linux-toradex.git/include/linux/proc_fs.h, branch v2.6.25.17

[NET]: Make /proc/net a symlink on /proc/self/net (v3)

2008-03-07T19:08:40+00:00

Current /proc/net is done with so called "shadows", but current
implementation is broken and has little chances to get fixed.

The problem is that dentries subtree of /proc/net directory has
fancy revalidation rules to make processes living in different
net namespaces see different entries in /proc/net subtree, but
currently, tasks see in the /proc/net subdir the contents of any
other namespace, depending on who opened the file first.

The proposed fix is to turn /proc/net into a symlink, which points
to /proc/self/net, which in turn shows what previously was in
/proc/net - the network-related info, from the net namespace the
appropriate task lives in.

# ls -l /proc/net
lrwxrwxrwx  1 root root 8 Mar  5 15:17 /proc/net -> self/net

In other words - this behaves like /proc/mounts, but unlike
"mounts", "net" is not a file, but a directory.

Changes from v2:
* Fixed discrepancy of /proc/net nlink count and selinux labeling
  screwup pointed out by Stephen.

  To get the correct nlink count the ->getattr callback for /proc/net
  is overridden to read one from the net->proc_net entry.

  To make selinux still work the net->proc_net entry is initialized
  properly, i.e. with the "net" name and the proc_net parent.

Selinux fixes are
Acked-by:  Stephen Smalley 

Changes from v1:
* Fixed a task_struct leak in get_proc_task_net, pointed out by Paul.

Signed-off-by: Pavel Emelyanov 
Acked-by: "Eric W. Biederman" 
Signed-off-by: David S. Miller

d_path: Make proc_get_link() use a struct path argument

2008-02-15T05:17:08+00:00

proc_get_link() is always called with a dentry and a vfsmount from a struct
path.  Make proc_get_link() take it directly as an argument.

Signed-off-by: Jan Blunck 
Acked-by: Christoph Hellwig 
Cc: Al Viro 
Cc: "J. Bruce Fields" 
Cc: Neil Brown 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: fix ->open'less usage due to ->proc_fops flip

2008-02-08T17:22:24+00:00

Typical PDE creation code looks like:

	pde = create_proc_entry("foo", 0, NULL);
	if (pde)
		pde->proc_fops = &foo_proc_fops;

Notice that PDE is first created, only then ->proc_fops is set up to
final value. This is a problem because right after creation
a) PDE is fully visible in /proc , and
b) ->proc_fops are proc_file_operations which do not have ->open callback. So, it's
   possible to ->read without ->open (see one class of oopses below).

The fix is new API called proc_create() which makes sure ->proc_fops are
set up before gluing PDE to main tree. Typical new code looks like:

	pde = proc_create("foo", 0, NULL, &foo_proc_fops);
	if (!pde)
		return -ENOMEM;

Fix most networking users for a start.

In the long run, create_proc_entry() for regular files will go.

BUG: unable to handle kernel NULL pointer dereference at virtual address 00000024
printing eip: c1188c1b *pdpt = 000000002929e001 *pde = 0000000000000000
Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC
last sysfs file: /sys/block/sda/sda1/dev
Modules linked in: foo af_packet ipv6 cpufreq_ondemand loop serio_raw psmouse k8temp hwmon sr_mod cdrom

Pid: 24679, comm: cat Not tainted (2.6.24-rc3-mm1 #2)
EIP: 0060:[] EFLAGS: 00210002 CPU: 0
EIP is at mutex_lock_nested+0x75/0x25d
EAX: 000006fe EBX: fffffffb ECX: 00001000 EDX: e9340570
ESI: 00000020 EDI: 00200246 EBP: e9340570 ESP: e8ea1ef8
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process cat (pid: 24679, ti=E8EA1000 task=E9340570 task.ti=E8EA1000)
Stack: 00000000 c106f7ce e8ee05b4 00000000 00000001 458003d0 f6fb6f20 fffffffb
       00000000 c106f7aa 00001000 c106f7ce 08ae9000 f6db53f0 00000020 00200246
       00000000 00000002 00000000 00200246 00200246 e8ee05a0 fffffffb e8ee0550
Call Trace:
 [] seq_read+0x24/0x28a
 [] seq_read+0x0/0x28a
 [] seq_read+0x24/0x28a
 [] seq_read+0x0/0x28a
 [] proc_reg_read+0x60/0x73
 [] proc_reg_read+0x0/0x73
 [] vfs_read+0x6c/0x8b
 [] sys_read+0x3c/0x63
 [] sysenter_past_esp+0x5f/0xa5
 [] destroy_inode+0x24/0x33
 =======================
INFO: lockdep is turned off.
Code: 75 21 68 e1 1a 19 c1 68 87 00 00 00 68 b8 e8 1f c1 68 25 73 1f c1 e8 84 06 e9 ff e8 52 b8 e7 ff 83 c4 10 9c 5f fa e8 28 89 ea ff  fe 4e 04 79 0a f3 90 80 7e 04 00 7e f8 eb f0 39 76 34 74 33
EIP: [] mutex_lock_nested+0x75/0x25d SS:ESP 0068:e8ea1ef8

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Alexey Dobriyan 
Cc: "Eric W. Biederman" 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: seqfile convert proc_pid_status to properly handle pid namespaces

2008-02-08T17:22:24+00:00

Currently we possibly lookup the pid in the wrong pid namespace.  So
seq_file convert proc_pid_status which ensures the proper pid namespaces is
passed in.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: another build fix]
[akpm@linux-foundation.org: s390 build fix]
[akpm@linux-foundation.org: fix task_name() output]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Eric W. Biederman 
Cc: Andrew Morgan 
Cc: Serge Hallyn 
Cc: Cedric Le Goater 
Cc: Pavel Emelyanov 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Paul Menage 
Cc: Paul Jackson 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: implement proc_single_file_operations

2008-02-08T17:22:23+00:00

Currently many /proc/pid files use a crufty precursor to the current seq_file
api, and they don't have direct access to the pid_namespace or the pid of for
which they are displaying data.

So implement proc_single_file_operations to make the seq_file routines easy to
use, and to give access to the full state of the pid of we are displaying data
for.

Signed-off-by: Eric W. Biederman 
Cc: Oleg Nesterov 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

maps4: move clear_refs code to task_mmu.c

2008-02-05T17:44:16+00:00

This puts all the clear_refs code where it belongs and probably lets things
compile on MMU-less systems as well.

Signed-off-by: Matt Mackall 
Cc: Jeremy Fitzhardinge 
Cc: David Rientjes 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[ATM]: Oops reading net/atm/arp

2008-01-28T23:01:36+00:00

cat /proc/net/atm/arp causes the NULL pointer dereference in the
get_proc_net+0xc/0x3a. This happens as proc_get_net believes that the
parent proc dir entry contains struct net.

Fix this assumption for "net/atm" case.

The problem is introduced by the commit c0097b07abf5f92ab135d024dd41bd2aada1512f
from Eric W. Biederman/Daniel Lezcano.

Signed-off-by: Denis V. Lunev 
Signed-off-by: David S. Miller

proc: fix proc_dir_entry refcounting

2007-12-05T17:21:20+00:00

Creating PDEs with refcount 0 and "deleted" flag has problems (see below).
Switch to usual scheme:
* PDE is created with refcount 1
* every de_get does +1
* every de_put() and remove_proc_entry() do -1
* once refcount reaches 0, PDE is freed.

This elegantly fixes at least two following races (both observed) without
introducing new locks, without abusing old locks, without spreading
lock_kernel():

1) PDE leak

remove_proc_entry			de_put
-----------------			------
			[refcnt = 1]
if (atomic_read(&de->count) == 0)
					if (atomic_dec_and_test(&de->count))
						if (de->deleted)
							/* also not taken! */
							free_proc_entry(de);
else
	de->deleted = 1;
		[refcount=0, deleted=1]

2) use after free

remove_proc_entry			de_put
-----------------			------
			[refcnt = 1]

					if (atomic_dec_and_test(&de->count))
if (atomic_read(&de->count) == 0)
	free_proc_entry(de);
						/* boom! */
						if (de->deleted)
							free_proc_entry(de);

BUG: unable to handle kernel paging request at virtual address 6b6b6b6b
printing eip: c10acdda *pdpt = 00000000338f8001 *pde = 0000000000000000
Oops: 0000 [#1] PREEMPT SMP
Modules linked in: af_packet ipv6 cpufreq_ondemand loop serio_raw psmouse k8temp hwmon sr_mod cdrom
Pid: 23161, comm: cat Not tainted (2.6.24-rc2-8c0863403f109a43d7000b4646da4818220d501f #4)
EIP: 0060:[] EFLAGS: 00210097 CPU: 1
EIP is at strnlen+0x6/0x18
EAX: 6b6b6b6b EBX: 6b6b6b6b ECX: 6b6b6b6b EDX: fffffffe
ESI: c128fa3b EDI: f380bf34 EBP: ffffffff ESP: f380be44
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process cat (pid: 23161, ti=f380b000 task=f38f2570 task.ti=f380b000)
Stack: c10ac4f0 00000278 c12ce000 f43cd2a8 00000163 00000000 7da86067 00000400
       c128fa20 00896b18 f38325a8 c128fe20 ffffffff 00000000 c11f291e 00000400
       f75be300 c128fa20 f769c9a0 c10ac779 f380bf34 f7bfee70 c1018e6b f380bf34
Call Trace:
 [] vsnprintf+0x2ad/0x49b
 [] vscnprintf+0x14/0x1f
 [] vprintk+0xc5/0x2f9
 [] handle_fasteoi_irq+0x0/0xab
 [] do_IRQ+0x9f/0xb7
 [] preempt_schedule_irq+0x3f/0x5b
 [] need_resched+0x1f/0x21
 [] printk+0x1b/0x1f
 [] de_put+0x3d/0x50
 [] proc_delete_inode+0x38/0x41
 [] proc_delete_inode+0x0/0x41
 [] generic_delete_inode+0x5e/0xc6
 [] iput+0x60/0x62
 [] d_kill+0x2d/0x46
 [] dput+0xdc/0xe4
 [] __fput+0xb0/0xcd
 [] filp_close+0x48/0x4f
 [] sys_close+0x67/0xa5
 [] sysenter_past_esp+0x5f/0x85
=======================
Code: c9 74 0c f2 ae 74 05 bf 01 00 00 00 4f 89 fa 5f 89 d0 c3 85 c9 57 89 c7 89 d0 74 05 f2 ae 75 01 4f 89 f8 5f c3 89 c1 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 c3 90 90 90 57 83 c9
EIP: [] strnlen+0x6/0x18 SS:ESP 0068:f380be44

Also, remove broken usage of ->deleted from reiserfs: if sget() succeeds,
module is already pinned and remove_proc_entry() can't happen => nobody
can mark PDE deleted.

Dummy proc root in netns code is not marked with refcount 1. AFAICS, we
never get it, it's just for proper /proc/net removal. I double checked
CLONE_NETNS continues to work.

Patch survives many hours of modprobe/rmmod/cat loops without new bugs
which can be attributed to refcounting.

Signed-off-by: Alexey Dobriyan 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[NETNS]: Fix /proc/net breakage

2007-12-01T13:33:17+00:00

Well I clearly goofed when I added the initial network namespace support
for /proc/net.  Currently things work but there are odd details visible to
user space, even when we have a single network namespace.

Since we do not cache proc_dir_entry dentries at the moment we can just
modify ->lookup to return a different directory inode depending on the
network namespace of the process looking at /proc/net, replacing the
current technique of using a magic and fragile follow_link method.

To accomplish that this patch:
- introduces a shadow_proc method to allow different dentries to
  be returned from proc_lookup.
- Removes the old /proc/net follow_link magic
- Fixes a weakness in our not caching of proc generic dentries.

As shadow_proc uses a task struct to decided which dentry to return we can
go back later and fix the proc generic caching without modifying any code
that uses the shadow_proc method.

Signed-off-by: Eric W. Biederman 
Cc: "Rafael J. Wysocki" 
Cc: Pavel Machek 
Cc: Pavel Emelyanov 
Cc: "David S. Miller" 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Herbert Xu

[NET]: Kill proc_net_create()

2007-11-07T12:10:52+00:00

There are no more users.

Signed-off-by: David S. Miller