linux-toradex.git/net/atm/lec.c, branch v4.18-rc3

atm: Preserve value of skb->truesize when accounting to vcc

2018-06-16T23:27:01+00:00

ATM accounts for in-flight TX packets in sk_wmem_alloc of the VCC on
which they are to be sent. But it doesn't take ownership of those
packets from the sock (if any) which originally owned them. They should
remain owned by their actual sender until they've left the box.

There's a hack in pskb_expand_head() to avoid adjusting skb->truesize
for certain skbs, precisely to avoid messing up sk_wmem_alloc
accounting. Ideally that hack would cover the ATM use case too, but it
doesn't — skbs which aren't owned by any sock, for example PPP control
frames, still get their truesize adjusted when the low-level ATM driver
adds headroom.

This has always been an issue, it seems. The truesize of a packet
increases, and sk_wmem_alloc on the VCC goes negative. But this wasn't
for normal traffic, only for control frames. So I think we just got away
with it, and we probably needed to send 2GiB of LCP echo frames before
the misaccounting would ever have caused a problem and caused
atm_may_send() to start refusing packets.

Commit 14afee4b609 ("net: convert sock.sk_wmem_alloc from atomic_t to
refcount_t") did exactly what it was intended to do, and turned this
mostly-theoretical problem into a real one, causing PPPoATM to fail
immediately as sk_wmem_alloc underflows and atm_may_send() *immediately*
starts refusing to allow new packets.

The least intrusive solution to this problem is to stash the value of
skb->truesize that was accounted to the VCC, in a new member of the
ATM_SKB(skb) structure. Then in atm_pop_raw() subtract precisely that
value instead of the then-current value of skb->truesize.

Fixes: 158f323b9868 ("net: adjust skb->truesize in pskb_expand_head()")
Signed-off-by: David Woodhouse 
Tested-by: Kevin Darbyshire-Bryant 
Signed-off-by: David S. Miller

proc: introduce proc_create_seq_private

2018-05-16T05:23:35+00:00

Variant of proc_create_data that directly take a struct seq_operations
argument + a private state size and drastically reduces the boilerplate
code in the callers.

All trivial callers converted over.

Signed-off-by: Christoph Hellwig

net: atm: Fix potential Spectre v1

2018-05-04T16:52:47+00:00

ioc_data.dev_num can be controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:
net/atm/lec.c:702 lec_vcc_attach() warn: potential spectre issue
'dev_lec'

Fix this by sanitizing ioc_data.dev_num before using it to index
dev_lec. Also, notice that there is another instance in which array
dev_lec is being indexed using ioc_data.dev_num at line 705:
lec_vcc_added(netdev_priv(dev_lec[ioc_data.dev_num]),

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva 
Signed-off-by: David S. Miller

net: Use octal not symbolic permissions

2018-03-26T16:07:48+00:00

Prefer the direct use of octal for permissions.

Done with checkpatch -f --types=SYMBOLIC_PERMS --fix-inplace
and some typing.

Miscellanea:

o Whitespace neatening around these conversions.

Signed-off-by: Joe Perches 
Signed-off-by: David S. Miller

net: delete /proc THIS_MODULE references

2018-01-16T20:01:33+00:00

/proc has been ignoring struct file_operations::owner field for 10 years.
Specifically, it started with commit 786d7e1612f0b0adb6046f19b906609e4fe8b1ba
("Fix rmmod/read/write races in /proc entries"). Notice the chunk where
inode->i_fop is initialized with proxy struct file_operations for
regular files:

	-               if (de->proc_fops)
	-                       inode->i_fop = de->proc_fops;
	+               if (de->proc_fops) {
	+                       if (S_ISREG(inode->i_mode))
	+                               inode->i_fop = &proc_reg_file_ops;
	+                       else
	+                               inode->i_fop = de->proc_fops;
	+               }

VFS stopped pinning module at this point.

Signed-off-by: Alexey Dobriyan 
Signed-off-by: David S. Miller

treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts

2017-11-22T00:35:54+00:00

With all callbacks converted, and the timer callback prototype
switched over, the TIMER_FUNC_TYPE cast is no longer needed,
so remove it. Conversion was done with the following scripts:

    perl -pi -e 's|\(TIMER_FUNC_TYPE\)||g' \
        $(git grep TIMER_FUNC_TYPE | cut -d: -f1 | sort -u)

    perl -pi -e 's|\(TIMER_DATA_TYPE\)||g' \
        $(git grep TIMER_DATA_TYPE | cut -d: -f1 | sort -u)

The now unused macros are also dropped from include/linux/timer.h.

Signed-off-by: Kees Cook

net: atm: Convert timers to use timer_setup()

2017-10-18T11:40:27+00:00

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly. Also drops a redundant initialization
that is already set up by DEFINE_TIMER.

Cc: "David S. Miller" 
Cc: Hans Liljestrand 
Cc: "Reshetova, Elena" 
Cc: Bhumika Goyal 
Cc: Johannes Berg 
Cc: Roopa Prabhu 
Cc: Augusto Mecking Caringi 
Cc: Jarod Wilson 
Cc: Kalle Valo 
Cc: Thomas Gleixner 
Cc: Alexey Dobriyan 
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook 
Signed-off-by: David S. Miller

net: atm: make atmdev_ops const

2017-08-10T05:43:50+00:00

Make these const as they are only stored in the ops field of a atm_dev
structure, which is const.
Done using Coccinelle.

Signed-off-by: Bhumika Goyal 
Signed-off-by: David S. Miller

net, atm: convert lec_arp_table.usage from atomic_t to refcount_t

2017-07-04T21:35:16+00:00

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova 
Signed-off-by: Hans Liljestrand 
Signed-off-by: Kees Cook 
Signed-off-by: David Windsor 
Signed-off-by: David S. Miller

net: convert sock.sk_wmem_alloc from atomic_t to refcount_t

2017-07-01T14:39:08+00:00

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova 
Signed-off-by: Hans Liljestrand 
Signed-off-by: Kees Cook 
Signed-off-by: David Windsor 
Signed-off-by: David S. Miller