diff mbox

[PATCHv2,1/1] vfs: renumber FMODE_NONOTIFY and add to uniqueness check

Message ID 1416828199-3414-2-git-send-email-drysdale@google.com
State Not Applicable
Delegated to: David Miller
Headers show

Commit Message

David Drysdale Nov. 24, 2014, 11:23 a.m. UTC 
Fix clashing values for O_PATH and FMODE_NONOTIFY on sparc.
The clashing O_PATH value was added in 5229645bdc35f1cc43eb ("vfs: add
nonconflicting values for O_PATH") but this can't be changed as it
is user-visible.

FMODE_NONOTIFY is only used internally in the kernel, but it is in
the same numbering space as the other O_* flags, as indicated by the
comment at the top of include/uapi/asm-generic/fcntl.h (and its use
in fs/notify/fanotify/fanotify_user.c).  So renumber it to avoid
the clash.

All of this has happened before (12ed2e36c98aec6c4155, "fanotify:
FMODE_NONOTIFY and __O_SYNC in sparc conflict"), and all of this
will happen again -- so update the uniqueness check in fcntl_init()
to include __FMODE_NONOTIFY.

Signed-off-by: David Drysdale <drysdale@google.com>
Acked-by: David S. Miller <davem@davemloft.net>
---
 fs/fcntl.c                       | 5 +++--
 include/linux/fs.h               | 2 +-
 include/uapi/asm-generic/fcntl.h | 2 +-
 3 files changed, 5 insertions(+), 4 deletions(-)

Comments

Jan Kara Nov. 24, 2014, 11:30 a.m. UTC | #1 
On Mon 24-11-14 11:23:19, David Drysdale wrote:
> Fix clashing values for O_PATH and FMODE_NONOTIFY on sparc.
> The clashing O_PATH value was added in 5229645bdc35f1cc43eb ("vfs: add
> nonconflicting values for O_PATH") but this can't be changed as it
> is user-visible.
> 
> FMODE_NONOTIFY is only used internally in the kernel, but it is in
> the same numbering space as the other O_* flags, as indicated by the
> comment at the top of include/uapi/asm-generic/fcntl.h (and its use
> in fs/notify/fanotify/fanotify_user.c).  So renumber it to avoid
> the clash.
> 
> All of this has happened before (12ed2e36c98aec6c4155, "fanotify:
> FMODE_NONOTIFY and __O_SYNC in sparc conflict"), and all of this
> will happen again -- so update the uniqueness check in fcntl_init()
> to include __FMODE_NONOTIFY.
> 
> Signed-off-by: David Drysdale <drysdale@google.com>
> Acked-by: David S. Miller <davem@davemloft.net>
  Looks good. You can add:
Acked-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/fcntl.c                       | 5 +++--
>  include/linux/fs.h               | 2 +-
>  include/uapi/asm-generic/fcntl.h | 2 +-
>  3 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index 99d440a4a6ba..ee85cd4e136a 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -740,14 +740,15 @@ static int __init fcntl_init(void)
>  	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
>  	 * is defined as O_NONBLOCK on some platforms and not on others.
>  	 */
> -	BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
> +	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
>  		O_RDONLY	| O_WRONLY	| O_RDWR	|
>  		O_CREAT		| O_EXCL	| O_NOCTTY	|
>  		O_TRUNC		| O_APPEND	| /* O_NONBLOCK	| */
>  		__O_SYNC	| O_DSYNC	| FASYNC	|
>  		O_DIRECT	| O_LARGEFILE	| O_DIRECTORY	|
>  		O_NOFOLLOW	| O_NOATIME	| O_CLOEXEC	|
> -		__FMODE_EXEC	| O_PATH	| __O_TMPFILE
> +		__FMODE_EXEC	| O_PATH	| __O_TMPFILE	|
> +		__FMODE_NONOTIFY
>  		));
>  
>  	fasync_cache = kmem_cache_create("fasync_cache",
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 9ab779e8a63c..fc1c2488adbc 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -134,7 +134,7 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
>  #define FMODE_CAN_WRITE         ((__force fmode_t)0x40000)
>  
>  /* File was opened by fanotify and shouldn't generate fanotify events */
> -#define FMODE_NONOTIFY		((__force fmode_t)0x1000000)
> +#define FMODE_NONOTIFY		((__force fmode_t)0x4000000)
>  
>  /*
>   * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
> diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
> index 7543b3e51331..e063effe0cc1 100644
> --- a/include/uapi/asm-generic/fcntl.h
> +++ b/include/uapi/asm-generic/fcntl.h
> @@ -5,7 +5,7 @@
>  
>  /*
>   * FMODE_EXEC is 0x20
> - * FMODE_NONOTIFY is 0x1000000
> + * FMODE_NONOTIFY is 0x4000000
>   * These cannot be used by userspace O_* until internal and external open
>   * flags are split.
>   * -Eric Paris
> -- 
> 2.1.0.rc2.206.gedb03e5
>
Heinrich Schuchardt Dec. 25, 2014, 2:47 p.m. UTC | #2 
Hello Andrew,

could you, please, consider the patch proposed in
https://lkml.org/lkml/2014/11/24/196
for inclusion into the mm-tree.

This 2nd version of the patch considers the review comments in the 
thread starting at https://lkml.org/lkml/2014/11/21/141.

Best regards

Heinrich Schuchardt


On 24.11.2014 12:30, Jan Kara wrote:
> On Mon 24-11-14 11:23:19, David Drysdale wrote:
>> Fix clashing values for O_PATH and FMODE_NONOTIFY on sparc.
>> The clashing O_PATH value was added in 5229645bdc35f1cc43eb ("vfs: add
>> nonconflicting values for O_PATH") but this can't be changed as it
>> is user-visible.
>>
>> FMODE_NONOTIFY is only used internally in the kernel, but it is in
>> the same numbering space as the other O_* flags, as indicated by the
>> comment at the top of include/uapi/asm-generic/fcntl.h (and its use
>> in fs/notify/fanotify/fanotify_user.c).  So renumber it to avoid
>> the clash.
>>
>> All of this has happened before (12ed2e36c98aec6c4155, "fanotify:
>> FMODE_NONOTIFY and __O_SYNC in sparc conflict"), and all of this
>> will happen again -- so update the uniqueness check in fcntl_init()
>> to include __FMODE_NONOTIFY.
>>
>> Signed-off-by: David Drysdale <drysdale@google.com>
>> Acked-by: David S. Miller <davem@davemloft.net>
>    Looks good. You can add:
> Acked-by: Jan Kara <jack@suse.cz>
>
> 								Honza
>
>> ---
>>   fs/fcntl.c                       | 5 +++--
>>   include/linux/fs.h               | 2 +-
>>   include/uapi/asm-generic/fcntl.h | 2 +-
>>   3 files changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/fcntl.c b/fs/fcntl.c
>> index 99d440a4a6ba..ee85cd4e136a 100644
>> --- a/fs/fcntl.c
>> +++ b/fs/fcntl.c
>> @@ -740,14 +740,15 @@ static int __init fcntl_init(void)
>>   	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
>>   	 * is defined as O_NONBLOCK on some platforms and not on others.
>>   	 */
>> -	BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
>> +	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
>>   		O_RDONLY	| O_WRONLY	| O_RDWR	|
>>   		O_CREAT		| O_EXCL	| O_NOCTTY	|
>>   		O_TRUNC		| O_APPEND	| /* O_NONBLOCK	| */
>>   		__O_SYNC	| O_DSYNC	| FASYNC	|
>>   		O_DIRECT	| O_LARGEFILE	| O_DIRECTORY	|
>>   		O_NOFOLLOW	| O_NOATIME	| O_CLOEXEC	|
>> -		__FMODE_EXEC	| O_PATH	| __O_TMPFILE
>> +		__FMODE_EXEC	| O_PATH	| __O_TMPFILE	|
>> +		__FMODE_NONOTIFY
>>   		));
>>
>>   	fasync_cache = kmem_cache_create("fasync_cache",
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 9ab779e8a63c..fc1c2488adbc 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -134,7 +134,7 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
>>   #define FMODE_CAN_WRITE         ((__force fmode_t)0x40000)
>>
>>   /* File was opened by fanotify and shouldn't generate fanotify events */
>> -#define FMODE_NONOTIFY		((__force fmode_t)0x1000000)
>> +#define FMODE_NONOTIFY		((__force fmode_t)0x4000000)
>>
>>   /*
>>    * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
>> diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
>> index 7543b3e51331..e063effe0cc1 100644
>> --- a/include/uapi/asm-generic/fcntl.h
>> +++ b/include/uapi/asm-generic/fcntl.h
>> @@ -5,7 +5,7 @@
>>
>>   /*
>>    * FMODE_EXEC is 0x20
>> - * FMODE_NONOTIFY is 0x1000000
>> + * FMODE_NONOTIFY is 0x4000000
>>    * These cannot be used by userspace O_* until internal and external open
>>    * flags are split.
>>    * -Eric Paris
>> --
>> 2.1.0.rc2.206.gedb03e5
>>

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Andrew Morton Jan. 7, 2015, 12:29 a.m. UTC | #3 
On Mon, 24 Nov 2014 11:23:19 +0000 David Drysdale <drysdale@google.com> wrote:

> Fix clashing values for O_PATH and FMODE_NONOTIFY on sparc.
> The clashing O_PATH value was added in 5229645bdc35f1cc43eb ("vfs: add
> nonconflicting values for O_PATH") but this can't be changed as it
> is user-visible.
> 
> FMODE_NONOTIFY is only used internally in the kernel, but it is in
> the same numbering space as the other O_* flags, as indicated by the
> comment at the top of include/uapi/asm-generic/fcntl.h (and its use
> in fs/notify/fanotify/fanotify_user.c).  So renumber it to avoid
> the clash.
> 
> All of this has happened before (12ed2e36c98aec6c4155, "fanotify:
> FMODE_NONOTIFY and __O_SYNC in sparc conflict"), and all of this
> will happen again -- so update the uniqueness check in fcntl_init()
> to include __FMODE_NONOTIFY.

What are the user-visible runtime effects of the bug?

Please always include this info when fixing bugs, so people can work
out which kernel version(s) need the fix.

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David Drysdale Jan. 8, 2015, 9:06 a.m. UTC | #4 
On Wed, Jan 7, 2015 at 12:29 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Mon, 24 Nov 2014 11:23:19 +0000 David Drysdale <drysdale@google.com> wrote:
>
>> Fix clashing values for O_PATH and FMODE_NONOTIFY on sparc.
>> The clashing O_PATH value was added in 5229645bdc35f1cc43eb ("vfs: add
>> nonconflicting values for O_PATH") but this can't be changed as it
>> is user-visible.
>>
>> FMODE_NONOTIFY is only used internally in the kernel, but it is in
>> the same numbering space as the other O_* flags, as indicated by the
>> comment at the top of include/uapi/asm-generic/fcntl.h (and its use
>> in fs/notify/fanotify/fanotify_user.c).  So renumber it to avoid
>> the clash.
>>
>> All of this has happened before (12ed2e36c98aec6c4155, "fanotify:
>> FMODE_NONOTIFY and __O_SYNC in sparc conflict"), and all of this
>> will happen again -- so update the uniqueness check in fcntl_init()
>> to include __FMODE_NONOTIFY.
>
> What are the user-visible runtime effects of the bug?
>
> Please always include this info when fixing bugs, so people can work
> out which kernel version(s) need the fix.

I don't know for sure what the user-visible effects are -- I noticed
the problem from the source and I don't have a sparc system (the only
affected architecture) to test with.  But I'd guess that...

The likely user-visible effect (on sparc) of the clash would be that:
- Filesystem activity on files opened with O_PATH does not get
  reported via the fanotify(7) API.
- The file descriptors for accessed objects reported via the
  fanotify(7) API will effectively have O_PATH set, and so will
  have the limitations described for O_PATH in the open(2) manpage.

However, we'd need some intersection of sparc/fanotify folk to verify
those guesses -- Eric / David, any thoughts?

Thanks,
David
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diff mbox

Patch

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 99d440a4a6ba..ee85cd4e136a 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -740,14 +740,15 @@  static int __init fcntl_init(void)
 	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
 	 * is defined as O_NONBLOCK on some platforms and not on others.
 	 */
-	BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
+	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
 		O_RDONLY	| O_WRONLY	| O_RDWR	|
 		O_CREAT		| O_EXCL	| O_NOCTTY	|
 		O_TRUNC		| O_APPEND	| /* O_NONBLOCK	| */
 		__O_SYNC	| O_DSYNC	| FASYNC	|
 		O_DIRECT	| O_LARGEFILE	| O_DIRECTORY	|
 		O_NOFOLLOW	| O_NOATIME	| O_CLOEXEC	|
-		__FMODE_EXEC	| O_PATH	| __O_TMPFILE
+		__FMODE_EXEC	| O_PATH	| __O_TMPFILE	|
+		__FMODE_NONOTIFY
 		));
 
 	fasync_cache = kmem_cache_create("fasync_cache",
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9ab779e8a63c..fc1c2488adbc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -134,7 +134,7 @@  typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #define FMODE_CAN_WRITE         ((__force fmode_t)0x40000)
 
 /* File was opened by fanotify and shouldn't generate fanotify events */
-#define FMODE_NONOTIFY		((__force fmode_t)0x1000000)
+#define FMODE_NONOTIFY		((__force fmode_t)0x4000000)
 
 /*
  * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
index 7543b3e51331..e063effe0cc1 100644
--- a/include/uapi/asm-generic/fcntl.h
+++ b/include/uapi/asm-generic/fcntl.h
@@ -5,7 +5,7 @@ 
 
 /*
  * FMODE_EXEC is 0x20
- * FMODE_NONOTIFY is 0x1000000
+ * FMODE_NONOTIFY is 0x4000000
  * These cannot be used by userspace O_* until internal and external open
  * flags are split.
  * -Eric Paris