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* [PATCH] ksmbd: decode and honor DOS attribute validity flags
@ 2026-11-13 22:16 koraynilay
  2026-11-14  0:26 ` Namjae Jeon
  0 siblings, 1 reply; 3+ messages in thread
From: koraynilay @ 2026-11-13 22:16 UTC (permalink / raw)
  To: Namjae Jeon
  Cc: Sergey Senozhatsky, Tom Talpey, ChenXiaoSong, Hyunchul Lee,
	linux-cifs, linux-kernel, koraynilay

Currently, when setting file attributes via FSCTL_SET_SPARSE,
FSCTL_SET_COMPRESSION or FileBasicInformation, ksmbd hardcodes
flags = 0x51 (XATTR_DOSINFO_ATTRIB | XATTR_DOSINFO_CREATE_TIME |
XATTR_DOSINFO_ITIME). This injects unrequested creation time and itime
into user.DOSATTRIB on disk, even though the client only requested an
attribute modification.

Furthermore, ndr_decode_dos_attr() discards the validity flags on read
by reading them into NULL. When reading a file with an attribute-only
xattr (flags = 0x01, where create_time on disk is 0), ksmbd treats the 0
as a valid timestamp and reports NTTIME(0) instead of falling back to
the underlying filesystem's btime. Modifying any attribute via
set_file_basic_info() then clobbers the xattr back to 0x51.

Fix this by:
1. decoding da->flags in ndr_decode_dos_attr() and only updating
   create_time and itime if their validity flags are set (in
   smb2_update_xattrs() and ksmbd_vfs_fill_dentry_attrs());
2. reading existing attributes and only setting XATTR_DOSINFO_ATTRIB in
   fsctl_set_sparse(), __ksmbd_vfs_set_compression(), and
   set_file_basic_info() so unrequested timestamps are not injected.

Reproducer, with /tmp as the local filesystem folder exported as [test]
in ksmbd.conf and /mnt as the smb folder mounted with mount -t cifs:

  mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass

test with sparse (for compression, use chattr +c instead of fallocate):

  echo data > /tmp/sparse.txt
  chmod 777 /tmp/sparse.txt

  stat -c 'Local btime (%n): %w' /tmp/sparse.txt
  getfattr -n user.DOSATTRIB -e hex /tmp/sparse.txt

  # punching hole via CIFS triggers FSCTL_SET_SPARSE
  fallocate -p -o 0 -l 4 /mnt/sparse.txt
  getfattr -n user.DOSATTRIB -e hex /tmp/sparse.txt

  stat -c 'CIFS btime (%n):  %w' /mnt/sparse.txt
  smbclient //127.0.0.1/test -U user%pass -c 'allinfo sparse.txt'

  # evict cache so btime is read fresh again
  umount /mnt
  mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
  stat -c 'CIFS btime (%n):  %w' /mnt/sparse.txt

which prints:

  Local btime (/tmp/sparse.txt): 2026-11-13 21:13:27.167926440 +0000
  /tmp/sparse.txt: user.DOSATTRIB: No such attribute

  # file: tmp/sparse.txt
  user.DOSATTRIB=0x000004000400000051000000200200000000000000000000209542d3b373dd01
     0x51 = 0x1 | 0x10 | 0x40 -----^^         |      unrequested --^^^^^^^^^^^^^^^^
   (ATTRIB | CREATE_TIME | ITIME)             |   creation time = btime
                                     SPARSE --^
  CIFS btime (/mnt/sparse.txt):  2026-11-13 21:13:27.167926400 +0000
  [...]
  create_time:    Fri Nov 13 21:13:27 2026 UTC
  [...]
  CIFS btime (/mnt/sparse.txt):  2026-11-13 21:13:27.167926400 +0000

test with setmode:

  echo data > /tmp/attrib.txt
  chmod 777 /tmp/attrib.txt

  stat -c 'Local btime (%n): %w' /tmp/attrib.txt
  getfattr -n user.DOSATTRIB -e hex /tmp/attrib.txt

  # modify attribute via CIFS
  smbclient //127.0.0.1/test -U user%pass -c 'setmode attrib.txt +r'
  getfattr -n user.DOSATTRIB -e hex /tmp/attrib.txt

  stat -c 'CIFS btime (%n):  %w' /mnt/attrib.txt
  smbclient //127.0.0.1/test -U user%pass -c 'allinfo attrib.txt'

  # evict cache so btime is read fresh again
  umount /mnt
  mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
  stat -c 'CIFS btime (%n):  %w' /mnt/attrib.txt

which prints:

  Local btime (/tmp/attrib.txt): 2026-11-13 21:13:27.195647069 +0000
  /tmp/attrib.txt: user.DOSATTRIB: No such attribute

  # file: tmp/attrib.txt
  user.DOSATTRIB=0x000004000400000051000000210000000000000000000000f6cf46d3b373dd01
     0x51 = 0x1 | 0x10 | 0x40 -----^^       |        unrequested --^^^^^^^^^^^^^^^^
   (ATTRIB | CREATE_TIME | ITIME)           |     creation time = btime
                                 READONLY --^
  CIFS btime (/mnt/attrib.txt):  2026-11-13 21:13:27.195647000 +0000
  [...]
  create_time:    Fri Nov 13 21:13:27 2026 UTC
  [...]
  CIFS btime (/mnt/attrib.txt):  2026-11-13 21:13:27.195647000 +0000

After this patch, the outputs should be:

sparse:

  Local btime (/tmp/sparse.txt): 2026-11-13 21:20:25.856425751 +0000
  /tmp/sparse.txt: user.DOSATTRIB: No such attribute
  # file: tmp/sparse.txt
  user.DOSATTRIB=0x0000040004000000010000002002000000000000000000000000000000000000
          0x01 = 0x1 (ATTRIB) -----^^         | no creation time --^^^^^^^^^^^^^^^^
                                     SPARSE --^
  CIFS btime (/mnt/sparse.txt):  2026-11-13 21:20:25.856425700 +0000
  create_time:    Fri Nov 13 21:20:26 2026 UTC
  CIFS btime (/mnt/sparse.txt):  2026-11-13 21:20:25.856425700 +0000

setmode:

  Local btime (/tmp/attrib.txt): 2026-11-13 21:20:25.976415893 +0000
  /tmp/attrib.txt: user.DOSATTRIB: No such attribute
  # file: tmp/attrib.txt
  user.DOSATTRIB=0x0000040004000000010000002100000000000000000000000000000000000000
          0x01 = 0x1 (ATTRIB) -----^^       |   no creation time --^^^^^^^^^^^^^^^^
                                 READONLY --^
  CIFS btime (/mnt/attrib.txt):  2026-11-13 21:20:25.976415800 +0000
  create_time:    Fri Nov 13 21:20:26 2026 UTC
  CIFS btime (/mnt/attrib.txt):  2026-11-13 21:20:25.976415800 +0000

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") # ndr decode/basic info
Fixes: f44158485826 ("cifsd: add file operations") # ksmbd_vfs_fill_dentry_attrs
Fixes: 159e727f763d ("ksmbd: persist FSCTL_SET_SPARSE state") # sparse
Fixes: 0fb327626ad9 ("ksmbd: support file compression attributes") # compression
Cc: stable@vger.kernel.org
Assisted-by: Gemini:3.8-flash-high antigravity-cli-1.5.3
Signed-off-by: koraynilay <koray.fra@gmail.com>
---
This should be (hopefully) the last of the fixes needed to implement ptime[1].
Thanks for testing all of them and merging them <3

Best,
koraynilay

[1]: https://lore.kernel.org/all/20261101015551.786044-1-koray.fra@gmail.com/T/#t


 fs/smb/server/ndr.c     |  2 +-
 fs/smb/server/smb2pdu.c | 35 +++++++++++++++++++++++------------
 fs/smb/server/vfs.c     |  8 +++-----
 3 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/fs/smb/server/ndr.c b/fs/smb/server/ndr.c
index 7e546c22e284..b5190528340f 100644
--- a/fs/smb/server/ndr.c
+++ b/fs/smb/server/ndr.c
@@ -256,7 +256,7 @@ int ndr_decode_dos_attr(struct ndr *n, struct xattr_dos_attrib *da)
 		return -EINVAL;
 	}
 
-	ret = ndr_read_int32(n, NULL);
+	ret = ndr_read_int32(n, &da->flags);
 	if (ret)
 		return ret;
 
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 806748ac2cb8..605f45e6801b 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -3733,8 +3733,10 @@ static void smb2_update_xattrs(struct ksmbd_tree_connect *tcon,
 	if (rc > 0) {
 		if (store_dos_attrs) {
 			fp->f_ci->m_fattr = cpu_to_le32(da.attr);
-			fp->create_time = da.create_time;
-			fp->itime = da.itime;
+			if (da.flags & XATTR_DOSINFO_CREATE_TIME)
+				fp->create_time = da.create_time;
+			if (da.flags & XATTR_DOSINFO_ITIME)
+				fp->itime = da.itime;
 		} else {
 			fp->f_ci->m_fattr &=
 				~(FILE_ATTRIBUTE_COMPRESSED_LE |
@@ -8905,12 +8907,24 @@ static int set_file_basic_info(struct ksmbd_file *fp,
 	    (crtime > 0 || file_info->Attributes)) {
 		struct xattr_dos_attrib da = {0};
 
-		da.version = 4;
-		da.itime = fp->itime;
-		da.create_time = fp->create_time;
-		da.attr = le32_to_cpu(fp->f_ci->m_fattr);
-		da.flags = XATTR_DOSINFO_ATTRIB | XATTR_DOSINFO_CREATE_TIME |
-			XATTR_DOSINFO_ITIME;
+		rc = ksmbd_vfs_get_dos_attrib_xattr(idmap, fp->filp->f_path.dentry, &da);
+		if (rc <= 0) {
+			da.version = 4;
+			da.flags = 0;
+		}
+
+		/*
+		 * itime gets preserved when reading the xattr if already present
+		 * otherwise don't write it as it wasn't asked for by the client
+		 */
+		if (crtime > 0) {
+			da.create_time = fp->create_time;
+			da.flags |= XATTR_DOSINFO_CREATE_TIME;
+		}
+		if (file_info->Attributes) {
+			da.attr = le32_to_cpu(fp->f_ci->m_fattr);
+			da.flags |= XATTR_DOSINFO_ATTRIB;
+		}
 
 		rc = ksmbd_vfs_set_dos_attrib_xattr(idmap, &filp->f_path, &da,
 				true);
@@ -11743,10 +11757,7 @@ static inline int fsctl_set_sparse(struct ksmbd_work *work, u64 id,
 						     fp->filp->f_path.dentry, &da);
 		if (ret <= 0) {
 			da.version = 4;
-			da.itime = fp->itime;
-			da.create_time = fp->create_time;
-			da.flags = XATTR_DOSINFO_CREATE_TIME |
-				XATTR_DOSINFO_ITIME;
+			da.flags = 0;
 		}
 
 		da.attr = le32_to_cpu(fp->f_ci->m_fattr);
diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 0c95d4668370..f48c6b37b78a 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -1936,7 +1936,8 @@ int ksmbd_vfs_fill_dentry_attrs(struct ksmbd_work *work,
 		rc = ksmbd_vfs_get_dos_attrib_xattr(idmap, dentry, &da);
 		if (rc > 0) {
 			ksmbd_kstat->file_attributes = cpu_to_le32(da.attr);
-			ksmbd_kstat->create_time = da.create_time;
+			if (da.flags & XATTR_DOSINFO_CREATE_TIME)
+				ksmbd_kstat->create_time = da.create_time;
 		} else {
 			ksmbd_debug(VFS, "fail to load dos attribute.\n");
 		}
@@ -2475,10 +2476,7 @@ static int __ksmbd_vfs_set_compression(struct ksmbd_work *work,
 		rc = ksmbd_vfs_get_dos_attrib_xattr(idmap, dentry, &da);
 		if (rc <= 0) {
 			da.version = 4;
-			da.itime = fp->itime;
-			da.create_time = fp->create_time;
-			da.flags = XATTR_DOSINFO_CREATE_TIME |
-				XATTR_DOSINFO_ITIME;
+			da.flags = 0;
 		}
 
 		da.attr = le32_to_cpu(fp->f_ci->m_fattr);

base-commit: e9399de313199e9ffc1035755479a65ae4b3c5cf
prerequisite-patch-id: 049ae0eba275b5be35a238833107e0b251a55aa2
-- 
2.56.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH] ksmbd: decode and honor DOS attribute validity flags
  2026-11-13 22:16 [PATCH] ksmbd: decode and honor DOS attribute validity flags koraynilay
@ 2026-11-14  0:26 ` Namjae Jeon
  2026-11-14  0:58   ` koraynilay
  0 siblings, 1 reply; 3+ messages in thread
From: Namjae Jeon @ 2026-11-14  0:26 UTC (permalink / raw)
  To: koraynilay
  Cc: Sergey Senozhatsky, Tom Talpey, ChenXiaoSong, Hyunchul Lee,
	linux-cifs, linux-kernel

On Sat, Nov 14, 2026 at 7:16 AM koraynilay <koray.fra@gmail.com> wrote:
>
> Currently, when setting file attributes via FSCTL_SET_SPARSE,
> FSCTL_SET_COMPRESSION or FileBasicInformation, ksmbd hardcodes
> flags = 0x51 (XATTR_DOSINFO_ATTRIB | XATTR_DOSINFO_CREATE_TIME |
> XATTR_DOSINFO_ITIME). This injects unrequested creation time and itime
> into user.DOSATTRIB on disk, even though the client only requested an
> attribute modification.
>
> Furthermore, ndr_decode_dos_attr() discards the validity flags on read
> by reading them into NULL. When reading a file with an attribute-only
> xattr (flags = 0x01, where create_time on disk is 0), ksmbd treats the 0
> as a valid timestamp and reports NTTIME(0) instead of falling back to
> the underlying filesystem's btime. Modifying any attribute via
> set_file_basic_info() then clobbers the xattr back to 0x51.
>
> Fix this by:
> 1. decoding da->flags in ndr_decode_dos_attr() and only updating
>    create_time and itime if their validity flags are set (in
>    smb2_update_xattrs() and ksmbd_vfs_fill_dentry_attrs());
> 2. reading existing attributes and only setting XATTR_DOSINFO_ATTRIB in
>    fsctl_set_sparse(), __ksmbd_vfs_set_compression(), and
>    set_file_basic_info() so unrequested timestamps are not injected.
>
> Reproducer, with /tmp as the local filesystem folder exported as [test]
> in ksmbd.conf and /mnt as the smb folder mounted with mount -t cifs:
>
>   mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
>
> test with sparse (for compression, use chattr +c instead of fallocate):
>
>   echo data > /tmp/sparse.txt
>   chmod 777 /tmp/sparse.txt
>
>   stat -c 'Local btime (%n): %w' /tmp/sparse.txt
>   getfattr -n user.DOSATTRIB -e hex /tmp/sparse.txt
>
>   # punching hole via CIFS triggers FSCTL_SET_SPARSE
>   fallocate -p -o 0 -l 4 /mnt/sparse.txt
>   getfattr -n user.DOSATTRIB -e hex /tmp/sparse.txt
>
>   stat -c 'CIFS btime (%n):  %w' /mnt/sparse.txt
>   smbclient //127.0.0.1/test -U user%pass -c 'allinfo sparse.txt'
>
>   # evict cache so btime is read fresh again
>   umount /mnt
>   mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
>   stat -c 'CIFS btime (%n):  %w' /mnt/sparse.txt
>
> which prints:
>
>   Local btime (/tmp/sparse.txt): 2026-11-13 21:13:27.167926440 +0000
>   /tmp/sparse.txt: user.DOSATTRIB: No such attribute
>
>   # file: tmp/sparse.txt
>   user.DOSATTRIB=0x000004000400000051000000200200000000000000000000209542d3b373dd01
>      0x51 = 0x1 | 0x10 | 0x40 -----^^         |      unrequested --^^^^^^^^^^^^^^^^
>    (ATTRIB | CREATE_TIME | ITIME)             |   creation time = btime
>                                      SPARSE --^
>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:13:27.167926400 +0000
>   [...]
>   create_time:    Fri Nov 13 21:13:27 2026 UTC
>   [...]
>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:13:27.167926400 +0000
>
> test with setmode:
>
>   echo data > /tmp/attrib.txt
>   chmod 777 /tmp/attrib.txt
>
>   stat -c 'Local btime (%n): %w' /tmp/attrib.txt
>   getfattr -n user.DOSATTRIB -e hex /tmp/attrib.txt
>
>   # modify attribute via CIFS
>   smbclient //127.0.0.1/test -U user%pass -c 'setmode attrib.txt +r'
>   getfattr -n user.DOSATTRIB -e hex /tmp/attrib.txt
>
>   stat -c 'CIFS btime (%n):  %w' /mnt/attrib.txt
>   smbclient //127.0.0.1/test -U user%pass -c 'allinfo attrib.txt'
>
>   # evict cache so btime is read fresh again
>   umount /mnt
>   mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
>   stat -c 'CIFS btime (%n):  %w' /mnt/attrib.txt
>
> which prints:
>
>   Local btime (/tmp/attrib.txt): 2026-11-13 21:13:27.195647069 +0000
>   /tmp/attrib.txt: user.DOSATTRIB: No such attribute
>
>   # file: tmp/attrib.txt
>   user.DOSATTRIB=0x000004000400000051000000210000000000000000000000f6cf46d3b373dd01
>      0x51 = 0x1 | 0x10 | 0x40 -----^^       |        unrequested --^^^^^^^^^^^^^^^^
>    (ATTRIB | CREATE_TIME | ITIME)           |     creation time = btime
>                                  READONLY --^
>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:13:27.195647000 +0000
>   [...]
>   create_time:    Fri Nov 13 21:13:27 2026 UTC
>   [...]
>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:13:27.195647000 +0000
>
> After this patch, the outputs should be:
>
> sparse:
>
>   Local btime (/tmp/sparse.txt): 2026-11-13 21:20:25.856425751 +0000
>   /tmp/sparse.txt: user.DOSATTRIB: No such attribute
>   # file: tmp/sparse.txt
>   user.DOSATTRIB=0x0000040004000000010000002002000000000000000000000000000000000000
>           0x01 = 0x1 (ATTRIB) -----^^         | no creation time --^^^^^^^^^^^^^^^^
>                                      SPARSE --^
>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:20:25.856425700 +0000
>   create_time:    Fri Nov 13 21:20:26 2026 UTC
>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:20:25.856425700 +0000
>
> setmode:
>
>   Local btime (/tmp/attrib.txt): 2026-11-13 21:20:25.976415893 +0000
>   /tmp/attrib.txt: user.DOSATTRIB: No such attribute
>   # file: tmp/attrib.txt
>   user.DOSATTRIB=0x0000040004000000010000002100000000000000000000000000000000000000
>           0x01 = 0x1 (ATTRIB) -----^^       |   no creation time --^^^^^^^^^^^^^^^^
>                                  READONLY --^
>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:20:25.976415800 +0000
>   create_time:    Fri Nov 13 21:20:26 2026 UTC
>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:20:25.976415800 +0000
>
> Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") # ndr decode/basic info
> Fixes: f44158485826 ("cifsd: add file operations") # ksmbd_vfs_fill_dentry_attrs
> Fixes: 159e727f763d ("ksmbd: persist FSCTL_SET_SPARSE state") # sparse
> Fixes: 0fb327626ad9 ("ksmbd: support file compression attributes") # compression
> Cc: stable@vger.kernel.org
> Assisted-by: Gemini:3.8-flash-high antigravity-cli-1.5.3
> Signed-off-by: koraynilay <koray.fra@gmail.com>
Can you check Sashiko's review comments ?

https://sashiko.dev/#/patchset/20261113221610.392113-1-koray.fra%40gmail.com

Thanks.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] ksmbd: decode and honor DOS attribute validity flags
  2026-11-14  0:26 ` Namjae Jeon
@ 2026-11-14  0:58   ` koraynilay
  0 siblings, 0 replies; 3+ messages in thread
From: koraynilay @ 2026-11-14  0:58 UTC (permalink / raw)
  To: Namjae Jeon, koraynilay
  Cc: Sergey Senozhatsky, Tom Talpey, ChenXiaoSong, Hyunchul Lee,
	linux-cifs, linux-kernel

[-- Attachment #1: Type: text/plain, Size: 6473 bytes --]

On Sat Nov 14, 2026 at 1:26 AM CET, Namjae Jeon wrote:
> On Sat, Nov 14, 2026 at 7:16 AM koraynilay <koray.fra@gmail.com> wrote:
>>
>> Currently, when setting file attributes via FSCTL_SET_SPARSE,
>> FSCTL_SET_COMPRESSION or FileBasicInformation, ksmbd hardcodes
>> flags = 0x51 (XATTR_DOSINFO_ATTRIB | XATTR_DOSINFO_CREATE_TIME |
>> XATTR_DOSINFO_ITIME). This injects unrequested creation time and itime
>> into user.DOSATTRIB on disk, even though the client only requested an
>> attribute modification.
>>
>> Furthermore, ndr_decode_dos_attr() discards the validity flags on read
>> by reading them into NULL. When reading a file with an attribute-only
>> xattr (flags = 0x01, where create_time on disk is 0), ksmbd treats the 0
>> as a valid timestamp and reports NTTIME(0) instead of falling back to
>> the underlying filesystem's btime. Modifying any attribute via
>> set_file_basic_info() then clobbers the xattr back to 0x51.
>>
>> Fix this by:
>> 1. decoding da->flags in ndr_decode_dos_attr() and only updating
>>    create_time and itime if their validity flags are set (in
>>    smb2_update_xattrs() and ksmbd_vfs_fill_dentry_attrs());
>> 2. reading existing attributes and only setting XATTR_DOSINFO_ATTRIB in
>>    fsctl_set_sparse(), __ksmbd_vfs_set_compression(), and
>>    set_file_basic_info() so unrequested timestamps are not injected.
>>
>> Reproducer, with /tmp as the local filesystem folder exported as [test]
>> in ksmbd.conf and /mnt as the smb folder mounted with mount -t cifs:
>>
>>   mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
>>
>> test with sparse (for compression, use chattr +c instead of fallocate):
>>
>>   echo data > /tmp/sparse.txt
>>   chmod 777 /tmp/sparse.txt
>>
>>   stat -c 'Local btime (%n): %w' /tmp/sparse.txt
>>   getfattr -n user.DOSATTRIB -e hex /tmp/sparse.txt
>>
>>   # punching hole via CIFS triggers FSCTL_SET_SPARSE
>>   fallocate -p -o 0 -l 4 /mnt/sparse.txt
>>   getfattr -n user.DOSATTRIB -e hex /tmp/sparse.txt
>>
>>   stat -c 'CIFS btime (%n):  %w' /mnt/sparse.txt
>>   smbclient //127.0.0.1/test -U user%pass -c 'allinfo sparse.txt'
>>
>>   # evict cache so btime is read fresh again
>>   umount /mnt
>>   mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
>>   stat -c 'CIFS btime (%n):  %w' /mnt/sparse.txt
>>
>> which prints:
>>
>>   Local btime (/tmp/sparse.txt): 2026-11-13 21:13:27.167926440 +0000
>>   /tmp/sparse.txt: user.DOSATTRIB: No such attribute
>>
>>   # file: tmp/sparse.txt
>>   user.DOSATTRIB=0x000004000400000051000000200200000000000000000000209542d3b373dd01
>>      0x51 = 0x1 | 0x10 | 0x40 -----^^         |      unrequested --^^^^^^^^^^^^^^^^
>>    (ATTRIB | CREATE_TIME | ITIME)             |   creation time = btime
>>                                      SPARSE --^
>>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:13:27.167926400 +0000
>>   [...]
>>   create_time:    Fri Nov 13 21:13:27 2026 UTC
>>   [...]
>>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:13:27.167926400 +0000
>>
>> test with setmode:
>>
>>   echo data > /tmp/attrib.txt
>>   chmod 777 /tmp/attrib.txt
>>
>>   stat -c 'Local btime (%n): %w' /tmp/attrib.txt
>>   getfattr -n user.DOSATTRIB -e hex /tmp/attrib.txt
>>
>>   # modify attribute via CIFS
>>   smbclient //127.0.0.1/test -U user%pass -c 'setmode attrib.txt +r'
>>   getfattr -n user.DOSATTRIB -e hex /tmp/attrib.txt
>>
>>   stat -c 'CIFS btime (%n):  %w' /mnt/attrib.txt
>>   smbclient //127.0.0.1/test -U user%pass -c 'allinfo attrib.txt'
>>
>>   # evict cache so btime is read fresh again
>>   umount /mnt
>>   mount -t cifs //127.0.0.1/test /mnt -o username=user,password=pass
>>   stat -c 'CIFS btime (%n):  %w' /mnt/attrib.txt
>>
>> which prints:
>>
>>   Local btime (/tmp/attrib.txt): 2026-11-13 21:13:27.195647069 +0000
>>   /tmp/attrib.txt: user.DOSATTRIB: No such attribute
>>
>>   # file: tmp/attrib.txt
>>   user.DOSATTRIB=0x000004000400000051000000210000000000000000000000f6cf46d3b373dd01
>>      0x51 = 0x1 | 0x10 | 0x40 -----^^       |        unrequested --^^^^^^^^^^^^^^^^
>>    (ATTRIB | CREATE_TIME | ITIME)           |     creation time = btime
>>                                  READONLY --^
>>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:13:27.195647000 +0000
>>   [...]
>>   create_time:    Fri Nov 13 21:13:27 2026 UTC
>>   [...]
>>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:13:27.195647000 +0000
>>
>> After this patch, the outputs should be:
>>
>> sparse:
>>
>>   Local btime (/tmp/sparse.txt): 2026-11-13 21:20:25.856425751 +0000
>>   /tmp/sparse.txt: user.DOSATTRIB: No such attribute
>>   # file: tmp/sparse.txt
>>   user.DOSATTRIB=0x0000040004000000010000002002000000000000000000000000000000000000
>>           0x01 = 0x1 (ATTRIB) -----^^         | no creation time --^^^^^^^^^^^^^^^^
>>                                      SPARSE --^
>>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:20:25.856425700 +0000
>>   create_time:    Fri Nov 13 21:20:26 2026 UTC
>>   CIFS btime (/mnt/sparse.txt):  2026-11-13 21:20:25.856425700 +0000
>>
>> setmode:
>>
>>   Local btime (/tmp/attrib.txt): 2026-11-13 21:20:25.976415893 +0000
>>   /tmp/attrib.txt: user.DOSATTRIB: No such attribute
>>   # file: tmp/attrib.txt
>>   user.DOSATTRIB=0x0000040004000000010000002100000000000000000000000000000000000000
>>           0x01 = 0x1 (ATTRIB) -----^^       |   no creation time --^^^^^^^^^^^^^^^^
>>                                  READONLY --^
>>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:20:25.976415800 +0000
>>   create_time:    Fri Nov 13 21:20:26 2026 UTC
>>   CIFS btime (/mnt/attrib.txt):  2026-11-13 21:20:25.976415800 +0000
>>
>> Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") # ndr decode/basic info
>> Fixes: f44158485826 ("cifsd: add file operations") # ksmbd_vfs_fill_dentry_attrs
>> Fixes: 159e727f763d ("ksmbd: persist FSCTL_SET_SPARSE state") # sparse
>> Fixes: 0fb327626ad9 ("ksmbd: support file compression attributes") # compression
>> Cc: stable@vger.kernel.org
>> Assisted-by: Gemini:3.8-flash-high antigravity-cli-1.5.3
>> Signed-off-by: koraynilay <koray.fra@gmail.com>
> Can you check Sashiko's review comments ?
>
> https://sashiko.dev/#/patchset/20261113221610.392113-1-koray.fra%40gmail.com

Yes thanks, I am able to reproduce what sashiko said, I'll send a v2.

Best,
koraynilay

>
> Thanks.



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2026-11-13 22:16 [PATCH] ksmbd: decode and honor DOS attribute validity flags koraynilay
2026-11-14  0:26 ` Namjae Jeon
2026-11-14  0:58   ` koraynilay

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