linux/samples
Josef Bacik 484611357c bpf: allow access into map value arrays
Suppose you have a map array value that is something like this

struct foo {
	unsigned iter;
	int array[SOME_CONSTANT];
};

You can easily insert this into an array, but you cannot modify the contents of
foo->array[] after the fact.  This is because we have no way to verify we won't
go off the end of the array at verification time.  This patch provides a start
for this work.  We accomplish this by keeping track of a minimum and maximum
value a register could be while we're checking the code.  Then at the time we
try to do an access into a MAP_VALUE we verify that the maximum offset into that
region is a valid access into that memory region.  So in practice, code such as
this

unsigned index = 0;

if (foo->iter >= SOME_CONSTANT)
	foo->iter = index;
else
	index = foo->iter++;
foo->array[index] = bar;

would be allowed, as we can verify that index will always be between 0 and
SOME_CONSTANT-1.  If you wish to use signed values you'll have to have an extra
check to make sure the index isn't less than 0, or do something like index %=
SOME_CONSTANT.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-29 01:35:35 -04:00
..
bpf bpf: allow access into map value arrays 2016-09-29 01:35:35 -04:00
configfs configfs: remove old API 2015-10-13 22:17:57 -07:00
connector samples: connector: from Documentation to samples directory 2016-04-28 07:47:35 -06:00
hidraw HID: samples/hidraw: make it possible to select device 2015-03-15 10:11:21 -04:00
hw_breakpoint perf: Add context field to perf_event 2011-07-01 11:06:38 +02:00
kdb kdb: Add kdb kernel module sample 2010-10-29 13:14:39 -05:00
kfifo kfifo API type safety 2013-11-15 09:32:23 +09:00
kobject samples/kobject: be explicit in the module license 2015-03-25 13:41:42 +01:00
kprobes samples/kretprobe: fix the wrong type 2016-08-04 08:50:07 -04:00
livepatch livepatch: reuse module loader code to write relocations 2016-04-01 15:00:11 +02:00
pktgen samples: Add an IPv6 '-6' option to the pktgen scripts 2016-07-20 22:16:02 -07:00
rpmsg rpmsg: use module_rpmsg_driver in existing drivers and examples 2016-05-06 11:09:01 -07:00
seccomp samples/seccomp: Add standalone config option 2016-07-07 10:58:03 -07:00
trace_events Sample: Trace_event: Correct the comments 2015-11-02 14:09:15 -05:00
trace_printk tracing: Add trace_printk sample code 2016-06-20 09:54:21 -04:00
uhid HID: uhid: improve uhid example client 2013-09-04 11:35:14 +02:00
v4l [media] vb2: replace void *alloc_ctxs by struct device *alloc_devs 2016-07-08 14:45:07 -03:00
Kconfig Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-07-29 17:38:46 -07:00
Makefile tracing: Add trace_printk sample code 2016-06-20 09:54:21 -04:00