[libcamera-devel] [PATCH] libcamera: Open files with O_CLOEXEC

[Laurent Pinchart]

Hi Kieran,

On Mon, Mar 27, 2023 at 04:17:17PM +0100, Kieran Bingham wrote:
> Quoting Laurent Pinchart via libcamera-devel (2023-03-26 11:01:55)
> > Files opened internally in libcamera without the O_CLOEXEC file will
> > remain open upon a call to one of the exec(3) functions. As exec()
> > doesn't destroy local or global objects, this can lead to various side
> > effects. Avoid this by opening file descriptors with O_CLOEXEC for all
> > internal files.
> 
> This seems more prolific than it should be.
> 
> It makes me think we should enforce it with a helper instead but I'm not
> sure if that's much different to adding a checkstyle rule!?

Wider usage of the File class may help.

> Anyway, this seems reasonable otherwise.
> 
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  src/ipa/vimc/vimc.cpp                            | 2 +-
> >  src/libcamera/base/file.cpp                      | 5 ++++-
> >  src/libcamera/media_device.cpp                   | 2 +-
> >  src/libcamera/pipeline/raspberrypi/dma_heaps.cpp | 2 +-
> >  4 files changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/src/ipa/vimc/vimc.cpp b/src/ipa/vimc/vimc.cpp
> > index d5fabaf13ec6..2c255778990a 100644
> > --- a/src/ipa/vimc/vimc.cpp
> > +++ b/src/ipa/vimc/vimc.cpp
> > @@ -168,7 +168,7 @@ void IPAVimc::initTrace()
> >         if (ret)
> >                 return;
> >  
> > -       ret = ::open(ipa::vimc::VimcIPAFIFOPath.c_str(), O_WRONLY);
> > +       ret = ::open(ipa::vimc::VimcIPAFIFOPath.c_str(), O_WRONLY | O_CLOEXEC);
> >         if (ret < 0) {
> >                 ret = errno;
> >                 LOG(IPAVimc, Error) << "Failed to open vimc IPA test FIFO: "
> > diff --git a/src/libcamera/base/file.cpp b/src/libcamera/base/file.cpp
> > index fb3e276d6ccd..d1ab1aa57462 100644
> > --- a/src/libcamera/base/file.cpp
> > +++ b/src/libcamera/base/file.cpp
> > @@ -163,6 +163,9 @@ bool File::exists() const
> >   * attempt to create the file with initial permissions set to 0666 (modified by
> >   * the process' umask).
> >   *
> > + * The file is opened with the O_CLOEXEC flag, and will be closed automatically
> > + * when a new binary is executed with one of the exec(3) functions.
> > + *
> >   * The error() status is updated.
> >   *
> >   * \return True on success, false otherwise
> > @@ -178,7 +181,7 @@ bool File::open(File::OpenMode mode)
> >         if (mode & OpenModeFlag::WriteOnly)
> >                 flags |= O_CREAT;
> >  
> > -       fd_ = UniqueFD(::open(name_.c_str(), flags, 0666));
> > +       fd_ = UniqueFD(::open(name_.c_str(), flags | O_CLOEXEC, 0666));
> >         if (!fd_.isValid()) {
> >                 error_ = -errno;
> >                 return false;
> > diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
> > index 52c8e66e9e99..2949816b4a64 100644
> > --- a/src/libcamera/media_device.cpp
> > +++ b/src/libcamera/media_device.cpp
> > @@ -477,7 +477,7 @@ int MediaDevice::open()
> >                 return -EBUSY;
> >         }
> >  
> > -       fd_ = UniqueFD(::open(deviceNode_.c_str(), O_RDWR));
> > +       fd_ = UniqueFD(::open(deviceNode_.c_str(), O_RDWR | O_CLOEXEC));
> >         if (!fd_.isValid()) {
> >                 int ret = -errno;
> >                 LOG(MediaDevice, Error)
> > diff --git a/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp b/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp
> > index 6b644406c90f..317b1fc17161 100644
> > --- a/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp
> > +++ b/src/libcamera/pipeline/raspberrypi/dma_heaps.cpp
> > @@ -37,7 +37,7 @@ namespace RPi {
> >  DmaHeap::DmaHeap()
> >  {
> >         for (const char *name : heapNames) {
> > -               int ret = ::open(name, O_RDWR, 0);
> > +               int ret = ::open(name, O_RDWR | O_CLOEXEC, 0);
> >                 if (ret < 0) {
> >                         ret = errno;
> >                         LOG(RPI, Debug) << "Failed to open " << name << ": "

-- 
Regards,

Laurent Pinchart