* [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash()
@ 2024-03-07 12:22 Roberto Sassu
2024-03-07 14:31 ` Seth Forshee
0 siblings, 1 reply; 4+ messages in thread
From: Roberto Sassu @ 2024-03-07 12:22 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, paul, jmorris, serge
Cc: linux-integrity, linux-security-module, linux-kernel,
Roberto Sassu, stable, linux-fsdevel, Christian Brauner,
Seth Forshee
From: Roberto Sassu <roberto.sassu@huawei.com>
Use __vfs_getxattr() instead of vfs_getxattr(), in preparation for
deprecating using the vfs_ interfaces for retrieving fscaps.
__vfs_getxattr() is only used for debugging purposes, to check if kernel
space and user space see the same xattr value.
Cc: stable@vger.kernel.org # 5.14.x
Cc: linux-fsdevel@vger.kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Fixes: 907a399de7b0 ("evm: Check xattr size discrepancy between kernel and user")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/evm/evm_crypto.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index b1ffd4cc0b44..168d98c63513 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -278,8 +278,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
if (size < 0)
continue;
- user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
- xattr->name, NULL, 0);
+ user_space_size = __vfs_getxattr(dentry, inode, xattr->name,
+ NULL, 0);
if (user_space_size != size)
pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
dentry->d_name.name, xattr->name, size,
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash()
2024-03-07 12:22 [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash() Roberto Sassu
@ 2024-03-07 14:31 ` Seth Forshee
2024-03-07 14:36 ` Roberto Sassu
0 siblings, 1 reply; 4+ messages in thread
From: Seth Forshee @ 2024-03-07 14:31 UTC (permalink / raw)
To: Roberto Sassu
Cc: zohar, dmitry.kasatkin, eric.snowberg, paul, jmorris, serge,
linux-integrity, linux-security-module, linux-kernel,
Roberto Sassu, stable, linux-fsdevel, Christian Brauner
On Thu, Mar 07, 2024 at 01:22:39PM +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Use __vfs_getxattr() instead of vfs_getxattr(), in preparation for
> deprecating using the vfs_ interfaces for retrieving fscaps.
>
> __vfs_getxattr() is only used for debugging purposes, to check if kernel
> space and user space see the same xattr value.
__vfs_getxattr() won't give you the value as seen by userspace though.
Userspace goes through vfs_getxattr() -> xattr_getsecurity() ->
cap_inode_getsecurity(), which does the conversion to the value
userspace sees. __vfs_getxattr() just gives the raw disk data.
I'm also currently working on changes to my fscaps series that will make
it so that __vfs_getxattr() also cannot be used to read fscaps xattrs.
I'll fix this and other code in EVM which will be broken by that change
as part of the next version too.
>
> Cc: stable@vger.kernel.org # 5.14.x
> Cc: linux-fsdevel@vger.kernel.org
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> Fixes: 907a399de7b0 ("evm: Check xattr size discrepancy between kernel and user")
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
> security/integrity/evm/evm_crypto.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
> index b1ffd4cc0b44..168d98c63513 100644
> --- a/security/integrity/evm/evm_crypto.c
> +++ b/security/integrity/evm/evm_crypto.c
> @@ -278,8 +278,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
> if (size < 0)
> continue;
>
> - user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
> - xattr->name, NULL, 0);
> + user_space_size = __vfs_getxattr(dentry, inode, xattr->name,
> + NULL, 0);
> if (user_space_size != size)
> pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
> dentry->d_name.name, xattr->name, size,
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash()
2024-03-07 14:31 ` Seth Forshee
@ 2024-03-07 14:36 ` Roberto Sassu
2024-03-07 15:02 ` Roberto Sassu
0 siblings, 1 reply; 4+ messages in thread
From: Roberto Sassu @ 2024-03-07 14:36 UTC (permalink / raw)
To: Seth Forshee
Cc: zohar, dmitry.kasatkin, eric.snowberg, paul, jmorris, serge,
linux-integrity, linux-security-module, linux-kernel,
Roberto Sassu, stable, linux-fsdevel, Christian Brauner
On Thu, 2024-03-07 at 08:31 -0600, Seth Forshee wrote:
> On Thu, Mar 07, 2024 at 01:22:39PM +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> >
> > Use __vfs_getxattr() instead of vfs_getxattr(), in preparation for
> > deprecating using the vfs_ interfaces for retrieving fscaps.
> >
> > __vfs_getxattr() is only used for debugging purposes, to check if kernel
> > space and user space see the same xattr value.
>
> __vfs_getxattr() won't give you the value as seen by userspace though.
> Userspace goes through vfs_getxattr() -> xattr_getsecurity() ->
> cap_inode_getsecurity(), which does the conversion to the value
> userspace sees. __vfs_getxattr() just gives the raw disk data.
>
> I'm also currently working on changes to my fscaps series that will make
> it so that __vfs_getxattr() also cannot be used to read fscaps xattrs.
> I'll fix this and other code in EVM which will be broken by that change
> as part of the next version too.
You are right, thank you!
Roberto
> >
> > Cc: stable@vger.kernel.org # 5.14.x
> > Cc: linux-fsdevel@vger.kernel.org
> > Cc: Christian Brauner <brauner@kernel.org>
> > Cc: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> > Fixes: 907a399de7b0 ("evm: Check xattr size discrepancy between kernel and user")
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > ---
> > security/integrity/evm/evm_crypto.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
> > index b1ffd4cc0b44..168d98c63513 100644
> > --- a/security/integrity/evm/evm_crypto.c
> > +++ b/security/integrity/evm/evm_crypto.c
> > @@ -278,8 +278,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
> > if (size < 0)
> > continue;
> >
> > - user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
> > - xattr->name, NULL, 0);
> > + user_space_size = __vfs_getxattr(dentry, inode, xattr->name,
> > + NULL, 0);
> > if (user_space_size != size)
> > pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
> > dentry->d_name.name, xattr->name, size,
> > --
> > 2.34.1
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash()
2024-03-07 14:36 ` Roberto Sassu
@ 2024-03-07 15:02 ` Roberto Sassu
0 siblings, 0 replies; 4+ messages in thread
From: Roberto Sassu @ 2024-03-07 15:02 UTC (permalink / raw)
To: Seth Forshee
Cc: zohar, dmitry.kasatkin, eric.snowberg, paul, jmorris, serge,
linux-integrity, linux-security-module, linux-kernel,
Roberto Sassu, stable, linux-fsdevel, Christian Brauner
On Thu, 2024-03-07 at 15:36 +0100, Roberto Sassu wrote:
> On Thu, 2024-03-07 at 08:31 -0600, Seth Forshee wrote:
> > On Thu, Mar 07, 2024 at 01:22:39PM +0100, Roberto Sassu wrote:
> > > From: Roberto Sassu <roberto.sassu@huawei.com>
> > >
> > > Use __vfs_getxattr() instead of vfs_getxattr(), in preparation for
> > > deprecating using the vfs_ interfaces for retrieving fscaps.
> > >
> > > __vfs_getxattr() is only used for debugging purposes, to check if kernel
> > > space and user space see the same xattr value.
> >
> > __vfs_getxattr() won't give you the value as seen by userspace though.
> > Userspace goes through vfs_getxattr() -> xattr_getsecurity() ->
> > cap_inode_getsecurity(), which does the conversion to the value
> > userspace sees. __vfs_getxattr() just gives the raw disk data.
> >
> > I'm also currently working on changes to my fscaps series that will make
> > it so that __vfs_getxattr() also cannot be used to read fscaps xattrs.
> > I'll fix this and other code in EVM which will be broken by that change
> > as part of the next version too.
>
> You are right, thank you!
(Apologies, I should have been more careful).
Roberto
> Roberto
>
> > >
> > > Cc: stable@vger.kernel.org # 5.14.x
> > > Cc: linux-fsdevel@vger.kernel.org
> > > Cc: Christian Brauner <brauner@kernel.org>
> > > Cc: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> > > Fixes: 907a399de7b0 ("evm: Check xattr size discrepancy between kernel and user")
> > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > > ---
> > > security/integrity/evm/evm_crypto.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
> > > index b1ffd4cc0b44..168d98c63513 100644
> > > --- a/security/integrity/evm/evm_crypto.c
> > > +++ b/security/integrity/evm/evm_crypto.c
> > > @@ -278,8 +278,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
> > > if (size < 0)
> > > continue;
> > >
> > > - user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
> > > - xattr->name, NULL, 0);
> > > + user_space_size = __vfs_getxattr(dentry, inode, xattr->name,
> > > + NULL, 0);
> > > if (user_space_size != size)
> > > pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
> > > dentry->d_name.name, xattr->name, size,
> > > --
> > > 2.34.1
> > >
^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-03-07 12:22 [PATCH] evm: Change vfs_getxattr() with __vfs_getxattr() in evm_calc_hmac_or_hash() Roberto Sassu
2024-03-07 14:31 ` Seth Forshee
2024-03-07 14:36 ` Roberto Sassu
2024-03-07 15:02 ` Roberto Sassu
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