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![Mickaël Salaün](/assets/img/avatar_default.png)
hostfs creates a new inode for each opened or created file, which created useless inode allocations and forbade identifying a host file with a kernel inode. Fix this uncommon filesystem behavior by tying kernel inodes to host file's inode and device IDs. Even if the host filesystem inodes may be recycled, this cannot happen while a file referencing it is opened, which is the case with hostfs. It should be noted that hostfs inode IDs may not be unique for the same hostfs superblock because multiple host's (backed) superblocks may be used. Delete inodes when dropping them to force backed host's file descriptors closing. This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes Landlock fully supported by UML. This is very useful for testing changes. These changes also factor out and simplify some helpers thanks to the new hostfs_inode_update() and the hostfs_iget() revamp: read_name(), hostfs_create(), hostfs_lookup(), hostfs_mknod(), and hostfs_fill_sb_common(). A following commit with new Landlock tests check this new hostfs inode consistency. Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Acked-by: Richard Weinberger <richard@nod.at> Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
411 lines
7.4 KiB
C
411 lines
7.4 KiB
C
/*
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* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <stdio.h>
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#include <stddef.h>
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#include <unistd.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/vfs.h>
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#include <sys/syscall.h>
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#include "hostfs.h"
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#include <utime.h>
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static void stat64_to_hostfs(const struct stat64 *buf, struct hostfs_stat *p)
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{
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p->ino = buf->st_ino;
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p->mode = buf->st_mode;
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p->nlink = buf->st_nlink;
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p->uid = buf->st_uid;
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p->gid = buf->st_gid;
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p->size = buf->st_size;
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p->atime.tv_sec = buf->st_atime;
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p->atime.tv_nsec = 0;
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p->ctime.tv_sec = buf->st_ctime;
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p->ctime.tv_nsec = 0;
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p->mtime.tv_sec = buf->st_mtime;
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p->mtime.tv_nsec = 0;
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p->blksize = buf->st_blksize;
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p->blocks = buf->st_blocks;
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p->maj = os_major(buf->st_rdev);
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p->min = os_minor(buf->st_rdev);
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p->dev = buf->st_dev;
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}
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int stat_file(const char *path, struct hostfs_stat *p, int fd)
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{
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struct stat64 buf;
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if (fd >= 0) {
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if (fstat64(fd, &buf) < 0)
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return -errno;
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} else if (lstat64(path, &buf) < 0) {
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return -errno;
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}
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stat64_to_hostfs(&buf, p);
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return 0;
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}
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int access_file(char *path, int r, int w, int x)
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{
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int mode = 0;
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if (r)
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mode = R_OK;
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if (w)
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mode |= W_OK;
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if (x)
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mode |= X_OK;
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if (access(path, mode) != 0)
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return -errno;
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else return 0;
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}
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int open_file(char *path, int r, int w, int append)
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{
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int mode = 0, fd;
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if (r && !w)
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mode = O_RDONLY;
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else if (!r && w)
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mode = O_WRONLY;
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else if (r && w)
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mode = O_RDWR;
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else panic("Impossible mode in open_file");
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if (append)
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mode |= O_APPEND;
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fd = open64(path, mode);
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if (fd < 0)
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return -errno;
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else return fd;
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}
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void *open_dir(char *path, int *err_out)
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{
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DIR *dir;
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dir = opendir(path);
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*err_out = errno;
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return dir;
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}
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void seek_dir(void *stream, unsigned long long pos)
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{
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DIR *dir = stream;
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seekdir(dir, pos);
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}
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char *read_dir(void *stream, unsigned long long *pos_out,
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unsigned long long *ino_out, int *len_out,
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unsigned int *type_out)
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{
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DIR *dir = stream;
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struct dirent *ent;
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ent = readdir(dir);
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if (ent == NULL)
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return NULL;
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*len_out = strlen(ent->d_name);
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*ino_out = ent->d_ino;
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*type_out = ent->d_type;
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*pos_out = ent->d_off;
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return ent->d_name;
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}
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int read_file(int fd, unsigned long long *offset, char *buf, int len)
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{
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int n;
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n = pread64(fd, buf, len, *offset);
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if (n < 0)
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return -errno;
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*offset += n;
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return n;
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}
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int write_file(int fd, unsigned long long *offset, const char *buf, int len)
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{
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int n;
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n = pwrite64(fd, buf, len, *offset);
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if (n < 0)
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return -errno;
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*offset += n;
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return n;
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}
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int lseek_file(int fd, long long offset, int whence)
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{
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int ret;
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ret = lseek64(fd, offset, whence);
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if (ret < 0)
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return -errno;
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return 0;
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}
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int fsync_file(int fd, int datasync)
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{
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int ret;
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if (datasync)
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ret = fdatasync(fd);
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else
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ret = fsync(fd);
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if (ret < 0)
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return -errno;
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return 0;
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}
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int replace_file(int oldfd, int fd)
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{
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return dup2(oldfd, fd);
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}
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void close_file(void *stream)
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{
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close(*((int *) stream));
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}
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void close_dir(void *stream)
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{
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closedir(stream);
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}
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int file_create(char *name, int mode)
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{
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int fd;
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fd = open64(name, O_CREAT | O_RDWR, mode);
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if (fd < 0)
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return -errno;
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return fd;
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}
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int set_attr(const char *file, struct hostfs_iattr *attrs, int fd)
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{
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struct hostfs_stat st;
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struct timeval times[2];
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int err, ma;
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if (attrs->ia_valid & HOSTFS_ATTR_MODE) {
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if (fd >= 0) {
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if (fchmod(fd, attrs->ia_mode) != 0)
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return -errno;
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} else if (chmod(file, attrs->ia_mode) != 0) {
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return -errno;
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}
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}
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if (attrs->ia_valid & HOSTFS_ATTR_UID) {
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if (fd >= 0) {
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if (fchown(fd, attrs->ia_uid, -1))
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return -errno;
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} else if (chown(file, attrs->ia_uid, -1)) {
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return -errno;
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}
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}
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if (attrs->ia_valid & HOSTFS_ATTR_GID) {
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if (fd >= 0) {
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if (fchown(fd, -1, attrs->ia_gid))
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return -errno;
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} else if (chown(file, -1, attrs->ia_gid)) {
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return -errno;
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}
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}
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if (attrs->ia_valid & HOSTFS_ATTR_SIZE) {
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if (fd >= 0) {
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if (ftruncate(fd, attrs->ia_size))
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return -errno;
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} else if (truncate(file, attrs->ia_size)) {
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return -errno;
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}
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}
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/*
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* Update accessed and/or modified time, in two parts: first set
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* times according to the changes to perform, and then call futimes()
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* or utimes() to apply them.
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*/
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ma = (HOSTFS_ATTR_ATIME_SET | HOSTFS_ATTR_MTIME_SET);
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if (attrs->ia_valid & ma) {
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err = stat_file(file, &st, fd);
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if (err != 0)
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return err;
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times[0].tv_sec = st.atime.tv_sec;
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times[0].tv_usec = st.atime.tv_nsec / 1000;
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times[1].tv_sec = st.mtime.tv_sec;
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times[1].tv_usec = st.mtime.tv_nsec / 1000;
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if (attrs->ia_valid & HOSTFS_ATTR_ATIME_SET) {
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times[0].tv_sec = attrs->ia_atime.tv_sec;
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times[0].tv_usec = attrs->ia_atime.tv_nsec / 1000;
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}
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if (attrs->ia_valid & HOSTFS_ATTR_MTIME_SET) {
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times[1].tv_sec = attrs->ia_mtime.tv_sec;
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times[1].tv_usec = attrs->ia_mtime.tv_nsec / 1000;
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}
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if (fd >= 0) {
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if (futimes(fd, times) != 0)
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return -errno;
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} else if (utimes(file, times) != 0) {
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return -errno;
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}
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}
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/* Note: ctime is not handled */
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if (attrs->ia_valid & (HOSTFS_ATTR_ATIME | HOSTFS_ATTR_MTIME)) {
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err = stat_file(file, &st, fd);
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attrs->ia_atime = st.atime;
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attrs->ia_mtime = st.mtime;
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if (err != 0)
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return err;
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}
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return 0;
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}
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int make_symlink(const char *from, const char *to)
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{
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int err;
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err = symlink(to, from);
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if (err)
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return -errno;
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return 0;
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}
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int unlink_file(const char *file)
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{
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int err;
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err = unlink(file);
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if (err)
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return -errno;
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return 0;
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}
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int do_mkdir(const char *file, int mode)
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{
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int err;
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err = mkdir(file, mode);
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if (err)
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return -errno;
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return 0;
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}
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int hostfs_do_rmdir(const char *file)
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{
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int err;
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err = rmdir(file);
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if (err)
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return -errno;
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return 0;
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}
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int do_mknod(const char *file, int mode, unsigned int major, unsigned int minor)
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{
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int err;
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err = mknod(file, mode, os_makedev(major, minor));
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if (err)
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return -errno;
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return 0;
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}
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int link_file(const char *to, const char *from)
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{
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int err;
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err = link(to, from);
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if (err)
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return -errno;
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return 0;
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}
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int hostfs_do_readlink(char *file, char *buf, int size)
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{
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int n;
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n = readlink(file, buf, size);
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if (n < 0)
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return -errno;
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if (n < size)
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buf[n] = '\0';
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return n;
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}
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int rename_file(char *from, char *to)
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{
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int err;
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err = rename(from, to);
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if (err < 0)
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return -errno;
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return 0;
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}
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int rename2_file(char *from, char *to, unsigned int flags)
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{
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int err;
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#ifndef SYS_renameat2
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# ifdef __x86_64__
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# define SYS_renameat2 316
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# endif
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# ifdef __i386__
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# define SYS_renameat2 353
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# endif
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#endif
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#ifdef SYS_renameat2
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err = syscall(SYS_renameat2, AT_FDCWD, from, AT_FDCWD, to, flags);
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if (err < 0) {
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if (errno != ENOSYS)
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return -errno;
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else
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return -EINVAL;
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}
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return 0;
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#else
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return -EINVAL;
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#endif
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}
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int do_statfs(char *root, long *bsize_out, long long *blocks_out,
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long long *bfree_out, long long *bavail_out,
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long long *files_out, long long *ffree_out,
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void *fsid_out, int fsid_size, long *namelen_out)
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{
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struct statfs64 buf;
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int err;
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err = statfs64(root, &buf);
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if (err < 0)
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return -errno;
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*bsize_out = buf.f_bsize;
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*blocks_out = buf.f_blocks;
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*bfree_out = buf.f_bfree;
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*bavail_out = buf.f_bavail;
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*files_out = buf.f_files;
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*ffree_out = buf.f_ffree;
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memcpy(fsid_out, &buf.f_fsid,
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sizeof(buf.f_fsid) > fsid_size ? fsid_size :
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sizeof(buf.f_fsid));
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*namelen_out = buf.f_namelen;
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return 0;
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}
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