#include <linux/capability.h>
#include <linux/file.h>
#include <linux/fcntl.h>
+#include <linux/device_cgroup.h>
#include <asm/namei.h>
#include <asm/uaccess.h>
if (retval)
return retval;
+ retval = devcgroup_inode_permission(inode, mask);
+ if (retval)
+ return retval;
+
return security_inode_permission(inode, mask, nd);
}
return -EACCES;
flag &= ~O_TRUNC;
- } else if (IS_RDONLY(inode) && (acc_mode & MAY_WRITE))
- return -EROFS;
+ }
error = vfs_permission(nd, acc_mode);
if (error)
return flag;
}
+static int open_will_write_to_fs(int flag, struct inode *inode)
+{
+ /*
+ * We'll never write to the fs underlying
+ * a device file.
+ */
+ if (special_file(inode->i_mode))
+ return 0;
+ return (flag & O_TRUNC);
+}
+
/*
- * Note that the low bits of "flag" aren't the same as in the open
- * system call. See open_to_namei_flags().
+ * Note that the low bits of the passed in "open_flag"
+ * are not the same as in the local variable "flag". See
+ * open_to_namei_flags() for more details.
*/
struct file *do_filp_open(int dfd, const char *pathname,
int open_flag, int mode)
{
+ struct file *filp;
struct nameidata nd;
int acc_mode, error;
struct path path;
struct dentry *dir;
int count = 0;
+ int will_write;
int flag = open_to_namei_flags(open_flag);
acc_mode = ACC_MODE(flag);
}
if (IS_ERR(nd.intent.open.file)) {
- mutex_unlock(&dir->d_inode->i_mutex);
error = PTR_ERR(nd.intent.open.file);
- goto exit_dput;
+ goto exit_mutex_unlock;
}
/* Negative dentry, just create the file */
if (!path.dentry->d_inode) {
- error = __open_namei_create(&nd, &path, flag, mode);
+ /*
+ * This write is needed to ensure that a
+ * ro->rw transition does not occur between
+ * the time when the file is created and when
+ * a permanent write count is taken through
+ * the 'struct file' in nameidata_to_filp().
+ */
+ error = mnt_want_write(nd.path.mnt);
if (error)
+ goto exit_mutex_unlock;
+ error = __open_namei_create(&nd, &path, flag, mode);
+ if (error) {
+ mnt_drop_write(nd.path.mnt);
goto exit;
- return nameidata_to_filp(&nd, open_flag);
+ }
+ filp = nameidata_to_filp(&nd, open_flag);
+ mnt_drop_write(nd.path.mnt);
+ return filp;
}
/*
if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
goto exit;
ok:
+ /*
+ * Consider:
+ * 1. may_open() truncates a file
+ * 2. a rw->ro mount transition occurs
+ * 3. nameidata_to_filp() fails due to
+ * the ro mount.
+ * That would be inconsistent, and should
+ * be avoided. Taking this mnt write here
+ * ensures that (2) can not occur.
+ */
+ will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode);
+ if (will_write) {
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit;
+ }
error = may_open(&nd, acc_mode, flag);
- if (error)
+ if (error) {
+ if (will_write)
+ mnt_drop_write(nd.path.mnt);
goto exit;
- return nameidata_to_filp(&nd, open_flag);
+ }
+ filp = nameidata_to_filp(&nd, open_flag);
+ /*
+ * It is now safe to drop the mnt write
+ * because the filp has had a write taken
+ * on its behalf.
+ */
+ if (will_write)
+ mnt_drop_write(nd.path.mnt);
+ return filp;
+exit_mutex_unlock:
+ mutex_unlock(&dir->d_inode->i_mutex);
exit_dput:
path_put_conditional(&path, &nd);
exit:
if (!dir->i_op || !dir->i_op->mknod)
return -EPERM;
+ error = devcgroup_inode_mknod(mode, dev);
+ if (error)
+ return error;
+
error = security_inode_mknod(dir, dentry, mode, dev);
if (error)
return error;
return error;
}
+static int may_mknod(mode_t mode)
+{
+ switch (mode & S_IFMT) {
+ case S_IFREG:
+ case S_IFCHR:
+ case S_IFBLK:
+ case S_IFIFO:
+ case S_IFSOCK:
+ case 0: /* zero mode translates to S_IFREG */
+ return 0;
+ case S_IFDIR:
+ return -EPERM;
+ default:
+ return -EINVAL;
+ }
+}
+
asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
unsigned dev)
{
if (error)
goto out;
dentry = lookup_create(&nd, 0);
- error = PTR_ERR(dentry);
-
+ if (IS_ERR(dentry)) {
+ error = PTR_ERR(dentry);
+ goto out_unlock;
+ }
if (!IS_POSIXACL(nd.path.dentry->d_inode))
mode &= ~current->fs->umask;
- if (!IS_ERR(dentry)) {
- switch (mode & S_IFMT) {
+ error = may_mknod(mode);
+ if (error)
+ goto out_dput;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_dput;
+ switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
break;
case S_IFIFO: case S_IFSOCK:
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
break;
- case S_IFDIR:
- error = -EPERM;
- break;
- default:
- error = -EINVAL;
- }
- dput(dentry);
}
+ mnt_drop_write(nd.path.mnt);
+out_dput:
+ dput(dentry);
+out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path);
out:
if (!IS_POSIXACL(nd.path.dentry->d_inode))
mode &= ~current->fs->umask;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_dput;
error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+ mnt_drop_write(nd.path.mnt);
+out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
if (IS_ERR(dentry))
goto out_unlock;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_dput;
error = vfs_symlink(nd.path.dentry->d_inode, dentry, from, S_IALLUGO);
+ mnt_drop_write(nd.path.mnt);
+out_dput:
dput(dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto out_unlock;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_dput;
error = vfs_link(old_nd.path.dentry, nd.path.dentry->d_inode, new_dentry);
+ mnt_drop_write(nd.path.mnt);
+out_dput:
dput(new_dentry);
out_unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
if (new_dentry == trap)
goto exit5;
+ error = mnt_want_write(oldnd.path.mnt);
+ if (error)
+ goto exit5;
error = vfs_rename(old_dir->d_inode, old_dentry,
new_dir->d_inode, new_dentry);
+ mnt_drop_write(oldnd.path.mnt);
exit5:
dput(new_dentry);
exit4:
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff