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Merge branch 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kern…
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…el/git/viro/vfs

Pull mqueue/bpf vfs cleanups from Al Viro:
 "mqueue and bpf go through rather painful and similar contortions to
  create objects in their dentry trees. Provide a primitive for doing
  that without abusing ->mknod(), switch bpf and mqueue to it.

  Another mqueue-related thing that has ended up in that branch is
  on-demand creation of internal mount (based upon the work of Giuseppe
  Scrivano)"

* 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  mqueue: switch to on-demand creation of internal mount
  tidy do_mq_open() up a bit
  mqueue: clean prepare_open() up
  do_mq_open(): move all work prior to dentry_open() into a helper
  mqueue: fold mq_attr_ok() into mqueue_get_inode()
  move dentry_open() calls up into do_mq_open()
  mqueue: switch to vfs_mkobj(), quit abusing ->d_fsdata
  bpf_obj_do_pin(): switch to vfs_mkobj(), quit abusing ->mknod()
  new primitive: vfs_mkobj()
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@torvalds
torvalds committed Jan 31, 2018
2 parents 168fe32 + 36735a6 commit 8b0fdf6
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Showing 4 changed files with 158 additions and 158 deletions.
21 changes: 21 additions & 0 deletions fs/namei.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2895,6 +2895,27 @@ int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
}
EXPORT_SYMBOL(vfs_create);

int vfs_mkobj(struct dentry *dentry, umode_t mode,
int (*f)(struct dentry *, umode_t, void *),
void *arg)
{
struct inode *dir = dentry->d_parent->d_inode;
int error = may_create(dir, dentry);
if (error)
return error;

mode &= S_IALLUGO;
mode |= S_IFREG;
error = security_inode_create(dir, dentry, mode);
if (error)
return error;
error = f(dentry, mode, arg);
if (!error)
fsnotify_create(dir, dentry);
return error;
}
EXPORT_SYMBOL(vfs_mkobj);

bool may_open_dev(const struct path *path)
{
return !(path->mnt->mnt_flags & MNT_NODEV) &&
Expand Down
4 changes: 4 additions & 0 deletions include/linux/fs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1608,6 +1608,10 @@ extern int vfs_whiteout(struct inode *, struct dentry *);
extern struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode,
int open_flag);

int vfs_mkobj(struct dentry *, umode_t,
int (*f)(struct dentry *, umode_t, void *),
void *);

/*
* VFS file helper functions.
*/
Expand Down
241 changes: 111 additions & 130 deletions ipc/mqueue.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -270,13 +270,30 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
* that means the min(mq_maxmsg, max_priorities) * struct
* posix_msg_tree_node.
*/

ret = -EINVAL;
if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
goto out_inode;
if (capable(CAP_SYS_RESOURCE)) {
if (info->attr.mq_maxmsg > HARD_MSGMAX ||
info->attr.mq_msgsize > HARD_MSGSIZEMAX)
goto out_inode;
} else {
if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
goto out_inode;
}
ret = -EOVERFLOW;
/* check for overflow */
if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
goto out_inode;
mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
sizeof(struct posix_msg_tree_node);

mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
info->attr.mq_msgsize);

mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
if (mq_bytes + mq_treesize < mq_bytes)
goto out_inode;
mq_bytes += mq_treesize;
spin_lock(&mq_lock);
if (u->mq_bytes + mq_bytes < u->mq_bytes ||
u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
Expand Down Expand Up @@ -308,8 +325,9 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
struct ipc_namespace *ns = sb->s_fs_info;
struct ipc_namespace *ns = data;

sb->s_fs_info = ns;
sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
sb->s_blocksize = PAGE_SIZE;
sb->s_blocksize_bits = PAGE_SHIFT;
Expand All @@ -326,18 +344,44 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
return 0;
}

static struct file_system_type mqueue_fs_type;
/*
* Return value is pinned only by reference in ->mq_mnt; it will
* live until ipcns dies. Caller does not need to drop it.
*/
static struct vfsmount *mq_internal_mount(void)
{
struct ipc_namespace *ns = current->nsproxy->ipc_ns;
struct vfsmount *m = ns->mq_mnt;
if (m)
return m;
m = kern_mount_data(&mqueue_fs_type, ns);
spin_lock(&mq_lock);
if (unlikely(ns->mq_mnt)) {
spin_unlock(&mq_lock);
if (!IS_ERR(m))
kern_unmount(m);
return ns->mq_mnt;
}
if (!IS_ERR(m))
ns->mq_mnt = m;
spin_unlock(&mq_lock);
return m;
}

static struct dentry *mqueue_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
struct ipc_namespace *ns;
if (flags & SB_KERNMOUNT) {
ns = data;
data = NULL;
} else {
ns = current->nsproxy->ipc_ns;
}
return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super);
struct vfsmount *m;
if (flags & SB_KERNMOUNT)
return mount_nodev(fs_type, flags, data, mqueue_fill_super);
m = mq_internal_mount();
if (IS_ERR(m))
return ERR_CAST(m);
atomic_inc(&m->mnt_sb->s_active);
down_write(&m->mnt_sb->s_umount);
return dget(m->mnt_root);
}

static void init_once(void *foo)
Expand Down Expand Up @@ -416,11 +460,11 @@ static void mqueue_evict_inode(struct inode *inode)
put_ipc_ns(ipc_ns);
}

static int mqueue_create(struct inode *dir, struct dentry *dentry,
umode_t mode, bool excl)
static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
{
struct inode *dir = dentry->d_parent->d_inode;
struct inode *inode;
struct mq_attr *attr = dentry->d_fsdata;
struct mq_attr *attr = arg;
int error;
struct ipc_namespace *ipc_ns;

Expand Down Expand Up @@ -461,6 +505,12 @@ static int mqueue_create(struct inode *dir, struct dentry *dentry,
return error;
}

static int mqueue_create(struct inode *dir, struct dentry *dentry,
umode_t mode, bool excl)
{
return mqueue_create_attr(dentry, mode, NULL);
}

static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
Expand Down Expand Up @@ -691,96 +741,46 @@ static void remove_notification(struct mqueue_inode_info *info)
info->notify_user_ns = NULL;
}

static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
{
int mq_treesize;
unsigned long total_size;

if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
return -EINVAL;
if (capable(CAP_SYS_RESOURCE)) {
if (attr->mq_maxmsg > HARD_MSGMAX ||
attr->mq_msgsize > HARD_MSGSIZEMAX)
return -EINVAL;
} else {
if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
attr->mq_msgsize > ipc_ns->mq_msgsize_max)
return -EINVAL;
}
/* check for overflow */
if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
return -EOVERFLOW;
mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
sizeof(struct posix_msg_tree_node);
total_size = attr->mq_maxmsg * attr->mq_msgsize;
if (total_size + mq_treesize < total_size)
return -EOVERFLOW;
return 0;
}

/*
* Invoked when creating a new queue via sys_mq_open
*/
static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
struct path *path, int oflag, umode_t mode,
static int prepare_open(struct dentry *dentry, int oflag, int ro,
umode_t mode, struct filename *name,
struct mq_attr *attr)
{
const struct cred *cred = current_cred();
int ret;

if (attr) {
ret = mq_attr_ok(ipc_ns, attr);
if (ret)
return ERR_PTR(ret);
/* store for use during create */
path->dentry->d_fsdata = attr;
} else {
struct mq_attr def_attr;

def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
ipc_ns->mq_msg_default);
def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
ipc_ns->mq_msgsize_default);
ret = mq_attr_ok(ipc_ns, &def_attr);
if (ret)
return ERR_PTR(ret);
}

mode &= ~current_umask();
ret = vfs_create(dir, path->dentry, mode, true);
path->dentry->d_fsdata = NULL;
if (ret)
return ERR_PTR(ret);
return dentry_open(path, oflag, cred);
}

/* Opens existing queue */
static struct file *do_open(struct path *path, int oflag)
{
static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
MAY_READ | MAY_WRITE };
int acc;

if (d_really_is_negative(dentry)) {
if (!(oflag & O_CREAT))
return -ENOENT;
if (ro)
return ro;
audit_inode_parent_hidden(name, dentry->d_parent);
return vfs_mkobj(dentry, mode & ~current_umask(),
mqueue_create_attr, attr);
}
/* it already existed */
audit_inode(name, dentry, 0);
if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
return -EEXIST;
if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
return ERR_PTR(-EINVAL);
return -EINVAL;
acc = oflag2acc[oflag & O_ACCMODE];
if (inode_permission(d_inode(path->dentry), acc))
return ERR_PTR(-EACCES);
return dentry_open(path, oflag, current_cred());
return inode_permission(d_inode(dentry), acc);
}

static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
struct mq_attr *attr)
{
struct path path;
struct file *filp;
struct vfsmount *mnt = mq_internal_mount();
struct dentry *root;
struct filename *name;
struct path path;
int fd, error;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
struct vfsmount *mnt = ipc_ns->mq_mnt;
struct dentry *root = mnt->mnt_root;
int ro;

if (IS_ERR(mnt))
return PTR_ERR(mnt);

audit_mq_open(oflag, mode, attr);

if (IS_ERR(name = getname(u_name)))
Expand All @@ -791,46 +791,22 @@ static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
goto out_putname;

ro = mnt_want_write(mnt); /* we'll drop it in any case */
error = 0;
root = mnt->mnt_root;
inode_lock(d_inode(root));
path.dentry = lookup_one_len(name->name, root, strlen(name->name));
if (IS_ERR(path.dentry)) {
error = PTR_ERR(path.dentry);
goto out_putfd;
}
path.mnt = mntget(mnt);

if (oflag & O_CREAT) {
if (d_really_is_positive(path.dentry)) { /* entry already exists */
audit_inode(name, path.dentry, 0);
if (oflag & O_EXCL) {
error = -EEXIST;
goto out;
}
filp = do_open(&path, oflag);
} else {
if (ro) {
error = ro;
goto out;
}
audit_inode_parent_hidden(name, root);
filp = do_create(ipc_ns, d_inode(root), &path,
oflag, mode, attr);
}
} else {
if (d_really_is_negative(path.dentry)) {
error = -ENOENT;
goto out;
}
audit_inode(name, path.dentry, 0);
filp = do_open(&path, oflag);
error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
if (!error) {
struct file *file = dentry_open(&path, oflag, current_cred());
if (!IS_ERR(file))
fd_install(fd, file);
else
error = PTR_ERR(file);
}

if (!IS_ERR(filp))
fd_install(fd, filp);
else
error = PTR_ERR(filp);
out:
path_put(&path);
out_putfd:
if (error) {
Expand Down Expand Up @@ -864,6 +840,9 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
struct vfsmount *mnt = ipc_ns->mq_mnt;

if (!mnt)
return -ENOENT;

name = getname(u_name);
if (IS_ERR(name))
return PTR_ERR(name);
Expand Down Expand Up @@ -1590,28 +1569,26 @@ int mq_init_ns(struct ipc_namespace *ns)
ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
ns->mq_msg_default = DFLT_MSG;
ns->mq_msgsize_default = DFLT_MSGSIZE;
ns->mq_mnt = NULL;

ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
if (IS_ERR(ns->mq_mnt)) {
int err = PTR_ERR(ns->mq_mnt);
ns->mq_mnt = NULL;
return err;
}
return 0;
}

void mq_clear_sbinfo(struct ipc_namespace *ns)
{
ns->mq_mnt->mnt_sb->s_fs_info = NULL;
if (ns->mq_mnt)
ns->mq_mnt->mnt_sb->s_fs_info = NULL;
}

void mq_put_mnt(struct ipc_namespace *ns)
{
kern_unmount(ns->mq_mnt);
if (ns->mq_mnt)
kern_unmount(ns->mq_mnt);
}

static int __init init_mqueue_fs(void)
{
struct vfsmount *m;
int error;

mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
Expand All @@ -1633,6 +1610,10 @@ static int __init init_mqueue_fs(void)
if (error)
goto out_filesystem;

m = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
if (IS_ERR(m))
goto out_filesystem;
init_ipc_ns.mq_mnt = m;
return 0;

out_filesystem:
Expand Down
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