> > +/**
> > + * exec_permission - check for general execute permission on file
> > + * @inode: inode to check access rights for
> > + * @mask: right to check for
> > + *
> > + * Exec permission on a regular file is denied if none of the execute
> > + * bits are set.
> > + *
> > + * This needs to be called by filesystems which define a
> > + * ->permission() method, and don't call generic_permission().
> > + */
> > +int exec_permission(struct inode *inode, int mask)
> > +{
> > + if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
> > + !(inode->i_mode & S_IXUGO))
> > + return -EACCES;
> > +
> > + return 0;
> > +}
>
> Hmm... What if !(mask & MAY_EXEC)? AFAICS, the above will return 0.
> A better approach would be to use something like
>
> if (!(mask & MAY_EXEC))
> return -EACCES;
> if (S_ISREG(inode->i_mode) && !(inode->i_mode & S_IXUGO))
> return -EACCES;
> return 0;
No, we don't want to deny read or write (that's up to the filesystem
how it handles it), just want to deny execute if no x bits are set in
the mode.
I didn't really pay attention to individual filesystems, including
NFS, just mechanically moved the check from permission() to
->permission(). So it's possible that the code could be further
optimized in some cases.
Miklos
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