1 /* $NetBSD: open_as.c,v 1.1.1.1 2009/06/23 10:09:00 tron Exp $ */
2
3 /*++
4 /* NAME
5 /* open_as 3
6 /* SUMMARY
7 /* open file as user
8 /* SYNOPSIS
9 /* #include <fcntl.h>
10 /* #include <open_as.h>
11 /*
12 /* int open_as(path, flags, mode, euid, egid)
13 /* const char *path;
14 /* int mode;
15 /* uid_t euid;
16 /* gid_t egid;
17 /* DESCRIPTION
18 /* open_as() opens the named \fIpath\fR with the named \fIflags\fR
19 /* and \fImode\fR, and with the effective rights specified by \fIeuid\fR
20 /* and \fIegid\fR. A -1 result means the open failed.
21 /* DIAGNOSTICS
22 /* Fatal error: no permission to change privilege level.
23 /* SEE ALSO
24 /* set_eugid(3) switch effective rights
25 /* LICENSE
26 /* .ad
27 /* .fi
28 /* The Secure Mailer license must be distributed with this software.
29 /* AUTHOR(S)
30 /* Wietse Venema
31 /* IBM T.J. Watson Research
32 /* P.O. Box 704
33 /* Yorktown Heights, NY 10598, USA
34 /*--*/
35
36 /* System library. */
37
38 #include <sys_defs.h>
39 #include <fcntl.h>
40 #include <unistd.h>
41
42 /* Utility library. */
43
44 #include "msg.h"
45 #include "set_eugid.h"
46 #include "open_as.h"
47
48 /* open_as - open file as user */
49
open_as(const char * path,int flags,int mode,uid_t euid,gid_t egid)50 int open_as(const char *path, int flags, int mode, uid_t euid, gid_t egid)
51 {
52 uid_t saved_euid = geteuid();
53 gid_t saved_egid = getegid();
54 int fd;
55
56 /*
57 * Switch to the target user privileges.
58 */
59 set_eugid(euid, egid);
60
61 /*
62 * Open that file.
63 */
64 fd = open(path, flags, mode);
65
66 /*
67 * Restore saved privileges.
68 */
69 set_eugid(saved_euid, saved_egid);
70
71 return (fd);
72 }
73