linux-kernel - RE: [PATCH 1/5] ima: Set file->f_mode instead of file->f_flags in ima_calc_file

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Message-ID: <d20f3ea6f2fe425bb8234b1bd5a2f6a9@huawei.com>
Date:   Wed, 22 Apr 2020 15:39:18 +0000
From:   Roberto Sassu <roberto.sassu@...wei.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
CC:     "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Krzysztof Struczynski <krzysztof.struczynski@...wei.com>,
        Silviu Vlasceanu <Silviu.Vlasceanu@...wei.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Goldwyn Rodrigues <rgoldwyn@...e.com>
Subject: RE: [PATCH 1/5] ima: Set file->f_mode instead of file->f_flags in
 ima_calc_file_hash()

> -----Original Message-----
> From: linux-integrity-owner@...r.kernel.org [mailto:linux-integrity-
> owner@...r.kernel.org] On Behalf Of Mimi Zohar
> Sent: Wednesday, April 22, 2020 2:03 PM
> To: Roberto Sassu <roberto.sassu@...wei.com>
> Cc: linux-integrity@...r.kernel.org; linux-security-module@...r.kernel.org;
> linux-kernel@...r.kernel.org; Krzysztof Struczynski
> <krzysztof.struczynski@...wei.com>; Silviu Vlasceanu
> <Silviu.Vlasceanu@...wei.com>; stable@...r.kernel.org; Goldwyn
> Rodrigues <rgoldwyn@...e.com>
> Subject: Re: [PATCH 1/5] ima: Set file->f_mode instead of file->f_flags in
> ima_calc_file_hash()
> 
> [CC'ing Goldwyn Rodrigues]
> 
> Hi Roberto,
> 
> On Wed, 2020-03-25 at 17:11 +0100, Roberto Sassu wrote:
> > Commit a408e4a86b36 ("ima: open a new file instance if no read
> > permissions") tries to create a new file descriptor to calculate a file
> > digest if the file has not been opened with O_RDONLY flag. However, if a
> > new file descriptor cannot be obtained, it sets the FMODE_READ flag to
> > file->f_flags instead of file->f_mode.
> >
> > This patch fixes this issue by replacing f_flags with f_mode as it was
> > before that commit.
> >
> > Cc: stable@...r.kernel.org # 4.20.x
> > Fixes: a408e4a86b36 ("ima: open a new file instance if no read
> permissions")
> > Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> > ---
> >  security/integrity/ima/ima_crypto.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/integrity/ima/ima_crypto.c
> b/security/integrity/ima/ima_crypto.c
> > index 423c84f95a14..8ab17aa867dd 100644
> > --- a/security/integrity/ima/ima_crypto.c
> > +++ b/security/integrity/ima/ima_crypto.c
> > @@ -436,7 +436,7 @@ int ima_calc_file_hash(struct file *file, struct
> ima_digest_data *hash)
> >  			 */
> 
> Thanks, Roberto.  The comment above here and the rest of the code
> refers to flags.  Both should be updated as well to reflect using
> f_mode.
> 
> >  			pr_info_ratelimited("Unable to reopen file for
> reading.\n");
> >  			f = file;
> > -			f->f_flags |= FMODE_READ;
> > +			f->f_mode |= FMODE_READ;
> >  			modified_flags = true;
> 
> The variable should be changed to "modified_mode".

Ok. I will send a new version of the patch.

Thanks

Roberto

HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Li Jian, Shi Yanli


> >  		} else {
> >  			new_file_instance = true;
> > @@ -456,7 +456,7 @@ int ima_calc_file_hash(struct file *file, struct
> ima_digest_data *hash)
> >  	if (new_file_instance)
> >  		fput(f);
> >  	else if (modified_flags)
> > -		f->f_flags &= ~FMODE_READ;
> > +		f->f_mode &= ~FMODE_READ;
> >  	return rc;
> >  }
> >