[PATCH] cifs: Add mount options for backup intent (try #5)

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From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>

---
 fs/cifs/cifs_fs_sb.h |    4 ++++
 fs/cifs/cifsacl.c    |   18 ++++++++++++------
 fs/cifs/cifsglob.h   |    7 ++++++-
 fs/cifs/cifsproto.h  |    1 +
 fs/cifs/connect.c    |   16 ++++++++++++++++
 fs/cifs/dir.c        |   10 ++++++++--
 fs/cifs/file.c       |   12 ++++++++++--
 fs/cifs/link.c       |   17 ++++++++++++-----
 fs/cifs/misc.c       |   17 +++++++++++++++++
 9 files changed, 86 insertions(+), 16 deletions(-)

diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index 7260e11..500d658 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 d0f59fa..b244e07 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 95dad9d..fa2f80a 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 8df28e9..937c78e 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 f4af4cc..62b7927 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -883,6 +883,8 @@ 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)
@@ -1442,6 +1444,12 @@ 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) {
+			kstrtouint(value, 0, &vol->backupuid);
+			vol->backupuid_specified = true;
+		} else if (!strnicmp(data, "backupgid", 9) && value && *value) {
+			kstrtouint(value, 0, &vol->backupgid);
+			vol->backupgid_specified = true;
 		} else
 			printk(KERN_WARNING "CIFS: Unknown mount option %s\n",
 						data);
@@ -2733,6 +2741,10 @@ 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",
@@ -2763,6 +2775,10 @@ 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 72d448b..0a818a6 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 9f41a10..97e4be3 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 db3f18c..8693b5d 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 7c16933..1bc5f30 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -676,3 +676,20 @@ void cifs_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock)
 		cinode->clientCanCacheRead = false;
 	}
 }
+
+bool
+backup_cred(struct cifs_sb_info *cifs_sb)
+{
+	bool rc = false;
+
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPUID) {
+		if (cifs_sb->mnt_backupuid == current_fsuid())
+			rc = true;
+	}
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_BACKUPGID) {
+		if (in_group_p(cifs_sb->mnt_backupgid))
+			rc = true;
+	}
+
+	return rc;
+}
-- 
1.6.0.2

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