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

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Date: Wed, 24 Jan 2024 20:10:06 +0000
From: "Verma, Vishal L" <vishal.l.verma@...el.com>
To: "zohar@...ux.ibm.com" <zohar@...ux.ibm.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 14:15 -0500, Mimi Zohar wrote:
> 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.
> 
Ah, thanks for confirming! Would you like me to send a revert patch or
will you do it?

Thanks,
Vishal