linux-toradex.git/net/sunrpc/cache.c, branch v4.4.93

sunrpc/cache: drop reference when sunrpc_cache_pipe_upcall() detects a race

2016-05-04T21:48:54+00:00

commit a6ab1e8126d205238defbb55d23661a3a5c6a0d8 upstream.

sunrpc_cache_pipe_upcall() can detect a race if CACHE_PENDING is no longer
set.  In this case it aborts the queuing of the upcall.
However it has already taken a new counted reference on "h" and
doesn't "put" it, even though it frees the data structure holding the reference.

So let's delay the "cache_get" until we know we need it.

Fixes: f9e1aedc6c79 ("sunrpc/cache: remove races with queuing an upcall.")
Signed-off-by: NeilBrown 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

sunrpc/cache: fix off-by-one in qword_get()

2016-03-03T23:07:29+00:00

commit b7052cd7bcf3c1478796e93e3dff2b44c9e82943 upstream.

The qword_get() function NUL-terminates its output buffer.  If the input
string is in hex format \xXXXX... and the same length as the output
buffer, there is an off-by-one:

  int qword_get(char **bpp, char *dest, int bufsize)
  {
      ...
      while (len < bufsize) {
          ...
          *dest++ = (h << 4) | l;
          len++;
      }
      ...
      *dest = '\0';
      return len;
  }

This patch ensures the NUL terminator doesn't fall outside the output
buffer.

Signed-off-by: Stefan Hajnoczi 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

sunrpc/cache: make cache flushing more reliable.

2015-10-23T19:57:30+00:00

The caches used to store sunrpc authentication information can be
flushed by writing a timestamp to a file in /proc.

This timestamp has a one-second resolution and any entry in cache that
was last_refreshed *before* that time is treated as expired.

This is problematic as it is not possible to reliably flush the cache
without interrupting NFS service.
If the current time is written to the "flush" file, any entry that was
added since the current second started will still be treated as valid.
If one second beyond than the current time is written to the file
then no entries can be valid until the second ticks over.  This will
mean that no NFS request will be handled for up to 1 second.

To resolve this issue we make two changes:

1/ treat an entry as expired if the timestamp when it was last_refreshed
  is before *or the same as* the expiry time.  This means that current
  code which writes out the current time will now flush the cache
  reliably.

2/ when a new entry in added to the cache -  set the last_refresh timestamp
  to 1 second *beyond* the current flush time, when that not in the
  past.
  This ensures that newly added entries will always be valid.

Now that we have a very reliable way to flush the cache, and also
since we are using "since-boot" timestamps which are monotonic,
change cache_purge() to set the smallest future flush_time which
will work, and leave it there: don't revert to '1'.

Also disable the setting of the 'flush_time' far into the future.
That has never been useful and is now awkward as it would cause
last_refresh times to be strange.
Finally: if a request is made to set the 'flush_time' to the current
second, assume the intent is to flush the cache and advance it, if
necessary, to 1 second beyond the current 'flush_time' so that all
active entries will be deemed to be expired.

As part of this we need to add a 'cache_detail' arg to cache_init()
and cache_fresh_locked() so they can find the current ->flush_time.

Signed-off-by: NeilBrown 
Reported-by: Olaf Kirch 
Signed-off-by: J. Bruce Fields

sunrpc: Switch to using hash list instead single list

2015-08-13T12:59:03+00:00

Switch using list_head for cache_head in cache_detail,
it is useful of remove an cache_head entry directly from cache_detail.

v8, using hash list, not head list

Signed-off-by: Kinglong Mee 
Reviewed-by: NeilBrown 
Signed-off-by: J. Bruce Fields

sunrpc/nfsd: Remove redundant code by exports seq_operations functions

2015-08-13T12:59:02+00:00

Nfsd has implement a site of seq_operations functions as sunrpc's cache.
Just exports sunrpc's codes, and remove nfsd's redundant codes.

v8, same as v6

Signed-off-by: Kinglong Mee 
Reviewed-by: NeilBrown 
Signed-off-by: J. Bruce Fields

sunrpc: Store cache_detail in seq_file's private directly

2015-08-13T12:59:01+00:00

Cleanup.

Just store cache_detail in seq_file's private,
an allocated handle is redundant.

v8, same as v6.

Signed-off-by: Kinglong Mee 
Reviewed-by: NeilBrown 
Signed-off-by: J. Bruce Fields

lib/string_helpers.c: change semantics of string_escape_mem

2015-04-15T23:35:24+00:00

The current semantics of string_escape_mem are inadequate for one of its
current users, vsnprintf().  If that is to honour its contract, it must
know how much space would be needed for the entire escaped buffer, and
string_escape_mem provides no way of obtaining that (short of allocating a
large enough buffer (~4 times input string) to let it play with, and
that's definitely a big no-no inside vsnprintf).

So change the semantics for string_escape_mem to be more snprintf-like:
Return the size of the output that would be generated if the destination
buffer was big enough, but of course still only write to the part of dst
it is allowed to, and (contrary to snprintf) don't do '\0'-termination.
It is then up to the caller to detect whether output was truncated and to
append a '\0' if desired.  Also, we must output partial escape sequences,
otherwise a call such as snprintf(buf, 3, "%1pE", "\123") would cause
printf to write a \0 to buf[2] but leaving buf[0] and buf[1] with whatever
they previously contained.

This also fixes a bug in the escaped_string() helper function, which used
to unconditionally pass a length of "end-buf" to string_escape_mem();
since the latter doesn't check osz for being insanely large, it would
happily write to dst.  For example, kasprintf(GFP_KERNEL, "something and
then %pE", ...); is an easy way to trigger an oops.

In test-string_helpers.c, the -ENOMEM test is replaced with testing for
getting the expected return value even if the buffer is too small.  We
also ensure that nothing is written (by relying on a NULL pointer deref)
if the output size is 0 by passing NULL - this has to work for
kasprintf("%pE") to work.

In net/sunrpc/cache.c, I think qword_add still has the same semantics.
Someone should definitely double-check this.

In fs/proc/array.c, I made the minimum possible change, but longer-term it
should stop poking around in seq_file internals.

[andriy.shevchenko@linux.intel.com: simplify qword_add]
[andriy.shevchenko@linux.intel.com: add missed curly braces]
Signed-off-by: Rasmus Villemoes 
Acked-by: Andy Shevchenko 
Signed-off-by: Andy Shevchenko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sunrpc: fix braino in ->poll()

2015-03-08T19:53:46+00:00

POLL_OUT isn't what callers of ->poll() are expecting to see; it's
actually __SI_POLL | 2 and it's a siginfo code, not a poll bitmap
bit...

Signed-off-by: Al Viro 
Cc: stable@vger.kernel.org
Cc: Bruce Fields 
Signed-off-by: Linus Torvalds

sunrpc/cache: convert to use string_escape_str()

2014-12-09T16:30:20+00:00

There is nice kernel helper to escape a given strings by provided rules. Let's
use it instead of custom approach.

Signed-off-by: Andy Shevchenko 
[bfields@redhat.com: fix length calculation]
Signed-off-by: J. Bruce Fields

SUNRPC: Fix printk that is not only for nfsd

2014-05-08T18:59:51+00:00

Signed-off-by: Kinglong Mee 
Signed-off-by: J. Bruce Fields