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TOMOYO Linux performs pathname based access control.
To remove factors that make pathname based access control difficult
(e.g. symbolic links, "..", "//" etc.), TOMOYO Linux derives realpath
of requested pathname from "struct dentry" and "struct vfsmount".
The maximum length of string data is limited to 4000 including trailing '\0'.
Since TOMOYO Linux uses '\ooo' style representation for non ASCII printable
characters, maybe TOMOYO Linux should be able to support 16336 (which means
(NAME_MAX * (PATH_MAX / (NAME_MAX + 1)) * 4 + (PATH_MAX / (NAME_MAX + 1)))
including trailing '\0'), but I think 4000 is enough for practical use.
TOMOYO uses only 0x21 - 0x7E (as printable characters) and 0x20 (as word
delimiter) and 0x0A (as line delimiter).
0x01 - 0x20 and 0x80 - 0xFF is handled in \ooo style representation.
The reason to use \ooo is to guarantee that "%s" won't damage logs.
Userland program can request
open("/tmp/file granted.\nAccess /tmp/file ", O_WRONLY | O_CREAT, 0600)
and logging such crazy pathname using "Access %s denied.\n" format will cause
"fabrication of logs" like
Access /tmp/file granted.
Access /tmp/file denied.
TOMOYO converts such characters to \ooo so that the logs will become
Access /tmp/file\040granted.\012Access\040/tmp/file denied.
and the administrator can read the logs safely using /bin/cat .
Likewise, a crazy request like
open("/tmp/\x01\x02\x03\x04\x05\x06\x07\x08\x09", O_WRONLY | O_CREAT, 0600)
will be processed safely by converting to
Access /tmp/\001\002\003\004\005\006\007\010\011 denied.
Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp>
Signed-off-by: James Morris <jmorris@namei.org>
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Based on discussions on linux-audit, as per Steve Grubb's request
http://lkml.org/lkml/2009/2/6/269, the following changes were made:
- forced audit result to be either 0 or 1.
- made template names const
- Added new stand-alone message type: AUDIT_INTEGRITY_RULE
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Conflicts:
fs/namei.c
Manually merged per:
diff --cc fs/namei.c
index 734f2b5,bbc15c2..0000000
--- a/fs/namei.c
+++ b/fs/namei.c
@@@ -860,9 -848,8 +849,10 @@@ static int __link_path_walk(const char
nd->flags |= LOOKUP_CONTINUE;
err = exec_permission_lite(inode);
if (err == -EAGAIN)
- err = vfs_permission(nd, MAY_EXEC);
+ err = inode_permission(nd->path.dentry->d_inode,
+ MAY_EXEC);
+ if (!err)
+ err = ima_path_check(&nd->path, MAY_EXEC);
if (err)
break;
@@@ -1525,14 -1506,9 +1509,14 @@@ int may_open(struct path *path, int acc
flag &= ~O_TRUNC;
}
- error = vfs_permission(nd, acc_mode);
+ error = inode_permission(inode, acc_mode);
if (error)
return error;
+
- error = ima_path_check(&nd->path,
++ error = ima_path_check(path,
+ acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC));
+ if (error)
+ return error;
/*
* An append-only file must be opened in append mode for writing.
*/
Signed-off-by: James Morris <jmorris@namei.org>
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Fix ima_delete_rules() definition so sparse doesn't complain.
Signed-off-by: James Morris <jmorris@namei.org>
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The number of calls to ima_path_check()/ima_file_free()
should be balanced. An extra call to fput(), indicates
the file could have been accessed without first being
measured.
Although f_count is incremented/decremented in places other
than fget/fput, like fget_light/fput_light and get_file, the
current task must already hold a file refcnt. The call to
__fput() is delayed until the refcnt becomes 0, resulting
in ima_file_free() flagging any changes.
- add hook to increment opencount for IPC shared memory(SYSV),
shmat files, and /dev/zero
- moved NULL iint test in opencount_get()
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Sequentialize access to the policy file
- permit multiple attempts to replace default policy with a valid policy
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Support for a user loadable policy through securityfs
with support for LSM specific policy data.
- free invalid rule in ima_parse_add_rule()
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Make the measurement lists available through securityfs.
- removed test for NULL return code from securityfs_create_file/dir
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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IMA provides hardware (TPM) based measurement and attestation for
file measurements. As the Trusted Computing (TPM) model requires,
IMA measures all files before they are accessed in any way (on the
integrity_bprm_check, integrity_path_check and integrity_file_mmap
hooks), and commits the measurements to the TPM. Once added to the
TPM, measurements can not be removed.
In addition, IMA maintains a list of these file measurements, which
can be used to validate the aggregate value stored in the TPM. The
TPM can sign these measurements, and thus the system can prove, to
itself and to a third party, the system's integrity in a way that
cannot be circumvented by malicious or compromised software.
- alloc ima_template_entry before calling ima_store_template()
- log ima_add_boot_aggregate() failure
- removed unused IMA_TEMPLATE_NAME_LEN
- replaced hard coded string length with #define name
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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If there is an error creating a file through securityfs_create_file,
NULL is not returned, rather the error is propagated.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove SELinux hooks which do nothing except defer to the capabilites
hooks (or in one case, replicates the function).
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
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Remove secondary ops call to shm_shmat, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to unix_stream_connect, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to task_kill, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to task_setrlimit, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove unused cred_commit hook from SELinux. This
currently calls into the capabilities hook, which is a noop.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to task_create, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to file_mprotect, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to inode_setattr, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to inode_permission, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to inode_follow_link, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to inode_mknod, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to inode_unlink, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to inode_link, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to sb_umount, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to sb_mount, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to bprm_committed_creds, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove secondary ops call to bprm_committing_creds, which is
a noop in capabilities.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Remove unused bprm_check_security hook from SELinux. This
currently calls into the capabilities hook, which is a noop.
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Given just how hard it is to find the code that uses MAY_APPEND
it's probably not a big surprise that this went unnoticed for so
long. The Smack rules loading code is incorrectly setting the
MAY_READ bit when MAY_APPEND is requested.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Context mounts and genfs labeled file systems behave differently with respect to
setting file system labels. This patch brings genfs labeled file systems in line
with context mounts in that setxattr calls to them should return EOPNOTSUPP and
fscreate calls will be ignored.
Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@macbook.localdomain>
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There is no easy way to tell if a file system supports SELinux security labeling.
Because of this a new flag is being added to the super block security structure
to indicate that the particular super block supports labeling. This flag is set
for file systems using the xattr, task, and transition labeling methods unless
that behavior is overridden by context mounts.
Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@macbook.localdomain>
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code.
The super block security structure currently has three fields for what are
essentially flags. The flags field is used for mount options while two other
char fields are used for initialization and proc flags. These latter two fields are
essentially bit fields since the only used values are 0 and 1. These fields
have been collapsed into the flags field and new bit masks have been added for
them. The code is also fixed to work with these new flags.
Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@macbook.localdomain>
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Plug this leak.
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <stable@kernel.org>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The devcgroup_inode_permission() hook in the devices whitelist cgroup has
always bypassed access checks on fifos. But the mknod hook did not. The
devices whitelist is only about block and char devices, and fifos can't
even be added to the whitelist, so fifos can't be created at all except by
tasks which have 'a' in their whitelist (meaning they have access to all
devices).
Fix the behavior by bypassing access checks to mkfifo.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: James Morris <jmorris@namei.org>
Reported-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Cc: <stable@kernel.org> [2.6.27.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We should use list_for_each_entry_rcu in RCU read site.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix a regression in cap_capable() due to:
commit 3b11a1decef07c19443d24ae926982bc8ec9f4c0
Author: David Howells <dhowells@redhat.com>
Date: Fri Nov 14 10:39:26 2008 +1100
CRED: Differentiate objective and effective subjective credentials on a task
The problem is that the above patch allows a process to have two sets of
credentials, and for the most part uses the subjective credentials when
accessing current's creds.
There is, however, one exception: cap_capable(), and thus capable(), uses the
real/objective credentials of the target task, whether or not it is the current
task.
Ordinarily this doesn't matter, since usually the two cred pointers in current
point to the same set of creds. However, sys_faccessat() makes use of this
facility to override the credentials of the calling process to make its test,
without affecting the creds as seen from other processes.
One of the things sys_faccessat() does is to make an adjustment to the
effective capabilities mask, which cap_capable(), as it stands, then ignores.
The affected capability check is in generic_permission():
if (!(mask & MAY_EXEC) || execute_ok(inode))
if (capable(CAP_DAC_OVERRIDE))
return 0;
This change passes the set of credentials to be tested down into the commoncap
and SELinux code. The security functions called by capable() and
has_capability() select the appropriate set of credentials from the process
being checked.
This can be tested by compiling the following program from the XFS testsuite:
/*
* t_access_root.c - trivial test program to show permission bug.
*
* Written by Michael Kerrisk - copyright ownership not pursued.
* Sourced from: http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-10/6030.html
*/
#include <limits.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#define UID 500
#define GID 100
#define PERM 0
#define TESTPATH "/tmp/t_access"
static void
errExit(char *msg)
{
perror(msg);
exit(EXIT_FAILURE);
} /* errExit */
static void
accessTest(char *file, int mask, char *mstr)
{
printf("access(%s, %s) returns %d\n", file, mstr, access(file, mask));
} /* accessTest */
int
main(int argc, char *argv[])
{
int fd, perm, uid, gid;
char *testpath;
char cmd[PATH_MAX + 20];
testpath = (argc > 1) ? argv[1] : TESTPATH;
perm = (argc > 2) ? strtoul(argv[2], NULL, 8) : PERM;
uid = (argc > 3) ? atoi(argv[3]) : UID;
gid = (argc > 4) ? atoi(argv[4]) : GID;
unlink(testpath);
fd = open(testpath, O_RDWR | O_CREAT, 0);
if (fd == -1) errExit("open");
if (fchown(fd, uid, gid) == -1) errExit("fchown");
if (fchmod(fd, perm) == -1) errExit("fchmod");
close(fd);
snprintf(cmd, sizeof(cmd), "ls -l %s", testpath);
system(cmd);
if (seteuid(uid) == -1) errExit("seteuid");
accessTest(testpath, 0, "0");
accessTest(testpath, R_OK, "R_OK");
accessTest(testpath, W_OK, "W_OK");
accessTest(testpath, X_OK, "X_OK");
accessTest(testpath, R_OK | W_OK, "R_OK | W_OK");
accessTest(testpath, R_OK | X_OK, "R_OK | X_OK");
accessTest(testpath, W_OK | X_OK, "W_OK | X_OK");
accessTest(testpath, R_OK | W_OK | X_OK, "R_OK | W_OK | X_OK");
exit(EXIT_SUCCESS);
} /* main */
This can be run against an Ext3 filesystem as well as against an XFS
filesystem. If successful, it will show:
[root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043
---------- 1 dhowells dhowells 0 2008-12-31 03:00 /tmp/xxx
access(/tmp/xxx, 0) returns 0
access(/tmp/xxx, R_OK) returns 0
access(/tmp/xxx, W_OK) returns 0
access(/tmp/xxx, X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK) returns 0
access(/tmp/xxx, R_OK | X_OK) returns -1
access(/tmp/xxx, W_OK | X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1
If unsuccessful, it will show:
[root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043
---------- 1 dhowells dhowells 0 2008-12-31 02:56 /tmp/xxx
access(/tmp/xxx, 0) returns 0
access(/tmp/xxx, R_OK) returns -1
access(/tmp/xxx, W_OK) returns -1
access(/tmp/xxx, X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK) returns -1
access(/tmp/xxx, R_OK | X_OK) returns -1
access(/tmp/xxx, W_OK | X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1
I've also tested the fix with the SELinux and syscalls LTP testsuites.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: J. Bruce Fields <bfields@citi.umich.edu>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
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[ver #2]"
This reverts commit 14eaddc967b16017d4a1a24d2be6c28ecbe06ed8.
David has a better version to come.
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
inotify: fix type errors in interfaces
fix breakage in reiserfs_new_inode()
fix the treatment of jfs special inodes
vfs: remove duplicate code in get_fs_type()
add a vfs_fsync helper
sys_execve and sys_uselib do not call into fsnotify
zero i_uid/i_gid on inode allocation
inode->i_op is never NULL
ntfs: don't NULL i_op
isofs check for NULL ->i_op in root directory is dead code
affs: do not zero ->i_op
kill suid bit only for regular files
vfs: lseek(fd, 0, SEEK_CUR) race condition
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... and don't bother in callers. Don't bother with zeroing i_blocks,
while we are at it - it's already been zeroed.
i_mode is not worth the effort; it has no common default value.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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We used to have rather schizophrenic set of checks for NULL ->i_op even
though it had been eliminated years ago. You'd need to go out of your
way to set it to NULL explicitly _and_ a bunch of code would die on
such inodes anyway. After killing two remaining places that still
did that bogosity, all that crap can go away.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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I started playing with pahole today and decided to put it against the
selinux structures. Found we could save a little bit of space on x86_64
(and no harm on i686) just reorganizing some structs.
Object size changes:
av_inherit: 24 -> 16
selinux_class_perm: 48 -> 40
context: 80 -> 72
Admittedly there aren't many of av_inherit or selinux_class_perm's in
the kernel (33 and 1 respectively) But the change to the size of struct
context reverberate out a bit. I can get some hard number if they are
needed, but I don't see why they would be. We do change which cacheline
context->len and context->str would be on, but I don't see that as a
problem since we are clearly going to have to load both if the context
is to be of any value. I've run with the patch and don't seem to be
having any problems.
An example of what's going on using struct av_inherit would be:
form: to:
struct av_inherit { struct av_inherit {
u16 tclass; const char **common_pts;
const char **common_pts; u32 common_base;
u32 common_base; u16 tclass;
};
(notice all I did was move u16 tclass to the end of the struct instead
of the beginning)
Memory layout before the change:
struct av_inherit {
u16 tclass; /* 2 */
/* 6 bytes hole */
const char** common_pts; /* 8 */
u32 common_base; /* 4 */
/* 4 byes padding */
/* size: 24, cachelines: 1 */
/* sum members: 14, holes: 1, sum holes: 6 */
/* padding: 4 */
};
Memory layout after the change:
struct av_inherit {
const char ** common_pts; /* 8 */
u32 common_base; /* 4 */
u16 tclass; /* 2 */
/* 2 bytes padding */
/* size: 16, cachelines: 1 */
/* sum members: 14, holes: 0, sum holes: 0 */
/* padding: 2 */
};
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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Fix a regression in cap_capable() due to:
commit 5ff7711e635b32f0a1e558227d030c7e45b4a465
Author: David Howells <dhowells@redhat.com>
Date: Wed Dec 31 02:52:28 2008 +0000
CRED: Differentiate objective and effective subjective credentials on a task
The problem is that the above patch allows a process to have two sets of
credentials, and for the most part uses the subjective credentials when
accessing current's creds.
There is, however, one exception: cap_capable(), and thus capable(), uses the
real/objective credentials of the target task, whether or not it is the current
task.
Ordinarily this doesn't matter, since usually the two cred pointers in current
point to the same set of creds. However, sys_faccessat() makes use of this
facility to override the credentials of the calling process to make its test,
without affecting the creds as seen from other processes.
One of the things sys_faccessat() does is to make an adjustment to the
effective capabilities mask, which cap_capable(), as it stands, then ignores.
The affected capability check is in generic_permission():
if (!(mask & MAY_EXEC) || execute_ok(inode))
if (capable(CAP_DAC_OVERRIDE))
return 0;
This change splits capable() from has_capability() down into the commoncap and
SELinux code. The capable() security op now only deals with the current
process, and uses the current process's subjective creds. A new security op -
task_capable() - is introduced that can check any task's objective creds.
strictly the capable() security op is superfluous with the presence of the
task_capable() op, however it should be faster to call the capable() op since
two fewer arguments need be passed down through the various layers.
This can be tested by compiling the following program from the XFS testsuite:
/*
* t_access_root.c - trivial test program to show permission bug.
*
* Written by Michael Kerrisk - copyright ownership not pursued.
* Sourced from: http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-10/6030.html
*/
#include <limits.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#define UID 500
#define GID 100
#define PERM 0
#define TESTPATH "/tmp/t_access"
static void
errExit(char *msg)
{
perror(msg);
exit(EXIT_FAILURE);
} /* errExit */
static void
accessTest(char *file, int mask, char *mstr)
{
printf("access(%s, %s) returns %d\n", file, mstr, access(file, mask));
} /* accessTest */
int
main(int argc, char *argv[])
{
int fd, perm, uid, gid;
char *testpath;
char cmd[PATH_MAX + 20];
testpath = (argc > 1) ? argv[1] : TESTPATH;
perm = (argc > 2) ? strtoul(argv[2], NULL, 8) : PERM;
uid = (argc > 3) ? atoi(argv[3]) : UID;
gid = (argc > 4) ? atoi(argv[4]) : GID;
unlink(testpath);
fd = open(testpath, O_RDWR | O_CREAT, 0);
if (fd == -1) errExit("open");
if (fchown(fd, uid, gid) == -1) errExit("fchown");
if (fchmod(fd, perm) == -1) errExit("fchmod");
close(fd);
snprintf(cmd, sizeof(cmd), "ls -l %s", testpath);
system(cmd);
if (seteuid(uid) == -1) errExit("seteuid");
accessTest(testpath, 0, "0");
accessTest(testpath, R_OK, "R_OK");
accessTest(testpath, W_OK, "W_OK");
accessTest(testpath, X_OK, "X_OK");
accessTest(testpath, R_OK | W_OK, "R_OK | W_OK");
accessTest(testpath, R_OK | X_OK, "R_OK | X_OK");
accessTest(testpath, W_OK | X_OK, "W_OK | X_OK");
accessTest(testpath, R_OK | W_OK | X_OK, "R_OK | W_OK | X_OK");
exit(EXIT_SUCCESS);
} /* main */
This can be run against an Ext3 filesystem as well as against an XFS
filesystem. If successful, it will show:
[root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043
---------- 1 dhowells dhowells 0 2008-12-31 03:00 /tmp/xxx
access(/tmp/xxx, 0) returns 0
access(/tmp/xxx, R_OK) returns 0
access(/tmp/xxx, W_OK) returns 0
access(/tmp/xxx, X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK) returns 0
access(/tmp/xxx, R_OK | X_OK) returns -1
access(/tmp/xxx, W_OK | X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1
If unsuccessful, it will show:
[root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043
---------- 1 dhowells dhowells 0 2008-12-31 02:56 /tmp/xxx
access(/tmp/xxx, 0) returns 0
access(/tmp/xxx, R_OK) returns -1
access(/tmp/xxx, W_OK) returns -1
access(/tmp/xxx, X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK) returns -1
access(/tmp/xxx, R_OK | X_OK) returns -1
access(/tmp/xxx, W_OK | X_OK) returns -1
access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1
I've also tested the fix with the SELinux and syscalls LTP testsuites.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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git://git.infradead.org/users/pcmoore/lblnet-2.6_next into next
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Don't store the field->op in the messy (and very inconvenient for e.g.
audit_comparator()) form; translate to dense set of values and do full
validation of userland-submitted value while we are at it.
->audit_init_rule() and ->audit_match_rule() get new values now; in-tree
instances updated.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (77 commits)
x86: setup_per_cpu_areas() cleanup
cpumask: fix compile error when CONFIG_NR_CPUS is not defined
cpumask: use alloc_cpumask_var_node where appropriate
cpumask: convert shared_cpu_map in acpi_processor* structs to cpumask_var_t
x86: use cpumask_var_t in acpi/boot.c
x86: cleanup some remaining usages of NR_CPUS where s/b nr_cpu_ids
sched: put back some stack hog changes that were undone in kernel/sched.c
x86: enable cpus display of kernel_max and offlined cpus
ia64: cpumask fix for is_affinity_mask_valid()
cpumask: convert RCU implementations, fix
xtensa: define __fls
mn10300: define __fls
m32r: define __fls
h8300: define __fls
frv: define __fls
cris: define __fls
cpumask: CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
cpumask: zero extra bits in alloc_cpumask_var_node
cpumask: replace for_each_cpu_mask_nr with for_each_cpu in kernel/time/
cpumask: convert mm/
...
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