ANDROID: sdcardfs: Don't use OVERRIDE_CRED macroLA.UM.6.8.r1-07800-SDM710.0

The macro hides some control flow, making it easier
to run into bugs.

bug: 111642636

Change-Id: I37ec207c277d97c4e7f1e8381bc9ae743ad78435
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Git-repo: https://android.googlesource.com/kernel/msm
Git-commit: c17e2d402c61d1738cb2fbccf4c29ae85279509c
Signed-off-by: Dennis Cagle <dcagle@codeaurora.org>

4 files changed, 66 insertions, 190 deletions

diff --git a/fs/sdcardfs/file.c b/fs/sdcardfs/file.c
index 5ac0b0bbb0ec..399531bc1f6f 100644
--- a/fs/sdcardfs/file.c
+++ b/fs/sdcardfs/file.c
@@ -115,7 +115,11 @@ static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd,
 		goto out;
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(sbi, saved_cred, SDCARDFS_I(file_inode(file)));
+	saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
+	if (!saved_cred) {
+		err = -ENOMEM;
+		goto out;
+	}
 
 	if (lower_file->f_op->unlocked_ioctl)
 		err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
@@ -124,7 +128,7 @@ static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd,
 	if (!err)
 		sdcardfs_copy_and_fix_attrs(file_inode(file),
 				      file_inode(lower_file));
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out:
 	return err;
 }
@@ -146,12 +150,16 @@ static long sdcardfs_compat_ioctl(struct file *file, unsigned int cmd,
 		goto out;
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(sbi, saved_cred, SDCARDFS_I(file_inode(file)));
+	saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
+	if (!saved_cred) {
+		err = -ENOMEM;
+		goto out;
+	}
 
 	if (lower_file->f_op->compat_ioctl)
 		err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
 
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out:
 	return err;
 }
@@ -238,7 +246,11 @@ static int sdcardfs_open(struct inode *inode, struct file *file)
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(sbi, saved_cred, SDCARDFS_I(inode));
+	saved_cred = override_fsids(sbi, SDCARDFS_I(inode)->data);
+	if (!saved_cred) {
+		err = -ENOMEM;
+		goto out_err;
+	}
 
 	file->private_data =
 		kzalloc(sizeof(struct sdcardfs_file_info), GFP_KERNEL);
@@ -268,7 +280,7 @@ static int sdcardfs_open(struct inode *inode, struct file *file)
 		sdcardfs_copy_and_fix_attrs(inode, sdcardfs_lower_inode(inode));
 
 out_revert_cred:
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_err:
 	dput(parent);
 	return err;
diff --git a/fs/sdcardfs/inode.c b/fs/sdcardfs/inode.c
index bffec57e81ab..9d3e65fc9518 100644
--- a/fs/sdcardfs/inode.c
+++ b/fs/sdcardfs/inode.c
@@ -22,7 +22,6 @@
 #include <linux/fs_struct.h>
 #include <linux/ratelimit.h>
 
-/* Do not directly use this function. Use OVERRIDE_CRED() instead. */
 const struct cred *override_fsids(struct sdcardfs_sb_info *sbi,
 		struct sdcardfs_inode_data *data)
 {
@@ -50,7 +49,6 @@ const struct cred *override_fsids(struct sdcardfs_sb_info *sbi,
 	return old_cred;
 }
 
-/* Do not directly use this function, use REVERT_CRED() instead. */
 void revert_fsids(const struct cred *old_cred)
 {
 	const struct cred *cur_cred;
@@ -78,7 +76,10 @@ static int sdcardfs_create(struct inode *dir, struct dentry *dentry,
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
+	saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb),
+					SDCARDFS_I(dir)->data);
+	if (!saved_cred)
+		return -ENOMEM;
 
 	sdcardfs_get_lower_path(dentry, &lower_path);
 	lower_dentry = lower_path.dentry;
@@ -120,53 +121,11 @@ out:
 out_unlock:
 	unlock_dir(lower_parent_dentry);
 	sdcardfs_put_lower_path(dentry, &lower_path);
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_eacces:
 	return err;
 }
 
-#if 0
-static int sdcardfs_link(struct dentry *old_dentry, struct inode *dir,
-		       struct dentry *new_dentry)
-{
-	struct dentry *lower_old_dentry;
-	struct dentry *lower_new_dentry;
-	struct dentry *lower_dir_dentry;
-	u64 file_size_save;
-	int err;
-	struct path lower_old_path, lower_new_path;
-
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb));
-
-	file_size_save = i_size_read(d_inode(old_dentry));
-	sdcardfs_get_lower_path(old_dentry, &lower_old_path);
-	sdcardfs_get_lower_path(new_dentry, &lower_new_path);
-	lower_old_dentry = lower_old_path.dentry;
-	lower_new_dentry = lower_new_path.dentry;
-	lower_dir_dentry = lock_parent(lower_new_dentry);
-
-	err = vfs_link(lower_old_dentry, d_inode(lower_dir_dentry),
-		       lower_new_dentry, NULL);
-	if (err || !d_inode(lower_new_dentry))
-		goto out;
-
-	err = sdcardfs_interpose(new_dentry, dir->i_sb, &lower_new_path);
-	if (err)
-		goto out;
-	fsstack_copy_attr_times(dir, d_inode(lower_new_dentry));
-	fsstack_copy_inode_size(dir, d_inode(lower_new_dentry));
-	set_nlink(d_inode(old_dentry),
-		  sdcardfs_lower_inode(d_inode(old_dentry))->i_nlink);
-	i_size_write(d_inode(new_dentry), file_size_save);
-out:
-	unlock_dir(lower_dir_dentry);
-	sdcardfs_put_lower_path(old_dentry, &lower_old_path);
-	sdcardfs_put_lower_path(new_dentry, &lower_new_path);
-	REVERT_CRED();
-	return err;
-}
-#endif
-
 static int sdcardfs_unlink(struct inode *dir, struct dentry *dentry)
 {
 	int err;
@@ -183,7 +142,10 @@ static int sdcardfs_unlink(struct inode *dir, struct dentry *dentry)
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
+	saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb),
+						SDCARDFS_I(dir)->data);
+	if (!saved_cred)
+		return -ENOMEM;
 
 	sdcardfs_get_lower_path(dentry, &lower_path);
 	lower_dentry = lower_path.dentry;
@@ -214,43 +176,11 @@ out:
 	unlock_dir(lower_dir_dentry);
 	dput(lower_dentry);
 	sdcardfs_put_lower_path(dentry, &lower_path);
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_eacces:
 	return err;
 }
 
-#if 0
-static int sdcardfs_symlink(struct inode *dir, struct dentry *dentry,
-			  const char *symname)
-{
-	int err;
-	struct dentry *lower_dentry;
-	struct dentry *lower_parent_dentry = NULL;
-	struct path lower_path;
-
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb));
-
-	sdcardfs_get_lower_path(dentry, &lower_path);
-	lower_dentry = lower_path.dentry;
-	lower_parent_dentry = lock_parent(lower_dentry);
-
-	err = vfs_symlink(d_inode(lower_parent_dentry), lower_dentry, symname);
-	if (err)
-		goto out;
-	err = sdcardfs_interpose(dentry, dir->i_sb, &lower_path);
-	if (err)
-		goto out;
-	fsstack_copy_attr_times(dir, sdcardfs_lower_inode(dir));
-	fsstack_copy_inode_size(dir, d_inode(lower_parent_dentry));
-
-out:
-	unlock_dir(lower_parent_dentry);
-	sdcardfs_put_lower_path(dentry, &lower_path);
-	REVERT_CRED();
-	return err;
-}
-#endif
-
 static int touch(char *abs_path, mode_t mode)
 {
 	struct file *filp = filp_open(abs_path, O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW, mode);
@@ -291,7 +221,10 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
+	saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb),
+						SDCARDFS_I(dir)->data);
+	if (!saved_cred)
+		return -ENOMEM;
 
 	/* check disk space */
 	if (!check_min_free_space(dentry, 0, 1)) {
@@ -370,13 +303,21 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
 	if (make_nomedia_in_obb ||
 		((pd->perm == PERM_ANDROID)
 				&& (qstr_case_eq(&dentry->d_name, &q_data)))) {
-		REVERT_CRED(saved_cred);
-		OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(d_inode(dentry)));
+		revert_fsids(saved_cred);
+		saved_cred = override_fsids(sbi,
+					SDCARDFS_I(d_inode(dentry))->data);
+		if (!saved_cred) {
+			pr_err("sdcardfs: failed to set up .nomedia in %s: %d\n",
+						lower_path.dentry->d_name.name,
+						-ENOMEM);
+			goto out;
+		}
 		set_fs_pwd(current->fs, &lower_path);
 		touch_err = touch(".nomedia", 0664);
 		if (touch_err) {
 			pr_err("sdcardfs: failed to create .nomedia in %s: %d\n",
-							lower_path.dentry->d_name.name, touch_err);
+						lower_path.dentry->d_name.name,
+						touch_err);
 			goto out;
 		}
 	}
@@ -389,7 +330,7 @@ out:
 out_unlock:
 	sdcardfs_put_lower_path(dentry, &lower_path);
 out_revert:
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_eacces:
 	return err;
 }
@@ -409,7 +350,10 @@ static int sdcardfs_rmdir(struct inode *dir, struct dentry *dentry)
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
+	saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb),
+						SDCARDFS_I(dir)->data);
+	if (!saved_cred)
+		return -ENOMEM;
 
 	/* sdcardfs_get_real_lower(): in case of remove an user's obb dentry
 	 * the dentry on the original path should be deleted.
@@ -434,44 +378,11 @@ static int sdcardfs_rmdir(struct inode *dir, struct dentry *dentry)
 out:
 	unlock_dir(lower_dir_dentry);
 	sdcardfs_put_real_lower(dentry, &lower_path);
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_eacces:
 	return err;
 }
 
-#if 0
-static int sdcardfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
-			dev_t dev)
-{
-	int err;
-	struct dentry *lower_dentry;
-	struct dentry *lower_parent_dentry = NULL;
-	struct path lower_path;
-
-	OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb));
-
-	sdcardfs_get_lower_path(dentry, &lower_path);
-	lower_dentry = lower_path.dentry;
-	lower_parent_dentry = lock_parent(lower_dentry);
-
-	err = vfs_mknod(d_inode(lower_parent_dentry), lower_dentry, mode, dev);
-	if (err)
-		goto out;
-
-	err = sdcardfs_interpose(dentry, dir->i_sb, &lower_path);
-	if (err)
-		goto out;
-	fsstack_copy_attr_times(dir, sdcardfs_lower_inode(dir));
-	fsstack_copy_inode_size(dir, d_inode(lower_parent_dentry));
-
-out:
-	unlock_dir(lower_parent_dentry);
-	sdcardfs_put_lower_path(dentry, &lower_path);
-	REVERT_CRED();
-	return err;
-}
-#endif
-
 /*
  * The locking rules in sdcardfs_rename are complex.  We could use a simpler
  * superblock-level name-space lock for renames and copy-ups.
@@ -500,7 +411,10 @@ static int sdcardfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(SDCARDFS_SB(old_dir->i_sb), saved_cred, SDCARDFS_I(new_dir));
+	saved_cred = override_fsids(SDCARDFS_SB(old_dir->i_sb),
+						SDCARDFS_I(new_dir)->data);
+	if (!saved_cred)
+		return -ENOMEM;
 
 	sdcardfs_get_real_lower(old_dentry, &lower_old_path);
 	sdcardfs_get_lower_path(new_dentry, &lower_new_path);
@@ -547,7 +461,7 @@ out:
 	dput(lower_new_dir_dentry);
 	sdcardfs_put_real_lower(old_dentry, &lower_old_path);
 	sdcardfs_put_lower_path(new_dentry, &lower_new_path);
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_eacces:
 	return err;
 }
@@ -664,33 +578,7 @@ static int sdcardfs_permission(struct vfsmount *mnt, struct inode *inode, int ma
 	if (IS_POSIXACL(inode))
 		pr_warn("%s: This may be undefined behavior...\n", __func__);
 	err = generic_permission(&tmp, mask);
-	/* XXX
-	 * Original sdcardfs code calls inode_permission(lower_inode,.. )
-	 * for checking inode permission. But doing such things here seems
-	 * duplicated work, because the functions called after this func,
-	 * such as vfs_create, vfs_unlink, vfs_rename, and etc,
-	 * does exactly same thing, i.e., they calls inode_permission().
-	 * So we just let they do the things.
-	 * If there are any security hole, just uncomment following if block.
-	 */
-#if 0
-	if (!err) {
-		/*
-		 * Permission check on lower_inode(=EXT4).
-		 * we check it with AID_MEDIA_RW permission
-		 */
-		struct inode *lower_inode;
-
-		OVERRIDE_CRED(SDCARDFS_SB(inode->sb));
-
-		lower_inode = sdcardfs_lower_inode(inode);
-		err = inode_permission(lower_inode, mask);
-
-		REVERT_CRED();
-	}
-#endif
 	return err;
-
 }
 
 static int sdcardfs_setattr_wrn(struct dentry *dentry, struct iattr *ia)
@@ -768,7 +656,10 @@ static int sdcardfs_setattr(struct vfsmount *mnt, struct dentry *dentry, struct
 		goto out_err;
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED(SDCARDFS_SB(dentry->d_sb), saved_cred, SDCARDFS_I(inode));
+	saved_cred = override_fsids(SDCARDFS_SB(dentry->d_sb),
+						SDCARDFS_I(inode)->data);
+	if (!saved_cred)
+		return -ENOMEM;
 
 	sdcardfs_get_lower_path(dentry, &lower_path);
 	lower_dentry = lower_path.dentry;
@@ -827,7 +718,7 @@ static int sdcardfs_setattr(struct vfsmount *mnt, struct dentry *dentry, struct
 
 out:
 	sdcardfs_put_lower_path(dentry, &lower_path);
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_err:
 	return err;
 }
@@ -909,13 +800,6 @@ const struct inode_operations sdcardfs_dir_iops = {
 	.setattr	= sdcardfs_setattr_wrn,
 	.setattr2	= sdcardfs_setattr,
 	.getattr	= sdcardfs_getattr,
-	/* XXX Following operations are implemented,
-	 *     but FUSE(sdcard) or FAT does not support them
-	 *     These methods are *NOT* perfectly tested.
-	.symlink	= sdcardfs_symlink,
-	.link		= sdcardfs_link,
-	.mknod		= sdcardfs_mknod,
-	 */
 };
 
 const struct inode_operations sdcardfs_main_iops = {
diff --git a/fs/sdcardfs/lookup.c b/fs/sdcardfs/lookup.c
index 843fcd216116..e1bff0da1925 100644
--- a/fs/sdcardfs/lookup.c
+++ b/fs/sdcardfs/lookup.c
@@ -428,7 +428,12 @@ struct dentry *sdcardfs_lookup(struct inode *dir, struct dentry *dentry,
 	}
 
 	/* save current_cred and override it */
-	OVERRIDE_CRED_PTR(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
+	saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb),
+						SDCARDFS_I(dir)->data);
+	if (!saved_cred) {
+		ret = ERR_PTR(-ENOMEM);
+		goto out_err;
+	}
 
 	sdcardfs_get_lower_path(parent, &lower_parent_path);
 
@@ -459,7 +464,7 @@ struct dentry *sdcardfs_lookup(struct inode *dir, struct dentry *dentry,
 
 out:
 	sdcardfs_put_lower_path(parent, &lower_parent_path);
-	REVERT_CRED(saved_cred);
+	revert_fsids(saved_cred);
 out_err:
 	dput(parent);
 	return ret;
diff --git a/fs/sdcardfs/sdcardfs.h b/fs/sdcardfs/sdcardfs.h
index eda8e7aa6911..b2e7db857dcf 100644
--- a/fs/sdcardfs/sdcardfs.h
+++ b/fs/sdcardfs/sdcardfs.h
@@ -88,31 +88,6 @@
 		(x)->i_mode = ((x)->i_mode & S_IFMT) | 0775;\
 	} while (0)
 
-/* OVERRIDE_CRED() and REVERT_CRED()
- *	OVERRIDE_CRED()
- *		backup original task->cred
- *		and modifies task->cred->fsuid/fsgid to specified value.
- *	REVERT_CRED()
- *		restore original task->cred->fsuid/fsgid.
- * These two macro should be used in pair, and OVERRIDE_CRED() should be
- * placed at the beginning of a function, right after variable declaration.
- */
-#define OVERRIDE_CRED(sdcardfs_sbi, saved_cred, info)		\
-	do {	\
-		saved_cred = override_fsids(sdcardfs_sbi, info->data);	\
-		if (!saved_cred)	\
-			return -ENOMEM;	\
-	} while (0)
-
-#define OVERRIDE_CRED_PTR(sdcardfs_sbi, saved_cred, info)	\
-	do {	\
-		saved_cred = override_fsids(sdcardfs_sbi, info->data);	\
-		if (!saved_cred)	\
-			return ERR_PTR(-ENOMEM);	\
-	} while (0)
-
-#define REVERT_CRED(saved_cred)	revert_fsids(saved_cred)
-
 /* Android 5.0 support */
 
 /* Permission mode for a specific node. Controls how file permissions