9 files changed, 95 insertions, 16 deletions

diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index 7260e11e21f8..500d65859279 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -43,6 +43,8 @@
 #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_BACKUPUID 0x200000 /* backup intent bit for a user */
+#define CIFS_MOUNT_CIFS_BACKUPGID 0x400000 /* backup intent bit for a group */
 
 struct cifs_sb_info {
         struct rb_root tlink_tree;
@@ -55,6 +57,8 @@ struct cifs_sb_info {
         atomic_t active;
         uid_t   mnt_uid;
         gid_t   mnt_gid;
+        uid_t   mnt_backupuid;
+        gid_t   mnt_backupgid;
         mode_t  mnt_file_mode;
         mode_t  mnt_dir_mode;
         unsigned int mnt_cifs_flags;
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index d0f59faefb78..b244e07c3048 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 +956,12 @@ 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 (backup_cred(cifs_sb))
+                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 +998,7 @@ 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);
@@ -1006,7 +1009,10 @@ static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
         tcon = tlink_tcon(tlink);
         xid = GetXid();
 
-        rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, WRITE_DAC, 0,
+        if (backup_cred(cifs_sb))
+                create_options |= CREATE_OPEN_BACKUP_INTENT;
+
+        rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, WRITE_DAC, create_options,
                          &fid, &oplock, NULL, cifs_sb->local_nls,
                          cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
         if (rc) {
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d734dee9d495..9551437a2498 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -167,6 +167,8 @@ struct smb_vol {
         uid_t cred_uid;
         uid_t linux_uid;
         gid_t linux_gid;
+        uid_t backupuid;
+        gid_t backupgid;
         mode_t file_mode;
         mode_t dir_mode;
         unsigned secFlg;
@@ -179,6 +181,8 @@ struct smb_vol {
         bool noperm:1;
         bool no_psx_acl:1; /* set if posix acl support should be disabled */
         bool cifs_acl:1;
+        bool backupuid_specified; /* mount option  backupuid  is specified */
+        bool backupgid_specified; /* mount option  backupgid  is specified */
         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 +223,8 @@ 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_BACKUPUID | CIFS_MOUNT_CIFS_BACKUPGID)
 
 #define CIFS_MS_MASK (MS_RDONLY | MS_MANDLOCK | MS_NOEXEC | MS_NOSUID | \
                       MS_NODEV | MS_SYNCHRONOUS)
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 03dc945d94a3..9ddb1eccde69 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -90,6 +90,7 @@ extern int SendReceiveBlockingLock(const unsigned int xid,
 extern int checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length);
 extern bool is_valid_oplock_break(struct smb_hdr *smb,
                                   struct TCP_Server_Info *);
+extern bool backup_cred(struct cifs_sb_info *);
 extern bool is_size_safe_to_change(struct cifsInodeInfo *, __u64 eof);
 extern void cifs_update_eof(struct cifsInodeInfo *cifsi, loff_t offset,
                             unsigned int bytes_written);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index abbc6c3fe3f1..70dd2c418276 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -831,6 +831,7 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
 {
         char *value, *data, *end;
         char *mountdata_copy = NULL, *options;
+        int err;
         unsigned int  temp_len, i, j;
         char separator[2];
         short int override_uid = -1;
@@ -887,6 +888,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
                         cFYI(1, "Null separator not allowed");
                 }
         }
+        vol->backupuid_specified = false; /* no backup intent for a user */
+        vol->backupgid_specified = false; /* no backup intent for a group */
 
         while ((data = strsep(&options, separator)) != NULL) {
                 if (!*data)
@@ -1446,6 +1449,22 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
                         vol->mfsymlinks = true;
                 } else if (strnicmp(data, "multiuser", 8) == 0) {
                         vol->multiuser = true;
+                } else if (!strnicmp(data, "backupuid", 9) && value && *value) {
+                        err = kstrtouint(value, 0, &vol->backupuid);
+                        if (err < 0) {
+                                cERROR(1, "%s: Invalid backupuid value",
+                                        __func__);
+                                goto cifs_parse_mount_err;
+                        }
+                        vol->backupuid_specified = true;
+                } else if (!strnicmp(data, "backupgid", 9) && value && *value) {
+                        err = kstrtouint(value, 0, &vol->backupgid);
+                        if (err < 0) {
+                                cERROR(1, "%s: Invalid backupgid value",
+                                        __func__);
+                                goto cifs_parse_mount_err;
+                        }
+                        vol->backupgid_specified = true;
                 } else
                         printk(KERN_WARNING "CIFS: Unknown mount option %s\n",
                                                 data);
@@ -2737,6 +2756,10 @@ void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 
         cifs_sb->mnt_uid = pvolume_info->linux_uid;
         cifs_sb->mnt_gid = pvolume_info->linux_gid;
+        if (pvolume_info->backupuid_specified)
+                cifs_sb->mnt_backupuid = pvolume_info->backupuid;
+        if (pvolume_info->backupgid_specified)
+                cifs_sb->mnt_backupgid = pvolume_info->backupgid;
         cifs_sb->mnt_file_mode = pvolume_info->file_mode;
         cifs_sb->mnt_dir_mode = pvolume_info->dir_mode;
         cFYI(1, "file mode: 0x%x  dir mode: 0x%x",
@@ -2767,6 +2790,10 @@ 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->backupuid_specified)
+                cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_CIFS_BACKUPUID;
+        if (pvolume_info->backupgid_specified)
+                cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_CIFS_BACKUPGID;
         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 4dd5333753fa..0c8098d54d2b 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -244,6 +244,9 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
         if (!tcon->unix_ext && (mode & S_IWUGO) == 0)
                 create_options |= CREATE_OPTION_READONLY;
 
+        if (backup_cred(cifs_sb))
+                create_options |= CREATE_OPEN_BACKUP_INTENT;
+
         if (tcon->ses->capabilities & CAP_NT_SMBS)
                 rc = CIFSSMBOpen(xid, tcon, full_path, disposition,
                          desiredAccess, create_options,
@@ -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 +435,11 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, int mode,
                 return rc;
         }
 
-        /* FIXME: would WRITE_OWNER | WRITE_DAC be better? */
+        if (backup_cred(cifs_sb))
+                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 8e184150cfb5..237192ae7587 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 +211,12 @@ cifs_nt_open(char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
         if (!buf)
                 return -ENOMEM;
 
+        if (backup_cred(cifs_sb))
+                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 +469,7 @@ 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 +529,9 @@ static int cifs_reopen_file(struct cifsFileInfo *pCifsFile, bool can_flush)
 
         desiredAccess = cifs_convert_flags(pCifsFile->f_flags);
 
+        if (backup_cred(cifs_sb))
+                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 +539,7 @@ 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 db3f18cdf024..8693b5d0e180 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 +208,11 @@ CIFSCreateMFSymLink(const int xid, struct cifs_tcon *tcon,
                 return rc;
         }
 
+        if (backup_cred(cifs_sb))
+                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 +568,7 @@ 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);
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 4a1801b3195f..703ef5c6fdb1 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -675,3 +675,18 @@ void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
                 cinode->clientCanCacheRead = false;
         }
 }
+
+bool
+backup_cred(struct cifs_sb_info *cifs_sb)
+{
+        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
+                if (cifs_sb->mnt_backupuid == current_fsuid())
+                        return true;
+        }
+        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
+                if (in_group_p(cifs_sb->mnt_backupgid))
+                        return true;
+        }
+
+        return false;
+}