[PATCH] cifs: Add mount option named backup

Steve French smfrench at gmail.com
Fri Aug 12 11:19:44 MDT 2011


On Fri, Aug 12, 2011 at 12:19 PM, Steve French <smfrench at gmail.com> 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 at gmail.com> wrote:
>> From: Shirish Pargaonkar <shirishpargaonkar at gmail.com>
>>
>>
>> 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 at gmail.com>
>> ---
>>  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
>



-- 
Thanks,

Steve


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