[linux-cifs-client] [PATCH 6/7] [CIFS] when not using unix extensions, check for and set ATTR_READONLY on create

[Jeff Layton]

When creating a file, set ATTR_READONLY if the create mode has no write
bits set and we're not using unix extensions.

There are some comments about this being problematic due to the VFS
splitting creates into 2 parts. I'm not sure what that's actually
talking about, but I'm assuming that it has something to do with how
mknod is implemented. In the simple case where we have no unix
extensions and we're just creating a regular file, there's no reason
we can't set ATTR_READONLY.

Signed-off-by: Jeff Layton <jlayton at redhat.com>
---
 fs/cifs/cifspdu.h |    1 +
 fs/cifs/cifssmb.c |   16 ++++++----------
 fs/cifs/dir.c     |   16 +++++++++++++---
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index a0d26b5..c43bf4b 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -340,6 +340,7 @@
 #define OPEN_NO_RECALL          0x00400000
 #define OPEN_FREE_SPACE_QUERY   0x00800000	/* should be zero */
 #define CREATE_OPTIONS_MASK     0x007FFFFF
+#define CREATE_OPTION_READONLY	0x10000000
 #define CREATE_OPTION_SPECIAL   0x20000000   /* system. NB not sent over wire */
 
 /* ImpersonationLevel flags */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index cfd9750..95fbba4 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1224,11 +1224,8 @@ OldOpenRetry:
 	else /* BB FIXME BB */
 		pSMB->FileAttributes = cpu_to_le16(0/*ATTR_NORMAL*/);
 
-	/* if ((omode & S_IWUGO) == 0)
-		pSMB->FileAttributes |= cpu_to_le32(ATTR_READONLY);*/
-	/*  Above line causes problems due to vfs splitting create into two
-	    pieces - need to set mode after file created not while it is
-	    being created */
+	if (create_options & CREATE_OPTION_READONLY)
+		pSMB->FileAttributes |= cpu_to_le16(ATTR_READONLY);
 
 	/* BB FIXME BB */
 /*	pSMB->CreateOptions = cpu_to_le32(create_options &
@@ -1331,17 +1328,16 @@ openRetry:
 		pSMB->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
 	else
 		pSMB->FileAttributes = cpu_to_le32(ATTR_NORMAL);
+
 	/* XP does not handle ATTR_POSIX_SEMANTICS */
 	/* but it helps speed up case sensitive checks for other
 	servers such as Samba */
 	if (tcon->ses->capabilities & CAP_UNIX)
 		pSMB->FileAttributes |= cpu_to_le32(ATTR_POSIX_SEMANTICS);
 
-	/* if ((omode & S_IWUGO) == 0)
-		pSMB->FileAttributes |= cpu_to_le32(ATTR_READONLY);*/
-	/*  Above line causes problems due to vfs splitting create into two
-		pieces - need to set mode after file created not while it is
-		being created */
+	if (create_options & CREATE_OPTION_READONLY)
+		pSMB->FileAttributes |= cpu_to_le32(ATTR_READONLY);
+
 	pSMB->ShareAccess = cpu_to_le32(FILE_SHARE_ALL);
 	pSMB->CreateDisposition = cpu_to_le32(openDisposition);
 	pSMB->CreateOptions = cpu_to_le32(create_options & CREATE_OPTIONS_MASK);
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 84abd0a..c159734 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -119,6 +119,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 {
 	int rc = -ENOENT;
 	int xid;
+	int create_options = CREATE_NOT_DIR;
 	int oplock = 0;
 	int desiredAccess = GENERIC_READ | GENERIC_WRITE;
 	__u16 fileHandle;
@@ -176,9 +177,19 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 		FreeXid(xid);
 		return -ENOMEM;
 	}
+
+	mode &= ~current->fs->umask;
+
+	/*
+	 * if we're not using unix extensions, see if we need to set
+	 * ATTR_READONLY on the create call
+	 */
+	if (!pTcon->unix_ext && (mode & S_IWUGO) == 0)
+		create_options |= CREATE_OPTION_READONLY;
+
 	if (cifs_sb->tcon->ses->capabilities & CAP_NT_SMBS)
 		rc = CIFSSMBOpen(xid, pTcon, full_path, disposition,
-			 desiredAccess, CREATE_NOT_DIR,
+			 desiredAccess, create_options,
 			 &fileHandle, &oplock, buf, cifs_sb->local_nls,
 			 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
 	else
@@ -187,7 +198,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 	if (rc == -EIO) {
 		/* old server, retry the open legacy style */
 		rc = SMBLegacyOpen(xid, pTcon, full_path, disposition,
-			desiredAccess, CREATE_NOT_DIR,
+			desiredAccess, create_options,
 			&fileHandle, &oplock, buf, cifs_sb->local_nls,
 			cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
 	}
@@ -197,7 +208,6 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 		/* If Open reported that we actually created a file
 		then we now have to set the mode if possible */
 		if ((pTcon->unix_ext) && (oplock & CIFS_CREATE_ACTION)) {
-			mode &= ~current->fs->umask;
 			if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID) {
 				CIFSSMBUnixSetPerms(xid, pTcon, full_path, mode,
 					(__u64)current->fsuid,
-- 
1.5.3.6