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ksmbd: require source read access for duplicate extents

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FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to
vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB
access mask granted to the source handle. A handle opened with attribute
access can consequently be used to copy file contents into an
attacker-readable destination.

Require FILE_READ_DATA on the source handle before either VFS operation,
matching other ksmbd data-copy paths.

Cc: stable@vger.kernel.org
Reported-by: Musaab Khan <musaab.khan@protonmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Namjae Jeon
2026-06-13 22:00:02 +09:00
committed by Steve French
parent b383bcad3d
commit cedff600f1
1 changed files with 4 additions and 0 deletions
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4
fs/smb/server/smb2pdu.c
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@@ -8778,6 +8778,10 @@ int smb2_ioctl(struct ksmbd_work *work)
ret = -EACCES;
goto dup_ext_out;
}
if (!(fp_in->daccess & FILE_READ_DATA_LE)) {
ret = -EACCES;
goto dup_ext_out;
}
src_off = le64_to_cpu(dup_ext->SourceFileOffset);
dst_off = le64_to_cpu(dup_ext->TargetFileOffset);