check to see
whether the parent was allowed to trace any process. As mentioned above,
these have been split. For PTRACE_ATTACH and /proc, capable() is now
used, and for PTRACE_TRACEME, has_capability() is used.(3) cap_safe_nice() only ever saw current, so now uses capable().
(4) smack_setprocattr() rejected accesses to tasks other than current just
after calling __capable(), so the order of these two tests have been
switched and capable() is used instead.(5) In smack_file_send_sigiotask(), we need to allow privileged processes to
receive SIGIO on files they're manipulating.(6) In smack_task_wait(), we let a process wait for a privileged process,
whether or not the process doing the waiting is privileged.I've tested this with the LTP SELinux and syscalls testscripts.
Signed-off-by: David Howells
Acked-by: Serge Hallyn
Acked-by: Casey Schaufler
Acked-by: Andrew G. Morgan
Acked-by: Al Viro
Signed-off-by: James Morris
05 Jul, 2008
1 commit
-
This commit includes a bugfix for the fragile setuid fixup code in the
case that filesystem capabilities are supported (in access()). The effect
of this fix is gated on filesystem capability support because changing
securebits is only supported when filesystem capabilities support is
configured.)[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrew G. Morgan
Acked-by: Serge Hallyn
Acked-by: David Howells
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Jun, 2008
1 commit
-
Source code out there hard-codes a notion of what the
_LINUX_CAPABILITY_VERSION #define means in terms of the semantics of the
raw capability system calls capget() and capset(). Its unfortunate, but
true.Since the confusing header file has been in a released kernel, there is
software that is erroneously using 64-bit capabilities with the semantics
of 32-bit compatibilities. These recently compiled programs may suffer
corruption of their memory when sys_getcap() overwrites more memory than
they are coded to expect, and the raising of added capabilities when using
sys_capset().As such, this patch does a number of things to clean up the situation
for all. It1. forces the _LINUX_CAPABILITY_VERSION define to always retain its
legacy value.2. adopts a new #define strategy for the kernel's internal
implementation of the preferred magic.3. deprecates v2 capability magic in favor of a new (v3) magic
number. The functionality of v3 is entirely equivalent to v2,
the only difference being that the v2 magic causes the kernel
to log a "deprecated" warning so the admin can find applications
that may be using v2 inappropriately.[User space code continues to be encouraged to use the libcap API which
protects the application from details like this. libcap-2.10 is the first
to support v3 capabilities.]Fixes issue reported in https://bugzilla.redhat.com/show_bug.cgi?id=447518.
Thanks to Bojan Smojver for the report.[akpm@linux-foundation.org: s/depreciate/deprecate/g]
[akpm@linux-foundation.org: be robust about put_user size]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrew G. Morgan
Cc: Serge E. Hallyn
Cc: Bojan Smojver
Cc: stable@kernel.org
Signed-off-by: Andrew Morton
Signed-off-by: Chris Wright
30 Apr, 2008
1 commit
-
Cast the CAP_*_SET macros to be of kernel_cap_t type to avoid compiler
warnings.Signed-off-by: David Howells
Signed-off-by: Linus Torvalds
28 Apr, 2008
1 commit
-
Filesystem capability support makes it possible to do away with (set)uid-0
based privilege and use capabilities instead. That is, with filesystem
support for capabilities but without this present patch, it is (conceptually)
possible to manage a system with capabilities alone and never need to obtain
privilege via (set)uid-0.Of course, conceptually isn't quite the same as currently possible since few
user applications, certainly not enough to run a viable system, are currently
prepared to leverage capabilities to exercise privilege. Further, many
applications exist that may never get upgraded in this way, and the kernel
will continue to want to support their setuid-0 base privilege needs.Where pure-capability applications evolve and replace setuid-0 binaries, it is
desirable that there be a mechanisms by which they can contain their
privilege. In addition to leveraging the per-process bounding and inheritable
sets, this should include suppressing the privilege of the uid-0 superuser
from the process' tree of children.The feature added by this patch can be leveraged to suppress the privilege
associated with (set)uid-0. This suppression requires CAP_SETPCAP to
initiate, and only immediately affects the 'current' process (it is inherited
through fork()/exec()). This reimplementation differs significantly from the
historical support for securebits which was system-wide, unwieldy and which
has ultimately withered to a dead relic in the source of the modern kernel.With this patch applied a process, that is capable(CAP_SETPCAP), can now drop
all legacy privilege (through uid=0) for itself and all subsequently
fork()'d/exec()'d children with:prctl(PR_SET_SECUREBITS, 0x2f);
This patch represents a no-op unless CONFIG_SECURITY_FILE_CAPABILITIES is
enabled at configure time.[akpm@linux-foundation.org: fix uninitialised var warning]
[serue@us.ibm.com: capabilities: use cap_task_prctl when !CONFIG_SECURITY]
Signed-off-by: Andrew G. Morgan
Acked-by: Serge Hallyn
Reviewed-by: James Morris
Cc: Stephen Smalley
Cc: Paul Moore
Signed-off-by: Serge E. Hallyn
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Feb, 2008
5 commits
-
Smack is the Simplified Mandatory Access Control Kernel.
Smack implements mandatory access control (MAC) using labels
attached to tasks and data containers, including files, SVIPC,
and other tasks. Smack is a kernel based scheme that requires
an absolute minimum of application support and a very small
amount of configuration data.Smack uses extended attributes and
provides a set of general mount options, borrowing technics used
elsewhere. Smack uses netlabel for CIPSO labeling. Smack provides
a pseudo-filesystem smackfs that is used for manipulation of
system Smack attributes.The patch, patches for ls and sshd, a README, a startup script,
and x86 binaries for ls and sshd are also available onhttp://www.schaufler-ca.com
Development has been done using Fedora Core 7 in a virtual machine
environment and on an old Sony laptop.Smack provides mandatory access controls based on the label attached
to a task and the label attached to the object it is attempting to
access. Smack labels are deliberately short (1-23 characters) text
strings. Single character labels using special characters are reserved
for system use. The only operation applied to Smack labels is equality
comparison. No wildcards or expressions, regular or otherwise, are
used. Smack labels are composed of printable characters and may not
include "/".A file always gets the Smack label of the task that created it.
Smack defines and uses these labels:
"*" - pronounced "star"
"_" - pronounced "floor"
"^" - pronounced "hat"
"?" - pronounced "huh"The access rules enforced by Smack are, in order:
1. Any access requested by a task labeled "*" is denied.
2. A read or execute access requested by a task labeled "^"
is permitted.
3. A read or execute access requested on an object labeled "_"
is permitted.
4. Any access requested on an object labeled "*" is permitted.
5. Any access requested by a task on an object with the same
label is permitted.
6. Any access requested that is explicitly defined in the loaded
rule set is permitted.
7. Any other access is denied.Rules may be explicitly defined by writing subject,object,access
triples to /smack/load.Smack rule sets can be easily defined that describe Bell&LaPadula
sensitivity, Biba integrity, and a variety of interesting
configurations. Smack rule sets can be modified on the fly to
accommodate changes in the operating environment or even the time
of day.Some practical use cases:
Hierarchical levels. The less common of the two usual uses
for MLS systems is to define hierarchical levels, often
unclassified, confidential, secret, and so on. To set up smack
to support this, these rules could be defined:C Unclass rx
S C rx
S Unclass rx
TS S rx
TS C rx
TS Unclass rxA TS process can read S, C, and Unclass data, but cannot write it.
An S process can read C and Unclass. Note that specifying that
TS can read S and S can read C does not imply TS can read C, it
has to be explicitly stated.Non-hierarchical categories. This is the more common of the
usual uses for an MLS system. Since the default rule is that a
subject cannot access an object with a different label no
access rules are required to implement compartmentalization.A case that the Bell & LaPadula policy does not allow is demonstrated
with this Smack access rule:A case that Bell&LaPadula does not allow that Smack does:
ESPN ABC r
ABC ESPN rOn my portable video device I have two applications, one that
shows ABC programming and the other ESPN programming. ESPN wants
to show me sport stories that show up as news, and ABC will
only provide minimal information about a sports story if ESPN
is covering it. Each side can look at the other's info, neither
can change the other. Neither can see what FOX is up to, which
is just as well all things considered.Another case that I especially like:
SatData Guard w
Guard Publish wA program running with the Guard label opens a UDP socket and
accepts messages sent by a program running with a SatData label.
The Guard program inspects the message to ensure it is wholesome
and if it is sends it to a program running with the Publish label.
This program then puts the information passed in an appropriate
place. Note that the Guard program cannot write to a Publish
file system object because file system semanitic require read as
well as write.The four cases (categories, levels, mutual read, guardbox) here
are all quite real, and problems I've been asked to solve over
the years. The first two are easy to do with traditonal MLS systems
while the last two you can't without invoking privilege, at least
for a while.Signed-off-by: Casey Schaufler
Cc: Joshua Brindle
Cc: Paul Moore
Cc: Stephen Smalley
Cc: Chris Wright
Cc: James Morris
Cc: "Ahmed S. Darwish"
Cc: Andrew G. Morgan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The capability bounding set is a set beyond which capabilities cannot grow.
Currently cap_bset is per-system. It can be manipulated through sysctl,
but only init can add capabilities. Root can remove capabilities. By
default it includes all caps except CAP_SETPCAP.This patch makes the bounding set per-process when file capabilities are
enabled. It is inherited at fork from parent. Noone can add elements,
CAP_SETPCAP is required to remove them.One example use of this is to start a safer container. For instance, until
device namespaces or per-container device whitelists are introduced, it is
best to take CAP_MKNOD away from a container.The bounding set will not affect pP and pE immediately. It will only
affect pP' and pE' after subsequent exec()s. It also does not affect pI,
and exec() does not constrain pI'. So to really start a shell with no way
of regain CAP_MKNOD, you would doprctl(PR_CAPBSET_DROP, CAP_MKNOD);
cap_t cap = cap_get_proc();
cap_value_t caparray[1];
caparray[0] = CAP_MKNOD;
cap_set_flag(cap, CAP_INHERITABLE, 1, caparray, CAP_DROP);
cap_set_proc(cap);
cap_free(cap);The following test program will get and set the bounding
set (but not pI). For instance./bset get
(lists capabilities in bset)
./bset drop cap_net_raw
(starts shell with new bset)
(use capset, setuid binary, or binary with
file capabilities to try to increase caps)************************************************************
cap_bound.c
************************************************************
#include
#include
#include
#include
#include
#include
#include#ifndef PR_CAPBSET_READ
#define PR_CAPBSET_READ 23
#endif#ifndef PR_CAPBSET_DROP
#define PR_CAPBSET_DROP 24
#endifint usage(char *me)
{
printf("Usage: %s get\n", me);
printf(" %s drop \n", me);
return 1;
}#define numcaps 32
char *captable[numcaps] = {
"cap_chown",
"cap_dac_override",
"cap_dac_read_search",
"cap_fowner",
"cap_fsetid",
"cap_kill",
"cap_setgid",
"cap_setuid",
"cap_setpcap",
"cap_linux_immutable",
"cap_net_bind_service",
"cap_net_broadcast",
"cap_net_admin",
"cap_net_raw",
"cap_ipc_lock",
"cap_ipc_owner",
"cap_sys_module",
"cap_sys_rawio",
"cap_sys_chroot",
"cap_sys_ptrace",
"cap_sys_pacct",
"cap_sys_admin",
"cap_sys_boot",
"cap_sys_nice",
"cap_sys_resource",
"cap_sys_time",
"cap_sys_tty_config",
"cap_mknod",
"cap_lease",
"cap_audit_write",
"cap_audit_control",
"cap_setfcap"
};int getbcap(void)
{
int comma=0;
unsigned long i;
int ret;printf("i know of %d capabilities\n", numcaps);
printf("capability bounding set:");
for (i=0; i< 0)
perror("prctl");
else if (ret==1)
printf("%s%s", (comma++) ? ", " : " ", captable[i]);
}
printf("\n");
return 0;
}int capdrop(char *str)
{
unsigned long i;int found=0;
for (i=0; i
Signed-off-by: Andrew G. Morgan
Cc: Stephen Smalley
Cc: James Morris
Cc: Chris Wright
Cc: Casey Schaufler a
Signed-off-by: "Serge E. Hallyn"
Tested-by: Jiri Slaby
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
KaiGai Kohei observed that this line in the linux header is not needed.
Signed-off-by: Andrew G. Morgan
Cc: KaiGai Kohei
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The patch supports legacy (32-bit) capability userspace, and where possible
translates 32-bit capabilities to/from userspace and the VFS to 64-bit
kernel space capabilities. If a capability set cannot be compressed into
32-bits for consumption by user space, the system call fails, with -ERANGE.FWIW libcap-2.00 supports this change (and earlier capability formats)
http://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/
[akpm@linux-foundation.org: coding-syle fixes]
[akpm@linux-foundation.org: use get_task_comm()]
[ezk@cs.sunysb.edu: build fix]
[akpm@linux-foundation.org: do not initialise statics to 0 or NULL]
[akpm@linux-foundation.org: unused var]
[serue@us.ibm.com: export __cap_ symbols]
Signed-off-by: Andrew G. Morgan
Cc: Stephen Smalley
Acked-by: Serge Hallyn
Cc: Chris Wright
Cc: James Morris
Cc: Casey Schaufler
Signed-off-by: Erez Zadok
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Revert b68680e4731abbd78863063aaa0dca2a6d8cc723 to make way for the next
patch: "Add 64-bit capability support to the kernel".We want to keep the vfs_cap_data.data[] structure, using two 'data's for
64-bit caps (and later three for 96-bit caps), whereas
b68680e4731abbd78863063aaa0dca2a6d8cc723 had gotten rid of the 'data' struct
made its members inline.The 64-bit caps patch keeps the stack abuse fix at get_file_caps(), which was
the more important part of that patch.[akpm@linux-foundation.org: coding-style fixes]
Cc: Stephen Smalley
Cc: Serge Hallyn
Cc: Chris Wright
Cc: James Morris
Cc: Casey Schaufler
Cc: Andrew Morgan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 Oct, 2007
1 commit
-
Simplify the vfs_cap_data structure.
Also fix get_file_caps which was declaring
__le32 v1caps[XATTR_CAPS_SZ] on the stack, but
XATTR_CAPS_SZ is already * sizeof(__le32).[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Serge E. Hallyn
Cc: Andrew Morgan
Cc: Chris Wright
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 Oct, 2007
1 commit
-
The non-filesystem capability meaning of CAP_SETPCAP is that a process, p1,
can change the capabilities of another process, p2. This is not the
meaning that was intended for this capability at all, and this
implementation came about purely because, without filesystem capabilities,
there was no way to use capabilities without one process bestowing them on
another.Since we now have a filesystem support for capabilities we can fix the
implementation of CAP_SETPCAP.The most significant thing about this change is that, with it in effect, no
process can set the capabilities of another process.The capabilities of a program are set via the capability convolution
rules:pI(post-exec) = pI(pre-exec)
pP(post-exec) = (X(aka cap_bset) & fP) | (pI(post-exec) & fI)
pE(post-exec) = fE ? pP(post-exec) : 0at exec() time. As such, the only influence the pre-exec() program can
have on the post-exec() program's capabilities are through the pI
capability set.The correct implementation for CAP_SETPCAP (and that enabled by this patch)
is that it can be used to add extra pI capabilities to the current process
- to be picked up by subsequent exec()s when the above convolution rules
are applied.Here is how it works:
Let's say we have a process, p. It has capability sets, pE, pP and pI.
Generally, p, can change the value of its own pI to pI' where(pI' & ~pI) & ~pP = 0.
That is, the only new things in pI' that were not present in pI need to
be present in pP.The role of CAP_SETPCAP is basically to permit changes to pI beyond
the above:if (pE & CAP_SETPCAP) {
pI' = anything; /* ie., even (pI' & ~pI) & ~pP != 0 */
}This capability is useful for things like login, which (say, via
pam_cap) might want to raise certain inheritable capabilities for use
by the children of the logged-in user's shell, but those capabilities
are not useful to or needed by the login program itself.One such use might be to limit who can run ping. You set the
capabilities of the 'ping' program to be "= cap_net_raw+i", and then
only shells that have (pI & CAP_NET_RAW) will be able to run
it. Without CAP_SETPCAP implemented as described above, login(pam_cap)
would have to also have (pP & CAP_NET_RAW) in order to raise this
capability and pass it on through the inheritable set.Signed-off-by: Andrew Morgan
Signed-off-by: Serge E. Hallyn
Cc: Stephen Smalley
Cc: James Morris
Cc: Casey Schaufler
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Oct, 2007
1 commit
-
Implement file posix capabilities. This allows programs to be given a
subset of root's powers regardless of who runs them, without having to use
setuid and giving the binary all of root's powers.This version works with Kaigai Kohei's userspace tools, found at
http://www.kaigai.gr.jp/index.php. For more information on how to use this
patch, Chris Friedhoff has posted a nice page at
http://www.friedhoff.org/fscaps.html.Changelog:
Nov 27:
Incorporate fixes from Andrew Morton
(security-introduce-file-caps-tweaks and
security-introduce-file-caps-warning-fix)
Fix Kconfig dependency.
Fix change signaling behavior when file caps are not compiled in.Nov 13:
Integrate comments from Alexey: Remove CONFIG_ ifdef from
capability.h, and use %zd for printing a size_t.Nov 13:
Fix endianness warnings by sparse as suggested by Alexey
Dobriyan.Nov 09:
Address warnings of unused variables at cap_bprm_set_security
when file capabilities are disabled, and simultaneously clean
up the code a little, by pulling the new code into a helper
function.Nov 08:
For pointers to required userspace tools and how to use
them, see http://www.friedhoff.org/fscaps.html.Nov 07:
Fix the calculation of the highest bit checked in
check_cap_sanity().Nov 07:
Allow file caps to be enabled without CONFIG_SECURITY, since
capabilities are the default.
Hook cap_task_setscheduler when !CONFIG_SECURITY.
Move capable(TASK_KILL) to end of cap_task_kill to reduce
audit messages.Nov 05:
Add secondary calls in selinux/hooks.c to task_setioprio and
task_setscheduler so that selinux and capabilities with file
cap support can be stacked.Sep 05:
As Seth Arnold points out, uid checks are out of place
for capability code.Sep 01:
Define task_setscheduler, task_setioprio, cap_task_kill, and
task_setnice to make sure a user cannot affect a process in which
they called a program with some fscaps.One remaining question is the note under task_setscheduler: are we
ok with CAP_SYS_NICE being sufficient to confine a process to a
cpuset?It is a semantic change, as without fsccaps, attach_task doesn't
allow CAP_SYS_NICE to override the uid equivalence check. But since
it uses security_task_setscheduler, which elsewhere is used where
CAP_SYS_NICE can be used to override the uid equivalence check,
fixing it might be tough.task_setscheduler
note: this also controls cpuset:attach_task. Are we ok with
CAP_SYS_NICE being used to confine to a cpuset?
task_setioprio
task_setnice
sys_setpriority uses this (through set_one_prio) for another
process. Need same checks as setrlimitAug 21:
Updated secureexec implementation to reflect the fact that
euid and uid might be the same and nonzero, but the process
might still have elevated caps.Aug 15:
Handle endianness of xattrs.
Enforce capability version match between kernel and disk.
Enforce that no bits beyond the known max capability are
set, else return -EPERM.
With this extra processing, it may be worth reconsidering
doing all the work at bprm_set_security rather than
d_instantiate.Aug 10:
Always call getxattr at bprm_set_security, rather than
caching it at d_instantiate.[morgan@kernel.org: file-caps clean up for linux/capability.h]
[bunk@kernel.org: unexport cap_inode_killpriv]
Signed-off-by: Serge E. Hallyn
Cc: Stephen Smalley
Cc: James Morris
Cc: Chris Wright
Cc: Andrew Morgan
Signed-off-by: Andrew Morgan
Signed-off-by: Adrian Bunk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Jul, 2007
1 commit
-
Remove the obviously unnecessary includes of under the
include/linux/ directory, and fix the couple errors that are introduced as
a result of that.Signed-off-by: Robert P. J. Day
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
24 May, 2007
1 commit
-
include/linux/capability.h:397: warning: "struct task_struct" declared inside parameter list
include/linux/capability.h:397: warning: its scope is only this definition or declaration, which is probably not what you wantSigned-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
26 Mar, 2006
1 commit
-
Move capable() to kernel/capability.c and eliminate duplicate
implementations. Add __capable() function which can be used to check for
capabiilty of any process.Signed-off-by: Chris Wright
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Jan, 2006
1 commit
-
- Move capable() from sched.h to capability.h;
- Use where capable() is used
(in include/, block/, ipc/, kernel/, a few drivers/,
mm/, security/, & sound/;
many more drivers/ to go)Signed-off-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Sep, 2005
1 commit
-
Add a capability check to sys_set_zone_reclaim(). This syscall is not
something that should be available to a user.Signed-off-by: Martin Hicks
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Apr, 2005
1 commit
-
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.Let it rip!
