From 42a74f206b914db13ee1f5ae932dcd91a77c8579 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 15 Feb 2008 14:37:46 -0800 Subject: [PATCH] r/o bind mounts: elevate write count for ioctls() Some ioctl()s can cause writes to the filesystem. Take these, and make them use mnt_want/drop_write() instead. [AV: updated] Acked-by: Al Viro Signed-off-by: Christoph Hellwig Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/ext2/ioctl.c | 57 +++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 37 insertions(+), 20 deletions(-) (limited to 'fs/ext2') diff --git a/fs/ext2/ioctl.c b/fs/ext2/ioctl.c index b8ea11fee5c6..de876fa793e1 100644 --- a/fs/ext2/ioctl.c +++ b/fs/ext2/ioctl.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -23,6 +24,7 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) struct ext2_inode_info *ei = EXT2_I(inode); unsigned int flags; unsigned short rsv_window_size; + int ret; ext2_debug ("cmd = %u, arg = %lu\n", cmd, arg); @@ -34,14 +36,19 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) case EXT2_IOC_SETFLAGS: { unsigned int oldflags; - if (IS_RDONLY(inode)) - return -EROFS; + ret = mnt_want_write(filp->f_path.mnt); + if (ret) + return ret; - if (!is_owner_or_cap(inode)) - return -EACCES; + if (!is_owner_or_cap(inode)) { + ret = -EACCES; + goto setflags_out; + } - if (get_user(flags, (int __user *) arg)) - return -EFAULT; + if (get_user(flags, (int __user *) arg)) { + ret = -EFAULT; + goto setflags_out; + } if (!S_ISDIR(inode->i_mode)) flags &= ~EXT2_DIRSYNC_FL; @@ -50,7 +57,8 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) /* Is it quota file? Do not allow user to mess with it */ if (IS_NOQUOTA(inode)) { mutex_unlock(&inode->i_mutex); - return -EPERM; + ret = -EPERM; + goto setflags_out; } oldflags = ei->i_flags; @@ -63,7 +71,8 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) if ((flags ^ oldflags) & (EXT2_APPEND_FL | EXT2_IMMUTABLE_FL)) { if (!capable(CAP_LINUX_IMMUTABLE)) { mutex_unlock(&inode->i_mutex); - return -EPERM; + ret = -EPERM; + goto setflags_out; } } @@ -75,20 +84,26 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) ext2_set_inode_flags(inode); inode->i_ctime = CURRENT_TIME_SEC; mark_inode_dirty(inode); - return 0; +setflags_out: + mnt_drop_write(filp->f_path.mnt); + return ret; } case EXT2_IOC_GETVERSION: return put_user(inode->i_generation, (int __user *) arg); case EXT2_IOC_SETVERSION: if (!is_owner_or_cap(inode)) return -EPERM; - if (IS_RDONLY(inode)) - return -EROFS; - if (get_user(inode->i_generation, (int __user *) arg)) - return -EFAULT; - inode->i_ctime = CURRENT_TIME_SEC; - mark_inode_dirty(inode); - return 0; + ret = mnt_want_write(filp->f_path.mnt); + if (ret) + return ret; + if (get_user(inode->i_generation, (int __user *) arg)) { + ret = -EFAULT; + } else { + inode->i_ctime = CURRENT_TIME_SEC; + mark_inode_dirty(inode); + } + mnt_drop_write(filp->f_path.mnt); + return ret; case EXT2_IOC_GETRSVSZ: if (test_opt(inode->i_sb, RESERVATION) && S_ISREG(inode->i_mode) @@ -102,15 +117,16 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode)) return -ENOTTY; - if (IS_RDONLY(inode)) - return -EROFS; - - if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER)) + if (!is_owner_or_cap(inode)) return -EACCES; if (get_user(rsv_window_size, (int __user *)arg)) return -EFAULT; + ret = mnt_want_write(filp->f_path.mnt); + if (ret) + return ret; + if (rsv_window_size > EXT2_MAX_RESERVE_BLOCKS) rsv_window_size = EXT2_MAX_RESERVE_BLOCKS; @@ -131,6 +147,7 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) rsv->rsv_goal_size = rsv_window_size; } mutex_unlock(&ei->truncate_mutex); + mnt_drop_write(filp->f_path.mnt); return 0; } default: -- cgit v1.2.3