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Daniel Mack says:
====================
Add eBPF hooks for cgroups
This is v9 of the patch set to allow eBPF programs for network
filtering and accounting to be attached to cgroups, so that they apply
to all sockets of all tasks placed in that cgroup. The logic also
allows to be extendeded for other cgroup based eBPF logic.
Again, only minor details are updated in this version.
Changes from v8:
* Move the egress hooks into ip_finish_output() and ip6_finish_output()
so they run after the netfilter hooks. For IPv4 multicast, add a new
ip_mc_finish_output() callback that is invoked on success by
netfilter, and call the eBPF program from there.
Changes from v7:
* Replace the static inline function cgroup_bpf_run_filter() with
two specific macros for ingress and egress. This addresses David
Miller's concern regarding skb->sk vs. sk in the egress path.
Thanks a lot to Daniel Borkmann and Alexei Starovoitov for the
suggestions.
Changes from v6:
* Rebased to 4.9-rc2
* Add EXPORT_SYMBOL(__cgroup_bpf_run_filter). The kbuild test robot
now succeeds in building this version of the patch set.
* Switch from bpf_prog_run_save_cb() to bpf_prog_run_clear_cb() to not
tamper with the contents of skb->cb[]. Pointed out by Daniel
Borkmann.
* Use sk_to_full_sk() in the egress path, as suggested by Daniel
Borkmann.
* Renamed BPF_PROG_TYPE_CGROUP_SOCKET to BPF_PROG_TYPE_CGROUP_SKB, as
requested by David Ahern.
* Added Alexei's Acked-by tags.
Changes from v5:
* The eBPF programs now operate on L3 rather than on L2 of the packets,
and the egress hooks were moved from __dev_queue_xmit() to
ip*_output().
* For BPF_PROG_TYPE_CGROUP_SOCKET, disallow direct access to the skb
through BPF_LD_[ABS|IND] instructions, but hook up the
bpf_skb_load_bytes() access helper instead. Thanks to Daniel Borkmann
for the help.
Changes from v4:
* Plug an skb leak when dropping packets due to eBPF verdicts in
__dev_queue_xmit(). Spotted by Daniel Borkmann.
* Check for sk_fullsock(sk) in __cgroup_bpf_run_filter() so we don't
operate on timewait or request sockets. Suggested by Daniel Borkmann.
* Add missing @parent parameter in kerneldoc of __cgroup_bpf_update().
Spotted by Rami Rosen.
* Include linux/jump_label.h from bpf-cgroup.h to fix a kbuild error.
Changes from v3:
* Dropped the _FILTER suffix from BPF_PROG_TYPE_CGROUP_SOCKET_FILTER,
renamed BPF_ATTACH_TYPE_CGROUP_INET_{E,IN}GRESS to
BPF_CGROUP_INET_{IN,E}GRESS and alias BPF_MAX_ATTACH_TYPE to
__BPF_MAX_ATTACH_TYPE, as suggested by Daniel Borkmann.
* Dropped the attach_flags member from the anonymous struct for BPF
attach operations in union bpf_attr. They can be added later on via
CHECK_ATTR. Requested by Daniel Borkmann and Alexei.
* Release old_prog at the end of __cgroup_bpf_update rather that at
the beginning to fix a race gap between program updates and their
users. Spotted by Daniel Borkmann.
* Plugged an skb leak when dropping packets on the egress path.
Spotted by Daniel Borkmann.
* Add cgroups@vger.kernel.org to the loop, as suggested by Rami Rosen.
* Some minor coding style adoptions not worth mentioning in particular.
Changes from v2:
* Fixed the RCU locking details Tejun pointed out.
* Assert bpf_attr.flags == 0 in BPF_PROG_DETACH syscall handler.
Changes from v1:
* Moved all bpf specific cgroup code into its own file, and stub
out related functions for !CONFIG_CGROUP_BPF as static inline nops.
This way, the call sites are not cluttered with #ifdef guards while
the feature remains compile-time configurable.
* Implemented the new scheme proposed by Tejun. Per cgroup, store one
set of pointers that are pinned to the cgroup, and one for the
programs that are effective. When a program is attached or detached,
the change is propagated to all the cgroup's descendants. If a
subcgroup has its own pinned program, skip the whole subbranch in
order to allow delegation models.
* The hookup for egress packets is now done from __dev_queue_xmit().
* A static key is now used in both the ingress and egress fast paths
to keep performance penalties close to zero if the feature is
not in use.
* Overall cleanup to make the accessors use the program arrays.
This should make it much easier to add new program types, which
will then automatically follow the pinned vs. effective logic.
* Fixed locking issues, as pointed out by Eric Dumazet and Alexei
Starovoitov. Changes to the program array are now done with
xchg() and are protected by cgroup_mutex.
* eBPF programs are now expected to return 1 to let the packet pass,
not >= 0. Pointed out by Alexei.
* Operation is now limited to INET sockets, so local AF_UNIX sockets
are not affected. The enum members are renamed accordingly. In case
other socket families should be supported, this can be extended in
the future.
* The sample program learned to support both ingress and egress, and
can now optionally make the eBPF program drop packets by making it
return 0.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel release 4.x <http://kernel.org/>
These are the release notes for Linux version 4. 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,
Xtensa, Tilera TILE, AVR32, ARC 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, HTML, & man-pages, among others.
After installation, "make psdocs", "make pdfdocs", "make htmldocs",
or "make mandocs" will render the documentation in the requested format.
INSTALLING the kernel source:
- If you install the full sources, put the kernel tarball in a
directory where you have permissions (e.g. your home directory) and
unpack it:
xz -cd linux-4.X.tar.xz | tar xvf -
Replace "X" 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 4.x releases by patching. Patches are
distributed in the xz format. To install by patching, get all the
newer patch files, enter the top level directory of the kernel source
(linux-4.X) and execute:
xz -cd ../patch-4.x.xz | patch -p1
Replace "x" for all versions bigger than the version "X" of your current
source tree, _in_order_, and you should be ok. You may want to remove
the backup files (some-file-name~ or some-file-name.orig), and make sure
that there are no failed patches (some-file-name# or some-file-name.rej).
If there are, either you or I have made a mistake.
Unlike patches for the 4.x kernels, patches for the 4.x.y kernels
(also known as the -stable kernels) are not incremental but instead apply
directly to the base 4.x kernel. For example, if your base kernel is 4.0
and you want to apply the 4.0.3 patch, you must not first apply the 4.0.1
and 4.0.2 patches. Similarly, if you are running kernel version 4.0.2 and
want to jump to 4.0.3, you must first reverse the 4.0.2 patch (that is,
patch -R) _before_ applying the 4.0.3 patch. You can read more on this in
Documentation/applying-patches.txt
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.
- 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 4.x 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" allows you to specify an alternate
place for the output files (including .config).
Example:
kernel source code: /usr/src/linux-4.X
build directory: /home/name/build/kernel
To configure and build the kernel, use:
cd /usr/src/linux-4.X
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.
- Alternative configuration commands are:
"make config" Plain text interface.
"make menuconfig" Text based color menus, radiolists & dialogs.
"make nconfig" Enhanced text based color menus.
"make xconfig" Qt based configuration tool.
"make gconfig" 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.
Additionally updates the dependencies.
"make olddefconfig"
Like above, but sets new symbols to their default
values without prompting.
"make defconfig" Create a ./.config file by using the default
symbol values from either arch/$ARCH/defconfig
or arch/$ARCH/configs/${PLATFORM}_defconfig,
depending on the architecture.
"make ${PLATFORM}_defconfig"
Create a ./.config file by using the default
symbol values from
arch/$ARCH/configs/${PLATFORM}_defconfig.
Use "make help" to get a list of all available
platforms of your architecture.
"make allyesconfig"
Create a ./.config file by setting symbol
values to 'y' as much as possible.
"make allmodconfig"
Create a ./.config file by setting symbol
values to 'm' as much as possible.
"make allnoconfig" Create a ./.config file by setting symbol
values to 'n' as much as possible.
"make randconfig" Create a ./.config file by setting symbol
values to random values.
"make localmodconfig" Create a config based on current config and
loaded modules (lsmod). Disables any module
option that is not needed for the loaded modules.
To create a localmodconfig for another machine,
store the lsmod of that machine into a file
and pass it in as a LSMOD parameter.
target$ lsmod > /tmp/mylsmod
target$ scp /tmp/mylsmod host:/tmp
host$ make LSMOD=/tmp/mylsmod localmodconfig
The above also works when cross compiling.
"make localyesconfig" Similar to localmodconfig, except it will convert
all module options to built in (=y) options.
You can find more information on using the Linux kernel config tools
in Documentation/kbuild/kconfig.txt.
- 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
- 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".
- Verbose kernel compile/build output:
Normally, the kernel build system runs in a fairly quiet mode (but not
totally silent). However, sometimes you or other kernel developers need
to see compile, link, or other commands exactly as they are executed.
For this, use "verbose" build mode. This is done by passing
"V=1" to the "make" command, e.g.
make V=1 all
To have the build system also tell the reason for the rebuild of each
target, use "V=2". The default is "V=0".
- 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/x86/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/ .
Alternatively, 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.
- Alternatively, 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/x86/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.