linux-kernel - Re: [PATCH] ima: use full pathnames in measurement list

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Date:	Wed, 27 Jun 2012 14:18:40 +0300
From:	"Kasatkin, Dmitry" <dmitry.kasatkin@...el.com>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	James Morris <jmorris@...ei.org>,
	linux-security-module <linux-security-module@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ima: use full pathnames in measurement list

On Mon, Jun 25, 2012 at 1:45 PM, Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
> On Mon, 2012-06-25 at 12:29 +1000, James Morris wrote:
>> On Fri, 22 Jun 2012, Mimi Zohar wrote:
>>
>> > The IMA measurement list contains filename hints, which can be
>> > ambigious without the full pathname.  This patch replaces the
>> > filename hint with the full pathname, simplifying for userspace
>> > the correlating of file hash measurements with files.
>> >
>> > Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
>>
>> Are you posting this for review or do you want it applied to my tree?
>
> It was posted for review, but both are good.
>
> thanks,
>
> Mimi
>
>> > ---
>> >  security/integrity/ima/ima_main.c |   40 +++++++++++++++++++++++++++++++-----
>> >  1 files changed, 34 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
>> > index b17be79..91fa323 100644
>> > --- a/security/integrity/ima/ima_main.c
>> > +++ b/security/integrity/ima/ima_main.c
>> > @@ -54,6 +54,7 @@ static void ima_rdwr_violation_check(struct file *file)
>> >     fmode_t mode = file->f_mode;
>> >     int rc;
>> >     bool send_tomtou = false, send_writers = false;
>> > +   unsigned char *pathname = NULL, *pathbuf = NULL;
>> >
>> >     if (!S_ISREG(inode->i_mode) || !ima_initialized)
>> >             return;
>> > @@ -75,12 +76,25 @@ static void ima_rdwr_violation_check(struct file *file)
>> >  out:
>> >     mutex_unlock(&inode->i_mutex);
>> >
>> > +   if (!send_tomtou && !send_writers)
>> > +           return;
>> > +
>> > +   /* We will allow 11 spaces for ' (deleted)' to be appended */
>> > +   pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
>> > +   if (pathbuf) {
>> > +           pathname = d_path(&file->f_path, pathbuf, PATH_MAX + 11);
>> > +           if (IS_ERR(pathname))
>> > +                   pathname = NULL;
>> > +   }
>> >     if (send_tomtou)
>> > -           ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
>> > -                             "ToMToU");
>> > +           ima_add_violation(inode,
>> > +                             !pathname ? dentry->d_name.name : pathname,
>> > +                             "invalid_pcr", "ToMToU");
>> >     if (send_writers)
>> > -           ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
>> > -                             "open_writers");
>> > +           ima_add_violation(inode,
>> > +                             !pathname ? dentry->d_name.name : pathname,
>> > +                             "invalid_pcr", "open_writers");
>> > +   kfree(pathbuf);
>> >  }
>> >
>> >  static void ima_check_last_writer(struct integrity_iint_cache *iint,
>> > @@ -123,6 +137,7 @@ static int process_measurement(struct file *file, const unsigned char *filename,
>> >  {
>> >     struct inode *inode = file->f_dentry->d_inode;
>> >     struct integrity_iint_cache *iint;
>> > +   unsigned char *pathname = NULL, *pathbuf = NULL;
>> >     int rc = 0;
>> >
>> >     if (!ima_initialized || !S_ISREG(inode->i_mode))
>> > @@ -147,8 +162,21 @@ retry:
>> >             goto out;
>> >
>> >     rc = ima_collect_measurement(iint, file);
>> > -   if (!rc)
>> > -           ima_store_measurement(iint, file, filename);
>> > +   if (rc != 0)
>> > +           goto out;
>> > +
>> > +   if (function != BPRM_CHECK) {
>> > +           /* We will allow 11 spaces for ' (deleted)' to be appended */
>> > +           pathbuf = kmalloc(PATH_MAX + 11, GFP_KERNEL);
>> > +           if (pathbuf) {
>> > +                   pathname =
>> > +                       d_path(&file->f_path, pathbuf, PATH_MAX + 11);
>> > +                   if (IS_ERR(pathname))
>> > +                           pathname = NULL;
>> > +           }
>> > +   }
>> > +   ima_store_measurement(iint, file, !pathname ? filename : pathname);


ima_store_measurement() has such line:

strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);

It might happens to copy beginning of the path....

- Dmitry

>> > +   kfree(pathbuf);
>> >  out:
>> >     mutex_unlock(&iint->mutex);
>> >     return rc;
>> > --
>> > 1.7.7.6
>> >
>> >
>> >
>> > --
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>> > the body of a message to majordomo@...r.kernel.org
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>> >
>>
>
>
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