diff options
| -rw-r--r-- | usr.sbin/lpr/lpr/lpr.c | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/usr.sbin/lpr/lpr/lpr.c b/usr.sbin/lpr/lpr/lpr.c index aff4aaf..f43767c 100644 --- a/usr.sbin/lpr/lpr/lpr.c +++ b/usr.sbin/lpr/lpr/lpr.c @@ -133,7 +133,9 @@ main(argc, argv) char *arg, *cp, *printer, *p; char buf[BUFSIZ]; int c, i, f, errs; + int ret, didlink; struct stat stb; + struct stat statb1, statb2; struct printer myprinter, *pp = &myprinter; printer = NULL; @@ -398,6 +400,83 @@ main(argc, argv) } if (sflag) printf("%s: %s: not linked, copying instead\n", name, arg); + + if (f) { + /* + * The user wants the file removed after it is copied + * to the spool area, so see if the file can be moved + * instead of copy/unlink'ed. This is much faster and + * uses less spool space than copying the file. This + * can be very significant when running services like + * samba, pcnfs, CAP, et al. + */ + seteuid(euid); + didlink = 0; + /* + * There are several things to check to avoid any + * security issues. Some of these are redundant + * under BSD's, but are necessary when lpr is built + * under some other OS's (which I do do...) + */ + if (lstat(arg, &statb1) < 0) + goto nohardlink; + if (S_ISLNK(statb1.st_mode)) + goto nohardlink; + if (link(arg, dfname) != 0) + goto nohardlink; + didlink = 1; + /* + * Make sure the user hasn't tried to trick us via + * any race conditions + */ + if (lstat(dfname, &statb2) < 0) + goto nohardlink; + if (statb1.st_dev != statb2.st_dev) + goto nohardlink; + if (statb1.st_ino != statb2.st_ino) + goto nohardlink; + /* + * Skip if the file already had multiple hard links, + * because changing the owner and access-bits would + * change ALL versions of the file + */ + if (statb2.st_nlink > 2) + goto nohardlink; + /* + * If we can access and remove the original file + * without special setuid-ness then this method is + * safe. Otherwise, abandon the move and fall back + * to the (usual) copy method. + */ + seteuid(uid); + ret = access(dfname, R_OK); + if (ret == 0) + ret = unlink(arg); + seteuid(euid); + if (ret != 0) + goto nohardlink; + /* + * Unlink of user file was successful. Change the + * owner and permissions, add entries to the control + * file, and skip the file copying step. + */ + chown(dfname, pp->daemon_user, getegid()); + chmod(dfname, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); + seteuid(uid); + if (format == 'p') + card('T', title ? title : arg); + for (i = 0; i < ncopies; i++) + card(format, &dfname[inchar-2]); + card('U', &dfname[inchar-2]); + card('N', arg); + nact++; + continue; + nohardlink: + if (didlink) + unlink(dfname); + seteuid(uid); /* restore old uid */ + } /* end: if (f) */ + if ((i = open(arg, O_RDONLY)) < 0) { printf("%s: cannot open %s\n", name, arg); } else { |
