Kernel Tree For Xiaomi 11 Lite NE 5G
88b4a07e66
This is the transport code for public key functionality in eCryptfs. It manages encryption/decryption request queues with a transport mechanism. Currently, netlink is the only implemented transport. Each inode has a unique File Encryption Key (FEK). Under passphrase, a File Encryption Key Encryption Key (FEKEK) is generated from a salt/passphrase combo on mount. This FEKEK encrypts each FEK and writes it into the header of each file using the packet format specified in RFC 2440. This is all symmetric key encryption, so it can all be done via the kernel crypto API. These new patches introduce public key encryption of the FEK. There is no asymmetric key encryption support in the kernel crypto API, so eCryptfs pushes the FEK encryption and decryption out to a userspace daemon. After considering our requirements and determining the complexity of using various transport mechanisms, we settled on netlink for this communication. eCryptfs stores authentication tokens into the kernel keyring. These tokens correlate with individual keys. For passphrase mode of operation, the authentication token contains the symmetric FEKEK. For public key, the authentication token contains a PKI type and an opaque data blob managed by individual PKI modules in userspace. Each user who opens a file under an eCryptfs partition mounted in public key mode must be running a daemon. That daemon has the user's credentials and has access to all of the keys to which the user should have access. The daemon, when started, initializes the pluggable PKI modules available on the system and registers itself with the eCryptfs kernel module. Userspace utilities register public key authentication tokens into the user session keyring. These authentication tokens correlate key signatures with PKI modules and PKI blobs. The PKI blobs contain PKI-specific information necessary for the PKI module to carry out asymmetric key encryption and decryption. When the eCryptfs module parses the header of an existing file and finds a Tag 1 (Public Key) packet (see RFC 2440), it reads in the public key identifier (signature). The asymmetrically encrypted FEK is in the Tag 1 packet; eCryptfs puts together a decrypt request packet containing the signature and the encrypted FEK, then it passes it to the daemon registered for the current->euid via a netlink unicast to the PID of the daemon, which was registered at the time the daemon was started by the user. The daemon actually just makes calls to libecryptfs, which implements request packet parsing and manages PKI modules. libecryptfs grabs the public key authentication token for the given signature from the user session keyring. This auth tok tells libecryptfs which PKI module should receive the request. libecryptfs then makes a decrypt() call to the PKI module, and it passes along the PKI block from the auth tok. The PKI uses the blob to figure out how it should decrypt the data passed to it; it performs the decryption and passes the decrypted data back to libecryptfs. libecryptfs then puts together a reply packet with the decrypted FEK and passes that back to the eCryptfs module. The eCryptfs module manages these request callouts to userspace code via message context structs. The module maintains an array of message context structs and places the elements of the array on two lists: a free and an allocated list. When eCryptfs wants to make a request, it moves a msg ctx from the free list to the allocated list, sets its state to pending, and fires off the message to the user's registered daemon. When eCryptfs receives a netlink message (via the callback), it correlates the msg ctx struct in the alloc list with the data in the message itself. The msg->index contains the offset of the array of msg ctx structs. It verifies that the registered daemon PID is the same as the PID of the process that sent the message. It also validates a sequence number between the received packet and the msg ctx. Then, it copies the contents of the message (the reply packet) into the msg ctx struct, sets the state in the msg ctx to done, and wakes up the process that was sleeping while waiting for the reply. The sleeping process was whatever was performing the sys_open(). This process originally called ecryptfs_send_message(); it is now in ecryptfs_wait_for_response(). When it wakes up and sees that the msg ctx state was set to done, it returns a pointer to the message contents (the reply packet) and returns. If all went well, this packet contains the decrypted FEK, which is then copied into the crypt_stat struct, and life continues as normal. The case for creation of a new file is very similar, only instead of a decrypt request, eCryptfs sends out an encrypt request. > - We have a great clod of key mangement code in-kernel. Why is that > not suitable (or growable) for public key management? eCryptfs uses Howells' keyring to store persistent key data and PKI state information. It defers public key cryptographic transformations to userspace code. The userspace data manipulation request really is orthogonal to key management in and of itself. What eCryptfs basically needs is a secure way to communicate with a particular daemon for a particular task doing a syscall, based on the UID. Nothing running under another UID should be able to access that channel of communication. > - Is it appropriate that new infrastructure for public key > management be private to a particular fs? The messaging.c file contains a lot of code that, perhaps, could be extracted into a separate kernel service. In essence, this would be a sort of request/reply mechanism that would involve a userspace daemon. I am not aware of anything that does quite what eCryptfs does, so I was not aware of any existing tools to do just what we wanted. > What happens if one of these daemons exits without sending a quit > message? There is a stale uid<->pid association in the hash table for that user. When the user registers a new daemon, eCryptfs cleans up the old association and generates a new one. See ecryptfs_process_helo(). > - _why_ does it use netlink? Netlink provides the transport mechanism that would minimize the complexity of the implementation, given that we can have multiple daemons (one per user). I explored the possibility of using relayfs, but that would involve having to introduce control channels and a protocol for creating and tearing down channels for the daemons. We do not have to worry about any of that with netlink. Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| scripts | ||
| security | ||
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| usr | ||
| .gitignore | ||
| COPYING | ||
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| MAINTAINERS | ||
| Makefile | ||
| README | ||
| REPORTING-BUGS | ||
Linux kernel release 2.6.xx <http://kernel.org/>
These are the release notes for Linux version 2.6. Read them carefully,
as they tell you what this is all about, explain how to install the
kernel, and what to do if something goes wrong.
WHAT IS LINUX?
Linux is a clone of the operating system Unix, written from scratch by
Linus Torvalds with assistance from a loosely-knit team of hackers across
the Net. It aims towards POSIX and Single UNIX Specification compliance.
It has all the features you would expect in a modern fully-fledged Unix,
including true multitasking, virtual memory, shared libraries, demand
loading, shared copy-on-write executables, proper memory management,
and multistack networking including IPv4 and IPv6.
It is distributed under the GNU General Public License - see the
accompanying COPYING file for more details.
ON WHAT HARDWARE DOES IT RUN?
Although originally developed first for 32-bit x86-based PCs (386 or higher),
today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64, AXIS CRIS,
Cris, Xtensa, AVR32 and Renesas M32R architectures.
Linux is easily portable to most general-purpose 32- or 64-bit architectures
as long as they have a paged memory management unit (PMMU) and a port of the
GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
also been ported to a number of architectures without a PMMU, although
functionality is then obviously somewhat limited.
Linux has also been ported to itself. You can now run the kernel as a
userspace application - this is called UserMode Linux (UML).
DOCUMENTATION:
- There is a lot of documentation available both in electronic form on
the Internet and in books, both Linux-specific and pertaining to
general UNIX questions. I'd recommend looking into the documentation
subdirectories on any Linux FTP site for the LDP (Linux Documentation
Project) books. This README is not meant to be documentation on the
system: there are much better sources available.
- There are various README files in the Documentation/ subdirectory:
these typically contain kernel-specific installation notes for some
drivers for example. See Documentation/00-INDEX for a list of what
is contained in each file. Please read the Changes file, as it
contains information about the problems, which may result by upgrading
your kernel.
- The Documentation/DocBook/ subdirectory contains several guides for
kernel developers and users. These guides can be rendered in a
number of formats: PostScript (.ps), PDF, and HTML, among others.
After installation, "make psdocs", "make pdfdocs", or "make htmldocs"
will render the documentation in the requested format.
INSTALLING the kernel:
- If you install the full sources, put the kernel tarball in a
directory where you have permissions (eg. your home directory) and
unpack it:
gzip -cd linux-2.6.XX.tar.gz | tar xvf -
or
bzip2 -dc linux-2.6.XX.tar.bz2 | tar xvf -
Replace "XX" with the version number of the latest kernel.
Do NOT use the /usr/src/linux area! This area has a (usually
incomplete) set of kernel headers that are used by the library header
files. They should match the library, and not get messed up by
whatever the kernel-du-jour happens to be.
- You can also upgrade between 2.6.xx releases by patching. Patches are
distributed in the traditional gzip and the newer bzip2 format. To
install by patching, get all the newer patch files, enter the
top level directory of the kernel source (linux-2.6.xx) and execute:
gzip -cd ../patch-2.6.xx.gz | patch -p1
or
bzip2 -dc ../patch-2.6.xx.bz2 | patch -p1
(repeat xx for all versions bigger than the version of your current
source tree, _in_order_) and you should be ok. You may want to remove
the backup files (xxx~ or xxx.orig), and make sure that there are no
failed patches (xxx# or xxx.rej). If there are, either you or me has
made a mistake.
Unlike patches for the 2.6.x kernels, patches for the 2.6.x.y kernels
(also known as the -stable kernels) are not incremental but instead apply
directly to the base 2.6.x kernel. Please read
Documentation/applying-patches.txt for more information.
Alternatively, the script patch-kernel can be used to automate this
process. It determines the current kernel version and applies any
patches found.
linux/scripts/patch-kernel linux
The first argument in the command above is the location of the
kernel source. Patches are applied from the current directory, but
an alternative directory can be specified as the second argument.
- If you are upgrading between releases using the stable series patches
(for example, patch-2.6.xx.y), note that these "dot-releases" are
not incremental and must be applied to the 2.6.xx base tree. For
example, if your base kernel is 2.6.12 and you want to apply the
2.6.12.3 patch, you do not and indeed must not first apply the
2.6.12.1 and 2.6.12.2 patches. Similarly, if you are running kernel
version 2.6.12.2 and want to jump to 2.6.12.3, you must first
reverse the 2.6.12.2 patch (that is, patch -R) _before_ applying
the 2.6.12.3 patch.
You can read more on this in Documentation/applying-patches.txt
- Make sure you have no stale .o files and dependencies lying around:
cd linux
make mrproper
You should now have the sources correctly installed.
SOFTWARE REQUIREMENTS
Compiling and running the 2.6.xx kernels requires up-to-date
versions of various software packages. Consult
Documentation/Changes for the minimum version numbers required
and how to get updates for these packages. Beware that using
excessively old versions of these packages can cause indirect
errors that are very difficult to track down, so don't assume that
you can just update packages when obvious problems arise during
build or operation.
BUILD directory for the kernel:
When compiling the kernel all output files will per default be
stored together with the kernel source code.
Using the option "make O=output/dir" allow you to specify an alternate
place for the output files (including .config).
Example:
kernel source code: /usr/src/linux-2.6.N
build directory: /home/name/build/kernel
To configure and build the kernel use:
cd /usr/src/linux-2.6.N
make O=/home/name/build/kernel menuconfig
make O=/home/name/build/kernel
sudo make O=/home/name/build/kernel modules_install install
Please note: If the 'O=output/dir' option is used then it must be
used for all invocations of make.
CONFIGURING the kernel:
Do not skip this step even if you are only upgrading one minor
version. New configuration options are added in each release, and
odd problems will turn up if the configuration files are not set up
as expected. If you want to carry your existing configuration to a
new version with minimal work, use "make oldconfig", which will
only ask you for the answers to new questions.
- Alternate configuration commands are:
"make config" Plain text interface.
"make menuconfig" Text based color menus, radiolists & dialogs.
"make xconfig" X windows (Qt) based configuration tool.
"make gconfig" X windows (Gtk) based configuration tool.
"make oldconfig" Default all questions based on the contents of
your existing ./.config file and asking about
new config symbols.
"make silentoldconfig"
Like above, but avoids cluttering the screen
with questions already answered.
"make defconfig" Create a ./.config file by using the default
symbol values from arch/$ARCH/defconfig.
"make allyesconfig"
Create a ./.config file by setting symbol
values to 'y' as much as possible.
"make allmodconfig"
Create a ./.config file by setting symbol
values to 'm' as much as possible.
"make allnoconfig" Create a ./.config file by setting symbol
values to 'n' as much as possible.
"make randconfig" Create a ./.config file by setting symbol
values to random values.
The allyesconfig/allmodconfig/allnoconfig/randconfig variants can
also use the environment variable KCONFIG_ALLCONFIG to specify a
filename that contains config options that the user requires to be
set to a specific value. If KCONFIG_ALLCONFIG=filename is not used,
"make *config" checks for a file named "all{yes/mod/no/random}.config"
for symbol values that are to be forced. If this file is not found,
it checks for a file named "all.config" to contain forced values.
NOTES on "make config":
- having unnecessary drivers will make the kernel bigger, and can
under some circumstances lead to problems: probing for a
nonexistent controller card may confuse your other controllers
- compiling the kernel with "Processor type" set higher than 386
will result in a kernel that does NOT work on a 386. The
kernel will detect this on bootup, and give up.
- A kernel with math-emulation compiled in will still use the
coprocessor if one is present: the math emulation will just
never get used in that case. The kernel will be slightly larger,
but will work on different machines regardless of whether they
have a math coprocessor or not.
- the "kernel hacking" configuration details usually result in a
bigger or slower kernel (or both), and can even make the kernel
less stable by configuring some routines to actively try to
break bad code to find kernel problems (kmalloc()). Thus you
should probably answer 'n' to the questions for
"development", "experimental", or "debugging" features.
COMPILING the kernel:
- Make sure you have at least gcc 3.2 available.
For more information, refer to Documentation/Changes.
Please note that you can still run a.out user programs with this kernel.
- Do a "make" to create a compressed kernel image. It is also
possible to do "make install" if you have lilo installed to suit the
kernel makefiles, but you may want to check your particular lilo setup first.
To do the actual install you have to be root, but none of the normal
build should require that. Don't take the name of root in vain.
- If you configured any of the parts of the kernel as `modules', you
will also have to do "make modules_install".
- Keep a backup kernel handy in case something goes wrong. This is
especially true for the development releases, since each new release
contains new code which has not been debugged. Make sure you keep a
backup of the modules corresponding to that kernel, as well. If you
are installing a new kernel with the same version number as your
working kernel, make a backup of your modules directory before you
do a "make modules_install".
Alternatively, before compiling, use the kernel config option
"LOCALVERSION" to append a unique suffix to the regular kernel version.
LOCALVERSION can be set in the "General Setup" menu.
- In order to boot your new kernel, you'll need to copy the kernel
image (e.g. .../linux/arch/i386/boot/bzImage after compilation)
to the place where your regular bootable kernel is found.
- Booting a kernel directly from a floppy without the assistance of a
bootloader such as LILO, is no longer supported.
If you boot Linux from the hard drive, chances are you use LILO which
uses the kernel image as specified in the file /etc/lilo.conf. The
kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
/boot/bzImage. To use the new kernel, save a copy of the old image
and copy the new image over the old one. Then, you MUST RERUN LILO
to update the loading map!! If you don't, you won't be able to boot
the new kernel image.
Reinstalling LILO is usually a matter of running /sbin/lilo.
You may wish to edit /etc/lilo.conf to specify an entry for your
old kernel image (say, /vmlinux.old) in case the new one does not
work. See the LILO docs for more information.
After reinstalling LILO, you should be all set. Shutdown the system,
reboot, and enjoy!
If you ever need to change the default root device, video mode,
ramdisk size, etc. in the kernel image, use the 'rdev' program (or
alternatively the LILO boot options when appropriate). No need to
recompile the kernel to change these parameters.
- Reboot with the new kernel and enjoy.
IF SOMETHING GOES WRONG:
- If you have problems that seem to be due to kernel bugs, please check
the file MAINTAINERS to see if there is a particular person associated
with the part of the kernel that you are having trouble with. If there
isn't anyone listed there, then the second best thing is to mail
them to me (torvalds@linux-foundation.org), and possibly to any other
relevant mailing-list or to the newsgroup.
- In all bug-reports, *please* tell what kernel you are talking about,
how to duplicate the problem, and what your setup is (use your common
sense). If the problem is new, tell me so, and if the problem is
old, please try to tell me when you first noticed it.
- If the bug results in a message like
unable to handle kernel paging request at address C0000010
Oops: 0002
EIP: 0010:XXXXXXXX
eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
ds: xxxx es: xxxx fs: xxxx gs: xxxx
Pid: xx, process nr: xx
xx xx xx xx xx xx xx xx xx xx
or similar kernel debugging information on your screen or in your
system log, please duplicate it *exactly*. The dump may look
incomprehensible to you, but it does contain information that may
help debugging the problem. The text above the dump is also
important: it tells something about why the kernel dumped code (in
the above example it's due to a bad kernel pointer). More information
on making sense of the dump is in Documentation/oops-tracing.txt
- If you compiled the kernel with CONFIG_KALLSYMS you can send the dump
as is, otherwise you will have to use the "ksymoops" program to make
sense of the dump (but compiling with CONFIG_KALLSYMS is usually preferred).
This utility can be downloaded from
ftp://ftp.<country>.kernel.org/pub/linux/utils/kernel/ksymoops/ .
Alternately you can do the dump lookup by hand:
- In debugging dumps like the above, it helps enormously if you can
look up what the EIP value means. The hex value as such doesn't help
me or anybody else very much: it will depend on your particular
kernel setup. What you should do is take the hex value from the EIP
line (ignore the "0010:"), and look it up in the kernel namelist to
see which kernel function contains the offending address.
To find out the kernel function name, you'll need to find the system
binary associated with the kernel that exhibited the symptom. This is
the file 'linux/vmlinux'. To extract the namelist and match it against
the EIP from the kernel crash, do:
nm vmlinux | sort | less
This will give you a list of kernel addresses sorted in ascending
order, from which it is simple to find the function that contains the
offending address. Note that the address given by the kernel
debugging messages will not necessarily match exactly with the
function addresses (in fact, that is very unlikely), so you can't
just 'grep' the list: the list will, however, give you the starting
point of each kernel function, so by looking for the function that
has a starting address lower than the one you are searching for but
is followed by a function with a higher address you will find the one
you want. In fact, it may be a good idea to include a bit of
"context" in your problem report, giving a few lines around the
interesting one.
If you for some reason cannot do the above (you have a pre-compiled
kernel image or similar), telling me as much about your setup as
possible will help. Please read the REPORTING-BUGS document for details.
- Alternately, you can use gdb on a running kernel. (read-only; i.e. you
cannot change values or set break points.) To do this, first compile the
kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
You can now use all the usual gdb commands. The command to look up the
point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
with the EIP value.)
gdb'ing a non-running kernel currently fails because gdb (wrongly)
disregards the starting offset for which the kernel is compiled.