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  1. 13 10月, 2015 1 次提交
  3. 16 4月, 2015 1 次提交
  5. 23 2月, 2015 1 次提交
    • D
      VFS: (Scripted) Convert S_ISLNK/DIR/REG(dentry->d_inode) to d_is_*(dentry) · e36cb0b8
      由 David Howells 提交于 
      Convert the following where appropriate:

 (1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).

 (2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).

 (3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry).  This is actually more
     complicated than it appears as some calls should be converted to
     d_can_lookup() instead.  The difference is whether the directory in
     question is a real dir with a ->lookup op or whether it's a fake dir with
     a ->d_automount op.

In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).

Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer.  In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.

However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.

There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE.  Strictly, this was
intended for special directory entry types that don't have attached inodes.

The following perl+coccinelle script was used:

use strict;

my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
    die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
    print "No matches\n";
    exit(0);
}

my @cocci = (
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISLNK(E->d_inode->i_mode)',
    '+ d_is_symlink(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISDIR(E->d_inode->i_mode)',
    '+ d_is_dir(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISREG(E->d_inode->i_mode)',
    '+ d_is_reg(E)' );

my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);

foreach my $file (@callers) {
    chomp $file;
    print "Processing ", $file, "\n";
    system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
	die "spatch failed";
}

[AV: overlayfs parts skipped]
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      e36cb0b8
  7. 10 12月, 2014 1 次提交
  9. 04 9月, 2014 1 次提交
  11. 23 6月, 2014 2 次提交
  13. 31 5月, 2014 1 次提交
  15. 09 5月, 2014 1 次提交
    • C
      nfsd: clean up fh_auth usage · 5409e46f
      由 Christoph Hellwig 提交于 
      Use fh_fsid when reffering to the fsid part of the filehandle.  The
variable length auth field envisioned in nfsfh wasn't ever implemented.
Also clean up some lose ends around this and document the file handle
format better.

Btw, why do we even export nfsfh.h to userspace?  The file handle very
much is kernel private, and nothing in nfs-utils include the header
either.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
      5409e46f
  17. 30 10月, 2013 1 次提交
  19. 25 10月, 2013 1 次提交
  21. 03 10月, 2013 1 次提交
  23. 08 11月, 2012 1 次提交
  25. 31 7月, 2012 1 次提交
  27. 12 4月, 2012 1 次提交
  29. 04 1月, 2012 1 次提交
  31. 27 8月, 2011 2 次提交
  33. 11 4月, 2011 1 次提交
  35. 21 12月, 2009 1 次提交
  37. 20 12月, 2009 1 次提交
  39. 16 12月, 2009 2 次提交
  41. 15 12月, 2009 3 次提交
  43. 26 11月, 2009 1 次提交
    • J
      nfsd: simplify fh_verify access checks · 864f0f61
      由 J. Bruce Fields 提交于 
      All nfsd security depends on the security checks in fh_verify, and
especially on nfsd_setuser().

It therefore bothers me that the nfsd_setuser call may be made from
three different places, depending on whether the filehandle has already
been mapped to a dentry, and on whether subtreechecking is in force.

Instead, make an unconditional call in fh_verify(), so it's trivial to
verify that the call always occurs.

That leaves us with a redundant nfsd_setuser() call in the subtreecheck
case--it needs the correct user set earlier in order to check execute
permissions on the path to this filehandle--but I'm willing to accept
that minor inefficiency in the subtreecheck case in return for more
straightforward permission checking.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      864f0f61
  45. 14 11月, 2009 1 次提交
  47. 04 9月, 2009 1 次提交
  49. 03 9月, 2009 2 次提交
  51. 28 5月, 2009 1 次提交
    • G
      knfsd: remove unreported filehandle stats counters · 1dbd0d53
      由 Greg Banks 提交于 
      The file nfsfh.c contains two static variables nfsd_nr_verified and
nfsd_nr_put.  These are counters which are incremented as a side
effect of the fh_verify() fh_compose() and fh_put() operations,
i.e. at least twice per NFS call for any non-trivial workload.
Needless to say this makes the cacheline that contains them (and any
other innocent victims) a very hot contention point indeed under high
call-rate workloads on multiprocessor NFS server.  It also turns out
that these counters are not used anywhere.  They're not reported to
userspace, they're not used in logic, they're not even exported from
the object file (let alone the module).  All they do is waste CPU time.

So this patch removes them.

Tests on a 16 CPU Altix A4700 with 2 10gige Myricom cards, configured
separately (no bonding).  Workload is 640 client threads doing directory
traverals with random small reads, from server RAM.

Before
======

Kernel profile:

  %   cumulative   self              self     total
 time   samples   samples    calls   1/call   1/call  name
  6.05   2716.00  2716.00    30406     0.09     1.02  svc_process
  4.44   4706.00  1990.00     1975     1.01     1.01  spin_unlock_irqrestore
  3.72   6376.00  1670.00     1666     1.00     1.00  svc_export_put
  3.41   7907.00  1531.00     1786     0.86     1.02  nfsd_ofcache_lookup
  3.25   9363.00  1456.00    10965     0.13     1.01  nfsd_dispatch
  3.10  10752.00  1389.00     1376     1.01     1.01  nfsd_cache_lookup
  2.57  11907.00  1155.00     4517     0.26     1.03  svc_tcp_recvfrom
  ...
  2.21  15352.00  1003.00     1081     0.93     1.00  nfsd_choose_ofc  <----
  ^^^^

Here the function nfsd_choose_ofc() reads a global variable
which by accident happened to be located in the same cacheline as
nfsd_nr_verified.

Call rate:

nullarbor:~ # pmdumptext nfs3.server.calls
...
Thu Dec 13 00:15:27     184780.663
Thu Dec 13 00:15:28     184885.881
Thu Dec 13 00:15:29     184449.215
Thu Dec 13 00:15:30     184971.058
Thu Dec 13 00:15:31     185036.052
Thu Dec 13 00:15:32     185250.475
Thu Dec 13 00:15:33     184481.319
Thu Dec 13 00:15:34     185225.737
Thu Dec 13 00:15:35     185408.018
Thu Dec 13 00:15:36     185335.764

After
=====

kernel profile:

  %   cumulative   self              self     total
 time   samples   samples    calls   1/call   1/call  name
  6.33   2813.00  2813.00    29979     0.09     1.01  svc_process
  4.66   4883.00  2070.00     2065     1.00     1.00  spin_unlock_irqrestore
  4.06   6687.00  1804.00     2182     0.83     1.00  nfsd_ofcache_lookup
  3.20   8110.00  1423.00    10932     0.13     1.00  nfsd_dispatch
  3.03   9456.00  1346.00     1343     1.00     1.00  nfsd_cache_lookup
  2.62  10622.00  1166.00     4645     0.25     1.01  svc_tcp_recvfrom
[...]
  0.10  42586.00    44.00       74     0.59     1.00  nfsd_choose_ofc  <--- HA!!
  ^^^^

Call rate:

nullarbor:~ # pmdumptext nfs3.server.calls
...
Thu Dec 13 01:45:28     194677.118
Thu Dec 13 01:45:29     193932.692
Thu Dec 13 01:45:30     194294.364
Thu Dec 13 01:45:31     194971.276
Thu Dec 13 01:45:32     194111.207
Thu Dec 13 01:45:33     194999.635
Thu Dec 13 01:45:34     195312.594
Thu Dec 13 01:45:35     195707.293
Thu Dec 13 01:45:36     194610.353
Thu Dec 13 01:45:37     195913.662
Thu Dec 13 01:45:38     194808.675

i.e. about a 5.3% improvement in call rate.
Signed-off-by: NGreg Banks <gnb@melbourne.sgi.com>
Reviewed-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      1dbd0d53
  53. 08 1月, 2009 1 次提交
  55. 07 1月, 2009 1 次提交
  57. 14 11月, 2008 2 次提交
    • D
      CRED: Inaugurate COW credentials · d84f4f99
      由 David Howells 提交于 
      Inaugurate copy-on-write credentials management.  This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.

A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().

With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:

	struct cred *new = prepare_creds();
	int ret = blah(new);
	if (ret < 0) {
		abort_creds(new);
		return ret;
	}
	return commit_creds(new);

There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.

To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const.  The purpose of this is compile-time
discouragement of altering credentials through those pointers.  Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:

  (1) Its reference count may incremented and decremented.

  (2) The keyrings to which it points may be modified, but not replaced.

The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).

This patch and the preceding patches have been tested with the LTP SELinux
testsuite.

This patch makes several logical sets of alteration:

 (1) execve().

     This now prepares and commits credentials in various places in the
     security code rather than altering the current creds directly.

 (2) Temporary credential overrides.

     do_coredump() and sys_faccessat() now prepare their own credentials and
     temporarily override the ones currently on the acting thread, whilst
     preventing interference from other threads by holding cred_replace_mutex
     on the thread being dumped.

     This will be replaced in a future patch by something that hands down the
     credentials directly to the functions being called, rather than altering
     the task's objective credentials.

 (3) LSM interface.

     A number of functions have been changed, added or removed:

     (*) security_capset_check(), ->capset_check()
     (*) security_capset_set(), ->capset_set()

     	 Removed in favour of security_capset().

     (*) security_capset(), ->capset()

     	 New.  This is passed a pointer to the new creds, a pointer to the old
     	 creds and the proposed capability sets.  It should fill in the new
     	 creds or return an error.  All pointers, barring the pointer to the
     	 new creds, are now const.

     (*) security_bprm_apply_creds(), ->bprm_apply_creds()

     	 Changed; now returns a value, which will cause the process to be
     	 killed if it's an error.

     (*) security_task_alloc(), ->task_alloc_security()

     	 Removed in favour of security_prepare_creds().

     (*) security_cred_free(), ->cred_free()

     	 New.  Free security data attached to cred->security.

     (*) security_prepare_creds(), ->cred_prepare()

     	 New. Duplicate any security data attached to cred->security.

     (*) security_commit_creds(), ->cred_commit()

     	 New. Apply any security effects for the upcoming installation of new
     	 security by commit_creds().

     (*) security_task_post_setuid(), ->task_post_setuid()

     	 Removed in favour of security_task_fix_setuid().

     (*) security_task_fix_setuid(), ->task_fix_setuid()

     	 Fix up the proposed new credentials for setuid().  This is used by
     	 cap_set_fix_setuid() to implicitly adjust capabilities in line with
     	 setuid() changes.  Changes are made to the new credentials, rather
     	 than the task itself as in security_task_post_setuid().

     (*) security_task_reparent_to_init(), ->task_reparent_to_init()

     	 Removed.  Instead the task being reparented to init is referred
     	 directly to init's credentials.

	 NOTE!  This results in the loss of some state: SELinux's osid no
	 longer records the sid of the thread that forked it.

     (*) security_key_alloc(), ->key_alloc()
     (*) security_key_permission(), ->key_permission()

     	 Changed.  These now take cred pointers rather than task pointers to
     	 refer to the security context.

 (4) sys_capset().

     This has been simplified and uses less locking.  The LSM functions it
     calls have been merged.

 (5) reparent_to_kthreadd().

     This gives the current thread the same credentials as init by simply using
     commit_thread() to point that way.

 (6) __sigqueue_alloc() and switch_uid()

     __sigqueue_alloc() can't stop the target task from changing its creds
     beneath it, so this function gets a reference to the currently applicable
     user_struct which it then passes into the sigqueue struct it returns if
     successful.

     switch_uid() is now called from commit_creds(), and possibly should be
     folded into that.  commit_creds() should take care of protecting
     __sigqueue_alloc().

 (7) [sg]et[ug]id() and co and [sg]et_current_groups.

     The set functions now all use prepare_creds(), commit_creds() and
     abort_creds() to build and check a new set of credentials before applying
     it.

     security_task_set[ug]id() is called inside the prepared section.  This
     guarantees that nothing else will affect the creds until we've finished.

     The calling of set_dumpable() has been moved into commit_creds().

     Much of the functionality of set_user() has been moved into
     commit_creds().

     The get functions all simply access the data directly.

 (8) security_task_prctl() and cap_task_prctl().

     security_task_prctl() has been modified to return -ENOSYS if it doesn't
     want to handle a function, or otherwise return the return value directly
     rather than through an argument.

     Additionally, cap_task_prctl() now prepares a new set of credentials, even
     if it doesn't end up using it.

 (9) Keyrings.

     A number of changes have been made to the keyrings code:

     (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
     	 all been dropped and built in to the credentials functions directly.
     	 They may want separating out again later.

     (b) key_alloc() and search_process_keyrings() now take a cred pointer
     	 rather than a task pointer to specify the security context.

     (c) copy_creds() gives a new thread within the same thread group a new
     	 thread keyring if its parent had one, otherwise it discards the thread
     	 keyring.

     (d) The authorisation key now points directly to the credentials to extend
     	 the search into rather pointing to the task that carries them.

     (e) Installing thread, process or session keyrings causes a new set of
     	 credentials to be created, even though it's not strictly necessary for
     	 process or session keyrings (they're shared).

(10) Usermode helper.

     The usermode helper code now carries a cred struct pointer in its
     subprocess_info struct instead of a new session keyring pointer.  This set
     of credentials is derived from init_cred and installed on the new process
     after it has been cloned.

     call_usermodehelper_setup() allocates the new credentials and
     call_usermodehelper_freeinfo() discards them if they haven't been used.  A
     special cred function (prepare_usermodeinfo_creds()) is provided
     specifically for call_usermodehelper_setup() to call.

     call_usermodehelper_setkeys() adjusts the credentials to sport the
     supplied keyring as the new session keyring.

(11) SELinux.

     SELinux has a number of changes, in addition to those to support the LSM
     interface changes mentioned above:

     (a) selinux_setprocattr() no longer does its check for whether the
     	 current ptracer can access processes with the new SID inside the lock
     	 that covers getting the ptracer's SID.  Whilst this lock ensures that
     	 the check is done with the ptracer pinned, the result is only valid
     	 until the lock is released, so there's no point doing it inside the
     	 lock.

(12) is_single_threaded().

     This function has been extracted from selinux_setprocattr() and put into
     a file of its own in the lib/ directory as join_session_keyring() now
     wants to use it too.

     The code in SELinux just checked to see whether a task shared mm_structs
     with other tasks (CLONE_VM), but that isn't good enough.  We really want
     to know if they're part of the same thread group (CLONE_THREAD).

(13) nfsd.

     The NFS server daemon now has to use the COW credentials to set the
     credentials it is going to use.  It really needs to pass the credentials
     down to the functions it calls, but it can't do that until other patches
     in this series have been applied.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NJames Morris <jmorris@namei.org>
Signed-off-by: NJames Morris <jmorris@namei.org>
      d84f4f99
    • D
      CRED: Separate task security context from task_struct · b6dff3ec
      由 David Howells 提交于 
      Separate the task security context from task_struct.  At this point, the
security data is temporarily embedded in the task_struct with two pointers
pointing to it.

Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in
entry.S via asm-offsets.

With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NJames Morris <jmorris@namei.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NJames Morris <jmorris@namei.org>
      b6dff3ec
  59. 30 9月, 2008 1 次提交
    • J
      nfsd: permit unauthenticated stat of export root · 04716e66
      由 J. Bruce Fields 提交于 
      RFC 2623 section 2.3.2 permits the server to bypass gss authentication
checks for certain operations that a client may perform when mounting.
In the case of a client that doesn't have some form of credentials
available to it on boot, this allows it to perform the mount unattended.
(Presumably real file access won't be needed until a user with
credentials logs in.)

Being slightly more lenient allows lots of old clients to access
krb5-only exports, with the only loss being a small amount of
information leaked about the root directory of the export.

This affects only v2 and v3; v4 still requires authentication for all
access.

Thanks to Peter Staubach testing against a Solaris client, which
suggesting addition of v3 getattr, to the list, and to Trond for noting
that doing so exposes no additional information.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Cc: Peter Staubach <staubach@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
      04716e66
  61. 27 7月, 2008 1 次提交
  63. 01 7月, 2008 1 次提交
    • N
      nfsd: fix spurious EACCESS in reconnect_path() · 496d6c32
      由 Neil Brown 提交于 
      Thanks to Frank Van Maarseveen for the original problem report: "A
privileged process on an NFS client which drops privileges after using
them to change the current working directory, will experience incorrect
EACCES after an NFS server reboot. This problem can also occur after
memory pressure on the server, particularly when the client side is
quiet for some time."

This occurs because the filehandle points to a directory whose parents
are no longer in the dentry cache, and we're attempting to reconnect the
directory to its parents without adequate permissions to perform lookups
in the parent directories.

We can therefore fix the problem by acquiring the necessary capabilities
before attempting the reconnection.  We do this only in the
no_subtree_check case, since the documented behavior of the
subtree_check export option requires the server to check that the user
has lookup permissions on all parents.

The subtree_check case still has a problem, since reconnect_path()
unnecessarily requires both read and lookup permissions on all parent
directories.  However, a fix in that case would be more delicate, and
use of subtree_check is already discouraged for other reasons.
Signed-off-by: NNeil Brown <neilb@suse.de>
Cc: Frank van Maarseveen <frankvm@frankvm.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
      496d6c32
  65. 24 6月, 2008 1 次提交