From: Tyler Hicks <tyhicks@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
James Morris <jmorris@namei.org>,
"Serge E . Hallyn" <serge@hallyn.com>,
Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
Prakhar Srivastava <prsriva02@gmail.com>,
linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH 02/12] ima: Create a function to free a rule entry
Date: Thu, 25 Jun 2020 14:56:47 -0500 [thread overview]
Message-ID: <20200625195647.GB4694@sequoia> (raw)
In-Reply-To: <1593113613.27152.345.camel@linux.ibm.com>
On 2020-06-25 15:33:33, Mimi Zohar wrote:
> On Mon, 2020-06-22 at 19:32 -0500, Tyler Hicks wrote:
> > There are several possible pieces of allocated memory in a rule entry.
> > Create a function that can free all allocated memory for a given rule
> > entry.
> >
> > This patch introduces no functional changes but sets the groundwork for
> > some memory leak fixes.
> >
> > Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
>
> Having a function to release all memory associated with a policy rule
> in general is a good idea. However, in the case of the shallow copy,
> we're not removing any IMA rules, just updating the LSM info.
>
> There is an opportunity to transition from the builtin policy rules to
> a custom IMA policy. Afterwards IMA policy rules may only be
> appended.
>
> An IMA custom policy based on LSM info may be loaded prior to the LSM
> policy. These LSM based rules are inactive until the corresponding
> LSM rule is loaded. In some environments, LSM policies are loaded and
> removed frequently. The IMA rules themselves are not removed, just
> the LSM info is updated to reflect the current LSM info.
>
> > ---
> > security/integrity/ima/ima_policy.c | 33 +++++++++++++++++++++++++++--
> > 1 file changed, 31 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> > index 236a731492d1..1320333201c6 100644
> > --- a/security/integrity/ima/ima_policy.c
> > +++ b/security/integrity/ima/ima_policy.c
> > @@ -261,6 +261,27 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry)
> > security_filter_rule_free(entry->lsm[i].rule);
> > kfree(entry->lsm[i].args_p);
> > }
> > +}
> > +
> > +static void ima_free_rule(struct ima_rule_entry *entry)
> > +{
> > + if (!entry)
> > + return;
> > +
> > + /*
> > + * entry->template->fields may be allocated in ima_parse_rule() but that
> > + * reference is owned by the corresponding ima_template_desc element in
> > + * the defined_templates list and cannot be freed here
> > + */
> > +
> > + /*
> > + * When freeing newly added ima_rule_entry members, consider if you
> > + * need to disown any references after the shallow copy in
> > + * ima_lsm_copy_rule()
> > + */
> > + kfree(entry->fsname);
> > + kfree(entry->keyrings);
> > + ima_lsm_free_rule(entry);
> > kfree(entry);
> > }
> >
> > @@ -298,10 +319,18 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
> > pr_warn("rule for LSM \'%s\' is undefined\n",
> > (char *)entry->lsm[i].args_p);
> > }
> > +
> > + /* Disown all references that were shallow copied */
> > + entry->fsname = NULL;
> > + entry->keyrings = NULL;
> > + entry->template = NULL;
> > return nentry;
> >
> > out_err:
> > - ima_lsm_free_rule(nentry);
> > + nentry->fsname = NULL;
> > + nentry->keyrings = NULL;
> > + nentry->template = NULL;
> > + ima_free_rule(nentry);
>
> > return NULL;
> > }
> >
> > @@ -315,7 +344,7 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
> >
> > list_replace_rcu(&entry->list, &nentry->list);
> > synchronize_rcu();
> > - ima_lsm_free_rule(entry);
> > + ima_free_rule(entry);
>
> This should only update the LSM info, nothing else.
That's effectively what's happening since the fsname, keyrings, and
template pointers are being set to NULL, before exiting
ima_lsm_copy_rule(), in the ima_rule_entry that's going to be freed.
This patch is only introducing the function which can free all memory
associated with a rule and is starting to use it in place that a rule
entry is freed.
Would you rather me introduce ima_free_rule() for the upcoming memory
leak fixes in the series but not make use of it in
ima_lsm_update_rule()?
Tyler
>
> >
> > return 0;
> > }
next prev parent reply other threads:[~2020-06-25 19:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 0:32 [PATCH 00/12] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Tyler Hicks
2020-06-23 0:32 ` [PATCH 01/12] ima: Have the LSM free its audit rule Tyler Hicks
2020-06-23 0:55 ` Casey Schaufler
2020-06-23 3:04 ` Tyler Hicks
2020-06-23 23:04 ` Tyler Hicks
2020-06-25 19:41 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 02/12] ima: Create a function to free a rule entry Tyler Hicks
2020-06-25 19:33 ` Mimi Zohar
2020-06-25 19:56 ` Tyler Hicks [this message]
2020-06-25 20:32 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 03/12] ima: Free the entire rule when deleting a list of rules Tyler Hicks
2020-06-25 21:05 ` Mimi Zohar
2020-06-25 21:07 ` Mimi Zohar
2020-06-25 21:08 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 04/12] ima: Free the entire rule if it fails to parse Tyler Hicks
2020-06-23 0:32 ` [PATCH 05/12] ima: Fail rule parsing when buffer hook functions have an invalid action Tyler Hicks
2020-06-25 21:51 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 06/12] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond Tyler Hicks
2020-06-25 21:53 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 07/12] ima: Fail rule parsing when the KEY_CHECK " Tyler Hicks
2020-06-23 0:32 ` [PATCH 08/12] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements Tyler Hicks
2020-06-25 21:18 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 09/12] ima: Use correct type for " Tyler Hicks
2020-06-25 21:20 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 10/12] ima: Move validation of the keyrings conditional into ima_validate_rule() Tyler Hicks
2020-06-25 19:50 ` Tyler Hicks
2020-06-25 20:46 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 11/12] ima: Use the common function to detect LSM conditionals in a rule Tyler Hicks
2020-06-25 22:45 ` Mimi Zohar
2020-06-23 0:32 ` [PATCH 12/12] ima: Support additional conditionals in the KEXEC_CMDLINE hook function Tyler Hicks
2020-06-25 22:56 ` Mimi Zohar
2020-06-25 22:59 ` Tyler Hicks
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200625195647.GB4694@sequoia \
--to=tyhicks@linux.microsoft.com \
--cc=dmitry.kasatkin@gmail.com \
--cc=jmorris@namei.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=nramas@linux.microsoft.com \
--cc=prsriva02@gmail.com \
--cc=serge@hallyn.com \
--cc=zohar@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).