linux-stable.git/net/dns_resolver, branch v5.2

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21T08:50:46+00:00

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

dns_resolver: Allow used keys to be invalidated

2019-05-15T16:35:54+00:00

Allow used DNS resolver keys to be invalidated after use if the caller is
doing its own caching of the results.  This reduces the amount of resources
required.

Fix AFS to invalidate DNS results to kill off permanent failure records
that get lodged in the resolver keyring and prevent future lookups from
happening.

Fixes: 0a5143f2f89c ("afs: Implement VL server rotation")
Signed-off-by: David Howells

dns: remove redundant zero length namelen check

2019-04-11T21:01:08+00:00

The zero namelen check is redundant as it has already been checked
for zero at the start of the function.  Remove the redundant check.

Addresses-Coverity: ("Logically Dead Code")
Signed-off-by: Colin Ian King 
Signed-off-by: David S. Miller

dns: Allow the dns resolver to retrieve a server set

2018-10-04T16:40:52+00:00

Allow the DNS resolver to retrieve a set of servers and their associated
addresses, ports, preference and weight ratings.

In terms of communication with userspace, "srv=1" is added to the callout
string (the '1' indicating the maximum data version supported by the
kernel) to ask the userspace side for this.

If the userspace side doesn't recognise it, it will ignore the option and
return the usual text address list.

If the userspace side does recognise it, it will return some binary data
that begins with a zero byte that would cause the string parsers to give an
error.  The second byte contains the version of the data in the blob (this
may be between 1 and the version specified in the callout data).  The
remainder of the payload is version-specific.

In version 1, the payload looks like (note that this is packed):

	u8	Non-string marker (ie. 0)
	u8	Content (0 => Server list)
	u8	Version (ie. 1)
	u8	Source (eg. DNS_RECORD_FROM_DNS_SRV)
	u8	Status (eg. DNS_LOOKUP_GOOD)
	u8	Number of servers
	foreach-server {
		u16	Name length (LE)
		u16	Priority (as per SRV record) (LE)
		u16	Weight (as per SRV record) (LE)
		u16	Port (LE)
		u8	Source (eg. DNS_RECORD_FROM_NSS)
		u8	Status (eg. DNS_LOOKUP_GOT_NOT_FOUND)
		u8	Protocol (eg. DNS_SERVER_PROTOCOL_UDP)
		u8	Number of addresses
		char[]	Name (not NUL-terminated)
		foreach-address {
			u8		Family (AF_INET{,6})
			union {
				u8[4]	ipv4_addr
				u8[16]	ipv6_addr
			}
		}
	}

This can then be used to fetch a whole cell's VL-server configuration for
AFS, for example.

Signed-off-by: David Howells 
Signed-off-by: David S. Miller

net: remove blank lines at end of file

2018-07-24T21:10:43+00:00

Several files have extra line at end of file.

Signed-off-by: Stephen Hemminger 
Signed-off-by: David S. Miller

KEYS: DNS: fix parsing multiple options

2018-07-16T18:22:14+00:00

My recent fix for dns_resolver_preparse() printing very long strings was
incomplete, as shown by syzbot which still managed to hit the
WARN_ONCE() in set_precision() by adding a crafted "dns_resolver" key:

    precision 50001 too large
    WARNING: CPU: 7 PID: 864 at lib/vsprintf.c:2164 vsnprintf+0x48a/0x5a0

The bug this time isn't just a printing bug, but also a logical error
when multiple options ("#"-separated strings) are given in the key
payload.  Specifically, when separating an option string into name and
value, if there is no value then the name is incorrectly considered to
end at the end of the key payload, rather than the end of the current
option.  This bypasses validation of the option length, and also means
that specifying multiple options is broken -- which presumably has gone
unnoticed as there is currently only one valid option anyway.

A similar problem also applied to option values, as the kstrtoul() when
parsing the "dnserror" option will read past the end of the current
option and into the next option.

Fix these bugs by correctly computing the length of the option name and
by copying the option value, null-terminated, into a temporary buffer.

Reproducer for the WARN_ONCE() that syzbot hit:

    perl -e 'print "#A#", "\0" x 50000' | keyctl padd dns_resolver desc @s

Reproducer for "dnserror" option being parsed incorrectly (expected
behavior is to fail when seeing the unknown option "foo", actual
behavior was to read the dnserror value as "1#foo" and fail there):

    perl -e 'print "#dnserror=1#foo\0"' | keyctl padd dns_resolver desc @s

Reported-by: syzbot 
Fixes: 4a2d789267e0 ("DNS: If the DNS server returns an error, allow that to be cached [ver #2]")
Signed-off-by: Eric Biggers 
Signed-off-by: David S. Miller

KEYS: DNS: limit the length of option strings

2018-04-17T19:17:41+00:00

Adding a dns_resolver key whose payload contains a very long option name
resulted in that string being printed in full.  This hit the WARN_ONCE()
in set_precision() during the printk(), because printk() only supports a
precision of up to 32767 bytes:

    precision 1000000 too large
    WARNING: CPU: 0 PID: 752 at lib/vsprintf.c:2189 vsnprintf+0x4bc/0x5b0

Fix it by limiting option strings (combined name + value) to a much more
reasonable 128 bytes.  The exact limit is arbitrary, but currently the
only recognized option is formatted as "dnserror=%lu" which fits well
within this limit.

Also ratelimit the printks.

Reproducer:

    perl -e 'print "#", "A" x 1000000, "\x00"' | keyctl padd dns_resolver desc @s

This bug was found using syzkaller.

Reported-by: Mark Rutland 
Fixes: 4a2d789267e0 ("DNS: If the DNS server returns an error, allow that to be cached [ver #2]")
Signed-off-by: Eric Biggers 
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

afs: Support the AFS dynamic root

2018-02-06T14:43:37+00:00

Support the AFS dynamic root which is a pseudo-volume that doesn't connect
to any server resource, but rather is just a root directory that
dynamically creates mountpoint directories where the name of such a
directory is the name of the cell.

Such a mount can be created thus:

	mount -t afs none /afs -o dyn

Dynamic root superblocks aren't shared except by bind mounts and
propagation.  Cell root volumes can then be mounted by referring to them by
name, e.g.:

	ls /afs/grand.central.org/
	ls /afs/.grand.central.org/

The kernel will upcall to consult the DNS if the address wasn't supplied
directly.

Signed-off-by: David Howells

KEYS: Fix race between updating and finding a negative key

2017-10-18T08:12:40+00:00

Consolidate KEY_FLAG_INSTANTIATED, KEY_FLAG_NEGATIVE and the rejection
error into one field such that:

 (1) The instantiation state can be modified/read atomically.

 (2) The error can be accessed atomically with the state.

 (3) The error isn't stored unioned with the payload pointers.

This deals with the problem that the state is spread over three different
objects (two bits and a separate variable) and reading or updating them
atomically isn't practical, given that not only can uninstantiated keys
change into instantiated or rejected keys, but rejected keys can also turn
into instantiated keys - and someone accessing the key might not be using
any locking.

The main side effect of this problem is that what was held in the payload
may change, depending on the state.  For instance, you might observe the
key to be in the rejected state.  You then read the cached error, but if
the key semaphore wasn't locked, the key might've become instantiated
between the two reads - and you might now have something in hand that isn't
actually an error code.

The state is now KEY_IS_UNINSTANTIATED, KEY_IS_POSITIVE or a negative error
code if the key is negatively instantiated.  The key_is_instantiated()
function is replaced with key_is_positive() to avoid confusion as negative
keys are also 'instantiated'.

Additionally, barriering is included:

 (1) Order payload-set before state-set during instantiation.

 (2) Order state-read before payload-read when using the key.

Further separate barriering is necessary if RCU is being used to access the
payload content after reading the payload pointers.

Fixes: 146aa8b1453b ("KEYS: Merge the type-specific data with the payload data")
Cc: stable@vger.kernel.org # v4.4+
Reported-by: Eric Biggers 
Signed-off-by: David Howells 
Reviewed-by: Eric Biggers