linux-kernel - Re: [PATCH 1/2] exec: Restore EACCES of S

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Date:   Fri, 14 Aug 2020 10:13:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Marc Zyngier <maz@...nel.org>, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 1/2] exec: Restore EACCES of S_ISDIR execve()

On Fri, Aug 14, 2020 at 09:11:02AM +0200, Greg Kroah-Hartman wrote:
> On Thu, Aug 13, 2020 at 04:17:22PM -0700, Kees Cook wrote:
> > The return code for attempting to execute a directory has always been
> > EACCES. Adjust the S_ISDIR exec test to reflect the old errno instead
> > of the general EISDIR for other kinds of "open" attempts on directories.
> > 
> > Reported-by: Marc Zyngier <maz@...nel.org>
> > Link: https://lore.kernel.org/lkml/20200813151305.6191993b@why
> > Fixes: 633fb6ac3980 ("exec: move S_ISREG() check earlier")
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > ---
> >  fs/namei.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/namei.c b/fs/namei.c
> > index 2112e578dccc..e99e2a9da0f7 100644
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -2849,8 +2849,10 @@ static int may_open(const struct path *path, int acc_mode, int flag)
> >  	case S_IFLNK:
> >  		return -ELOOP;
> >  	case S_IFDIR:
> > -		if (acc_mode & (MAY_WRITE | MAY_EXEC))
> > +		if (acc_mode & MAY_WRITE)
> >  			return -EISDIR;
> > +		if (acc_mode & MAY_EXEC)
> > +			return -EACCES;
> >  		break;
> >  	case S_IFBLK:
> >  	case S_IFCHR:
> 
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@...gle.com>

And to round out the "let's use a different email address for each
response, to drive accounting tools crazy!" effort, you can also add:

Tested-by: Greg Kroah-Hartman <gregkh@...roid.com>

thanks,

greg "I don't have enough different email addresses" k-h