[PATCH 7/7] keys: Add tracepoints for the keyrings facility

[Justin Stitt]

Hi,

On Wed, Aug 21, 2024 at 01:36:15PM GMT, David Howells wrote:
> Add some tracepoints to aid in debuggin the keyrings facility and
> applications that use it.  A number of events and operations are traceable,
> including:
> 
>   - Allocation
>   - Refcounting
>   - Instantiation and negative instantiation/rejection
>   - Update
>   - Detection of key being dead
>   - Key quota changes
>   - Key quota failure
>   - Link, unlink and move
>   - Keyring clearance
>   - Revocation and invalidation
>   - Garbage collection
> 
> Signed-off-by: David Howells <dhowells at redhat.com>
> cc: Jarkko Sakkinen <jarkko at kernel.org>
> cc: keyrings at vger.kernel.org
> cc: linux-security-module at vger.kernel.org
> ---
>  include/trace/events/key.h | 401 +++++++++++++++++++++++++++++++++++++
>  security/keys/gc.c         |   4 +
>  security/keys/internal.h   |   1 +
>  security/keys/key.c        |  50 ++++-
>  security/keys/keyctl.c     |   2 +
>  security/keys/keyring.c    |  27 ++-
>  6 files changed, 472 insertions(+), 13 deletions(-)
>  create mode 100644 include/trace/events/key.h
> 
> diff --git a/include/trace/events/key.h b/include/trace/events/key.h
> new file mode 100644
> index 000000000000..b3f8c39cc0e8
> --- /dev/null
> +++ b/include/trace/events/key.h
> @@ -0,0 +1,401 @@

<snip>

> +	    TP_STRUCT__entry(
> +		    __field(key_serial_t,		key)
> +		    __field(uid_t,			uid)
> +		    __array(char,			type, 8)
> +		    __array(char,			desc, 24)
> +			     ),
> +
> +	    TP_fast_assign(
> +		    __entry->key = key->serial;
> +		    __entry->uid = from_kuid(&init_user_ns, key->uid);
> +		    strncpy(__entry->type, key->type->name, sizeof(__entry->type) - 1);
> +		    strncpy(__entry->desc, key->description ?: "", sizeof(__entry->desc) - 1);
> +		    __entry->type[sizeof(__entry->type) - 1] = 0;
> +		    __entry->desc[sizeof(__entry->desc) - 1] = 0;

Looks like these want to be NUL-terminated. Can we use strscpy or
strscpy_pad since strncpy is deprecated [1] for use on NUL-terminated
strings.

> +			   ),
> +
> +	    TP_printk("key=%08x uid=%08x t=%s d=%s",
> +		      __entry->key,
> +		      __entry->uid,
> +		      __entry->type,
> +		      __entry->desc)
> +	    );
> +

<snip>

[1]: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings

Thanks
Justin