extern/encfs
1
0
Fork 0
mirror of https://github.com/vgough/encfs.git synced 2024-11-25 01:13:12 +01:00
Code Issues Packages Projects Releases Wiki Activity

Revert "Remove open_readonly_workaround"

Browse Source 
Caused a regression: https://github.com/vgough/encfs/issues/181

Without this, "umask 0777 ; echo foo > bar" fails.

This reverts commit c2e046b694.
This commit is contained in:
Jakob Unterwurzacher 2016-06-25 14:48:45 +02:00
parent 2b3e6031eb
commit 4a691dc0bb
1 changed files with 31 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
encfs/RawFileIO.cpp
View File

@ -75,6 +75,32 @@ RawFileIO::~RawFileIO() {
Interface RawFileIO::interface() const { return RawFileIO_iface; }
/*
Workaround for opening a file for write when permissions don't allow.
Since the kernel has already checked permissions, we can assume it is ok to
provide access. So force it by changing permissions temporarily. Should
be called with a lock around it so that there won't be a race condition
with calls to lstat picking up the wrong permissions.
This works around the problem described in https://github.com/vgough/encfs/issues/181
Without this, "umask 0777 ; echo foo > bar" fails.
*/
static int open_readonly_workaround(const char *path, int flags) {
int fd = -1;
struct stat stbuf;
memset(&stbuf, 0, sizeof(struct stat));
if (lstat(path, &stbuf) != -1) {
// make sure user has read/write permission..
chmod(path, stbuf.st_mode | 0600);
fd = ::open(path, flags);
chmod(path, stbuf.st_mode);
} else {
RLOG(INFO) << "can't stat file " << path;
}
return fd;
}
/*
We shouldn't have to support all possible open flags, so untaint the flags
argument by only taking ones we understand and accept.
@ -107,6 +133,11 @@ int RawFileIO::open(int flags) {
VLOG(1) << "open file with flags " << finalFlags << ", result = " << newFd;
if ((newFd == -1) && (errno == EACCES)) {
VLOG(1) << "using readonly workaround for open";
newFd = open_readonly_workaround(name.c_str(), finalFlags);
}
if (newFd >= 0) {
if (oldfd >= 0) {
RLOG(ERROR) << "leaking FD?: oldfd = " << oldfd << ", fd = " << fd