1/* $NetBSD: subr_exec_fd.c,v 1.7 2014/09/05 09:20:59 matt Exp $ */
2
3/*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: subr_exec_fd.c,v 1.7 2014/09/05 09:20:59 matt Exp $");
31
32#include <sys/param.h>
33#include <sys/file.h>
34#include <sys/filedesc.h>
35#include <sys/mutex.h>
36#include <sys/namei.h>
37#include <sys/syslog.h>
38#include <sys/vnode.h>
39#include <sys/ktrace.h>
40
41void
42fd_ktrexecfd(void)
43{
44 proc_t *p;
45 filedesc_t *fdp;
46 fdfile_t *ff;
47 lwp_t *l;
48 fdtab_t *dt;
49 int fd;
50
51 l = curlwp;
52 p = l->l_proc;
53 fdp = p->p_fd;
54 dt = fdp->fd_dt;
55
56 for (fd = 0; fd <= fdp->fd_lastfile; fd++) {
57 if ((ff = dt->dt_ff[fd]) == NULL) {
58 KASSERT(fd >= NDFDFILE);
59 continue;
60 }
61 KASSERT(fd >= NDFDFILE ||
62 ff == (fdfile_t *)fdp->fd_dfdfile[fd]);
63 if (ff->ff_file == NULL)
64 continue;
65 ktr_execfd(fd, ff->ff_file->f_type);
66 }
67}
68
69/*
70 * It is unsafe for set[ug]id processes to be started with file
71 * descriptors 0..2 closed, as these descriptors are given implicit
72 * significance in the Standard C library. fdcheckstd() will create a
73 * descriptor referencing /dev/null for each of stdin, stdout, and
74 * stderr that is not already open.
75 */
76#define CHECK_UPTO 3
77int
78fd_checkstd(void)
79{
80 struct proc *p;
81 struct pathbuf *pb;
82 struct nameidata nd;
83 filedesc_t *fdp;
84 file_t *fp;
85 fdtab_t *dt;
86 struct proc *pp;
87 int fd, i, error, flags = FREAD|FWRITE;
88 char closed[CHECK_UPTO * 3 + 1], which[3 + 1];
89
90 p = curproc;
91 closed[0] = '\0';
92 if ((fdp = p->p_fd) == NULL)
93 return (0);
94 dt = fdp->fd_dt;
95 for (i = 0; i < CHECK_UPTO; i++) {
96 KASSERT(i >= NDFDFILE ||
97 dt->dt_ff[i] == (fdfile_t *)fdp->fd_dfdfile[i]);
98 if (dt->dt_ff[i]->ff_file != NULL)
99 continue;
100 snprintf(which, sizeof(which), ",%d", i);
101 strlcat(closed, which, sizeof(closed));
102 if ((error = fd_allocfile(&fp, &fd)) != 0)
103 return (error);
104 KASSERT(fd < CHECK_UPTO);
105 pb = pathbuf_create("/dev/null");
106 if (pb == NULL) {
107 return ENOMEM;
108 }
109 NDINIT(&nd, LOOKUP, FOLLOW, pb);
110 if ((error = vn_open(&nd, flags, 0)) != 0) {
111 pathbuf_destroy(pb);
112 fd_abort(p, fp, fd);
113 return (error);
114 }
115 fp->f_type = DTYPE_VNODE;
116 fp->f_vnode = nd.ni_vp;
117 fp->f_flag = flags;
118 fp->f_ops = &vnops;
119 VOP_UNLOCK(nd.ni_vp);
120 fd_affix(p, fp, fd);
121 pathbuf_destroy(pb);
122 }
123 if (closed[0] != '\0') {
124 mutex_enter(proc_lock);
125 pp = p->p_pptr;
126 mutex_enter(pp->p_lock);
127 log(LOG_WARNING, "set{u,g}id pid %d (%s) "
128 "was invoked by uid %d ppid %d (%s) "
129 "with fd %s closed\n",
130 p->p_pid, p->p_comm, kauth_cred_geteuid(pp->p_cred),
131 pp->p_pid, pp->p_comm, &closed[1]);
132 mutex_exit(pp->p_lock);
133 mutex_exit(proc_lock);
134 }
135 return (0);
136}
137#undef CHECK_UPTO
138