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Don't make Linux stat() open character devices to resolve its name.

Browse source 
The existing code calls kern_open() to resolve the vnode of a pathname
right after a stat(). This is not correct, because it causes random
character devices to be opened in /dev. This means ls'ing a tape
streamer will cause it to rewind, for example. Changes I have made:

- Add kern_statat_vnhook() to allow binary emulators to `post-process'
  struct stat, using the proper vnode.

- Remove unneeded printf's from stat() and statfs().

- Make the Linuxolator use kern_statat_vnhook(), replacing
  translate_path_major_minor_at().

- Let translate_fd_major_minor() use vp->v_rdev instead of
  vp->v_un.vu_cdev.

Result:

	crw-rw-rw- 1 root root   0, 14 Feb 20 13:54 /dev/ptmx
	crw--w---- 1 root adm  136,  0 Feb 20 14:03 /dev/pts/0
	crw--w---- 1 root adm  136,  1 Feb 20 14:02 /dev/pts/1
	crw--w---- 1 ed   tty  136,  2 Feb 20 14:03 /dev/pts/2

Before this commit, ptmx also had a major number of 136, because it
silently allocated and deallocated a pseudo-terminal. Device nodes that
cannot be opened now have proper major/minor-numbers.

Reviewed by:	kib, netchild, rdivacky (thanks!)
This commit is contained in:
Ed Schouten 2009-02-20 13:05:29 +00:00
parent 3d919b7521
commit 0eee862a54
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=188849
3 changed files with 63 additions and 51 deletions
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96
sys/compat/linux/linux_stats.c
View file

@ -62,6 +62,44 @@ __FBSDID("$FreeBSD$");
#include <security/mac/mac_framework.h>
static void
translate_vnhook_major_minor(struct vnode *vp, struct stat *sb)
{
int major, minor;
if (vp->v_type == VCHR && vp->v_rdev != NULL &&
linux_driver_get_major_minor(vp->v_rdev->si_name,
&major, &minor) == 0) {
sb->st_rdev = (major << 8 | minor);
}
}
static int
linux_kern_statat(struct thread *td, int flag, int fd, char *path,
enum uio_seg pathseg, struct stat *sbp)
{
return (kern_statat_vnhook(td, flag, fd, path, pathseg, sbp,
translate_vnhook_major_minor));
}
static int
linux_kern_stat(struct thread *td, char *path, enum uio_seg pathseg,
struct stat *sbp)
{
return (linux_kern_statat(td, 0, AT_FDCWD, path, pathseg, sbp));
}
static int
linux_kern_lstat(struct thread *td, char *path, enum uio_seg pathseg,
struct stat *sbp)
{
return (linux_kern_statat(td, AT_SYMLINK_NOFOLLOW, AT_FDCWD, path,
pathseg, sbp));
}
/*
* XXX: This was removed from newstat_copyout(), and almost identical
* XXX: code was in stat64_copyout(). findcdev() needs to be replaced
@ -102,14 +140,15 @@ static void
translate_fd_major_minor(struct thread *td, int fd, struct stat *buf)
{
struct file *fp;
struct vnode *vp;
int major, minor;
if ((!S_ISCHR(buf->st_mode) && !S_ISBLK(buf->st_mode)) ||
fget(td, fd, &fp) != 0)
return;
if (fp->f_vnode != NULL &&
fp->f_vnode->v_un.vu_cdev != NULL &&
linux_driver_get_major_minor(fp->f_vnode->v_un.vu_cdev->si_name,
vp = fp->f_vnode;
if (vp != NULL && vp->v_rdev != NULL &&
linux_driver_get_major_minor(vp->v_rdev->si_name,
&major, &minor) == 0) {
buf->st_rdev = (major << 8 | minor);
} else if (fp->f_type == DTYPE_PTS) {
@ -124,32 +163,6 @@ translate_fd_major_minor(struct thread *td, int fd, struct stat *buf)
fdrop(fp, td);
}
static void
translate_path_major_minor_at(struct thread *td, char *path,
struct stat *buf, int dfd)
{
struct proc *p = td->td_proc;
struct filedesc *fdp = p->p_fd;
int fd;
int temp;
if (!S_ISCHR(buf->st_mode) && !S_ISBLK(buf->st_mode))
return;
temp = td->td_retval[0];
if (kern_openat(td, dfd, path, UIO_SYSSPACE, O_RDONLY, 0) != 0)
return;
fd = td->td_retval[0];
td->td_retval[0] = temp;
translate_fd_major_minor(td, fd, buf);
fdclose(fdp, fdp->fd_ofiles[fd], fd, td);
}
static inline void
translate_path_major_minor(struct thread *td, char *path, struct stat *buf)
{
translate_path_major_minor_at(td, path, buf, AT_FDCWD);
}
static int
newstat_copyout(struct stat *buf, void *ubuf)
{
@ -187,9 +200,7 @@ linux_newstat(struct thread *td, struct linux_newstat_args *args)
printf(ARGS(newstat, "%s, *"), path);
#endif
error = kern_stat(td, path, UIO_SYSSPACE, &buf);
if (!error)
translate_path_major_minor(td, path, &buf);
error = linux_kern_stat(td, path, UIO_SYSSPACE, &buf);
LFREEPATH(path);
if (error)
return (error);
@ -210,9 +221,7 @@ linux_newlstat(struct thread *td, struct linux_newlstat_args *args)
printf(ARGS(newlstat, "%s, *"), path);
#endif
error = kern_lstat(td, path, UIO_SYSSPACE, &sb);
if (!error)
translate_path_major_minor(td, path, &sb);
error = linux_kern_lstat(td, path, UIO_SYSSPACE, &sb);
LFREEPATH(path);
if (error)
return (error);
@ -279,12 +288,11 @@ linux_stat(struct thread *td, struct linux_stat_args *args)
if (ldebug(stat))
printf(ARGS(stat, "%s, *"), path);
#endif
error = kern_stat(td, path, UIO_SYSSPACE, &buf);
error = linux_kern_stat(td, path, UIO_SYSSPACE, &buf);
if (error) {
LFREEPATH(path);
return (error);
}
translate_path_major_minor(td, path, &buf);
LFREEPATH(path);
return(stat_copyout(&buf, args->up));
}
@ -302,12 +310,11 @@ linux_lstat(struct thread *td, struct linux_lstat_args *args)
if (ldebug(lstat))
printf(ARGS(lstat, "%s, *"), path);
#endif
error = kern_lstat(td, path, UIO_SYSSPACE, &buf);
error = linux_kern_lstat(td, path, UIO_SYSSPACE, &buf);
if (error) {
LFREEPATH(path);
return (error);
}
translate_path_major_minor(td, path, &buf);
LFREEPATH(path);
return(stat_copyout(&buf, args->up));
}
@ -526,9 +533,7 @@ linux_stat64(struct thread *td, struct linux_stat64_args *args)
printf(ARGS(stat64, "%s, *"), filename);
#endif
error = kern_stat(td, filename, UIO_SYSSPACE, &buf);
if (!error)
translate_path_major_minor(td, filename, &buf);
error = linux_kern_stat(td, filename, UIO_SYSSPACE, &buf);
LFREEPATH(filename);
if (error)
return (error);
@ -549,9 +554,7 @@ linux_lstat64(struct thread *td, struct linux_lstat64_args *args)
printf(ARGS(lstat64, "%s, *"), args->filename);
#endif
error = kern_lstat(td, filename, UIO_SYSSPACE, &sb);
if (!error)
translate_path_major_minor(td, filename, &sb);
error = linux_kern_lstat(td, filename, UIO_SYSSPACE, &sb);
LFREEPATH(filename);
if (error)
return (error);
@ -597,8 +600,7 @@ linux_fstatat64(struct thread *td, struct linux_fstatat64_args *args)
printf(ARGS(fstatat64, "%i, %s, %i"), args->dfd, path, args->flag);
#endif
error = kern_statat(td, flag, dfd, path, UIO_SYSSPACE, &buf);
translate_path_major_minor_at(td, args->pathname, &buf, dfd);
error = linux_kern_statat(td, flag, dfd, path, UIO_SYSSPACE, &buf);
if (!error)
error = stat64_copyout(&buf, args->statbuf);
LFREEPATH(path);

15
sys/kern/vfs_syscalls.c
View file

@ -339,8 +339,6 @@ kern_statfs(struct thread *td, char *path, enum uio_seg pathseg,
out:
vfs_unbusy(mp);
VFS_UNLOCK_GIANT(vfslocked);
if (mtx_owned(&Giant))
printf("statfs(%d): %s: %d\n", vfslocked, path, error);
return (error);
}
@ -2343,6 +2341,15 @@ int
kern_statat(struct thread *td, int flag, int fd, char *path,
enum uio_seg pathseg, struct stat *sbp)
{
return (kern_statat_vnhook(td, flag, fd, path, pathseg, sbp, NULL));
}
int
kern_statat_vnhook(struct thread *td, int flag, int fd, char *path,
enum uio_seg pathseg, struct stat *sbp,
void (*hook)(struct vnode *vp, struct stat *sbp))
{
struct nameidata nd;
struct stat sb;
int error, vfslocked;
@ -2362,12 +2369,12 @@ kern_statat(struct thread *td, int flag, int fd, char *path,
SDT_PROBE(vfs, , stat, mode, path, sb.st_mode, 0, 0, 0);
if (S_ISREG(sb.st_mode))
SDT_PROBE(vfs, , stat, reg, path, pathseg, 0, 0, 0);
if (__predict_false(hook != NULL))
hook(nd.ni_vp, &sb);
}
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
if (mtx_owned(&Giant))
printf("stat(%d): %s\n", vfslocked, path);
if (error)
return (error);
*sbp = sb;

3
sys/sys/syscallsubr.h
View file

@ -193,6 +193,9 @@ int kern_stat(struct thread *td, char *path, enum uio_seg pathseg,
struct stat *sbp);
int kern_statat(struct thread *td, int flag, int fd, char *path,
enum uio_seg pathseg, struct stat *sbp);
int kern_statat_vnhook(struct thread *td, int flag, int fd, char *path,
enum uio_seg pathseg, struct stat *sbp,
void (*hook)(struct vnode *vp, struct stat *sbp));
int kern_statfs(struct thread *td, char *path, enum uio_seg pathseg,
struct statfs *buf);
int kern_symlink(struct thread *td, char *path, char *link,