When Capsicum starts creating capabilities to wrap existing file
descriptors, we will want to allocate a new descriptor without installing it in the FD array. Split falloc() into falloc_noinstall() and finstall(), and rewrite falloc() to call them with appropriate atomicity. Approved by: mentor (rwatson), re (bz)
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parent
12bc222e57
commit
c0467b5e6e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=223694
@ -1561,54 +1561,85 @@ fdavail(struct thread *td, int n)
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int
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falloc(struct thread *td, struct file **resultfp, int *resultfd, int flags)
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{
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struct proc *p = td->td_proc;
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struct file *fp;
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int error, i;
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int error, fd;
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error = falloc_noinstall(td, &fp);
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if (error)
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return (error); /* no reference held on error */
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error = finstall(td, fp, &fd, flags);
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if (error) {
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fdrop(fp, td); /* one reference (fp only) */
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return (error);
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}
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if (resultfp != NULL)
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*resultfp = fp; /* copy out result */
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else
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fdrop(fp, td); /* release local reference */
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if (resultfd != NULL)
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*resultfd = fd;
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return (0);
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}
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/*
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* Create a new open file structure without allocating a file descriptor.
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*/
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int
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falloc_noinstall(struct thread *td, struct file **resultfp)
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{
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struct file *fp;
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int maxuserfiles = maxfiles - (maxfiles / 20);
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static struct timeval lastfail;
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static int curfail;
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fp = uma_zalloc(file_zone, M_WAITOK | M_ZERO);
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KASSERT(resultfp != NULL, ("%s: resultfp == NULL", __func__));
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if ((openfiles >= maxuserfiles &&
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priv_check(td, PRIV_MAXFILES) != 0) ||
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openfiles >= maxfiles) {
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if (ppsratecheck(&lastfail, &curfail, 1)) {
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printf("kern.maxfiles limit exceeded by uid %i, please see tuning(7).\n",
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td->td_ucred->cr_ruid);
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printf("kern.maxfiles limit exceeded by uid %i, "
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"please see tuning(7).\n", td->td_ucred->cr_ruid);
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}
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uma_zfree(file_zone, fp);
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return (ENFILE);
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}
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atomic_add_int(&openfiles, 1);
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/*
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* If the process has file descriptor zero open, add the new file
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* descriptor to the list of open files at that point, otherwise
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* put it at the front of the list of open files.
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*/
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fp = uma_zalloc(file_zone, M_WAITOK | M_ZERO);
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refcount_init(&fp->f_count, 1);
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if (resultfp)
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fhold(fp);
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fp->f_cred = crhold(td->td_ucred);
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fp->f_ops = &badfileops;
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fp->f_data = NULL;
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fp->f_vnode = NULL;
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FILEDESC_XLOCK(p->p_fd);
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if ((error = fdalloc(td, 0, &i))) {
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FILEDESC_XUNLOCK(p->p_fd);
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fdrop(fp, td);
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if (resultfp)
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fdrop(fp, td);
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*resultfp = fp;
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return (0);
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}
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/*
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* Install a file in a file descriptor table.
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*/
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int
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finstall(struct thread *td, struct file *fp, int *fd, int flags)
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{
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struct filedesc *fdp = td->td_proc->p_fd;
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int error;
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KASSERT(fd != NULL, ("%s: fd == NULL", __func__));
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KASSERT(fp != NULL, ("%s: fp == NULL", __func__));
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FILEDESC_XLOCK(fdp);
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if ((error = fdalloc(td, 0, fd))) {
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FILEDESC_XUNLOCK(fdp);
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return (error);
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}
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p->p_fd->fd_ofiles[i] = fp;
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fhold(fp);
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fdp->fd_ofiles[*fd] = fp;
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if ((flags & O_CLOEXEC) != 0)
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p->p_fd->fd_ofileflags[i] |= UF_EXCLOSE;
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FILEDESC_XUNLOCK(p->p_fd);
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if (resultfp)
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*resultfp = fp;
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if (resultfd)
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*resultfd = i;
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fdp->fd_ofileflags[*fd] |= UF_EXCLOSE;
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FILEDESC_XUNLOCK(fdp);
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return (0);
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}
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@ -113,6 +113,8 @@ int dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
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int mode, int error);
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int falloc(struct thread *td, struct file **resultfp, int *resultfd,
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int flags);
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int falloc_noinstall(struct thread *td, struct file **resultfp);
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int finstall(struct thread *td, struct file *fp, int *resultfp, int flags);
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int fdalloc(struct thread *td, int minfd, int *result);
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int fdavail(struct thread *td, int n);
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int fdcheckstd(struct thread *td);
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