111 lines
3.2 KiB
C
111 lines
3.2 KiB
C
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/*++
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/* NAME
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/* mail_open_ok 3
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/* SUMMARY
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/* scrutinize mail queue file
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/* SYNOPSIS
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/* #include <mail_open_ok.h>
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/*
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/* int mail_open_ok(queue_name, queue_id, statp, pathp)
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/* const char *queue_name;
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/* const char *queue_id;
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/* struct stat *statp;
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/* char **pathp
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/* DESCRIPTION
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/* mail_open_ok() determines if it is OK to open the specified
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/* queue file.
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/*
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/* The queue name and queue id should conform to the syntax
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/* requirements for these names.
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/* Unfortunately, on some systems readdir() etc. can return bogus
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/* file names. For this reason, the code silently ignores invalid
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/* queue file names.
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/*
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/* The file should have mode 0700. Files with other permissions
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/* are silently ignored.
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/*
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/* The file should be a regular file.
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/* Files that do not satisfy this requirement are skipped with
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/* a warning.
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/*
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/* The file link count is not restricted. With a writable maildrop
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/* directory, refusal to deliver linked files is prone to denial of
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/* service attack; it's better to deliver mail too often than not.
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/*
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/* Upon return, the \fIstatp\fR argument receives the file
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/* attributes and \fIpathp\fR a copy of the file name. The file
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/* name is volatile. Make a copy if it is to be used for any
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/* appreciable amount of time.
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/* DIAGNOSTICS
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/* Warnings: bad file attributes (file type), multiple hard links.
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/* mail_open_ok() returns MAIL_OPEN_YES for good files, MAIL_OPEN_NO
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/* for anything else. It is left up to the system administrator to
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/* deal with non-file objects.
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/* BUGS
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/* mail_open_ok() examines a queue file without actually opening
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/* it, and therefore is susceptible to race conditions.
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/* LICENSE
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/* .ad
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/* .fi
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/* The Secure Mailer license must be distributed with this software.
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/* AUTHOR(S)
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/* Wietse Venema
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/* IBM T.J. Watson Research
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/* P.O. Box 704
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/* Yorktown Heights, NY 10598, USA
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/*--*/
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/* System libraries. */
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#include <sys_defs.h>
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#include <sys/stat.h>
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#include <errno.h>
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/* Utility library. */
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#include <msg.h>
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/* Global library. */
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#include "mail_queue.h"
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#include "mail_open_ok.h"
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/* mail_open_ok - see if this file is OK to open */
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int mail_open_ok(const char *queue_name, const char *queue_id,
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struct stat * statp, const char **path)
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{
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if (mail_queue_name_ok(queue_name) == 0) {
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msg_warn("bad mail queue name: %s", queue_name);
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return (MAIL_OPEN_NO);
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}
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if (mail_queue_id_ok(queue_id) == 0)
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return (MAIL_OPEN_NO);
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/*
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* I really would like to look up the file attributes *after* opening the
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* file so that we could save one directory traversal on systems without
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* name-to-inode cache. However, we don't necessarily always want to open
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* the file.
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*/
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*path = mail_queue_path((VSTRING *) 0, queue_name, queue_id);
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if (lstat(*path, statp) < 0) {
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if (errno != ENOENT)
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msg_warn("%s: %m", *path);
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return (MAIL_OPEN_NO);
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}
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if (!S_ISREG(statp->st_mode)) {
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msg_warn("%s: uid %d: not a regular file", *path, statp->st_uid);
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return (MAIL_OPEN_NO);
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}
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if ((statp->st_mode & S_IRWXU) != MAIL_QUEUE_STAT_READY)
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return (MAIL_OPEN_NO);
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if (statp->st_nlink > 1) {
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msg_warn("%s: uid %d: file has %d links", *path,
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statp->st_uid, (int) statp->st_nlink);
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}
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return (MAIL_OPEN_YES);
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}
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