1. 09 5月, 2009 2 次提交
  2. 03 5月, 2009 1 次提交
    • I
      alpha: binfmt_aout fix · 74641f58
      Ivan Kokshaysky 提交于
      This fixes the problem introduced by commit 3bfacef4 (get rid of
      special-casing the /sbin/loader on alpha): osf/1 ecoff binary segfaults
      when binfmt_aout built as module.  That happens because aout binary
      handler gets on the top of the binfmt list due to late registration, and
      kernel attempts to execute the binary without preparatory work that must
      be done by binfmt_loader.
      
      Fixed by changing the registration order of the default binfmt handlers
      using list_add_tail() and introducing insert_binfmt() function which
      places new handler on the top of the binfmt list.  This might be generally
      useful for installing arch-specific frontends for default handlers or just
      for overriding them.
      Signed-off-by: NIvan Kokshaysky <ink@jurassic.park.msu.ru>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Richard Henderson <rth@twiddle.net
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      74641f58
  3. 24 4月, 2009 2 次提交
    • O
      check_unsafe_exec: s/lock_task_sighand/rcu_read_lock/ · 437f7fdb
      Oleg Nesterov 提交于
      write_lock(&current->fs->lock) guarantees we can't wrongly miss
      LSM_UNSAFE_SHARE, this is what we care about. Use rcu_read_lock()
      instead of ->siglock to iterate over the sub-threads. We must see
      all CLONE_THREAD|CLONE_FS threads which didn't pass exit_fs(), it
      takes fs->lock too.
      
      With or without this patch we can miss the freshly cloned thread
      and set LSM_UNSAFE_SHARE, we don't care.
      Signed-off-by: NOleg Nesterov <oleg@redhat.com>
      Acked-by: NRoland McGrath <roland@redhat.com>
      [ Fixed lock/unlock typo  - Hugh ]
      Acked-by: NHugh Dickins <hugh@veritas.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      437f7fdb
    • O
      do_execve() must not clear fs->in_exec if it was set by another thread · 8c652f96
      Oleg Nesterov 提交于
      If do_execve() fails after check_unsafe_exec(), it clears fs->in_exec
      unconditionally. This is wrong if we race with our sub-thread which
      also does do_execve:
      
      	Two threads T1 and T2 and another process P, all share the same
      	->fs.
      
      	T1 starts do_execve(BAD_FILE). It calls check_unsafe_exec(), since
      	->fs is shared, we set LSM_UNSAFE but not ->in_exec.
      
      	P exits and decrements fs->users.
      
      	T2 starts do_execve(), calls check_unsafe_exec(), now ->fs is not
      	shared, we set fs->in_exec.
      
      	T1 continues, open_exec(BAD_FILE) fails, we clear ->in_exec and
      	return to the user-space.
      
      	T1 does clone(CLONE_FS /* without CLONE_THREAD */).
      
      	T2 continues without LSM_UNSAFE_SHARE while ->fs is shared with
      	another process.
      
      Change check_unsafe_exec() to return res = 1 if we set ->in_exec, and change
      do_execve() to clear ->in_exec depending on res.
      
      When do_execve() suceeds, it is safe to clear ->in_exec unconditionally.
      It can be set only if we don't share ->fs with another process, and since
      we already killed all sub-threads either ->in_exec == 0 or we are the
      only user of this ->fs.
      
      Also, we do not need fs->lock to clear fs->in_exec.
      Signed-off-by: NOleg Nesterov <oleg@redhat.com>
      Acked-by: NRoland McGrath <roland@redhat.com>
      Acked-by: NHugh Dickins <hugh@veritas.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8c652f96
  4. 01 4月, 2009 3 次提交
  5. 29 3月, 2009 1 次提交
    • H
      fix setuid sometimes doesn't · e426b64c
      Hugh Dickins 提交于
      Joe Malicki reports that setuid sometimes doesn't: very rarely,
      a setuid root program does not get root euid; and, by the way,
      they have a health check running lsof every few minutes.
      
      Right, check_unsafe_exec() notes whether the files_struct is being
      shared by more threads than will get killed by the exec, and if so
      sets LSM_UNSAFE_SHARE to make bprm_set_creds() careful about euid.
      But /proc/<pid>/fd and /proc/<pid>/fdinfo lookups make transient
      use of get_files_struct(), which also raises that sharing count.
      
      There's a rather simple fix for this: exec's check on files->count
      has been redundant ever since 2.6.1 made it unshare_files() (except
      while compat_do_execve() omitted to do so) - just remove that check.
      
      [Note to -stable: this patch will not apply before 2.6.29: earlier
      releases should just remove the files->count line from unsafe_exec().]
      Reported-by: NJoe Malicki <jmalicki@metacarta.com>
      Narrowed-down-by: NMichael Itz <mitz@metacarta.com>
      Tested-by: NJoe Malicki <jmalicki@metacarta.com>
      Signed-off-by: NHugh Dickins <hugh@veritas.com>
      Cc: stable@kernel.org
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e426b64c
  6. 12 2月, 2009 1 次提交
  7. 07 2月, 2009 1 次提交
    • D
      CRED: Fix SUID exec regression · 0bf2f3ae
      David Howells 提交于
      The patch:
      
      	commit a6f76f23
      	CRED: Make execve() take advantage of copy-on-write credentials
      
      moved the place in which the 'safeness' of a SUID/SGID exec was performed to
      before de_thread() was called.  This means that LSM_UNSAFE_SHARE is now
      calculated incorrectly.  This flag is set if any of the usage counts for
      fs_struct, files_struct and sighand_struct are greater than 1 at the time the
      determination is made.  All of which are true for threads created by the
      pthread library.
      
      However, since we wish to make the security calculation before irrevocably
      damaging the process so that we can return it an error code in the case where
      we decide we want to reject the exec request on this basis, we have to make the
      determination before calling de_thread().
      
      So, instead, we count up the number of threads (CLONE_THREAD) that are sharing
      our fs_struct (CLONE_FS), files_struct (CLONE_FILES) and sighand_structs
      (CLONE_SIGHAND/CLONE_THREAD) with us.  These will be killed by de_thread() and
      so can be discounted by check_unsafe_exec().
      
      We do have to be careful because CLONE_THREAD does not imply FS or FILES.
      
      We _assume_ that there will be no extra references to these structs held by the
      threads we're going to kill.
      
      This can be tested with the attached pair of programs.  Build the two programs
      using the Makefile supplied, and run ./test1 as a non-root user.  If
      successful, you should see something like:
      
      	[dhowells@andromeda tmp]$ ./test1
      	--TEST1--
      	uid=4043, euid=4043 suid=4043
      	exec ./test2
      	--TEST2--
      	uid=4043, euid=0 suid=0
      	SUCCESS - Correct effective user ID
      
      and if unsuccessful, something like:
      
      	[dhowells@andromeda tmp]$ ./test1
      	--TEST1--
      	uid=4043, euid=4043 suid=4043
      	exec ./test2
      	--TEST2--
      	uid=4043, euid=4043 suid=4043
      	ERROR - Incorrect effective user ID!
      
      The non-root user ID you see will depend on the user you run as.
      
      [test1.c]
      #include <stdio.h>
      #include <stdlib.h>
      #include <unistd.h>
      #include <pthread.h>
      
      static void *thread_func(void *arg)
      {
      	while (1) {}
      }
      
      int main(int argc, char **argv)
      {
      	pthread_t tid;
      	uid_t uid, euid, suid;
      
      	printf("--TEST1--\n");
      	getresuid(&uid, &euid, &suid);
      	printf("uid=%d, euid=%d suid=%d\n", uid, euid, suid);
      
      	if (pthread_create(&tid, NULL, thread_func, NULL) < 0) {
      		perror("pthread_create");
      		exit(1);
      	}
      
      	printf("exec ./test2\n");
      	execlp("./test2", "test2", NULL);
      	perror("./test2");
      	_exit(1);
      }
      
      [test2.c]
      #include <stdio.h>
      #include <stdlib.h>
      #include <unistd.h>
      
      int main(int argc, char **argv)
      {
      	uid_t uid, euid, suid;
      
      	getresuid(&uid, &euid, &suid);
      	printf("--TEST2--\n");
      	printf("uid=%d, euid=%d suid=%d\n", uid, euid, suid);
      
      	if (euid != 0) {
      		fprintf(stderr, "ERROR - Incorrect effective user ID!\n");
      		exit(1);
      	}
      	printf("SUCCESS - Correct effective user ID\n");
      	exit(0);
      }
      
      [Makefile]
      CFLAGS = -D_GNU_SOURCE -Wall -Werror -Wunused
      all: test1 test2
      
      test1: test1.c
      	gcc $(CFLAGS) -o test1 test1.c -lpthread
      
      test2: test2.c
      	gcc $(CFLAGS) -o test2 test2.c
      	sudo chown root.root test2
      	sudo chmod +s test2
      Reported-by: NDavid Smith <dsmith@redhat.com>
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Acked-by: NDavid Smith <dsmith@redhat.com>
      Signed-off-by: NJames Morris <jmorris@namei.org>
      0bf2f3ae
  8. 06 2月, 2009 1 次提交
  9. 14 1月, 2009 1 次提交
  10. 07 1月, 2009 3 次提交
  11. 06 1月, 2009 1 次提交
  12. 04 1月, 2009 1 次提交
  13. 01 1月, 2009 1 次提交
  14. 13 12月, 2008 1 次提交
  15. 10 12月, 2008 1 次提交
    • R
      tracehook: exec double-reporting fix · 85f33466
      Roland McGrath 提交于
      The patch 6341c393 "tracehook: exec" introduced a small regression in
      2.6.27 regarding binfmt_misc exec event reporting.  Since the reporting
      is now done in the common search_binary_handler() function, an exec
      of a misc binary will result in two (or possibly multiple) exec events
      being reported, instead of just a single one, because the misc handler
      contains a recursive call to search_binary_handler.
      
      To add to the confusion, if PTRACE_O_TRACEEXEC is not active, the multiple
      SIGTRAP signals will in fact cause only a single ptrace intercept, as the
      signals are not queued.  However, if PTRACE_O_TRACEEXEC is on, the debugger
      will actually see multiple ptrace intercepts (PTRACE_EVENT_EXEC).
      
      The test program included below demonstrates the problem.
      
      This change fixes the bug by calling tracehook_report_exec() only in the
      outermost search_binary_handler() call (bprm->recursion_depth == 0).
      
      The additional change to restore bprm->recursion_depth after each binfmt
      load_binary call is actually superfluous for this bug, since we test the
      value saved on entry to search_binary_handler().  But it keeps the use of
      of the depth count to its most obvious expected meaning.  Depending on what
      binfmt handlers do in certain cases, there could have been false-positive
      tests for recursion limits before this change.
      
          /* Test program using PTRACE_O_TRACEEXEC.
             This forks and exec's the first argument with the rest of the arguments,
             while ptrace'ing.  It expects to see one PTRACE_EVENT_EXEC stop and
             then a successful exit, with no other signals or events in between.
      
             Test for kernel doing two PTRACE_EVENT_EXEC stops for a binfmt_misc exec:
      
             $ gcc -g traceexec.c -o traceexec
             $ sudo sh -c 'echo :test:M::foobar::/bin/cat: > /proc/sys/fs/binfmt_misc/register'
             $ echo 'foobar test' > ./foobar
             $ chmod +x ./foobar
             $ ./traceexec ./foobar; echo $?
             ==> good <==
             foobar test
             0
             $
             ==> bad <==
             foobar test
             unexpected status 0x4057f != 0
             3
             $
      
          */
      
          #include <stdio.h>
          #include <sys/types.h>
          #include <sys/wait.h>
          #include <sys/ptrace.h>
          #include <unistd.h>
          #include <signal.h>
          #include <stdlib.h>
      
          static void
          wait_for (pid_t child, int expect)
          {
            int status;
            pid_t p = wait (&status);
            if (p != child)
      	{
      	  perror ("wait");
      	  exit (2);
      	}
            if (status != expect)
      	{
      	  fprintf (stderr, "unexpected status %#x != %#x\n", status, expect);
      	  exit (3);
      	}
          }
      
          int
          main (int argc, char **argv)
          {
            pid_t child = fork ();
      
            if (child < 0)
      	{
      	  perror ("fork");
      	  return 127;
      	}
            else if (child == 0)
      	{
      	  ptrace (PTRACE_TRACEME);
      	  raise (SIGUSR1);
      	  execv (argv[1], &argv[1]);
      	  perror ("execve");
      	  _exit (127);
      	}
      
            wait_for (child, W_STOPCODE (SIGUSR1));
      
            if (ptrace (PTRACE_SETOPTIONS, child,
      		  0L, (void *) (long) PTRACE_O_TRACEEXEC) != 0)
      	{
      	  perror ("PTRACE_SETOPTIONS");
      	  return 4;
      	}
      
            if (ptrace (PTRACE_CONT, child, 0L, 0L) != 0)
      	{
      	  perror ("PTRACE_CONT");
      	  return 5;
      	}
      
            wait_for (child, W_STOPCODE (SIGTRAP | (PTRACE_EVENT_EXEC << 8)));
      
            if (ptrace (PTRACE_CONT, child, 0L, 0L) != 0)
      	{
      	  perror ("PTRACE_CONT");
      	  return 6;
      	}
      
            wait_for (child, W_EXITCODE (0, 0));
      
            return 0;
          }
      Reported-by: NArnd Bergmann <arnd@arndb.de>
      CC: Ulrich Weigand <ulrich.weigand@de.ibm.com>
      Signed-off-by: NRoland McGrath <roland@redhat.com>
      85f33466
  16. 14 11月, 2008 5 次提交
    • D
      CRED: Make execve() take advantage of copy-on-write credentials · a6f76f23
      David Howells 提交于
      Make execve() take advantage of copy-on-write credentials, allowing it to set
      up the credentials in advance, and then commit the whole lot after the point
      of no return.
      
      This patch and the preceding patches have been tested with the LTP SELinux
      testsuite.
      
      This patch makes several logical sets of alteration:
      
       (1) execve().
      
           The credential bits from struct linux_binprm are, for the most part,
           replaced with a single credentials pointer (bprm->cred).  This means that
           all the creds can be calculated in advance and then applied at the point
           of no return with no possibility of failure.
      
           I would like to replace bprm->cap_effective with:
      
      	cap_isclear(bprm->cap_effective)
      
           but this seems impossible due to special behaviour for processes of pid 1
           (they always retain their parent's capability masks where normally they'd
           be changed - see cap_bprm_set_creds()).
      
           The following sequence of events now happens:
      
           (a) At the start of do_execve, the current task's cred_exec_mutex is
           	 locked to prevent PTRACE_ATTACH from obsoleting the calculation of
           	 creds that we make.
      
           (a) prepare_exec_creds() is then called to make a copy of the current
           	 task's credentials and prepare it.  This copy is then assigned to
           	 bprm->cred.
      
        	 This renders security_bprm_alloc() and security_bprm_free()
           	 unnecessary, and so they've been removed.
      
           (b) The determination of unsafe execution is now performed immediately
           	 after (a) rather than later on in the code.  The result is stored in
           	 bprm->unsafe for future reference.
      
           (c) prepare_binprm() is called, possibly multiple times.
      
           	 (i) This applies the result of set[ug]id binaries to the new creds
           	     attached to bprm->cred.  Personality bit clearance is recorded,
           	     but now deferred on the basis that the exec procedure may yet
           	     fail.
      
               (ii) This then calls the new security_bprm_set_creds().  This should
      	     calculate the new LSM and capability credentials into *bprm->cred.
      
      	     This folds together security_bprm_set() and parts of
      	     security_bprm_apply_creds() (these two have been removed).
      	     Anything that might fail must be done at this point.
      
               (iii) bprm->cred_prepared is set to 1.
      
      	     bprm->cred_prepared is 0 on the first pass of the security
      	     calculations, and 1 on all subsequent passes.  This allows SELinux
      	     in (ii) to base its calculations only on the initial script and
      	     not on the interpreter.
      
           (d) flush_old_exec() is called to commit the task to execution.  This
           	 performs the following steps with regard to credentials:
      
      	 (i) Clear pdeath_signal and set dumpable on certain circumstances that
      	     may not be covered by commit_creds().
      
               (ii) Clear any bits in current->personality that were deferred from
                   (c.i).
      
           (e) install_exec_creds() [compute_creds() as was] is called to install the
           	 new credentials.  This performs the following steps with regard to
           	 credentials:
      
               (i) Calls security_bprm_committing_creds() to apply any security
                   requirements, such as flushing unauthorised files in SELinux, that
                   must be done before the credentials are changed.
      
      	     This is made up of bits of security_bprm_apply_creds() and
      	     security_bprm_post_apply_creds(), both of which have been removed.
      	     This function is not allowed to fail; anything that might fail
      	     must have been done in (c.ii).
      
               (ii) Calls commit_creds() to apply the new credentials in a single
                   assignment (more or less).  Possibly pdeath_signal and dumpable
                   should be part of struct creds.
      
      	 (iii) Unlocks the task's cred_replace_mutex, thus allowing
      	     PTRACE_ATTACH to take place.
      
               (iv) Clears The bprm->cred pointer as the credentials it was holding
                   are now immutable.
      
               (v) Calls security_bprm_committed_creds() to apply any security
                   alterations that must be done after the creds have been changed.
                   SELinux uses this to flush signals and signal handlers.
      
           (f) If an error occurs before (d.i), bprm_free() will call abort_creds()
           	 to destroy the proposed new credentials and will then unlock
           	 cred_replace_mutex.  No changes to the credentials will have been
           	 made.
      
       (2) LSM interface.
      
           A number of functions have been changed, added or removed:
      
           (*) security_bprm_alloc(), ->bprm_alloc_security()
           (*) security_bprm_free(), ->bprm_free_security()
      
           	 Removed in favour of preparing new credentials and modifying those.
      
           (*) security_bprm_apply_creds(), ->bprm_apply_creds()
           (*) security_bprm_post_apply_creds(), ->bprm_post_apply_creds()
      
           	 Removed; split between security_bprm_set_creds(),
           	 security_bprm_committing_creds() and security_bprm_committed_creds().
      
           (*) security_bprm_set(), ->bprm_set_security()
      
           	 Removed; folded into security_bprm_set_creds().
      
           (*) security_bprm_set_creds(), ->bprm_set_creds()
      
           	 New.  The new credentials in bprm->creds should be checked and set up
           	 as appropriate.  bprm->cred_prepared is 0 on the first call, 1 on the
           	 second and subsequent calls.
      
           (*) security_bprm_committing_creds(), ->bprm_committing_creds()
           (*) security_bprm_committed_creds(), ->bprm_committed_creds()
      
           	 New.  Apply the security effects of the new credentials.  This
           	 includes closing unauthorised files in SELinux.  This function may not
           	 fail.  When the former is called, the creds haven't yet been applied
           	 to the process; when the latter is called, they have.
      
       	 The former may access bprm->cred, the latter may not.
      
       (3) SELinux.
      
           SELinux has a number of changes, in addition to those to support the LSM
           interface changes mentioned above:
      
           (a) The bprm_security_struct struct has been removed in favour of using
           	 the credentials-under-construction approach.
      
           (c) flush_unauthorized_files() now takes a cred pointer and passes it on
           	 to inode_has_perm(), file_has_perm() and dentry_open().
      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>
      a6f76f23
    • D
      CRED: Inaugurate COW credentials · d84f4f99
      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: Wrap current->cred and a few other accessors · 86a264ab
      David Howells 提交于
      Wrap current->cred and a few other accessors to hide their actual
      implementation.
      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>
      86a264ab
    • D
      CRED: Separate task security context from task_struct · b6dff3ec
      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
    • D
      CRED: Wrap task credential accesses in the filesystem subsystem · da9592ed
      David Howells 提交于
      Wrap access to task credentials so that they can be separated more easily from
      the task_struct during the introduction of COW creds.
      
      Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().
      
      Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
      sense to use RCU directly rather than a convenient wrapper; these will be
      addressed by later patches.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Reviewed-by: NJames Morris <jmorris@namei.org>
      Acked-by: NSerge Hallyn <serue@us.ibm.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: NJames Morris <jmorris@namei.org>
      da9592ed
  17. 20 10月, 2008 1 次提交
  18. 17 10月, 2008 3 次提交
  19. 16 10月, 2008 1 次提交
  20. 29 9月, 2008 1 次提交
    • B
      mm owner: fix race between swapoff and exit · 31a78f23
      Balbir Singh 提交于
      There's a race between mm->owner assignment and swapoff, more easily
      seen when task slab poisoning is turned on.  The condition occurs when
      try_to_unuse() runs in parallel with an exiting task.  A similar race
      can occur with callers of get_task_mm(), such as /proc/<pid>/<mmstats>
      or ptrace or page migration.
      
      CPU0                                    CPU1
                                              try_to_unuse
                                              looks at mm = task0->mm
                                              increments mm->mm_users
      task 0 exits
      mm->owner needs to be updated, but no
      new owner is found (mm_users > 1, but
      no other task has task->mm = task0->mm)
      mm_update_next_owner() leaves
                                              mmput(mm) decrements mm->mm_users
      task0 freed
                                              dereferencing mm->owner fails
      
      The fix is to notify the subsystem via mm_owner_changed callback(),
      if no new owner is found, by specifying the new task as NULL.
      
      Jiri Slaby:
      mm->owner was set to NULL prior to calling cgroup_mm_owner_callbacks(), but
      must be set after that, so as not to pass NULL as old owner causing oops.
      
      Daisuke Nishimura:
      mm_update_next_owner() may set mm->owner to NULL, but mem_cgroup_from_task()
      and its callers need to take account of this situation to avoid oops.
      
      Hugh Dickins:
      Lockdep warning and hang below exec_mmap() when testing these patches.
      exit_mm() up_reads mmap_sem before calling mm_update_next_owner(),
      so exec_mmap() now needs to do the same.  And with that repositioning,
      there's now no point in mm_need_new_owner() allowing for NULL mm.
      Reported-by: NHugh Dickins <hugh@veritas.com>
      Signed-off-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
      Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
      Signed-off-by: NDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
      Signed-off-by: NHugh Dickins <hugh@veritas.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Paul Menage <menage@google.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      31a78f23
  21. 29 7月, 2008 1 次提交
  22. 27 7月, 2008 5 次提交
  23. 26 7月, 2008 2 次提交