cifs: have find_readable/writable_file filter by fsuid

When we implement multiuser mounts, we'll need to filter filehandles
by fsuid. Add a flag for multiuser mounts and code to filter by
fsuid when it's set.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

6 files changed, 35 insertions, 16 deletions

diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index ba0afd3acff4..e04e6923d354 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -37,6 +37,7 @@
 #define CIFS_MOUNT_NOSSYNC      0x4000 /* don't do slow SMBflush on every sync*/
 #define CIFS_MOUNT_FSCACHE      0x8000 /* local caching enabled */
 #define CIFS_MOUNT_MF_SYMLINKS  0x10000 /* Minshall+French Symlinks enabled */
+#define CIFS_MOUNT_MULTIUSER    0x20000 /* multiuser mount */
 
 struct cifs_sb_info {
         struct cifsTconInfo *ptcon;     /* primary mount */
@@ -48,7 +49,7 @@ struct cifs_sb_info {
         gid_t   mnt_gid;
         mode_t  mnt_file_mode;
         mode_t  mnt_dir_mode;
-        int     mnt_cifs_flags;
+        unsigned int mnt_cifs_flags;
         int     prepathlen;
         char   *prepath; /* relative path under the share to mount to */
 #ifdef CONFIG_CIFS_DFS_UPCALL
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 2647ea410c4c..c9b4792ae825 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -615,7 +615,7 @@ static struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
         struct cifsFileInfo *open_file = NULL;
 
         if (inode)
-                open_file = find_readable_file(CIFS_I(inode));
+                open_file = find_readable_file(CIFS_I(inode), true);
         if (!open_file)
                 return get_cifs_acl_by_path(cifs_sb, path, pacllen);
 
@@ -685,7 +685,7 @@ static int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
 
         cFYI(DBG2, "set ACL for %s from mode 0x%x", path, inode->i_mode);
 
-        open_file = find_readable_file(CIFS_I(inode));
+        open_file = find_readable_file(CIFS_I(inode), true);
         if (!open_file)
                 return set_cifs_acl_by_path(cifs_sb, path, pnntsd, acllen);
 
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 7294723d0625..29a2ee8ae51f 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -78,9 +78,9 @@ 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 is_size_safe_to_change(struct cifsInodeInfo *, __u64 eof);
-extern struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *);
+extern struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *, bool);
 #ifdef CONFIG_CIFS_EXPERIMENTAL
-extern struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *);
+extern struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *, bool);
 #endif
 extern unsigned int smbCalcSize(struct smb_hdr *ptr);
 extern unsigned int smbCalcSize_LE(struct smb_hdr *ptr);
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 5adf47f28fed..e249b561ce8f 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -144,6 +144,7 @@ cifs_new_fileinfo(struct inode *newinode, __u16 fileHandle, struct file *file,
 
         pCifsFile->netfid = fileHandle;
         pCifsFile->pid = current->tgid;
+        pCifsFile->uid = current_fsuid();
         pCifsFile->pInode = igrab(newinode);
         pCifsFile->mnt = mnt;
         pCifsFile->pfile = file;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 24332d437150..80856f180711 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1168,9 +1168,15 @@ static ssize_t cifs_write(struct file *file, const char *write_data,
 }
 
 #ifdef CONFIG_CIFS_EXPERIMENTAL
-struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode)
+struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
+                                        bool fsuid_only)
 {
         struct cifsFileInfo *open_file = NULL;
+        struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
+
+        /* only filter by fsuid on multiuser mounts */
+        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
+                fsuid_only = false;
 
         read_lock(&GlobalSMBSeslock);
         /* we could simply get the first_list_entry since write-only entries
@@ -1179,6 +1185,8 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode)
         list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
                 if (open_file->closePend)
                         continue;
+                if (fsuid_only && open_file->uid != current_fsuid())
+                        continue;
                 if (open_file->pfile && ((open_file->pfile->f_flags & O_RDWR) ||
                     (open_file->pfile->f_flags & O_RDONLY))) {
                         if (!open_file->invalidHandle) {
@@ -1198,9 +1206,11 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode)
 }
 #endif
 
-struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode)
+struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode,
+                                        bool fsuid_only)
 {
         struct cifsFileInfo *open_file;
+        struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
         bool any_available = false;
         int rc;
 
@@ -1214,13 +1224,19 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode)
                 return NULL;
         }
 
+        /* only filter by fsuid on multiuser mounts */
+        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
+                fsuid_only = false;
+
         read_lock(&GlobalSMBSeslock);
 refind_writable:
         list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
-                if (open_file->closePend ||
-                    (!any_available && open_file->pid != current->tgid))
+                if (open_file->closePend)
+                        continue;
+                if (!any_available && open_file->pid != current->tgid)
+                        continue;
+                if (fsuid_only && open_file->uid != current_fsuid())
                         continue;
-
                 if (open_file->pfile &&
                     ((open_file->pfile->f_flags & O_RDWR) ||
                      (open_file->pfile->f_flags & O_WRONLY))) {
@@ -1315,7 +1331,7 @@ static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
         if (mapping->host->i_size - offset < (loff_t)to)
                 to = (unsigned)(mapping->host->i_size - offset);
 
-        open_file = find_writable_file(CIFS_I(mapping->host));
+        open_file = find_writable_file(CIFS_I(mapping->host), false);
         if (open_file) {
                 bytes_written = cifs_write(open_file->pfile, write_data,
                                            to-from, &offset);
@@ -1388,7 +1404,7 @@ static int cifs_writepages(struct address_space *mapping,
          * but it'll at least handle the return. Maybe it should be
          * a BUG() instead?
          */
-        open_file = find_writable_file(CIFS_I(mapping->host));
+        open_file = find_writable_file(CIFS_I(mapping->host), false);
         if (!open_file) {
                 kfree(iov);
                 return generic_writepages(mapping, wbc);
@@ -1505,7 +1521,8 @@ retry:
                                 break;
                 }
                 if (n_iov) {
-                        open_file = find_writable_file(CIFS_I(mapping->host));
+                        open_file = find_writable_file(CIFS_I(mapping->host),
+                                                        false);
                         if (!open_file) {
                                 cERROR(1, "No writable handles for inode");
                                 rc = -EBADF;
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index a39a1c451733..df29a3a3d80c 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -963,7 +963,7 @@ cifs_set_file_info(struct inode *inode, struct iattr *attrs, int xid,
         /*
          * If the file is already open for write, just use that fileid
          */
-        open_file = find_writable_file(cifsInode);
+        open_file = find_writable_file(cifsInode, true);
         if (open_file) {
                 netfid = open_file->netfid;
                 netpid = open_file->pid;
@@ -1813,7 +1813,7 @@ cifs_set_file_size(struct inode *inode, struct iattr *attrs,
          * writebehind data than the SMB timeout for the SetPathInfo
          * request would allow
          */
-        open_file = find_writable_file(cifsInode);
+        open_file = find_writable_file(cifsInode, true);
         if (open_file) {
                 __u16 nfid = open_file->netfid;
                 __u32 npid = open_file->pid;
@@ -1978,7 +1978,7 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs)
                 args->ctime = NO_CHANGE_64;
 
         args->device = 0;
-        open_file = find_writable_file(cifsInode);
+        open_file = find_writable_file(cifsInode, true);
         if (open_file) {
                 u16 nfid = open_file->netfid;
                 u32 npid = open_file->pid;