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Filename Latest commit message Latest commit date
Pali Rohár eeb4742501 ppp: Fix generating ppp unit id when ifname is not specified
commit 3125f26c514826077f2a4490b75e9b1c7a644c42 upstream.

When registering new ppp interface via PPPIOCNEWUNIT ioctl then kernel has
to choose interface name as this ioctl API does not support specifying it.

Kernel in this case register new interface with name "ppp<id>" where <id>
is the ppp unit id, which can be obtained via PPPIOCGUNIT ioctl. This
applies also in the case when registering new ppp interface via rtnl
without supplying IFLA_IFNAME.

PPPIOCNEWUNIT ioctl allows to specify own ppp unit id which will kernel
assign to ppp interface, in case this ppp id is not already used by other
ppp interface.

In case user does not specify ppp unit id then kernel choose the first free
ppp unit id. This applies also for case when creating ppp interface via
rtnl method as it does not provide a way for specifying own ppp unit id.

If some network interface (does not have to be ppp) has name "ppp<id>"
with this first free ppp id then PPPIOCNEWUNIT ioctl or rtnl call fails.

And registering new ppp interface is not possible anymore, until interface
which holds conflicting name is renamed. Or when using rtnl method with
custom interface name in IFLA_IFNAME.

As list of allocated / used ppp unit ids is not possible to retrieve from
kernel to userspace, userspace has no idea what happens nor which interface
is doing this conflict.

So change the algorithm how ppp unit id is generated. And choose the first
number which is not neither used as ppp unit id nor in some network
interface with pattern "ppp<id>".

This issue can be simply reproduced by following pppd call when there is no
ppp interface registered and also no interface with name pattern "ppp<id>":

    pppd ifname ppp1 +ipv6 noip noauth nolock local nodetach pty "pppd +ipv6 noip noauth nolock local nodetach notty"

Or by creating the one ppp interface (which gets assigned ppp unit id 0),
renaming it to "ppp1" and then trying to create a new ppp interface (which
will always fails as next free ppp unit id is 1, but network interface with
name "ppp1" exists).

This patch fixes above described issue by generating new and new ppp unit
id until some non-conflicting id with network interfaces is generated.

Signed-off-by: Pali Rohár <pali@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-15 13:08:04 +02:00
arch KVM: X86: MMU: Use the correct inherited permissions to get shadow page 2021-08-15 13:08:04 +02:00
block blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() 2021-08-12 13:20:58 +02:00
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto crypto: shash - avoid comparing pointers to exported functions under CFI 2021-07-14 16:53:13 +02:00
Documentation KVM: X86: MMU: Use the correct inherited permissions to get shadow page 2021-08-15 13:08:04 +02:00
drivers ppp: Fix generating ppp unit id when ifname is not specified 2021-08-15 13:08:04 +02:00
fs reiserfs: check directory items on read from disk 2021-08-12 13:21:05 +02:00
include tee: Correct inappropriate usage of TEE_SHM_DMA_BUF flag 2021-08-15 13:08:02 +02:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel tracing: Reject string operand in the histogram expression 2021-08-15 13:08:02 +02:00
lib lib/decompress_unlz4.c: correctly handle zero-padding around initrds. 2021-07-20 16:10:46 +02:00
LICENSES
mm mm: slab: fix kmem_cache_create failed when sysfs node not destroyed 2021-07-25 14:35:14 +02:00
net Bluetooth: defer cleanup of resources in hci_unregister_dev() 2021-08-12 13:20:58 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:53:30 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2021-08-12 13:21:00 +02:00
security smackfs: restrict bytes count in smk_set_cipso() 2021-07-19 08:53:18 +02:00
sound ALSA: hda: Add quirk for ASUS Flow x13 2021-08-15 13:08:04 +02:00
tools bpf, selftests: Adjust few selftest result_unpriv outcomes 2021-08-12 13:21:04 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:21:03 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.140 2021-08-12 13:21:05 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.