|
|
|
/*
|
|
|
|
* linux/fs/attr.c
|
|
|
|
*
|
|
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
|
|
* changes by Thomas Schoebel-Theuer
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include <linux/module.h>
|
|
|
|
#include <linux/time.h>
|
|
|
|
#include <linux/mm.h>
|
|
|
|
#include <linux/string.h>
|
|
|
|
#include <linux/capability.h>
|
[PATCH] inotify
inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:
* dnotify requires the opening of one fd per each directory
that you intend to watch. This quickly results in too many
open files and pins removable media, preventing unmount.
* dnotify is directory-based. You only learn about changes to
directories. Sure, a change to a file in a directory affects
the directory, but you are then forced to keep a cache of
stat structures.
* dnotify's interface to user-space is awful. Signals?
inotify provides a more usable, simple, powerful solution to file change
notification:
* inotify's interface is a system call that returns a fd, not SIGIO.
You get a single fd, which is select()-able.
* inotify has an event that says "the filesystem that the item
you were watching is on was unmounted."
* inotify can watch directories or files.
Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.
See Documentation/filesystems/inotify.txt.
Signed-off-by: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
20 years ago
|
|
|
#include <linux/fsnotify.h>
|
|
|
|
#include <linux/fcntl.h>
|
|
|
|
#include <linux/quotaops.h>
|
|
|
|
#include <linux/security.h>
|
|
|
|
|
|
|
|
/* Taken over from the old code... */
|
|
|
|
|
|
|
|
/* POSIX UID/GID verification for setting inode attributes. */
|
|
|
|
int inode_change_ok(struct inode *inode, struct iattr *attr)
|
|
|
|
{
|
|
|
|
int retval = -EPERM;
|
|
|
|
unsigned int ia_valid = attr->ia_valid;
|
|
|
|
|
|
|
|
/* If force is set do it anyway. */
|
|
|
|
if (ia_valid & ATTR_FORCE)
|
|
|
|
goto fine;
|
|
|
|
|
|
|
|
/* Make sure a caller can chown. */
|
|
|
|
if ((ia_valid & ATTR_UID) &&
|
|
|
|
(current->fsuid != inode->i_uid ||
|
|
|
|
attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
/* Make sure caller can chgrp. */
|
|
|
|
if ((ia_valid & ATTR_GID) &&
|
|
|
|
(current->fsuid != inode->i_uid ||
|
|
|
|
(!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
|
|
|
|
!capable(CAP_CHOWN))
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
/* Make sure a caller can chmod. */
|
|
|
|
if (ia_valid & ATTR_MODE) {
|
|
|
|
if (!is_owner_or_cap(inode))
|
|
|
|
goto error;
|
|
|
|
/* Also check the setgid bit! */
|
|
|
|
if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
|
|
|
|
inode->i_gid) && !capable(CAP_FSETID))
|
|
|
|
attr->ia_mode &= ~S_ISGID;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Check for setting the inode time. */
|
|
|
|
if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
|
|
|
|
if (!is_owner_or_cap(inode))
|
|
|
|
goto error;
|
|
|
|
}
|
|
|
|
fine:
|
|
|
|
retval = 0;
|
|
|
|
error:
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(inode_change_ok);
|
|
|
|
|
|
|
|
int inode_setattr(struct inode * inode, struct iattr * attr)
|
|
|
|
{
|
|
|
|
unsigned int ia_valid = attr->ia_valid;
|
|
|
|
|
|
|
|
if (ia_valid & ATTR_SIZE &&
|
|
|
|
attr->ia_size != i_size_read(inode)) {
|
|
|
|
int error = vmtruncate(inode, attr->ia_size);
|
|
|
|
if (error)
|
|
|
|
return error;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (ia_valid & ATTR_UID)
|
|
|
|
inode->i_uid = attr->ia_uid;
|
|
|
|
if (ia_valid & ATTR_GID)
|
|
|
|
inode->i_gid = attr->ia_gid;
|
|
|
|
if (ia_valid & ATTR_ATIME)
|
|
|
|
inode->i_atime = timespec_trunc(attr->ia_atime,
|
|
|
|
inode->i_sb->s_time_gran);
|
|
|
|
if (ia_valid & ATTR_MTIME)
|
|
|
|
inode->i_mtime = timespec_trunc(attr->ia_mtime,
|
|
|
|
inode->i_sb->s_time_gran);
|
|
|
|
if (ia_valid & ATTR_CTIME)
|
|
|
|
inode->i_ctime = timespec_trunc(attr->ia_ctime,
|
|
|
|
inode->i_sb->s_time_gran);
|
|
|
|
if (ia_valid & ATTR_MODE) {
|
|
|
|
umode_t mode = attr->ia_mode;
|
|
|
|
|
|
|
|
if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
|
|
|
|
mode &= ~S_ISGID;
|
|
|
|
inode->i_mode = mode;
|
|
|
|
}
|
|
|
|
mark_inode_dirty(inode);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(inode_setattr);
|
|
|
|
|
|
|
|
int notify_change(struct dentry * dentry, struct iattr * attr)
|
|
|
|
{
|
|
|
|
struct inode *inode = dentry->d_inode;
|
VFS: make notify_change pass ATTR_KILL_S*ID to setattr operations
When an unprivileged process attempts to modify a file that has the setuid or
setgid bits set, the VFS will attempt to clear these bits. The VFS will set
the ATTR_KILL_SUID or ATTR_KILL_SGID bits in the ia_valid mask, and then call
notify_change to clear these bits and set the mode accordingly.
With a networked filesystem (NFS and CIFS in particular but likely others),
the client machine or process may not have credentials that allow for setting
the mode. In some situations, this can lead to file corruption, an operation
failing outright because the setattr fails, or to races that lead to a mode
change being reverted.
In this situation, we'd like to just leave the handling of this to the server
and ignore these bits. The problem is that by the time the setattr op is
called, the VFS has already reinterpreted the ATTR_KILL_* bits into a mode
change. The setattr operation has no way to know its intent.
The following patch fixes this by making notify_change no longer clear the
ATTR_KILL_SUID and ATTR_KILL_SGID bits in the ia_valid before handing it off
to the setattr inode op. setattr can then check for the presence of these
bits, and if they're set it can assume that the mode change was only for the
purposes of clearing these bits.
This means that we now have an implicit assumption that notify_change is never
called with ATTR_MODE and either ATTR_KILL_S*ID bit set. Nothing currently
enforces that, so this patch also adds a BUG() if that occurs.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
17 years ago
|
|
|
mode_t mode = inode->i_mode;
|
|
|
|
int error;
|
|
|
|
struct timespec now;
|
|
|
|
unsigned int ia_valid = attr->ia_valid;
|
|
|
|
|
|
|
|
now = current_fs_time(inode->i_sb);
|
|
|
|
|
|
|
|
attr->ia_ctime = now;
|
|
|
|
if (!(ia_valid & ATTR_ATIME_SET))
|
|
|
|
attr->ia_atime = now;
|
|
|
|
if (!(ia_valid & ATTR_MTIME_SET))
|
|
|
|
attr->ia_mtime = now;
|
Implement file posix capabilities
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 setrlimit
Aug 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 <serue@us.ibm.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Andrew Morgan <morgan@kernel.org>
Signed-off-by: Andrew Morgan <morgan@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
17 years ago
|
|
|
if (ia_valid & ATTR_KILL_PRIV) {
|
|
|
|
attr->ia_valid &= ~ATTR_KILL_PRIV;
|
|
|
|
ia_valid &= ~ATTR_KILL_PRIV;
|
|
|
|
error = security_inode_need_killpriv(dentry);
|
|
|
|
if (error > 0)
|
|
|
|
error = security_inode_killpriv(dentry);
|
|
|
|
if (error)
|
|
|
|
return error;
|
|
|
|
}
|
VFS: make notify_change pass ATTR_KILL_S*ID to setattr operations
When an unprivileged process attempts to modify a file that has the setuid or
setgid bits set, the VFS will attempt to clear these bits. The VFS will set
the ATTR_KILL_SUID or ATTR_KILL_SGID bits in the ia_valid mask, and then call
notify_change to clear these bits and set the mode accordingly.
With a networked filesystem (NFS and CIFS in particular but likely others),
the client machine or process may not have credentials that allow for setting
the mode. In some situations, this can lead to file corruption, an operation
failing outright because the setattr fails, or to races that lead to a mode
change being reverted.
In this situation, we'd like to just leave the handling of this to the server
and ignore these bits. The problem is that by the time the setattr op is
called, the VFS has already reinterpreted the ATTR_KILL_* bits into a mode
change. The setattr operation has no way to know its intent.
The following patch fixes this by making notify_change no longer clear the
ATTR_KILL_SUID and ATTR_KILL_SGID bits in the ia_valid before handing it off
to the setattr inode op. setattr can then check for the presence of these
bits, and if they're set it can assume that the mode change was only for the
purposes of clearing these bits.
This means that we now have an implicit assumption that notify_change is never
called with ATTR_MODE and either ATTR_KILL_S*ID bit set. Nothing currently
enforces that, so this patch also adds a BUG() if that occurs.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
17 years ago
|
|
|
|
|
|
|
/*
|
|
|
|
* We now pass ATTR_KILL_S*ID to the lower level setattr function so
|
|
|
|
* that the function has the ability to reinterpret a mode change
|
|
|
|
* that's due to these bits. This adds an implicit restriction that
|
|
|
|
* no function will ever call notify_change with both ATTR_MODE and
|
|
|
|
* ATTR_KILL_S*ID set.
|
|
|
|
*/
|
|
|
|
if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
|
|
|
|
(ia_valid & ATTR_MODE))
|
|
|
|
BUG();
|
|
|
|
|
|
|
|
if (ia_valid & ATTR_KILL_SUID) {
|
|
|
|
if (mode & S_ISUID) {
|
VFS: make notify_change pass ATTR_KILL_S*ID to setattr operations
When an unprivileged process attempts to modify a file that has the setuid or
setgid bits set, the VFS will attempt to clear these bits. The VFS will set
the ATTR_KILL_SUID or ATTR_KILL_SGID bits in the ia_valid mask, and then call
notify_change to clear these bits and set the mode accordingly.
With a networked filesystem (NFS and CIFS in particular but likely others),
the client machine or process may not have credentials that allow for setting
the mode. In some situations, this can lead to file corruption, an operation
failing outright because the setattr fails, or to races that lead to a mode
change being reverted.
In this situation, we'd like to just leave the handling of this to the server
and ignore these bits. The problem is that by the time the setattr op is
called, the VFS has already reinterpreted the ATTR_KILL_* bits into a mode
change. The setattr operation has no way to know its intent.
The following patch fixes this by making notify_change no longer clear the
ATTR_KILL_SUID and ATTR_KILL_SGID bits in the ia_valid before handing it off
to the setattr inode op. setattr can then check for the presence of these
bits, and if they're set it can assume that the mode change was only for the
purposes of clearing these bits.
This means that we now have an implicit assumption that notify_change is never
called with ATTR_MODE and either ATTR_KILL_S*ID bit set. Nothing currently
enforces that, so this patch also adds a BUG() if that occurs.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
17 years ago
|
|
|
ia_valid = attr->ia_valid |= ATTR_MODE;
|
|
|
|
attr->ia_mode = (inode->i_mode & ~S_ISUID);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
if (ia_valid & ATTR_KILL_SGID) {
|
|
|
|
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
|
|
|
|
if (!(ia_valid & ATTR_MODE)) {
|
|
|
|
ia_valid = attr->ia_valid |= ATTR_MODE;
|
|
|
|
attr->ia_mode = inode->i_mode;
|
|
|
|
}
|
|
|
|
attr->ia_mode &= ~S_ISGID;
|
|
|
|
}
|
|
|
|
}
|
VFS: make notify_change pass ATTR_KILL_S*ID to setattr operations
When an unprivileged process attempts to modify a file that has the setuid or
setgid bits set, the VFS will attempt to clear these bits. The VFS will set
the ATTR_KILL_SUID or ATTR_KILL_SGID bits in the ia_valid mask, and then call
notify_change to clear these bits and set the mode accordingly.
With a networked filesystem (NFS and CIFS in particular but likely others),
the client machine or process may not have credentials that allow for setting
the mode. In some situations, this can lead to file corruption, an operation
failing outright because the setattr fails, or to races that lead to a mode
change being reverted.
In this situation, we'd like to just leave the handling of this to the server
and ignore these bits. The problem is that by the time the setattr op is
called, the VFS has already reinterpreted the ATTR_KILL_* bits into a mode
change. The setattr operation has no way to know its intent.
The following patch fixes this by making notify_change no longer clear the
ATTR_KILL_SUID and ATTR_KILL_SGID bits in the ia_valid before handing it off
to the setattr inode op. setattr can then check for the presence of these
bits, and if they're set it can assume that the mode change was only for the
purposes of clearing these bits.
This means that we now have an implicit assumption that notify_change is never
called with ATTR_MODE and either ATTR_KILL_S*ID bit set. Nothing currently
enforces that, so this patch also adds a BUG() if that occurs.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
17 years ago
|
|
|
if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
if (ia_valid & ATTR_SIZE)
|
|
|
|
down_write(&dentry->d_inode->i_alloc_sem);
|
|
|
|
|
|
|
|
if (inode->i_op && inode->i_op->setattr) {
|
|
|
|
error = security_inode_setattr(dentry, attr);
|
|
|
|
if (!error)
|
|
|
|
error = inode->i_op->setattr(dentry, attr);
|
|
|
|
} else {
|
|
|
|
error = inode_change_ok(inode, attr);
|
|
|
|
if (!error)
|
|
|
|
error = security_inode_setattr(dentry, attr);
|
|
|
|
if (!error) {
|
|
|
|
if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
|
|
|
|
(ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
|
|
|
|
error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
|
|
|
|
if (!error)
|
|
|
|
error = inode_setattr(inode, attr);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if (ia_valid & ATTR_SIZE)
|
|
|
|
up_write(&dentry->d_inode->i_alloc_sem);
|
|
|
|
|
[PATCH] inotify
inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:
* dnotify requires the opening of one fd per each directory
that you intend to watch. This quickly results in too many
open files and pins removable media, preventing unmount.
* dnotify is directory-based. You only learn about changes to
directories. Sure, a change to a file in a directory affects
the directory, but you are then forced to keep a cache of
stat structures.
* dnotify's interface to user-space is awful. Signals?
inotify provides a more usable, simple, powerful solution to file change
notification:
* inotify's interface is a system call that returns a fd, not SIGIO.
You get a single fd, which is select()-able.
* inotify has an event that says "the filesystem that the item
you were watching is on was unmounted."
* inotify can watch directories or files.
Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.
See Documentation/filesystems/inotify.txt.
Signed-off-by: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
20 years ago
|
|
|
if (!error)
|
|
|
|
fsnotify_change(dentry, ia_valid);
|
|
|
|
|
|
|
|
return error;
|
|
|
|
}
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(notify_change);
|