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fexecve(2): allow O_PATH file descriptors opened without O_EXEC

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This improves compatibility with Linux.

Noted by:	Drew DeVault <sir@cmpwn.com>
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32821
This commit is contained in:
Konstantin Belousov 2021-11-03 14:51:06 +02:00
parent 02de91d740
commit be10c0a910
3 changed files with 13 additions and 8 deletions
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3
lib/libc/sys/open.2
View File

@ -334,9 +334,6 @@ but advisory locking is not allowed
.It Xr close 2
.It Xr fstat 2
.It Xr fexecve 2
requires that
.Dv O_EXEC
was also specified at open time
.It Dv SCM_RIGHTS
can be passed over a
.Xr unix 4

5
sys/kern/kern_descrip.c
View File

@ -3213,8 +3213,9 @@ _fget(struct thread *td, int fd, struct file **fpp, int flags,
error = EBADF;
break;
case FEXEC:
if ((fp->f_flag & (FREAD | FEXEC)) == 0 ||
((fp->f_flag & FWRITE) != 0))
if (fp->f_ops != &path_fileops &&
((fp->f_flag & (FREAD | FEXEC)) == 0 ||
(fp->f_flag & FWRITE) != 0))
error = EBADF;
break;
case 0:

13
sys/kern/kern_exec.c
View File

@ -530,13 +530,20 @@ do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
}
} else {
AUDIT_ARG_FD(args->fd);
/*
* Descriptors opened only with O_EXEC or O_RDONLY are allowed.
* If the descriptors was not opened with O_PATH, then
* we require that it was opened with O_EXEC or
* O_RDONLY. In either case, exec_check_permissions()
* below checks _current_ file access mode regardless
* of the permissions additionally checked at the
* open(2).
*/
error = fgetvp_exec(td, args->fd, &cap_fexecve_rights,
&newtextvp);
if (error)
if (error != 0)
goto exec_fail;
if (vn_fullpath(newtextvp, &imgp->execpath,
&imgp->freepath) != 0)
imgp->execpath = args->fname;
@ -881,7 +888,7 @@ do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
/*
* Store the vp for use in kern.proc.pathname. This vnode was
* referenced by namei() or fgetvp_exec().
* referenced by namei() or by fexecve variant of fname handling.
*/
oldtextvp = p->p_textvp;
p->p_textvp = newtextvp;