On Fri, Aug 12, 2011 at 2:25 PM, Shirish Pargaonkar
<shirishpargaonkar@xxxxxxxxx> wrote:
> On Fri, Aug 12, 2011 at 12:19 PM, Steve French <smfrench@xxxxxxxxx> wrote:
>> Shirish or Manoj,
>> Could you give a little more detail on the failure scenario
>> and which files and information can not be accessed?
>>
>> A mount option may be the only choice, since there is
>> no equivalent for "open for backup intent" open flag,
>> and presumably no easy way to query whether a user is a member
>> of the "backup operators" group, but would a mount option be
>> a problem for other users of the same mount who don't have
>> backup operator privilege trying to open other files?
>>
>> On Fri, Aug 12, 2011 at 11:33 AM, <shirishpargaonkar@xxxxxxxxx> wrote:
>>> From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
>>>
>>>
>>> Add mount option backup.
>>>
>>> It allows an authenticated user to access files with the intent to back them
>>> up including their ACLs, who may not have access permission but has
>>> "Backup files and directories user right" on them (by virtue of being part
>>> of the built-in group Backup Operators.
>>>
>>> If an authenticated user is not part of the built-in group Backup Operators
>>> at the server, access to such files is denied.
>>>
>>>
>>> Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
>>> ---
>>> fs/cifs/cifs_fs_sb.h | 1 +
>>> fs/cifs/cifsacl.c | 18 +++++++++++++-----
>>> fs/cifs/cifsglob.h | 4 +++-
>>> fs/cifs/connect.c | 5 +++++
>>> fs/cifs/dir.c | 11 +++++++++--
>>> fs/cifs/file.c | 14 ++++++++++++--
>>> fs/cifs/link.c | 18 +++++++++++++-----
>>> 7 files changed, 56 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
>>> index 7260e11..8ba1b44 100644
>>> --- a/fs/cifs/cifs_fs_sb.h
>>> +++ b/fs/cifs/cifs_fs_sb.h
>>> @@ -43,6 +43,7 @@
>>> #define CIFS_MOUNT_STRICT_IO 0x40000 /* strict cache mode */
>>> #define CIFS_MOUNT_RWPIDFORWARD 0x80000 /* use pid forwarding for rw */
>>> #define CIFS_MOUNT_POSIXACL 0x100000 /* mirror of MS_POSIXACL in mnt_cifs_flags */
>>> +#define CIFS_MOUNT_CIFS_BACKUP 0x200000 /* open file with backup intent bit */
>>>
>>> struct cifs_sb_info {
>>> struct rb_root tlink_tree;
>>> diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
>>> index d0f59fa..24bc2dd 100644
>>> --- a/fs/cifs/cifsacl.c
>>> +++ b/fs/cifs/cifsacl.c
>>> @@ -945,7 +945,7 @@ static struct cifs_ntsd *get_cifs_acl_by_path(struct cifs_sb_info *cifs_sb,
>>> {
>>> struct cifs_ntsd *pntsd = NULL;
>>> int oplock = 0;
>>> - int xid, rc;
>>> + int xid, rc, create_options = 0;
>>> __u16 fid;
>>> struct cifs_tcon *tcon;
>>> struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
>>> @@ -956,9 +956,13 @@ static struct cifs_ntsd *get_cifs_acl_by_path(struct cifs_sb_info *cifs_sb,
>>> tcon = tlink_tcon(tlink);
>>> xid = GetXid();
>>>
>>> - rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, READ_CONTROL, 0,
>>> - &fid, &oplock, NULL, cifs_sb->local_nls,
>>> - cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>> +
>>> + rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, READ_CONTROL,
>>> + create_options, &fid, &oplock, NULL, cifs_sb->local_nls,
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> if (!rc) {
>>> rc = CIFSSMBGetCIFSACL(xid, tcon, fid, &pntsd, pacllen);
>>> CIFSSMBClose(xid, tcon, fid);
>>> @@ -995,7 +999,7 @@ static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
>>> struct cifs_ntsd *pnntsd, u32 acllen)
>>> {
>>> int oplock = 0;
>>> - int xid, rc;
>>> + int xid, rc, create_options = 0;
>>> __u16 fid;
>>> struct cifs_tcon *tcon;
>>> struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
>>> @@ -1006,6 +1010,10 @@ static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
>>> tcon = tlink_tcon(tlink);
>>> xid = GetXid();
>>>
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>> +
>>> rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, WRITE_DAC, 0,
>>> &fid, &oplock, NULL, cifs_sb->local_nls,
>>> cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
>>> index 95dad9d..3c6fd56 100644
>>> --- a/fs/cifs/cifsglob.h
>>> +++ b/fs/cifs/cifsglob.h
>>> @@ -179,6 +179,7 @@ struct smb_vol {
>>> bool noperm:1;
>>> bool no_psx_acl:1; /* set if posix acl support should be disabled */
>>> bool cifs_acl:1;
>>> + bool cifs_backup:1; /* to indicates backup intent during file open */
>>> bool no_xattr:1; /* set if xattr (EA) support should be disabled*/
>>> bool server_ino:1; /* use inode numbers from server ie UniqueId */
>>> bool direct_io:1;
>>> @@ -219,7 +220,8 @@ struct smb_vol {
>>> CIFS_MOUNT_OVERR_GID | CIFS_MOUNT_DYNPERM | \
>>> CIFS_MOUNT_NOPOSIXBRL | CIFS_MOUNT_NOSSYNC | \
>>> CIFS_MOUNT_FSCACHE | CIFS_MOUNT_MF_SYMLINKS | \
>>> - CIFS_MOUNT_MULTIUSER | CIFS_MOUNT_STRICT_IO)
>>> + CIFS_MOUNT_MULTIUSER | CIFS_MOUNT_STRICT_IO | \
>>> + CIFS_MOUNT_CIFS_BACKUP)
>>>
>>> #define CIFS_MS_MASK (MS_RDONLY | MS_MANDLOCK | MS_NOEXEC | MS_NOSUID | \
>>> MS_NODEV | MS_SYNCHRONOUS)
>>> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
>>> index 80c2e3a..352d6d6 100644
>>> --- a/fs/cifs/connect.c
>>> +++ b/fs/cifs/connect.c
>>> @@ -883,6 +883,7 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>>> cFYI(1, "Null separator not allowed");
>>> }
>>> }
>>> + vol->cifs_backup = 0; /* no backup intent */
>>>
>>> while ((data = strsep(&options, separator)) != NULL) {
>>> if (!*data)
>>> @@ -1405,6 +1406,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
>>> vol->rwpidforward = 1;
>>> } else if (strnicmp(data, "cifsacl", 7) == 0) {
>>> vol->cifs_acl = 1;
>>> + } else if (strnicmp(data, "backup", 7) == 0) {
>>> + vol->cifs_backup = 1;
>>> } else if (strnicmp(data, "nocifsacl", 9) == 0) {
>>> vol->cifs_acl = 0;
>>> } else if (strnicmp(data, "acl", 3) == 0) {
>>> @@ -2763,6 +2766,8 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
>>> cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_RWPIDFORWARD;
>>> if (pvolume_info->cifs_acl)
>>> cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_CIFS_ACL;
>>> + if (pvolume_info->cifs_backup)
>>> + cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_CIFS_BACKUP;
>>> if (pvolume_info->override_uid)
>>> cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_OVERR_UID;
>>> if (pvolume_info->override_gid)
>>> diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
>>> index ae576fb..fbecde6 100644
>>> --- a/fs/cifs/dir.c
>>> +++ b/fs/cifs/dir.c
>>> @@ -243,6 +243,9 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
>>> */
>>> if (!tcon->unix_ext && (mode & S_IWUGO) == 0)
>>> create_options |= CREATE_OPTION_READONLY;
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>>
>>> if (tcon->ses->capabilities & CAP_NT_SMBS)
>>> rc = CIFSSMBOpen(xid, tcon, full_path, disposition,
>>> @@ -357,6 +360,7 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, int mode,
>>> {
>>> int rc = -EPERM;
>>> int xid;
>>> + int create_options = CREATE_NOT_DIR | CREATE_OPTION_SPECIAL;
>>> struct cifs_sb_info *cifs_sb;
>>> struct tcon_link *tlink;
>>> struct cifs_tcon *pTcon;
>>> @@ -431,9 +435,12 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, int mode,
>>> return rc;
>>> }
>>>
>>> - /* FIXME: would WRITE_OWNER | WRITE_DAC be better? */
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>> +
>>> rc = CIFSSMBOpen(xid, pTcon, full_path, FILE_CREATE,
>>> - GENERIC_WRITE, CREATE_NOT_DIR | CREATE_OPTION_SPECIAL,
>>> + GENERIC_WRITE, create_options,
>>> &fileHandle, &oplock, buf, cifs_sb->local_nls,
>>> cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> if (rc)
>>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>>> index 9f41a10..39b06c4 100644
>>> --- a/fs/cifs/file.c
>>> +++ b/fs/cifs/file.c
>>> @@ -174,6 +174,7 @@ cifs_nt_open(char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
>>> int rc;
>>> int desiredAccess;
>>> int disposition;
>>> + int create_options = CREATE_NOT_DIR;
>>> FILE_ALL_INFO *buf;
>>>
>>> desiredAccess = cifs_convert_flags(f_flags);
>>> @@ -210,9 +211,13 @@ cifs_nt_open(char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
>>> if (!buf)
>>> return -ENOMEM;
>>>
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>> +
>>> if (tcon->ses->capabilities & CAP_NT_SMBS)
>>> rc = CIFSSMBOpen(xid, tcon, full_path, disposition,
>>> - desiredAccess, CREATE_NOT_DIR, pnetfid, poplock, buf,
>>> + desiredAccess, create_options, pnetfid, poplock, buf,
>>> cifs_sb->local_nls, cifs_sb->mnt_cifs_flags
>>> & CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> else
>>> @@ -465,6 +470,7 @@ static int cifs_reopen_file(struct cifsFileInfo *pCifsFile, bool can_flush)
>>> char *full_path = NULL;
>>> int desiredAccess;
>>> int disposition = FILE_OPEN;
>>> + int create_options = CREATE_NOT_DIR;
>>> __u16 netfid;
>>>
>>> xid = GetXid();
>>> @@ -524,6 +530,10 @@ static int cifs_reopen_file(struct cifsFileInfo *pCifsFile, bool can_flush)
>>>
>>> desiredAccess = cifs_convert_flags(pCifsFile->f_flags);
>>>
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>> +
>>> /* Can not refresh inode by passing in file_info buf to be returned
>>> by SMBOpen and then calling get_inode_info with returned buf
>>> since file might have write behind data that needs to be flushed
>>> @@ -531,7 +541,7 @@ static int cifs_reopen_file(struct cifsFileInfo *pCifsFile, bool can_flush)
>>> that inode was not dirty locally we could do this */
>>>
>>> rc = CIFSSMBOpen(xid, tcon, full_path, disposition, desiredAccess,
>>> - CREATE_NOT_DIR, &netfid, &oplock, NULL,
>>> + create_options, &netfid, &oplock, NULL,
>>> cifs_sb->local_nls, cifs_sb->mnt_cifs_flags &
>>> CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> if (rc) {
>>> diff --git a/fs/cifs/link.c b/fs/cifs/link.c
>>> index db3f18c..67e51b8 100644
>>> --- a/fs/cifs/link.c
>>> +++ b/fs/cifs/link.c
>>> @@ -183,14 +183,20 @@ CIFSFormatMFSymlink(u8 *buf, unsigned int buf_len, const char *link_str)
>>> static int
>>> CIFSCreateMFSymLink(const int xid, struct cifs_tcon *tcon,
>>> const char *fromName, const char *toName,
>>> - const struct nls_table *nls_codepage, int remap)
>>> + struct cifs_sb_info *cifs_sb)
>>> {
>>> int rc;
>>> int oplock = 0;
>>> + int remap;
>>> + int create_options = CREATE_NOT_DIR;
>>> __u16 netfid = 0;
>>> u8 *buf;
>>> unsigned int bytes_written = 0;
>>> struct cifs_io_parms io_parms;
>>> + struct nls_table *nls_codepage;
>>> +
>>> + nls_codepage = cifs_sb->local_nls;
>>> + remap = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR;
>>>
>>> buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
>>> if (!buf)
>>> @@ -202,8 +208,12 @@ CIFSCreateMFSymLink(const int xid, struct cifs_tcon *tcon,
>>> return rc;
>>> }
>>>
>>> + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL &&
>>> + cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUP)
>>> + create_options |= CREATE_OPEN_BACKUP_INTENT;
>>> +
>>> rc = CIFSSMBOpen(xid, tcon, fromName, FILE_CREATE, GENERIC_WRITE,
>>> - CREATE_NOT_DIR, &netfid, &oplock, NULL,
>>> + create_options, &netfid, &oplock, NULL,
>>> nls_codepage, remap);
>>> if (rc != 0) {
>>> kfree(buf);
>>> @@ -559,9 +569,7 @@ cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
>>> /* BB what if DFS and this volume is on different share? BB */
>>> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
>>> rc = CIFSCreateMFSymLink(xid, pTcon, full_path, symname,
>>> - cifs_sb->local_nls,
>>> - cifs_sb->mnt_cifs_flags &
>>> - CIFS_MOUNT_MAP_SPECIAL_CHR);
>>> + cifs_sb);
>>> else if (pTcon->unix_ext)
>>> rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
>>> cifs_sb->local_nls);
>>> --
>>> 1.6.0.2
>>>
>>>
>>
>>
>>
>> --
>> Thanks,
>>
>> Steve
>>
>
> On a Windows 2003 server, 'Back up files and directories policy is enabled
> and user named 'mahalcrow' is added to that policy.
>
> I mount a share from that Windows server by authenticating as user 'mahalcrow'.
>
> # mount -t cifs //cifstest1/myshare /mnt/smb_b -o
> backup,cifsacl,user=mahalcrow,pass=<passwd>
>
> # ls -l /mnt/smb_b/testfile2
> -rwx------ 1 administrator 10010 18 Aug 9 19:26 /mnt/smb_b/testfile2
>
> # /tmp/getcifsacl /mnt/smb_b/testfile2
> REVISION:0x1
> CONTROL:0x9404
> OWNER:CIFSTESTDOM\Administrator
> GROUP:CIFSTESTDOM\Domain Users
> ACL:CIFSTESTDOM\Administrator:ALLOWED/0x0/FULL
>
> So with the backup intent create option during open (nt_create_andx),
> an user who is neither owner of the file and not part of the only ACE
> in the ACL of this file, can still access the file.
>
>
> Now if I remove this user, mahalcrow, from the policy 'Back up files
> and directories' under
> Security Settings/Local Policies/user Rights Assignment/Security Options,
> unmount and remount the share and then try to access the file
> testfile2 from the
> mounted share, it fails, even with the backup intent mount option.
>
> # mount -t cifs //cifstest1/myshare /mnt/smb_b -o
> backup,cifsacl,user=mahalcrow,pass=<passwd>
> # ls -l /mnt/smb_b/testfile2
> -rwxr-xr-x 1 root root 18 Aug 9 19:26 /mnt/smb_b/testfile2
>
> # /tmp/getcifsacl /mnt/smb_b/testfile2
> getxattr error: 95
> REVISION:0x0
> CONTROL:0x0
>
>
> The change in policy on the server will not reflect on an existing smb
> connection though,
> if this user unmounts and remounts the same share, it would be effective.
>
> Regards,
>
> Shirish
>
Oh, forgot to mention, that without this mount option, backup,
access to file fails.
# ls -l /mnt/smb_b/testfile2
ls: cannot access /mnt/smb_b/testfile2: Permission denied
So this mount option backup, alongwith cifsacl mount option, now enables a
program/tool like robocopy to function as it should.
If and how a user is shut out from any of such accesses is upto the
cifs/smb server.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
