cifs: Add mount options for backup intent (try #6)
Add mount options backupuid and backugid.
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.
When mount options backupuid is specified, cifs client restricts the
use of backup intents to the user whose effective user id is specified
along with the mount option.
When mount options backupgid is specified, cifs client restricts the
use of backup intents to the users whose effective user id belongs to the
group id specified along with the mount option.
If an authenticated user is not part of the built-in group Backup Operators
at the server, access to such files is denied, even if allowed by the client.
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
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 @@
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 @@
{
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 @@
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 @@
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 @@
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 d734dee..9551437 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -167,6 +167,8 @@
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 @@
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 @@
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 03dc945..9ddb1ec 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -90,6 +90,7 @@
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 abbc6c3..70dd2c4 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -831,6 +831,7 @@
{
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 @@
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 @@
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 @@
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 @@
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 4dd5333..0c8098d 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -244,6 +244,9 @@
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 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 @@
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 8e18415..237192a 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -174,6 +174,7 @@
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 @@
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 @@
char *full_path = NULL;
int desiredAccess;
int disposition = FILE_OPEN;
+ int create_options = CREATE_NOT_DIR;
__u16 netfid;
xid = GetXid();
@@ -524,6 +529,9 @@
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 @@
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 @@
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 @@
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 @@
/* 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 4a1801b..703ef5c 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -675,3 +675,18 @@
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;
+}
