lib9p/backend/fs.c
John Carr 85c49d672a Use lstat instead of stat in fs_create.
Doesn't matter if the symlink target exists or not, so should use
lstat().
2016-03-21 16:27:44 +00:00

784 lines
16 KiB
C

/*
* Copyright 2016 Jakub Klama <jceel@FreeBSD.org>
* All rights reserved
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted providing that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
/*
* Based on libixp code: ©2007-2010 Kris Maglione <maglione.k at Gmail>
*/
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdbool.h>
#include <fcntl.h>
#include <errno.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <dirent.h>
#include <pwd.h>
#include <grp.h>
#include <libgen.h>
#include <sys/socket.h>
#include "../lib9p.h"
#include "../lib9p_impl.h"
#include "../log.h"
static struct openfile *open_fid(const char *);
static void dostat(struct l9p_stat *, char *, struct stat *, bool dotu);
static void generate_qid(struct stat *, struct l9p_qid *);
static void fs_attach(void *, struct l9p_request *);
static void fs_clunk(void *, struct l9p_request *);
static void fs_create(void *, struct l9p_request *);
static void fs_flush(void *, struct l9p_request *);
static void fs_open(void *, struct l9p_request *);
static void fs_read(void *, struct l9p_request *);
static void fs_remove(void *, struct l9p_request *);
static void fs_stat(void *, struct l9p_request *);
static void fs_walk(void *, struct l9p_request *);
static void fs_write(void *, struct l9p_request *);
static void fs_wstat(void *, struct l9p_request *);
static void fs_freefid(void *softc, struct l9p_openfile *f);
struct fs_softc
{
const char *fs_rootpath;
bool fs_readonly;
TAILQ_HEAD(, fs_tree) fs_auxtrees;
};
struct fs_tree
{
const char *fst_name;
const char *fst_path;
bool fst_readonly;
TAILQ_ENTRY(fs_tree) fst_link;
};
struct openfile
{
DIR *dir;
int fd;
char *name;
uid_t uid;
gid_t gid;
};
static struct openfile *
open_fid(const char *path)
{
struct openfile *ret;
ret = l9p_calloc(1, sizeof(*ret));
ret->fd = -1;
ret->name = strdup(path);
return (ret);
}
static void
dostat(struct l9p_stat *s, char *name, struct stat *buf, bool dotu)
{
struct passwd *user;
struct group *group;
memset(s, 0, sizeof(struct l9p_stat));
generate_qid(buf, &s->qid);
s->type = 0;
s->dev = 0;
s->mode = buf->st_mode & 0777;
if (S_ISDIR(buf->st_mode))
s->mode |= L9P_DMDIR;
if (S_ISLNK(buf->st_mode) && dotu)
s->mode |= L9P_DMSYMLINK;
if (S_ISCHR(buf->st_mode) || S_ISBLK(buf->st_mode))
s->mode |= L9P_DMDEVICE;
if (S_ISSOCK(buf->st_mode))
s->mode |= L9P_DMSOCKET;
if (S_ISFIFO(buf->st_mode))
s->mode |= L9P_DMNAMEDPIPE;
s->atime = (uint32_t)buf->st_atime;
s->mtime = (uint32_t)buf->st_mtime;
s->length = (uint64_t)buf->st_size;
/* XXX: not thread safe */
s->name = strdup(basename(name));
if (!dotu) {
user = getpwuid(buf->st_uid);
group = getgrgid(buf->st_gid);
s->uid = user != NULL ? strdup(user->pw_name) : NULL;
s->gid = group != NULL ? strdup(group->gr_name) : NULL;
s->muid = user != NULL ? strdup(user->pw_name) : NULL;
} else {
/*
* When using 9P2000.u, we don't need to bother about
* providing user and group names in textual form.
*/
s->n_uid = buf->st_uid;
s->n_gid = buf->st_gid;
s->n_muid = buf->st_uid;
if (S_ISLNK(buf->st_mode)) {
char target[MAXPATHLEN];
ssize_t ret = readlink(name, target, MAXPATHLEN);
if (ret < 0) {
s->extension = NULL;
return;
}
s->extension = strndup(target, (size_t)ret);
}
if (S_ISBLK(buf->st_mode)) {
asprintf(&s->extension, "b %d %d", major(buf->st_rdev),
minor(buf->st_rdev));
}
if (S_ISCHR(buf->st_mode)) {
asprintf(&s->extension, "c %d %d", major(buf->st_rdev),
minor(buf->st_rdev));
}
}
}
static void
generate_qid(struct stat *buf, struct l9p_qid *qid)
{
qid->path = buf->st_ino;
qid->version = 0;
if (S_ISREG(buf->st_mode))
qid->type |= L9P_QTFILE;
if (S_ISDIR(buf->st_mode))
qid->type |= L9P_QTDIR;
if (S_ISLNK(buf->st_mode))
qid->type |= L9P_QTSYMLINK;
}
static bool
check_access(struct stat *st, uid_t uid, int amode)
{
struct passwd *pwd;
int groups[NGROUPS_MAX];
int ngroups = NGROUPS_MAX;
int i;
if (uid == 0)
return (true);
if (st->st_uid == uid) {
if (amode == L9P_OREAD && st->st_mode & S_IRUSR)
return (true);
if (amode == L9P_OWRITE && st->st_mode & S_IWUSR)
return (true);
if (amode == L9P_OEXEC && st->st_mode & S_IXUSR)
return (true);
}
/* Check for "other" access */
if (amode == L9P_OREAD && st->st_mode & S_IROTH)
return (true);
if (amode == L9P_OWRITE && st->st_mode & S_IWOTH)
return (true);
if (amode == L9P_OEXEC && st->st_mode & S_IXOTH)
return (true);
/* Check for group access */
pwd = getpwuid(uid);
getgrouplist(pwd->pw_name, (int)pwd->pw_gid, groups, &ngroups);
for (i = 0; i < ngroups; i++) {
if (st->st_gid == (gid_t)groups[i]) {
if (amode == L9P_OREAD && st->st_mode & S_IRGRP)
return (true);
if (amode == L9P_OWRITE && st->st_mode & S_IWGRP)
return (true);
if (amode == L9P_OEXEC && st->st_mode & S_IXGRP)
return (true);
}
}
return (false);
}
static void
fs_attach(void *softc, struct l9p_request *req)
{
struct fs_softc *sc = (struct fs_softc *)softc;
struct openfile *file;
struct passwd *pwd;
uid_t uid;
assert(req->lr_fid != NULL);
file = open_fid(sc->fs_rootpath);
req->lr_fid->lo_qid.type = L9P_QTDIR;
req->lr_fid->lo_qid.path = (uintptr_t)req->lr_fid;
req->lr_fid->lo_aux = file;
req->lr_resp.rattach.qid = req->lr_fid->lo_qid;
uid = req->lr_req.tattach.n_uname;
if (req->lr_conn->lc_version >= L9P_2000U && uid != (uid_t)-1)
pwd = getpwuid(uid);
else
pwd = getpwnam(req->lr_req.tattach.uname);
if (pwd == NULL) {
l9p_respond(req, EPERM);
return;
}
file->uid = pwd->pw_uid;
file->gid = pwd->pw_gid;
l9p_respond(req, 0);
}
static void
fs_clunk(void *softc __unused, struct l9p_request *req)
{
struct openfile *file;
file = req->lr_fid->lo_aux;
assert(file != NULL);
if (file->dir) {
closedir(file->dir);
file->dir = NULL;
} else if (file->fd != -1) {
close(file->fd);
file->fd = -1;
}
l9p_respond(req, 0);
}
static void
fs_create(void *softc, struct l9p_request *req)
{
struct fs_softc *sc = softc;
struct openfile *file = req->lr_fid->lo_aux;
struct stat st;
char *newname;
mode_t mode = req->lr_req.tcreate.perm & 0777;
int fd;
assert(file != NULL);
if (sc->fs_readonly) {
l9p_respond(req, EROFS);
return;
}
asprintf(&newname, "%s/%s", file->name, req->lr_req.tcreate.name);
if (lstat(file->name, &st) != 0) {
l9p_respond(req, errno);
return;
}
if (!check_access(&st, file->uid, L9P_OWRITE)) {
l9p_respond(req, EPERM);
return;
}
if (req->lr_req.tcreate.perm & L9P_DMDIR)
mkdir(newname, mode);
else if (req->lr_req.tcreate.perm & L9P_DMSYMLINK) {
if (symlink(req->lr_req.tcreate.extension, newname) != 0) {
l9p_respond(req, errno);
return;
}
} else if (req->lr_req.tcreate.perm & L9P_DMNAMEDPIPE) {
if (mkfifo(newname, mode) != 0) {
l9p_respond(req, errno);
return;
}
} else if (req->lr_req.tcreate.perm & L9P_DMSOCKET) {
struct sockaddr_un sun;
int s = socket(AF_UNIX, SOCK_STREAM, 0);
if (s < 0) {
l9p_respond(req, errno);
return;
}
sun.sun_family = AF_UNIX;
sun.sun_len = sizeof(struct sockaddr_un);
strncpy(sun.sun_path, req->lr_req.tcreate.name,
sizeof(sun.sun_path));
fd = open(file->name, O_RDONLY);
if (fd < 0) {
l9p_respond(req, errno);
return;
}
if (bindat(fd, s, (struct sockaddr *)&sun,
sun.sun_len) < 0) {
l9p_respond(req, errno);
return;
}
if (close(fd) != 0) {
l9p_respond(req, errno);
return;
}
if (close(s) != 0) {
l9p_respond(req, errno);
return;
}
} else if (req->lr_req.tcreate.perm & L9P_DMDEVICE) {
char type;
int major, minor;
if (sscanf(req->lr_req.tcreate.extension, "%c %u %u",
&type, &major, &minor) < 2) {
l9p_respond(req, EINVAL);
return;
}
switch (type) {
case 'b':
if (mknod(newname, S_IFBLK | mode,
makedev(major, minor)) != 0)
{
l9p_respond(req, errno);
return;
}
break;
case 'c':
if (mknod(newname, S_IFCHR | mode,
makedev(major, minor)) != 0)
{
l9p_respond(req, errno);
return;
}
break;
default:
l9p_respond(req, EINVAL);
return;
}
} else {
file->fd = open(newname,
O_CREAT | O_TRUNC | req->lr_req.tcreate.mode,
mode);
}
if (lchown(newname, file->uid, file->gid) != 0) {
l9p_respond(req, errno);
return;
}
if (lstat(newname, &st) != 0) {
l9p_respond(req, errno);
return;
}
generate_qid(&st, &req->lr_resp.rcreate.qid);
l9p_respond(req, 0);
}
static void
fs_flush(void *softc __unused, struct l9p_request *req)
{
/* XXX: not used because this transport is synchronous */
l9p_respond(req, 0);
}
static void
fs_open(void *softc __unused, struct l9p_request *req)
{
struct l9p_connection *conn = req->lr_conn;
struct openfile *file = req->lr_fid->lo_aux;
struct stat st;
assert(file != NULL);
if (stat(file->name, &st) != 0) {
l9p_respond(req, errno);
return;
}
if (!check_access(&st, file->uid, req->lr_req.topen.mode)) {
l9p_respond(req, EPERM);
return;
}
if (S_ISDIR(st.st_mode))
file->dir = opendir(file->name);
else {
file->fd = open(file->name, req->lr_req.topen.mode);
if (file->fd < 0) {
l9p_respond(req, EPERM);
return;
}
}
generate_qid(&st, &req->lr_resp.ropen.qid);
req->lr_resp.ropen.iounit = conn->lc_max_io_size;
l9p_respond(req, 0);
}
static void
fs_read(void *softc __unused, struct l9p_request *req)
{
struct openfile *file;
struct l9p_stat l9stat;
bool dotu = req->lr_conn->lc_version >= L9P_2000U;
ssize_t ret;
file = req->lr_fid->lo_aux;
assert(file != NULL);
if (file->dir != NULL) {
struct dirent *d;
struct stat st;
for (;;) {
d = readdir(file->dir);
if (d) {
lstat(d->d_name, &st);
dostat(&l9stat, d->d_name, &st, dotu);
if (l9p_pack_stat(req, &l9stat) != 0) {
seekdir(file->dir, -1);
break;
}
continue;
}
break;
}
} else {
size_t niov = l9p_truncate_iov(req->lr_data_iov,
req->lr_data_niov, req->lr_req.io.count);
#if defined(__FreeBSD__)
ret = preadv(file->fd, req->lr_data_iov, niov,
req->lr_req.io.offset);
#else
/* XXX: not thread safe, should really use aio_listio. */
if (lseek(file->fd, (off_t)req->lr_req.io.offset, SEEK_SET) < 0)
{
l9p_respond(req, errno);
return;
}
ret = (uint32_t)readv(file->fd, req->lr_data_iov, (int)niov);
#endif
if (ret < 0) {
l9p_respond(req, errno);
return;
}
req->lr_resp.io.count = (uint32_t)ret;
}
l9p_respond(req, 0);
}
static void
fs_remove(void *softc, struct l9p_request *req)
{
struct fs_softc *sc = softc;
struct openfile *file;
struct stat st;
file = req->lr_fid->lo_aux;
assert(file);
if (sc->fs_readonly) {
l9p_respond(req, EROFS);
return;
}
if (lstat(file->name, &st) != 0) {
l9p_respond(req, errno);
return;
}
if (!check_access(&st, file->uid, L9P_OWRITE)) {
l9p_respond(req, EPERM);
return;
}
if (S_ISDIR(st.st_mode)) {
if (rmdir(file->name) != 0) {
l9p_respond(req, errno);
return;
}
} else {
if (unlink(file->name) != 0) {
l9p_respond(req, errno);
return;
}
}
l9p_respond(req, 0);
}
static void
fs_stat(void *softc __unused, struct l9p_request *req)
{
struct openfile *file;
struct stat st;
bool dotu = req->lr_conn->lc_version >= L9P_2000U;
file = req->lr_fid->lo_aux;
assert(file);
lstat(file->name, &st);
dostat(&req->lr_resp.rstat.stat, file->name, &st, dotu);
l9p_respond(req, 0);
}
static void
fs_walk(void *softc __unused, struct l9p_request *req)
{
uint16_t i;
struct stat buf;
struct openfile *file = req->lr_fid->lo_aux;
struct openfile *newfile;
char name[MAXPATHLEN];
strcpy(name, file->name);
for (i = 0; i < req->lr_req.twalk.nwname; i++) {
strcat(name, "/");
strcat(name, req->lr_req.twalk.wname[i]);
if (lstat(name, &buf) < 0){
l9p_respond(req, ENOENT);
return;
}
generate_qid(&buf, &req->lr_resp.rwalk.wqid[i]);
}
newfile = open_fid(name);
newfile->uid = file->uid;
newfile->gid = file->gid;
req->lr_newfid->lo_aux = newfile;
req->lr_resp.rwalk.nwqid = i;
l9p_respond(req, 0);
}
static void
fs_write(void *softc, struct l9p_request *req)
{
struct fs_softc *sc = softc;
struct openfile *file;
ssize_t ret;
file = req->lr_fid->lo_aux;
assert(file != NULL);
if (sc->fs_readonly) {
l9p_respond(req, EROFS);
return;
}
size_t niov = l9p_truncate_iov(req->lr_data_iov,
req->lr_data_niov, req->lr_req.io.count);
#if defined(__FreeBSD__)
ret = pwritev(file->fd, req->lr_data_iov, niov,
req->lr_req.io.offset);
#else
/* XXX: not thread safe, should really use aio_listio. */
if (lseek(file->fd, (off_t)req->lr_req.io.offset, SEEK_SET) < 0) {
l9p_respond(req, errno);
return;
}
ret = writev(file->fd, req->lr_data_iov,
(int)niov);
#endif
if (ret < 0) {
l9p_respond(req, errno);
return;
}
req->lr_resp.io.count = (uint32_t)ret;
l9p_respond(req, 0);
}
static void
fs_wstat(void *softc, struct l9p_request *req)
{
struct fs_softc *sc = softc;
struct openfile *file;
struct l9p_stat *l9stat = &req->lr_req.twstat.stat;
file = req->lr_fid->lo_aux;
assert(file != NULL);
/*
* XXX:
*
* stat(9P) sez:
*
* Either all the changes in wstat request happen, or none of them
* does: if the request succeeds, all changes were made; if it fails,
* none were.
*
* Atomicity is clearly missing in current implementation.
*/
if (sc->fs_readonly) {
l9p_respond(req, EROFS);
return;
}
if (l9stat->atime != (uint32_t)~0) {
/* XXX: not implemented, ignore */
}
if (l9stat->mtime != (uint32_t)~0) {
/* XXX: not implemented, ignore */
}
if (l9stat->dev != (uint32_t)~0) {
l9p_respond(req, EPERM);
return;
}
if (l9stat->length != (uint64_t)~0) {
if (file->dir != NULL) {
l9p_respond(req, EINVAL);
return;
}
if (truncate(file->name, (off_t)l9stat->length) != 0) {
l9p_respond(req, errno);
return;
}
}
if (req->lr_conn->lc_version >= L9P_2000U) {
if (lchown(file->name, l9stat->n_uid, l9stat->n_gid) != 0) {
l9p_respond(req, errno);
return;
}
}
if (l9stat->mode != (uint32_t)~0) {
if (chmod(file->name, l9stat->mode & 0777) != 0) {
l9p_respond(req, errno);
return;
}
}
if (strlen(l9stat->name) > 0) {
/* XXX: not thread safe */
char *dir = dirname(file->name);
char *newname;
asprintf(&newname, "%s/%s", dir, l9stat->name);
rename(file->name, newname);
free(newname);
}
l9p_respond(req, 0);
}
static void
fs_freefid(void *softc __unused, struct l9p_openfile *fid)
{
struct openfile *f = fid->lo_aux;
if (f == NULL) {
/* Nothing to do here */
return;
}
if (f->fd != -1)
close(f->fd);
if (f->dir)
closedir(f->dir);
free(f->name);
free(f);
}
int
l9p_backend_fs_init(struct l9p_backend **backendp, const char *root)
{
struct l9p_backend *backend;
struct fs_softc *sc;
backend = l9p_malloc(sizeof(*backend));
backend->attach = fs_attach;
backend->clunk = fs_clunk;
backend->create = fs_create;
backend->flush = fs_flush;
backend->open = fs_open;
backend->read = fs_read;
backend->remove = fs_remove;
backend->stat = fs_stat;
backend->walk = fs_walk;
backend->write = fs_write;
backend->wstat = fs_wstat;
backend->freefid = fs_freefid;
sc = l9p_malloc(sizeof(*sc));
sc->fs_rootpath = strdup(root);
sc->fs_readonly = false;
backend->softc = sc;
setpassent(1);
*backendp = backend;
return (0);
}