Merge rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

udev is a userspace application for populating /dev dynamically with

only entries for devices actually present. udev replaces devfs.

FUSE

----

Needs libfuse 2.4.0 or later.  Absolute minimum is 2.3.0 but mount

options 'direct_io' and 'kernel_cache' won't work.

Networking

==========

----

o <http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html>

FUSE

----

o <http://sourceforge.net/projects/fuse>

Networking

**********

point out some special detail about the sign-off. 

12) The canonical patch format

12) More references for submitting patches

The canonical patch subject line is:

    Subject: [PATCH 001/123] subsystem: summary phrase

The canonical patch message body contains the following:

  - A "from" line specifying the patch author.

  - An empty line.

  - The body of the explanation, which will be copied to the

    permanent changelog to describe this patch.

  - The "Signed-off-by:" lines, described above, which will

    also go in the changelog.

  - A marker line containing simply "---".

  - Any additional comments not suitable for the changelog.

  - The actual patch (diff output).

The Subject line format makes it very easy to sort the emails

alphabetically by subject line - pretty much any email reader will

support that - since because the sequence number is zero-padded,

the numerical and alphabetic sort is the same.

The "subsystem" in the email's Subject should identify which

area or subsystem of the kernel is being patched.

The "summary phrase" in the email's Subject should concisely

describe the patch which that email contains.  The "summary

phrase" should not be a filename.  Do not use the same "summary

phrase" for every patch in a whole patch series.

Bear in mind that the "summary phrase" of your email becomes

a globally-unique identifier for that patch.  It propagates

all the way into the git changelog.  The "summary phrase" may

later be used in developer discussions which refer to the patch.

People will want to google for the "summary phrase" to read

discussion regarding that patch.

A couple of example Subjects:

    Subject: [patch 2/5] ext2: improve scalability of bitmap searching

    Subject: [PATCHv2 001/207] x86: fix eflags tracking

The "from" line must be the very first line in the message body,

and has the form:

        From: Original Author <author@example.com>

The "from" line specifies who will be credited as the author of the

patch in the permanent changelog.  If the "from" line is missing,

then the "From:" line from the email header will be used to determine

the patch author in the changelog.

The explanation body will be committed to the permanent source

changelog, so should make sense to a competent reader who has long

since forgotten the immediate details of the discussion that might

have led to this patch.

The "---" marker line serves the essential purpose of marking for patch

handling tools where the changelog message ends.

One good use for the additional comments after the "---" marker is for

a diffstat, to show what files have changed, and the number of inserted

and deleted lines per file.  A diffstat is especially useful on bigger

patches.  Other comments relevant only to the moment or the maintainer,

not suitable for the permanent changelog, should also go here.

See more details on the proper patch format in the following

references.

13) More references for submitting patches

Andrew Morton, "The perfect patch" (tpp).

  <http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt>

Jeff Garzik, "Linux kernel patch submission format."

  <http://linux.yyz.us/patch-format.html>

Greg KH, "How to piss off a kernel subsystem maintainer"

  <http://www.kroah.com/log/2005/03/31/>

Kernel Documentation/CodingStyle

  <http://sosdg.org/~coywolf/lxr/source/Documentation/CodingStyle>

Linus Torvald's mail on the canonical patch format:

  <http://lkml.org/lkml/2005/4/7/183>

-----------------------------------

/sys/class/firmware/dell_rbu/data

/sys/devices/platform/dell_rbu/image_type

/sys/devices/platform/dell_rbu/data

/sys/devices/platform/dell_rbu/packet_size

The driver supports two types of update mechanism; monolithic and packetized.

These update mechanism depends upon the BIOS currently running on the system.

changed to packets during the driver load time by specifying the load

parameter image_type=packet.  This can also be changed later as below

echo packet > /sys/devices/platform/dell_rbu/image_type

Also echoing either mono ,packet or init in to image_type will free up the

memory allocated by the driver.

In packet update mode the packet size has to be given before any packets can

be downloaded. It is done as below

echo XXXX > /sys/devices/platform/dell_rbu/packet_size

In the packet update mechanism, the user neesd to create a new file having

packets of data arranged back to back. It can be done as follows

The user creates packets header, gets the chunk of the BIOS image and

placs it next to the packetheader; now, the packetheader + BIOS image chunk

added to geather should match the specified packet_size. This makes one

packet, the user needs to create more such packets out of the entire BIOS

image file and then arrange all these packets back to back in to one single

file.

This file is then copied to /sys/class/firmware/dell_rbu/data.

Once this file gets to the driver, the driver extracts packet_size data from

the file and spreads it accross the physical memory in contiguous packet_sized

space.

This method makes sure that all the packets get to the driver in a single operation.

In monolithic update the user simply get the BIOS image (.hdr file) and copies

to the data file as is without any change to the BIOS image itself.

Do the steps below to download the BIOS image.

1) echo 1 > /sys/class/firmware/dell_rbu/loading

The /sys/class/firmware/dell_rbu/ entries will remain till the following is

done.

echo -1 > /sys/class/firmware/dell_rbu/loading.

Until this step is completed the drivr cannot be unloaded.

Until this step is completed the driver cannot be unloaded.

Also echoing either mono ,packet or init in to image_type will free up the

memory allocated by the driver.

If an user by accident executes steps 1 and 3 above without executing step 2;

it will make the /sys/class/firmware/dell_rbu/ entries to disappear.

The entries can be recreated by doing the following

NOTE: echoing init in image_type does not change it original value.

Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to

read back the image downloaded. This is useful in case of packet update

mechanism where the above steps 1,2,3 will repeated for every packet.

By reading the /sys/devices/platform/dell_rbu/data file all packet data

downloaded can be verified in a single file.

The packets are arranged in this file one after the other in a FIFO order.

read back the image downloaded.

NOTE:

This driver requires a patch for firmware_class.c which has the addition

of request_firmware_nowait_nohotplug function to wortk

This driver requires a patch for firmware_class.c which has the modified

request_firmware_nowait function.

Also after updating the BIOS image an user mdoe application neeeds to execute

code which message the BIOS update request to the BIOS. So on the next reboot

the BIOS knows about the new image downloaded and it updates it self.

			      ===================

			      KEY REQUEST SERVICE

			      ===================

The key request service is part of the key retention service (refer to

Documentation/keys.txt). This document explains more fully how that the

requesting algorithm works.

The process starts by either the kernel requesting a service by calling

request_key():

	struct key *request_key(const struct key_type *type,

				const char *description,

				const char *callout_string);

Or by userspace invoking the request_key system call:

	key_serial_t request_key(const char *type,

				 const char *description,

				 const char *callout_info,

				 key_serial_t dest_keyring);

The main difference between the two access points is that the in-kernel

interface does not need to link the key to a keyring to prevent it from being

immediately destroyed. The kernel interface returns a pointer directly to the

key, and it's up to the caller to destroy the key.

The userspace interface links the key to a keyring associated with the process

to prevent the key from going away, and returns the serial number of the key to

the caller.

===========

THE PROCESS

===========

A request proceeds in the following manner:

 (1) Process A calls request_key() [the userspace syscall calls the kernel

     interface].

 (2) request_key() searches the process's subscribed keyrings to see if there's

     a suitable key there. If there is, it returns the key. If there isn't, and

     callout_info is not set, an error is returned. Otherwise the process

     proceeds to the next step.

 (3) request_key() sees that A doesn't have the desired key yet, so it creates

     two things:

     (a) An uninstantiated key U of requested type and description.

     (b) An authorisation key V that refers to key U and notes that process A

     	 is the context in which key U should be instantiated and secured, and

     	 from which associated key requests may be satisfied.

 (4) request_key() then forks and executes /sbin/request-key with a new session

     keyring that contains a link to auth key V.

 (5) /sbin/request-key execs an appropriate program to perform the actual

     instantiation.

 (6) The program may want to access another key from A's context (say a

     Kerberos TGT key). It just requests the appropriate key, and the keyring

     search notes that the session keyring has auth key V in its bottom level.

     This will permit it to then search the keyrings of process A with the

     UID, GID, groups and security info of process A as if it was process A,

     and come up with key W.

 (7) The program then does what it must to get the data with which to

     instantiate key U, using key W as a reference (perhaps it contacts a

     Kerberos server using the TGT) and then instantiates key U.

 (8) Upon instantiating key U, auth key V is automatically revoked so that it

     may not be used again.

 (9) The program then exits 0 and request_key() deletes key V and returns key

     U to the caller.

This also extends further. If key W (step 5 above) didn't exist, key W would be

created uninstantiated, another auth key (X) would be created [as per step 3]

and another copy of /sbin/request-key spawned [as per step 4]; but the context

specified by auth key X will still be process A, as it was in auth key V.

This is because process A's keyrings can't simply be attached to

/sbin/request-key at the appropriate places because (a) execve will discard two

of them, and (b) it requires the same UID/GID/Groups all the way through.

======================

NEGATIVE INSTANTIATION

======================

Rather than instantiating a key, it is possible for the possessor of an

authorisation key to negatively instantiate a key that's under construction.

This is a short duration placeholder that causes any attempt at re-requesting

the key whilst it exists to fail with error ENOKEY.

This is provided to prevent excessive repeated spawning of /sbin/request-key

processes for a key that will never be obtainable.

Should the /sbin/request-key process exit anything other than 0 or die on a

signal, the key under construction will be automatically negatively

instantiated for a short amount of time.

====================

THE SEARCH ALGORITHM

====================

A search of any particular keyring proceeds in the following fashion:

 (1) When the key management code searches for a key (keyring_search_aux) it

     firstly calls key_permission(SEARCH) on the keyring it's starting with,

     if this denies permission, it doesn't search further.

 (2) It considers all the non-keyring keys within that keyring and, if any key

     matches the criteria specified, calls key_permission(SEARCH) on it to see

     if the key is allowed to be found. If it is, that key is returned; if

     not, the search continues, and the error code is retained if of higher

     priority than the one currently set.

 (3) It then considers all the keyring-type keys in the keyring it's currently

     searching. It calls key_permission(SEARCH) on each keyring, and if this

     grants permission, it recurses, executing steps (2) and (3) on that

     keyring.

The process stops immediately a valid key is found with permission granted to

use it. Any error from a previous match attempt is discarded and the key is

returned.

When search_process_keyrings() is invoked, it performs the following searches

until one succeeds:

 (1) If extant, the process's thread keyring is searched.

 (2) If extant, the process's process keyring is searched.

 (3) The process's session keyring is searched.

 (4) If the process has a request_key() authorisation key in its session

     keyring then:

     (a) If extant, the calling process's thread keyring is searched.

     (b) If extant, the calling process's process keyring is searched.

     (c) The calling process's session keyring is searched.

The moment one succeeds, all pending errors are discarded and the found key is

returned.

Only if all these fail does the whole thing fail with the highest priority

error. Note that several errors may have come from LSM.

The error priority is:

	EKEYREVOKED > EKEYEXPIRED > ENOKEY

EACCES/EPERM are only returned on a direct search of a specific keyring where

the basal keyring does not grant Search permission.

======================

Keys have an owner user ID, a group access ID, and a permissions mask. The mask

has up to eight bits each for user, group and other access. Only five of each

set of eight bits are defined. These permissions granted are:

has up to eight bits each for possessor, user, group and other access. Only

five of each set of eight bits are defined. These permissions granted are:

 (*) View

     this way:

	SERIAL   FLAGS  USAGE EXPY PERM     UID   GID   TYPE      DESCRIPTION: SUMMARY

	00000001 I-----    39 perm 1f0000     0     0 keyring   _uid_ses.0: 1/4

	00000002 I-----     2 perm 1f0000     0     0 keyring   _uid.0: empty

	00000007 I-----     1 perm 1f0000     0     0 keyring   _pid.1: empty

	0000018d I-----     1 perm 1f0000     0     0 keyring   _pid.412: empty

	000004d2 I--Q--     1 perm 1f0000    32    -1 keyring   _uid.32: 1/4

	000004d3 I--Q--     3 perm 1f0000    32    -1 keyring   _uid_ses.32: empty

	00000892 I--QU-     1 perm 1f0000     0     0 user      metal:copper: 0

	00000893 I--Q-N     1  35s 1f0000     0     0 user      metal:silver: 0

	00000894 I--Q--     1  10h 1f0000     0     0 user      metal:gold: 0

	00000001 I-----    39 perm 1f1f0000     0     0 keyring   _uid_ses.0: 1/4

	00000002 I-----     2 perm 1f1f0000     0     0 keyring   _uid.0: empty

	00000007 I-----     1 perm 1f1f0000     0     0 keyring   _pid.1: empty

	0000018d I-----     1 perm 1f1f0000     0     0 keyring   _pid.412: empty

	000004d2 I--Q--     1 perm 1f1f0000    32    -1 keyring   _uid.32: 1/4

	000004d3 I--Q--     3 perm 1f1f0000    32    -1 keyring   _uid_ses.32: empty

	00000892 I--QU-     1 perm 1f000000     0     0 user      metal:copper: 0

	00000893 I--Q-N     1  35s 1f1f0000     0     0 user      metal:silver: 0

	00000894 I--Q--     1  10h 001f0000     0     0 user      metal:gold: 0

     The flags are:

     /sbin/request-key will be invoked in an attempt to obtain a key. The

     callout_info string will be passed as an argument to the program.

     See also Documentation/keys-request-key.txt.

The keyctl syscall functions are:

 (*) Read the payload data from a key:

	key_serial_t keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer,

	long keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer,

		    size_t buflen);

     This function attempts to read the payload data from the specified key

 (*) Instantiate a partially constructed key.

	key_serial_t keyctl(KEYCTL_INSTANTIATE, key_serial_t key,

	long keyctl(KEYCTL_INSTANTIATE, key_serial_t key,

		    const void *payload, size_t plen,

		    key_serial_t keyring);

 (*) Negatively instantiate a partially constructed key.

	key_serial_t keyctl(KEYCTL_NEGATE, key_serial_t key,

	long keyctl(KEYCTL_NEGATE, key_serial_t key,

		    unsigned timeout, key_serial_t keyring);

     If the kernel calls back to userspace to complete the instantiation of a

two different users opening the same file is left to the filesystem author to

solve.

Note that there are two different types of pointers to keys that may be

encountered:

 (*) struct key *

     This simply points to the key structure itself. Key structures will be at

     least four-byte aligned.

 (*) key_ref_t

     This is equivalent to a struct key *, but the least significant bit is set

     if the caller "possesses" the key. By "possession" it is meant that the

     calling processes has a searchable link to the key from one of its

     keyrings. There are three functions for dealing with these:

	key_ref_t make_key_ref(const struct key *key,

			       unsigned long possession);

	struct key *key_ref_to_ptr(const key_ref_t key_ref);

	unsigned long is_key_possessed(const key_ref_t key_ref);

     The first function constructs a key reference from a key pointer and

     possession information (which must be 0 or 1 and not any other value).

     The second function retrieves the key pointer from a reference and the

     third retrieves the possession flag.

When accessing a key's payload contents, certain precautions must be taken to

prevent access vs modification races. See the section "Notes on accessing

payload contents" for more information.

    If successful, the key will have been attached to the default keyring for

    implicitly obtained request-key keys, as set by KEYCTL_SET_REQKEY_KEYRING.

    See also Documentation/keys-request-key.txt.

(*) When it is no longer required, the key should be released using:

	void key_put(struct key *key);

    This can be called from interrupt context. If CONFIG_KEYS is not set then

    Or:

	void key_ref_put(key_ref_t key_ref);

    These can be called from interrupt context. If CONFIG_KEYS is not set then

    the argument will not be parsed.

(*) If a keyring was found in the search, this can be further searched by:

	struct key *keyring_search(struct key *keyring,

	key_ref_t keyring_search(key_ref_t keyring_ref,

				 const struct key_type *type,

				 const char *description)

    This searches the keyring tree specified for a matching key. Error ENOKEY

    is returned upon failure. If successful, the returned key will need to be

    released.

    is returned upon failure (use IS_ERR/PTR_ERR to determine). If successful,

    the returned key will need to be released.

    The possession attribute from the keyring reference is used to control

    access through the permissions mask and is propagated to the returned key

    reference pointer if successful.

(*) To check the validity of a key, this function can be called:

key->payload.data. One of the following ways must be selected to access the

data:

 (1) Unmodifyable key type.

 (1) Unmodifiable key type.

     If the key type does not have a modify method, then the key's payload can

     be accessed without any form of locking, provided that it's known to be