| Message ID | 20220429112601.1421947-8-zohar@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ima: support fs-verity digests and signatures | expand |
On 4/29/22 07:26, Mimi Zohar wrote: > Update the fsverity documentation related to IMA signature support. > > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> > --- > Documentation/filesystems/fsverity.rst | 35 +++++++++++++++++--------- > 1 file changed, 23 insertions(+), 12 deletions(-) > > diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst > index 8cc536d08f51..b7d42fd65e9d 100644 > --- a/Documentation/filesystems/fsverity.rst > +++ b/Documentation/filesystems/fsverity.rst > @@ -70,12 +70,23 @@ must live on a read-write filesystem because they are independently > updated and potentially user-installed, so dm-verity cannot be used. > > The base fs-verity feature is a hashing mechanism only; actually > -authenticating the files is up to userspace. However, to meet some > -users' needs, fs-verity optionally supports a simple signature > -verification mechanism where users can configure the kernel to require > -that all fs-verity files be signed by a key loaded into a keyring; see > -`Built-in signature verification`_. Support for fs-verity file hashes > -in IMA (Integrity Measurement Architecture) policies is also planned. > +authenticating the files may be done by: > + > +* Userspace-only > + > +* Builtin signature verification + userspace policy > + > + fs-verity optionally supports a simple signature verification > + mechanism where users can configure the kernel to require that > + all fs-verity files be signed by a key loaded into a keyring; > + see `Built-in signature verification`_. > + > +* Integrity Measurement Architecture (IMA) > + > + IMA supports including fs-verity file digests and signatures in the > + IMA measurement list and verifying fs-verity based file signatures > + stored as security.ima xattrs, based on policy. > + > > User API > ======== > @@ -653,12 +664,12 @@ weren't already directly answered in other parts of this document. > hashed and what to do with those hashes, such as log them, > authenticate them, or add them to a measurement list. > > - IMA is planned to support the fs-verity hashing mechanism as an > - alternative to doing full file hashes, for people who want the > - performance and security benefits of the Merkle tree based hash. > - But it doesn't make sense to force all uses of fs-verity to be > - through IMA. As a standalone filesystem feature, fs-verity > - already meets many users' needs, and it's testable like other > + IMA supports the fs-verity hashing mechanism as an alternative > + to full file hashes, for those who want the performance and > + security benefits of the Merkle tree based hash. However, it > + doesn't make sense to force all uses of fs-verity to be through > + IMA. fs-verity already meets many users' needs even as a > + standalone filesystem feature, and it's testable like other > filesystem features e.g. with xfstests. > > :Q: Isn't fs-verity useless because the attacker can just modify the Acked-by: Stefan Berger <stefanb@linux.ibm.com>
diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst index 8cc536d08f51..b7d42fd65e9d 100644 --- a/Documentation/filesystems/fsverity.rst +++ b/Documentation/filesystems/fsverity.rst @@ -70,12 +70,23 @@ must live on a read-write filesystem because they are independently updated and potentially user-installed, so dm-verity cannot be used. The base fs-verity feature is a hashing mechanism only; actually -authenticating the files is up to userspace. However, to meet some -users' needs, fs-verity optionally supports a simple signature -verification mechanism where users can configure the kernel to require -that all fs-verity files be signed by a key loaded into a keyring; see -`Built-in signature verification`_. Support for fs-verity file hashes -in IMA (Integrity Measurement Architecture) policies is also planned. +authenticating the files may be done by: + +* Userspace-only + +* Builtin signature verification + userspace policy + + fs-verity optionally supports a simple signature verification + mechanism where users can configure the kernel to require that + all fs-verity files be signed by a key loaded into a keyring; + see `Built-in signature verification`_. + +* Integrity Measurement Architecture (IMA) + + IMA supports including fs-verity file digests and signatures in the + IMA measurement list and verifying fs-verity based file signatures + stored as security.ima xattrs, based on policy. + User API ======== @@ -653,12 +664,12 @@ weren't already directly answered in other parts of this document. hashed and what to do with those hashes, such as log them, authenticate them, or add them to a measurement list. - IMA is planned to support the fs-verity hashing mechanism as an - alternative to doing full file hashes, for people who want the - performance and security benefits of the Merkle tree based hash. - But it doesn't make sense to force all uses of fs-verity to be - through IMA. As a standalone filesystem feature, fs-verity - already meets many users' needs, and it's testable like other + IMA supports the fs-verity hashing mechanism as an alternative + to full file hashes, for those who want the performance and + security benefits of the Merkle tree based hash. However, it + doesn't make sense to force all uses of fs-verity to be through + IMA. fs-verity already meets many users' needs even as a + standalone filesystem feature, and it's testable like other filesystem features e.g. with xfstests. :Q: Isn't fs-verity useless because the attacker can just modify the
Update the fsverity documentation related to IMA signature support. Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> --- Documentation/filesystems/fsverity.rst | 35 +++++++++++++++++--------- 1 file changed, 23 insertions(+), 12 deletions(-)