1 /* $NetBSD: subr_exec_fd.c,v 1.12 2021/06/29 22:40:53 dholland 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 1.12 2021/06/29 22:40:53 dholland Exp $");
31
32 #include <sys/param.h>
33 #include <sys/atomic.h>
34 #include <sys/file.h>
35 #include <sys/filedesc.h>
36 #include <sys/mutex.h>
37 #include <sys/namei.h>
38 #include <sys/syslog.h>
39 #include <sys/vnode.h>
40 #include <sys/ktrace.h>
41
42 void
fd_ktrexecfd(void)43 fd_ktrexecfd(void)
44 {
45 proc_t *p;
46 filedesc_t *fdp;
47 fdfile_t *ff;
48 lwp_t *l;
49 fdtab_t *dt;
50 file_t *fp;
51 int fd;
52
53 l = curlwp;
54 p = l->l_proc;
55 fdp = p->p_fd;
56 dt = atomic_load_consume(&fdp->fd_dt);
57
58 for (fd = 0; fd <= fdp->fd_lastfile; fd++) {
59 if ((ff = dt->dt_ff[fd]) == NULL) {
60 KASSERT(fd >= NDFDFILE);
61 continue;
62 }
63 KASSERT(fd >= NDFDFILE ||
64 ff == (fdfile_t *)fdp->fd_dfdfile[fd]);
65 if ((fp = atomic_load_consume(&ff->ff_file)) == NULL)
66 continue;
67 ktr_execfd(fd, fp->f_type);
68 }
69 }
70
71 /*
72 * It is unsafe for set[ug]id processes to be started with file
73 * descriptors 0..2 closed, as these descriptors are given implicit
74 * significance in the Standard C library. fd_checkstd() will create a
75 * descriptor referencing /dev/null for each of stdin, stdout, and
76 * stderr that is not already open.
77 */
78 #define CHECK_UPTO 3
79 int
fd_checkstd(void)80 fd_checkstd(void)
81 {
82 struct proc *p;
83 struct pathbuf *pb;
84 struct vnode *vp;
85 filedesc_t *fdp;
86 file_t *fp;
87 fdtab_t *dt;
88 struct proc *pp;
89 int fd, i, error, flags = FREAD|FWRITE;
90 char closed[CHECK_UPTO * 3 + 1], which[3 + 1];
91
92 p = curproc;
93 closed[0] = '\0';
94 if ((fdp = p->p_fd) == NULL)
95 return (0);
96 dt = atomic_load_consume(&fdp->fd_dt);
97 for (i = 0; i < CHECK_UPTO; i++) {
98 KASSERT(i >= NDFDFILE ||
99 dt->dt_ff[i] == (fdfile_t *)fdp->fd_dfdfile[i]);
100 if (dt->dt_ff[i]->ff_file != NULL)
101 continue;
102 snprintf(which, sizeof(which), ",%d", i);
103 strlcat(closed, which, sizeof(closed));
104 if ((error = fd_allocfile(&fp, &fd)) != 0)
105 return (error);
106 KASSERT(fd < CHECK_UPTO);
107 pb = pathbuf_create("/dev/null");
108 if (pb == NULL) {
109 return ENOMEM;
110 }
111 error = vn_open(NULL, pb, 0, flags, 0, &vp, NULL, NULL);
112 if (error != 0) {
113 pathbuf_destroy(pb);
114 fd_abort(p, fp, fd);
115 return (error);
116 }
117 fp->f_type = DTYPE_VNODE;
118 fp->f_vnode = vp;
119 fp->f_flag = flags;
120 fp->f_ops = &vnops;
121 VOP_UNLOCK(vp);
122 fd_affix(p, fp, fd);
123 pathbuf_destroy(pb);
124 }
125 if (closed[0] != '\0') {
126 mutex_enter(&proc_lock);
127 pp = p->p_pptr;
128 mutex_enter(pp->p_lock);
129 log(LOG_WARNING, "set{u,g}id pid %d (%s) "
130 "was invoked by uid %d ppid %d (%s) "
131 "with fd %s closed\n",
132 p->p_pid, p->p_comm, kauth_cred_geteuid(pp->p_cred),
133 pp->p_pid, pp->p_comm, &closed[1]);
134 mutex_exit(pp->p_lock);
135 mutex_exit(&proc_lock);
136 }
137 return (0);
138 }
139 #undef CHECK_UPTO
140