Messages in this thread | | | From | Paul Moore <> | Date | Fri, 16 Feb 2018 13:56:28 -0500 | Subject | Re: [RFC PATCH ghak21 4/4] audit: add parent of refused symlink to audit_names |
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On Thu, Feb 15, 2018 at 9:59 PM, Richard Guy Briggs <rgb@redhat.com> wrote: > On 2018-02-15 18:34, Paul Moore wrote: >> On Wed, Feb 14, 2018 at 11:18 AM, Richard Guy Briggs <rgb@redhat.com> wrote: >> > Audit link denied events for symlinks were missing the parent PATH >> > record. Add it. Since the full pathname may not be available, >> > reconstruct it from the path in the nameidata supplied. >> > >> > See: https://github.com/linux-audit/audit-kernel/issues/21 >> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com> >> > --- >> > fs/namei.c | 9 +++++++++ >> > 1 file changed, 9 insertions(+) >> > >> > diff --git a/fs/namei.c b/fs/namei.c >> > index 0edf133..bf1c046b 100644 >> > --- a/fs/namei.c >> > +++ b/fs/namei.c >> > @@ -923,6 +923,7 @@ static inline int may_follow_link(struct nameidata *nd) >> > const struct inode *inode; >> > const struct inode *parent; >> > kuid_t puid; >> > + char *pathname; >> > >> > if (!sysctl_protected_symlinks) >> > return 0; >> > @@ -945,6 +946,14 @@ static inline int may_follow_link(struct nameidata *nd) >> > if (nd->flags & LOOKUP_RCU) >> > return -ECHILD; >> > >> > + pathname = kmalloc(PATH_MAX + 1, GFP_KERNEL); >> > + if (!pathname) >> > + return -ENOMEM; >> > + audit_inode(getname_kernel(d_absolute_path(&nd->stack[0].link, pathname, >> > + PATH_MAX + 1)), >> > + nd->stack[0].link.dentry, 0); >> >> Hmm, it's been a while since I've looked at the audit vfs/inode code, >> but isn't the audit_inode() call directly above effectively a >> duplicate of the audit_inode(nd->name, nd->stack[0].link.dentry, 0) >> call you added in patch 3/4? > > It gets the full pathname string of the link, then converts it to a > struct filename*, and then below, we feed it that struct filename* with > the parent's dentry and the LOOKUP_PARENT flag to drop the last part of > the pathname and set the filetype to PARENT.
I think that last bit is what I was forgetting, thanks.
> I didn't try, it, but I expect if I feed it parent's dentry above, I'd > get only the parent pathname and when I feed it to audit_inode() below > it would again drop the last part of the pathname when the LOOKUP_PARENT > flag is included, or not label it as a filetype PARENT if we don't > include the flag to get the full parent pathname. > >> > + audit_inode(nd->name, nd->stack[0].link.dentry->d_parent, LOOKUP_PARENT); >> > + >> > audit_inode(nd->name, nd->stack[0].link.dentry, 0); >> > audit_log_link_denied("follow_link", &nd->stack[0].link); >> > return -EACCES; >> > -- >> > 1.8.3.1
-- paul moore www.paul-moore.com
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