linux-kernel - Re: [PATCH] KEYS: encrypted: Add check for strsep

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Date: Wed, 24 Jan 2024 14:15:06 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: "Verma, Vishal L" <vishal.l.verma@...el.com>,
        "paul@...l-moore.com"
	 <paul@...l-moore.com>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "dhowells@...hat.com"
	 <dhowells@...hat.com>,
        "yaelt@...gle.com" <yaelt@...gle.com>,
        "serge@...lyn.com"
	 <serge@...lyn.com>,
        "nichen@...as.ac.cn" <nichen@...as.ac.cn>,
        "sumit.garg@...aro.org"
	 <sumit.garg@...aro.org>,
        "jmorris@...ei.org" <jmorris@...ei.org>
Cc: "Jiang, Dave" <dave.jiang@...el.com>,
        "linux-integrity@...r.kernel.org"
 <linux-integrity@...r.kernel.org>,
        "linux-cxl@...r.kernel.org"
 <linux-cxl@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
 <linux-kernel@...r.kernel.org>,
        "Williams, Dan J"
 <dan.j.williams@...el.com>,
        "keyrings@...r.kernel.org"
 <keyrings@...r.kernel.org>,
        "linux-security-module@...r.kernel.org"
 <linux-security-module@...r.kernel.org>,
        "nvdimm@...ts.linux.dev"
 <nvdimm@...ts.linux.dev>
Subject: Re: [PATCH] KEYS: encrypted: Add check for strsep

On Wed, 2024-01-24 at 18:21 +0000, Verma, Vishal L wrote:
> On Wed, 2023-11-08 at 07:36 +0000, Chen Ni wrote:
> > Add check for strsep() in order to transfer the error.
> > 
> > Fixes: cd3bc044af48 ("KEYS: encrypted: Instantiate key with user-
> > provided decrypted data")
> > Signed-off-by: Chen Ni <nichen@...as.ac.cn>
> > ---
> >  security/keys/encrypted-keys/encrypted.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/security/keys/encrypted-keys/encrypted.c
> > b/security/keys/encrypted-keys/encrypted.c
> > index 8af2136069d2..76f55dd13cb8 100644
> > --- a/security/keys/encrypted-keys/encrypted.c
> > +++ b/security/keys/encrypted-keys/encrypted.c
> > @@ -237,6 +237,10 @@ static int datablob_parse(char *datablob, const
> > char **format,
> >  			break;
> >  		}
> >  		*decrypted_data = strsep(&datablob, " \t");
> > +		if (!*decrypted_data) {
> > +			pr_info("encrypted_key: decrypted_data is
> > missing\n");
> > +			break;
> > +		}
> 
> Hello,
> 
> This patch seems to break keyring usage in CXL and NVDIMM, with the
> "decrypted_data is missing" error path being hit. Reverting this commit
> fixes the tests. I'm not sure if there are valid scenarios where this is
> expected to be empty?
> 
> Here's an strace snippet of where the error occurs:
> 
>    keyctl(KEYCTL_SEARCH, KEY_SPEC_USER_KEYRING, "user", "nvdimm-master", 0) = 76300785
>    openat(AT_FDCWD, "/sys/devices/platform/cxl_acpi.0/root0/nvdimm-bridge0/ndbus0/nmem0/state", O_RDONLY|O_CLOEXEC) = 3
>    read(3, "idle\n", 1024)                 = 5
>    close(3)                                = 0
>    keyctl(KEYCTL_SEARCH, KEY_SPEC_USER_KEYRING, "encrypted", "nvdimm:0", 0) = -1 ENOKEY (Required key not available)
>    uname({sysname="Linux", nodename="fedora", ...}) = 0
>    newfstatat(AT_FDCWD, "/etc/ndctl/keys/nvdimm_0_fedora.blob", 0x7fff23fbc210, 0) = -1 ENOENT (No such file or directory)
>    add_key("encrypted", "nvdimm:0", "new enc32 user:nvdimm-master 32", 31, KEY_SPEC_USER_KEYRING) = -1 EINVAL (Invalid argument)


Indeed!  The user-provided decrypted data should be optional.   The change needs
to be reverted.

thanks,

Mimi