Do not fail if one of the two responses to AF_UNSPEC fails (BZ #14308)

[Fixes BZ #14308, #12994, #13651]

AF_UNSPEC results in sending two queries in parallel, one for the A
record and the other for the AAAA record.  If one of these is a
referral, then the query fails, which is wrong.  It should return at
least the one successful response.

The fix has two parts.  The first part makes the referral fall back to
the SERVFAIL path, which results in using the successful response.
There is a bug in that path however, due to which the second part is
necessary.  The bug here is that if the first response is a failure
and the second succeeds, __libc_res_nsearch does not detect that and
assumes a failure.  The case where the first response is a success and
the second fails, works correctly.

This condition is produced by buggy routers, so here's a crude
interposable library that can simulate such a condition.  The library
overrides the recvfrom syscall and modifies the header of the packet
received to reproduce this scenario.  It has two key variables:
mod_packet and first_error.

The mod_packet variable when set to 0, results in odd packets being
modified to be a referral.  When set to 1, even packets are modified
to be a referral.

The first_error causes the first response to be a failure so that a
domain-appended search is performed to test the second part of the
__libc_nsearch fix.

The driver for this fix is a simple getaddrinfo program that does an
AF_UNSPEC query.  I have omitted this since it should be easy to
implement.

I have tested this on x86_64.

The interceptor library source:

/* Override recvfrom and modify the header of the first DNS response to make it
   a referral and reproduce bz #845218.  We have to resort to this ugly hack
   because we cannot make bind return the buggy response of a referral for the
   AAAA record and an authoritative response for the A record.  */
 #define _GNU_SOURCE
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <stdio.h>
 #include <stdbool.h>
 #include <endian.h>
 #include <dlfcn.h>
 #include <stdlib.h>

/* Lifted from resolv/arpa/nameser_compat.h.  */
typedef struct {
    unsigned        id :16;         /*%< query identification number */
 #if BYTE_ORDER == BIG_ENDIAN
    /* fields in third byte */
    unsigned        qr: 1;          /*%< response flag */
    unsigned        opcode: 4;      /*%< purpose of message */
    unsigned        aa: 1;          /*%< authoritive answer */
    unsigned        tc: 1;          /*%< truncated message */
    unsigned        rd: 1;          /*%< recursion desired */
    /* fields
     * in
     * fourth
     * byte
     * */
    unsigned        ra: 1;          /*%< recursion available */
    unsigned        unused :1;      /*%< unused bits (MBZ as of 4.9.3a3) */
    unsigned        ad: 1;          /*%< authentic data from named */
    unsigned        cd: 1;          /*%< checking disabled by resolver */
    unsigned        rcode :4;       /*%< response code */
 #endif
 #if BYTE_ORDER == LITTLE_ENDIAN || BYTE_ORDER == PDP_ENDIAN
    /* fields
     * in
     * third
     * byte
     * */
    unsigned        rd :1;          /*%< recursion desired */
    unsigned        tc :1;          /*%< truncated message */
    unsigned        aa :1;          /*%< authoritive answer */
    unsigned        opcode :4;      /*%< purpose of message */
    unsigned        qr :1;          /*%< response flag */
    /* fields
     * in
     * fourth
     * byte
     * */
    unsigned        rcode :4;       /*%< response code */
    unsigned        cd: 1;          /*%< checking disabled by resolver */
    unsigned        ad: 1;          /*%< authentic data from named */
    unsigned        unused :1;      /*%< unused bits (MBZ as of 4.9.3a3) */
    unsigned        ra :1;          /*%< recursion available */
 #endif
    /* remaining
     * bytes
     * */
    unsigned        qdcount :16;    /*%< number of question entries */
    unsigned        ancount :16;    /*%< number of answer entries */
    unsigned        nscount :16;    /*%< number of authority entries */
    unsigned        arcount :16;    /*%< number of resource entries */
} HEADER;

static int done = 0;

/* Packets to modify.  0 for the odd packets and 1 for even packets.  */
static const int mod_packet = 0;

/* Set to true if the first request should result in an error, resulting in a
   search query.  */
static bool first_error = true;

static ssize_t (*real_recvfrom) (int sockfd, void *buf, size_t len, int flags,
			  struct sockaddr *src_addr, socklen_t *addrlen);

void
__attribute__ ((constructor))
init (void)
{
  real_recvfrom = dlsym (RTLD_NEXT, "recvfrom");

  if (real_recvfrom == NULL)
    {
      printf ("Failed to get reference to recvfrom: %s\n", dlerror ());
      printf ("Cannot simulate test\n");
      abort ();
    }
}

/* Modify the second packet that we receive to set the header in a manner as to
   reproduce BZ #845218.  */
static void
mod_buf (HEADER *h, int port)
{
  if (done % 2 == mod_packet || (first_error && done == 1))
    {
      printf ("(Modifying header)");

      if (first_error && done == 1)
	h->rcode = 3;
      else
	h->rcode = 0;	/* NOERROR == 0.  */
      h->ancount = 0;
      h->aa = 0;
      h->ra = 0;
      h->arcount = 0;
    }
  done++;
}

ssize_t
recvfrom (int sockfd, void *buf, size_t len, int flags,
	  struct sockaddr *src_addr, socklen_t *addrlen)
{
  ssize_t ret = real_recvfrom (sockfd, buf, len, flags, src_addr, addrlen);
  int port = htons (((struct sockaddr_in *) src_addr)->sin_port);
  struct in_addr addr = ((struct sockaddr_in *) src_addr)->sin_addr;
  const char *host = inet_ntoa (addr);
  printf ("\n*** From %s:%d: ", host, port);

  mod_buf (buf, port);

  printf ("returned %zd\n", ret);
  return ret;
}
Consolidate code to initialize nscd dataset header

This patch consolidates the code to initialize the header of a dataset
into a single set of functions (one for positive and another for
negative datasets) primarily to reduce repetition of code.  The
secondary reason is to simplify Patch 2/2 which fixes the problem of
an uninitialized byte in the header by initializing an unused field in
the structure and hence preventing a possible data leak into the cache
file.
Initialize all of datahead structure in nscd (BZ #16791)

The datahead structure has an unused padding field that remains
uninitialized.  Valgrind prints out a warning for it on querying a
netgroups entry.  This is harmless, but is a potential data leak since
it would result in writing out an uninitialized byte to the cache
file.  Besides, this happens only when there is a cache miss, so we're
not adding computation to any fast path.
Fix lll_unlock twice in pthread_cond_broadcast

lll_unlock() will be called again if it goes to "wake_all" in
pthread_cond_broadcast(). This may make another thread which is
waiting for lock in pthread_cond_timedwait() unlock.  So there are
more than one threads get the lock, it will break the shared data.

It's introduced by commit 8313cb997d2d("FUTEX_*_REQUEUE_PI support for
non-x86 code")
More fixes for unsafe compiler optimization

GCC 4.9 -ftree-loop-distribute-patterns now may transform loops in
memcpy.  Add the alias to internal GLIBC symbol to avoid PLT creation.
ChangeLog cleanup
conformtest: clean up POSIX expectations for stdlib.h, string.h.

Continuing the series of patches to clean up conformtest expectations
for "POSIX" (1995/6) based on review of the expectations against the
standard, this patch cleans up expectations for stdlib.h and
string.h.  Tested x86_64; no new XFAILs needed.

	* conform/data/stdlib.h-data [POSIX] (stddef.h): Do not allow
	header inclusion.
	[POSIX] (limits.h): Likewise.
	[POSIX] (math.h): Likewise.
	[POSIX] (sys/wait.h): Likewise.
	* conform/data/string.h-data [POSIX || UNIX98] (strtok_r): Require
	function.
	[POSIX] (stddef.h): Do not allow header inclusion.
Increase minimum Linux kernel version to 2.6.32.

This patch increases the minimum Linux kernel version for glibc to
2.6.32, as discussed in the thread starting at
<https://sourceware.org/ml/libc-alpha/2014-01/msg00511.html>.

This patch just does the minimal change to arch_minimum_kernel
settings (and LIBC_LINUX_VERSION, which determines the minimum kernel
headers version, as it doesn't make sense for that to be older than
the minimum kernel that can be used at runtime).  Followups would be
expected to do, roughly and not necessarily precisely in this order:

* Remove __LINUX_KERNEL_VERSION checks in kernel-features.h files
  where those checks are always true / always false for kernels 2.6.32
  and above.

* Otherwise simplify/improve conditionals in those files (for example,
  where defining once in the main file then undefining in
  architecture-specific files makes things clearer than having lots of
  separate definitions of the same macro), possibly fixing in the
  process cases where a macro should optimally have been defined for a
  given architecture but wasn't.  (In the review in preparation for
  this version increase I checked what the right conditions should be
  for all macros in the main kernel-features.h whose definitions there
  would have been affected by the increase - but I only fixed that
  subset of the issues found where --enable-kernel=2.6.32 would have
  caused a kernel feature to be wrongly assumed to be present, not any
  cases where a feature is not assumed but could be assumed.)

* Remove conditionals on __ASSUME_* where they can now be taken to be
  always-true, and the definitions when the macros are only used in
  Linux-specific files.

* Split more architectures out of the main kernel-features.h (like
  ex-ports architectures), once various of the architecture
  conditionals there have been eliminated so the new
  architecture-specific files are no larger than actually necessary.

Tested x86_64.

2014-03-27  Joseph Myers  <joseph@codesourcery.com>

	[BZ #9894]
	* sysdeps/unix/sysv/linux/configure.ac (LIBC_LINUX_VERSION):
	Change to 2.6.32.
	(arch_minimum_kernel): Change all 2.6.16 settings to 2.6.32.
	* sysdeps/unix/sysv/linux/configure: Regenerated.
	* sysdeps/unix/sysv/linux/microblaze/configure.ac: Remove file.
	* sysdeps/unix/sysv/linux/microblaze/configure: Likewise.
	* sysdeps/unix/sysv/linux/tile/configure.ac: Likewise.
	* sysdeps/unix/sysv/linux/tile/configure: Likewise.
	* README: Update reference to required Linux kernel version.
	* manual/install.texi (Linux): Update reference to required Linux
	kernel headers version.
	* INSTALL: Regenerated.
ARM: Fix R_ARM_IRELATIVE RELA relocations.

This patch fixes what I believe to be a bug in the handling of
R_ARM_IRELATIVE RELA relocations. At present, these are handled the
same as REL relocations: i.e. the addend is loaded from the relocation
address. Most of the time this isn't a problem because RELA relocations
aren't used on ARM (GNU/Linux at least) anyway, but it causes problems
with prelink, which uses RELA on all targets for its conflict table.
(Support for ifunc prelinking requires a prelink patch, not yet posted.)

Anyway, this patch works, though I'm not 100% sure if it is correct: I
notice that this code path received attention last year:

https://sourceware.org/ml/libc-ports/2013-07/msg00000.html

I'm not sure under what circumstances that patch would have had an
effect, nor if my patch conflicts with that case.

No regressions using Mentor's usual glibc cross-testing infrastructure.

	[BZ #16888]
	* sysdeps/arm/dl-machine.h (elf_machine_rela): Fix R_ARM_IRELATIVE
	handling.
Add deprecation header text to remaining ports/ChangeLog* files.
Move ports/ChangeLog* files to ChangeLog.old-ports*, remove ports/ directory.
Fix some sparc conform test failures in siginfo.h

	* sysdeps/unix/sysv/linux/sparc/bits/siginfo.h (EMT_TAGOVF): Protect
	with XOPEN cpp guards.
Fix some sparc -Wundef build warnings.

	* sysdeps/sparc/bits/string.h (_STRING_ARCH_unaligned): Define to
	0.
Correct sparc CPP guards for EMT_TAGOVF.

	* sysdeps/unix/sysv/linux/sparc/bits/siginfo.h (EMT_TAGOVF): Protect
	with __USE_GNU instead of XOPEN cpp guards.
Add round-mode context support to sparc.

	* sysdeps/sparc/fpu/fenv_private.h (HAVE_RM_CTX): Define.
	(libc_feholdexcept_setround_sparc_ctx): New function.
	(libc_fesetenv_sparc_ctx): Likewise.
	(libc_feupdateenv_sparc_ctx): Likewise.
	(libc_feholdsetround_sparc_ctx): Likewise.
	(libc_feholdexcept_setround_ctx): Define.
	(libc_feholdexcept_setroundf_ctx): Likewise.
	(libc_feholdexcept_setroundl_ctx): Likewise.
	(libc_fesetenv_ctx): Likewise.
	(libc_fesetenvf_ctx): Likewise.
	(libc_fesetenvl_ctx): Likewise.
	(libc_feupdateenv_ctx): Likewise.
	(libc_feupdateenvf_ctx): Likewise.
	(libc_feupdateenvl_ctx): Likewise.
	(libc_feresetround_ctx): Likewise.
	(libc_feresetroundf_ctx): Likewise.
	(libc_feresetroundl_ctx): Likewise.
	(libc_feholdsetround_ctx): Likewise.
	(libc_feholdsetroundf_ctx): Likewise.
	(libc_feholdsetroundl_ctx): Likewise.