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  1. 09 12月, 2006 3 次提交
  3. 08 12月, 2006 2 次提交
  5. 26 11月, 2006 1 次提交
    • V
      [PATCH] mounstats NULL pointer dereference · 701e054e
      由 Vasily Tarasov 提交于 
      OpenVZ developers team has encountered the following problem in 2.6.19-rc6
kernel. After some seconds of running script

while [[ 1 ]]
do
	find  /proc -name mountstats | xargs cat
done

this Oops appears:

BUG: unable to handle kernel NULL pointer dereference at virtual address
00000010
 printing eip:
c01a6b70
*pde = 00000000
Oops: 0000 [#1]
SMP
Modules linked in: xt_length ipt_ttl xt_tcpmss ipt_TCPMSS iptable_mangle
iptable_filter xt_multiport xt_limit ipt_tos ipt_REJECT ip_tables x_tables
parport_pc lp parport sunrpc af_packet thermal processor fan button battery
asus_acpi ac ohci_hcd ehci_hcd usbcore i2c_nforce2 i2c_core tg3 floppy
pata_amd
ide_cd cdrom sata_nv libata
CPU:    1
EIP:    0060:[<c01a6b70>]    Not tainted VLI
EFLAGS: 00010246   (2.6.19-rc6 #2)
EIP is at mountstats_open+0x70/0xf0
eax: 00000000   ebx: e6247030   ecx: e62470f8   edx: 00000000
esi: 00000000   edi: c01a6b00   ebp: c33b83c0   esp: f4105eb4
ds: 007b   es: 007b   ss: 0068
Process cat (pid: 6044, ti=f4105000 task=f4104a70 task.ti=f4105000)
Stack: c33b83c0 c04ee940 f46a4a80 c33b83c0 e4df31b4 c01a6b00 f4105000 c0169231
       e4df31b4 c33b83c0 c33b83c0 f4105f20 00000003 f4105000 c0169445 f2503cf0
       f7f8c4c0 00008000 c33b83c0 00000000 00008000 c0169350 f4105f20 00008000
Call Trace:
 [<c01a6b00>] mountstats_open+0x0/0xf0
 [<c0169231>] __dentry_open+0x181/0x250
 [<c0169445>] nameidata_to_filp+0x35/0x50
 [<c0169350>] do_filp_open+0x50/0x60
 [<c01873d6>] seq_read+0xc6/0x300
 [<c0169511>] get_unused_fd+0x31/0xc0
 [<c01696d3>] do_sys_open+0x63/0x110
 [<c01697a7>] sys_open+0x27/0x30
 [<c01030bd>] sysenter_past_esp+0x56/0x79
 =======================
Code: 45 74 8b 54 24 20 89 44 24 08 8b 42 f0 31 d2 e8 47 cb f8 ff 85 c0 89 c3
74 51 8d 80 a0 04 00 00 e8 46 06 2c 00 8b 83 48 04 00 00 <8b> 78 10 85 ff 74
03
f0 ff 07 b0 01 86 83 a0 04 00 00 f0 ff 4b
EIP: [<c01a6b70>] mountstats_open+0x70/0xf0 SS:ESP 0068:f4105eb4

The problem is that task->nsproxy can be equal NULL for some time during
task exit. This patch fixes the BUG.
Signed-off-by: NVasily Tarasov <vtaras@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      701e054e
  7. 21 10月, 2006 1 次提交
  9. 17 10月, 2006 1 次提交
  11. 02 10月, 2006 14 次提交
  13. 30 9月, 2006 1 次提交
  15. 16 7月, 2006 1 次提交
  17. 15 7月, 2006 2 次提交
  19. 01 7月, 2006 1 次提交
  21. 27 6月, 2006 13 次提交
    • E
      [PATCH] SELinux: Add sockcreate node to procattr API · 42c3e03e
      由 Eric Paris 提交于 
      Below is a patch to add a new /proc/self/attr/sockcreate A process may write a
context into this interface and all subsequent sockets created will be labeled
with that context.  This is the same idea as the fscreate interface where a
process can specify the label of a file about to be created.  At this time one
envisioned user of this will be xinetd.  It will be able to better label
sockets for the actual services.  At this time all sockets take the label of
the creating process, so all xinitd sockets would just be labeled the same.

I tested this by creating a tcp sender and listener.  The sender was able to
write to this new proc file and then create sockets with the specified label.
I am able to be sure the new label was used since the avc denial messages
kicked out by the kernel included both the new security permission
setsockcreate and all the socket denials were for the new label, not the label
of the running process.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NJames Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      42c3e03e
    • O
      [PATCH] cleanup next_tid() · c1df7fb8
      由 Oleg Nesterov 提交于 
      Try to make next_tid() a bit more readable and deletes unnecessary
"pid_alive(pos)" check.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      c1df7fb8
    • O
      [PATCH] simplify/fix first_tid() · a872ff0c
      由 Oleg Nesterov 提交于 
      first_tid:

	/* If nr exceeds the number of threads there is nothing todo */
	if (nr) {
		if (nr >= get_nr_threads(leader))
			goto done;
	}

This is not reliable: sub-threads can exit after this check, so the
'for' loop below can overlap and proc_task_readdir() can return an
already filldir'ed dirents.

	for (; pos && pid_alive(pos); pos = next_thread(pos)) {
		if (--nr > 0)
			continue;

Off-by-one error, will return 'leader' when nr == 1.

This patch tries to fix these problems and simplify the code.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      a872ff0c
    • E
      [PATCH] proc: Remove tasklist_lock from proc_task_readdir. · cc288738
      由 Eric W. Biederman 提交于 
      This is just like my previous removal of tasklist_lock from first_tgid, and
next_tgid.  It simply had to wait until it was rcu safe to walk the thread
list.

This should be the last instance of the tasklist_lock in proc.  So user
processes should not be able to influence the tasklist lock hold times.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      cc288738
    • E
      [PATCH] proc: Cleanup proc_fd_access_allowed · df26c40e
      由 Eric W. Biederman 提交于 
      In process of getting proc_fd_access_allowed to work it has developed a few
warts.  In particular the special case that always allows introspection and
the special case to allow inspection of kernel threads.

The special case for introspection is needed for /proc/self/mem.

The special case for kernel threads really should be overridable
by security modules.

So consolidate these checks into ptrace.c:may_attach().

The check to always allow introspection is trivial.

The check to allow access to kernel threads, and zombies is a little
trickier.  mem_read and mem_write already verify an mm exists so it isn't
needed twice.  proc_fd_access_allowed only doesn't want a check to verify
task->mm exits, s it prevents all access to kernel threads.  So just move
the task->mm check into ptrace_attach where it is needed for practical
reasons.

I did a quick audit and none of the security modules in the kernel seem to
care if they are passed a task without an mm into security_ptrace.  So the
above move should be safe and it allows security modules to come up with
more restrictive policy.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      df26c40e
    • E
      [PATCH] proc: Use sane permission checks on the /proc/<pid>/fd/ symlinks · 778c1144
      由 Eric W. Biederman 提交于 
      Since 2.2 we have been doing a chroot check to see if it is appropriate to
return a read or follow one of these magic symlinks.  The chroot check was
asking a question about the visibility of files to the calling process and
it was actually checking the destination process, and not the files
themselves.  That test was clearly bogus.

In my first pass through I simply fixed the test to check the visibility of
the files themselves.  That naive approach to fixing the permissions was
too strict and resulted in cases where a task could not even see all of
it's file descriptors.

What has disturbed me about relaxing this check is that file descriptors
are per-process private things, and they are occasionaly used a user space
capability tokens.  Looking a little farther into the symlink path on /proc
I did find userid checks and a check for capability (CAP_DAC_OVERRIDE) so
there were permissions checking this.

But I was still concerned about privacy.  Besides /proc there is only one
other way to find out this kind of information, and that is ptrace.  ptrace
has been around for a long time and it has a well established security
model.

So after thinking about it I finally realized that the permission checks
that make sense are the permission checks applied to ptrace_attach.  The
checks are simple per process, and won't cause nasty surprises for people
coming from less capable unices.

Unfortunately there is one case that the current ptrace_attach test does
not cover: Zombies and kernel threads.  Single stepping those kinds of
processes is impossible.  Being able to see which file descriptors are open
on these tasks is important to lsof, fuser and friends.  So for these
special processes I made the rule you can't find out unless you have
CAP_SYS_PTRACE.

These proc permission checks should now conform to the principle of least
surprise.  As well as using much less code to implement :)
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      778c1144
    • E
      [PATCH] proc: optimize proc_check_dentry_visible · 5b0c1dd3
      由 Eric W. Biederman 提交于 
      The code doesn't need to sleep to when making this check so I can just do the
comparison and not worry about the reference counts.

TODO: While looking at this I realized that my original cleanup did not push
the permission check far enough down into the stack.  The call of
proc_check_dentry_visible needs to move out of the generic proc
readlink/follow link code and into the individual get_link instances.
Otherwise the shared resources checks are not quite correct (shared
files_struct does not require a shared fs_struct), and there are races with
unshare.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      5b0c1dd3
    • E
      [PATCH] proc: Use struct pid not struct task_ref · 13b41b09
      由 Eric W. Biederman 提交于 
      Incrementally update my proc-dont-lock-task_structs-indefinitely patches so
that they work with struct pid instead of struct task_ref.

Mostly this is a straight 1-1 substitution.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      13b41b09
    • E
      [PATCH] proc: don't lock task_structs indefinitely · 99f89551
      由 Eric W. Biederman 提交于 
      Every inode in /proc holds a reference to a struct task_struct.  If a
directory or file is opened and remains open after the the task exits this
pinning continues.  With 8K stacks on a 32bit machine the amount pinned per
file descriptor is about 10K.

Normally I would figure a reasonable per user process limit is about 100
processes.  With 80 processes, with a 1000 file descriptors each I can trigger
the 00M killer on a 32bit kernel, because I have pinned about 800MB of useless
data.

This patch replaces the struct task_struct pointer with a pointer to a struct
task_ref which has a struct task_struct pointer.  The so the pinning of dead
tasks does not happen.

The code now has to contend with the fact that the task may now exit at any
time.  Which is a little but not muh more complicated.

With this change it takes about 1000 processes each opening up 1000 file
descriptors before I can trigger the OOM killer.  Much better.

[mlp@google.com: task_mmu small fixes]
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Paul Jackson <pj@sgi.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Albert Cahalan <acahalan@gmail.com>
Signed-off-by: NPrasanna Meda <mlp@google.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      99f89551
    • E
      [PATCH] proc: make PROC_NUMBUF the buffer size for holding integers as strings · 8578cea7
      由 Eric W. Biederman 提交于 
      Currently in /proc at several different places we define buffers to hold a
process id, or a file descriptor .  In most of them we use either a hard coded
number or a different define.  Modify them all to use PROC_NUMBUF, so the code
has a chance of being maintained.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      8578cea7
    • E
      [PATCH] simply fix first_tgid · 9cc8cbc7
      由 Eric W. Biederman 提交于 
      Like the bug Oleg spotted in first_tid there was also a small off by one
error in first_tgid, when a seek was done on the /proc directory.  This
fixes that and changes the code structure to make it a little more obvious
what is going on.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      9cc8cbc7
    • E
      [PATCH] proc: Remove tasklist_lock from proc_pid_lookup() and proc_task_lookup() · de758734
      由 Eric W. Biederman 提交于 
      Since we no longer need the tasklist_lock for get_task_struct the lookup
methods no longer need the tasklist_lock.

This just depends on my previous patch that makes get_task_struct() rcu
safe.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      de758734
    • E
      [PATCH] proc: Remove tasklist_lock from proc_pid_readdir · 454cc105
      由 Eric W. Biederman 提交于 
      We don't need the tasklist_lock to safely iterate through processes
anymore.

This depends on my previous to task patches that make get_task_struct rcu
safe, and that make next_task() rcu safe.  I haven't gotten
first_tid/next_tid yet only because next_thread is missing an
rcu_dereference.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      454cc105