From: Chris Allegretta Date: Mon, 4 Dec 2000 05:15:39 +0000 (+0000) Subject: Okay, forget O_EXCL, do lots of other obscure checks instead =) X-Git-Tag: v0.9.23~12 X-Git-Url: https://git.wh0rd.org/?a=commitdiff_plain;h=07f9ee059fdb91d16cb72f17fdfb9832a1fa13c5;p=nano.git Okay, forget O_EXCL, do lots of other obscure checks instead =) git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@381 35c25a1d-7b9e-4130-9fde-d3aeb78583b8 --- diff --git a/ChangeLog b/ChangeLog index 7b70192d..4e7d6d1f 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,9 +1,9 @@ CVS code - - files.c: write_file() - - Added O_EXCL to open call if tmp is set, more security which hopefully - fixes any remaining security issues. - Added tmp check to TMP_OPT section (how apropriate). + - Added new consistency checking code from securityfocus + article by Oliver Friedrichs. - winio.c: edit_add() - Off by one display error (fix by Rocco Corsi). diff --git a/files.c b/files.c index eb874ab0..76b12cb9 100644 --- a/files.c +++ b/files.c @@ -301,8 +301,8 @@ int write_file(char *name, int tmp) long size, lineswritten = 0; char buf[PATH_MAX + 1]; filestruct *fileptr; - int fd, mask = 0, realexists; - struct stat st; + int fd, mask = 0, realexists, anyexists; + struct stat st, st2; static char *realname = NULL; if (!strcmp(name, "")) { @@ -327,24 +327,18 @@ int write_file(char *name, int tmp) /* Check to see if the file is a regular file and FOLLOW_SYMLINKS is set. If so then don't do the delete and recreate code which would cause unexpected behavior */ - lstat(realname, &st); + anyexists = lstat(realname, &st); - /* New case: if the file exists, just give up. Easy way out of - all security issues */ - if (tmp && realexists != -1) + /* New case: if the file exists, just give up */ + if (tmp && anyexists != -1) return -1; else if (ISSET(FOLLOW_SYMLINKS) || !S_ISLNK(st.st_mode)) { - /* If tmp is set, use O_EXCL, more security, YAY! */ - if (tmp) - fd = open(realname, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC, - S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | - S_IWOTH); - else - fd = open(realname, O_WRONLY | O_CREAT | O_TRUNC, - S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | - S_IWOTH); - /* Open the file and truncate it. Trust the symlink. */ + fd = open(realname, O_WRONLY | O_CREAT | O_TRUNC, + S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | + S_IWOTH); + + /* First, just give up if we couldn't even open the file */ if (fd == -1) { if (!tmp && ISSET(TEMP_OPT)) { UNSET(TEMP_OPT); @@ -355,6 +349,25 @@ int write_file(char *name, int tmp) free(realname); return -1; } + + /* Now we fstat() the file, to make sure it's the same file still! + Thanks to Oliver Friedrichs(?) for this code from securityfocus */ + + if (fstat(fd, &st2) != 0) { + close(fd); + return -1; + } + + /* Here we make sure the inode and device numbers are the + * same in the file we actually opened, compared to the file + * we performed the initial lstat() call on. + */ + + if (st.st_ino != st2.st_ino || st.st_dev != st2.st_dev) { + close(fd); + return -1; + } + } /* Don't follow symlink. Create new file. */ else {