Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 292 insertions, 0 deletions

diff --git a/Documentation/admin-guide/module-signing.rst b/Documentation/admin-guide/module-signing.rst
new file mode 100644
index 000000000..7f2f127dc
--- /dev/null
+++ b/Documentation/admin-guide/module-signing.rst
@@ -0,0 +1,292 @@
+Kernel module signing facility
+------------------------------
+
+.. CONTENTS
+..
+.. - Overview.
+.. - Configuring module signing.
+.. - Generating signing keys.
+.. - Public keys in the kernel.
+.. - Manually signing modules.
+.. - Signed modules and stripping.
+.. - Loading signed modules.
+.. - Non-valid signatures and unsigned modules.
+.. - Administering/protecting the private key.
+
+
+========
+Overview
+========
+
+The kernel module signing facility cryptographically signs modules during
+installation and then checks the signature upon loading the module.  This
+allows increased kernel security by disallowing the loading of unsigned modules
+or modules signed with an invalid key.  Module signing increases security by
+making it harder to load a malicious module into the kernel.  The module
+signature checking is done by the kernel so that it is not necessary to have
+trusted userspace bits.
+
+This facility uses X.509 ITU-T standard certificates to encode the public keys
+involved.  The signatures are not themselves encoded in any industrial standard
+type.  The built-in facility currently only supports the RSA, NIST P-384 ECDSA
+and NIST FIPS-204 ML-DSA public key signing standards (though it is pluggable
+and permits others to be used).  For RSA and ECDSA, the possible hash
+algorithms that can be used are SHA-2 and SHA-3 of sizes 256, 384, and 512 (the
+algorithm is selected by data in the signature); ML-DSA does its own hashing,
+but is allowed to be used with a SHA512 hash for signed attributes.
+
+
+==========================
+Configuring module signing
+==========================
+
+The module signing facility is enabled by going to the
+:menuselection:`Enable Loadable Module Support` section of
+the kernel configuration and turning on::
+
+	CONFIG_MODULE_SIG	"Module signature verification"
+
+This has a number of options available:
+
+ (1) :menuselection:`Require modules to be validly signed`
+     (``CONFIG_MODULE_SIG_FORCE``)
+
+     This specifies how the kernel should deal with a module that has a
+     signature for which the key is not known or a module that is unsigned.
+
+     If this is off (ie. "permissive"), then modules for which the key is not
+     available and modules that are unsigned are permitted, but the kernel will
+     be marked as being tainted, and the concerned modules will be marked as
+     tainted, shown with the character 'E'.
+
+     If this is on (ie. "restrictive"), only modules that have a valid
+     signature that can be verified by a public key in the kernel's possession
+     will be loaded.  All other modules will generate an error.
+
+     Irrespective of the setting here, if the module has a signature block that
+     cannot be parsed, it will be rejected out of hand.
+
+
+ (2) :menuselection:`Automatically sign all modules`
+     (``CONFIG_MODULE_SIG_ALL``)
+
+     If this is on then modules will be automatically signed during the
+     modules_install phase of a build.  If this is off, then the modules must
+     be signed manually using::
+
+	scripts/sign-file
+
+
+ (3) :menuselection:`Which hash algorithm should modules be signed with?`
+
+     This presents a choice of which hash algorithm the installation phase will
+     sign the modules with:
+
+        =============================== ==========================================
+	``CONFIG_MODULE_SIG_SHA256``	:menuselection:`Sign modules with SHA-256`
+	``CONFIG_MODULE_SIG_SHA384``	:menuselection:`Sign modules with SHA-384`
+	``CONFIG_MODULE_SIG_SHA512``	:menuselection:`Sign modules with SHA-512`
+	``CONFIG_MODULE_SIG_SHA3_256``	:menuselection:`Sign modules with SHA3-256`
+	``CONFIG_MODULE_SIG_SHA3_384``	:menuselection:`Sign modules with SHA3-384`
+	``CONFIG_MODULE_SIG_SHA3_512``	:menuselection:`Sign modules with SHA3-512`
+        =============================== ==========================================
+
+     The algorithm selected here will also be built into the kernel (rather
+     than being a module) so that modules signed with that algorithm can have
+     their signatures checked without causing a dependency loop.
+
+
+ (4) :menuselection:`File name or PKCS#11 URI of module signing key`
+     (``CONFIG_MODULE_SIG_KEY``)
+
+     Setting this option to something other than its default of
+     ``certs/signing_key.pem`` will disable the autogeneration of signing keys
+     and allow the kernel modules to be signed with a key of your choosing.
+     The string provided should identify a file containing both a private key
+     and its corresponding X.509 certificate in PEM form, or — on systems where
+     the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI as defined by
+     RFC7512. In the latter case, the PKCS#11 URI should reference both a
+     certificate and a private key.
+
+     If the PEM file containing the private key is encrypted, or if the
+     PKCS#11 token requires a PIN, this can be provided at build time by
+     means of the ``KBUILD_SIGN_PIN`` variable.
+
+
+ (5) :menuselection:`Additional X.509 keys for default system keyring`
+     (``CONFIG_SYSTEM_TRUSTED_KEYS``)
+
+     This option can be set to the filename of a PEM-encoded file containing
+     additional certificates which will be included in the system keyring by
+     default.
+
+Note that enabling module signing adds a dependency on the OpenSSL devel
+packages to the kernel build processes for the tool that does the signing.
+
+
+=======================
+Generating signing keys
+=======================
+
+Cryptographic keypairs are required to generate and check signatures.  A
+private key is used to generate a signature and the corresponding public key is
+used to check it.  The private key is only needed during the build, after which
+it can be deleted or stored securely.  The public key gets built into the
+kernel so that it can be used to check the signatures as the modules are
+loaded.
+
+Under normal conditions, when ``CONFIG_MODULE_SIG_KEY`` is unchanged from its
+default, the kernel build will automatically generate a new keypair using
+openssl if one does not exist in the file::
+
+	certs/signing_key.pem
+
+during the building of vmlinux (the public part of the key needs to be built
+into vmlinux) using parameters in the::
+
+	certs/x509.genkey
+
+file (which is also generated if it does not already exist).
+
+One can select between RSA (``MODULE_SIG_KEY_TYPE_RSA``), ECDSA
+(``MODULE_SIG_KEY_TYPE_ECDSA``) and ML-DSA (``MODULE_SIG_KEY_TYPE_MLDSA_*``) to
+generate an RSA 4k, a NIST P-384 keypair or an ML-DSA 44, 65 or 87 keypair.
+
+It is strongly recommended that you provide your own x509.genkey file.
+
+Most notably, in the x509.genkey file, the req_distinguished_name section
+should be altered from the default::
+
+	[ req_distinguished_name ]
+	#O = Unspecified company
+	CN = Build time autogenerated kernel key
+	#emailAddress = unspecified.user@unspecified.company
+
+The generated RSA key size can also be set with::
+
+	[ req ]
+	default_bits = 4096
+
+
+It is also possible to manually generate the key private/public files using the
+x509.genkey key generation configuration file in the root node of the Linux
+kernel sources tree and the openssl command.  The following is an example to
+generate the public/private key files::
+
+	openssl req -new -nodes -utf8 -sha256 -days 36500 -batch -x509 \
+	   -config x509.genkey -outform PEM -out kernel_key.pem \
+	   -keyout kernel_key.pem
+
+The full pathname for the resulting kernel_key.pem file can then be specified
+in the ``CONFIG_MODULE_SIG_KEY`` option, and the certificate and key therein will
+be used instead of an autogenerated keypair.
+
+
+=========================
+Public keys in the kernel
+=========================
+
+The kernel contains a ring of public keys that can be viewed by root.  They're
+in a keyring called ".builtin_trusted_keys" that can be seen by::
+
+	[root@deneb ~]# cat /proc/keys
+	...
+	223c7853 I------     1 perm 1f030000     0     0 keyring   .builtin_trusted_keys: 1
+	302d2d52 I------     1 perm 1f010000     0     0 asymmetri Fedora kernel signing key: d69a84e6bce3d216b979e9505b3e3ef9a7118079: X509.RSA a7118079 []
+	...
+
+Beyond the public key generated specifically for module signing, additional
+trusted certificates can be provided in a PEM-encoded file referenced by the
+``CONFIG_SYSTEM_TRUSTED_KEYS`` configuration option.
+
+Further, the architecture code may take public keys from a hardware store and
+add those in also (e.g. from the UEFI key database).
+
+Finally, it is possible to add additional public keys by doing::
+
+	keyctl padd asymmetric "" [.builtin_trusted_keys-ID] <[key-file]
+
+e.g.::
+
+	keyctl padd asymmetric "" 0x223c7853 <my_public_key.x509
+
+Note, however, that the kernel will only permit keys to be added to
+``.builtin_trusted_keys`` **if** the new key's X.509 wrapper is validly signed by a key
+that is already resident in the ``.builtin_trusted_keys`` at the time the key was added.
+
+
+========================
+Manually signing modules
+========================
+
+To manually sign a module, use the scripts/sign-file tool available in
+the Linux kernel source tree.  The script requires 4 arguments:
+
+	1.  The hash algorithm (e.g., sha256)
+	2.  The private key filename or PKCS#11 URI
+	3.  The public key filename
+	4.  The kernel module to be signed
+
+The following is an example to sign a kernel module::
+
+	scripts/sign-file sha512 kernel-signkey.priv \
+		kernel-signkey.x509 module.ko
+
+The hash algorithm used does not have to match the one configured, but if it
+doesn't, you should make sure that hash algorithm is either built into the
+kernel or can be loaded without requiring itself.
+
+If the private key requires a passphrase or PIN, it can be provided in the
+$KBUILD_SIGN_PIN environment variable.
+
+
+============================
+Signed modules and stripping
+============================
+
+A signed module has a digital signature simply appended at the end.  The string
+``~Module signature appended~.`` at the end of the module's file confirms that a
+signature is present but it does not confirm that the signature is valid!
+
+Signed modules are BRITTLE as the signature is outside of the defined ELF
+container.  Thus they MAY NOT be stripped once the signature is computed and
+attached.  Note the entire module is the signed payload, including any and all
+debug information present at the time of signing.
+
+
+======================
+Loading signed modules
+======================
+
+Modules are loaded with insmod, modprobe, ``init_module()`` or
+``finit_module()``, exactly as for unsigned modules as no processing is
+done in userspace.  The signature checking is all done within the kernel.
+
+
+=========================================
+Non-valid signatures and unsigned modules
+=========================================
+
+If ``CONFIG_MODULE_SIG_FORCE`` is enabled or module.sig_enforce=1 is supplied on
+the kernel command line, the kernel will only load validly signed modules
+for which it has a public key.   Otherwise, it will also load modules that are
+unsigned.   Any module for which the kernel has a key, but which proves to have
+a signature mismatch will not be permitted to load.
+
+Any module that has an unparsable signature will be rejected.
+
+
+=========================================
+Administering/protecting the private key
+=========================================
+
+Since the private key is used to sign modules, viruses and malware could use
+the private key to sign modules and compromise the operating system.  The
+private key must be either destroyed or moved to a secure location and not kept
+in the root node of the kernel source tree.
+
+If you use the same private key to sign modules for multiple kernel
+configurations, you must ensure that the module version information is
+sufficient to prevent loading a module into a different kernel.  Either
+set ``CONFIG_MODVERSIONS=y`` or ensure that each configuration has a different
+kernel release string by changing ``EXTRAVERSION`` or ``CONFIG_LOCALVERSION``.