[PATCH v2] lsm_audit,selinux: pass IB device name by reference

[Richard Guy Briggs]

On 2021-05-12 16:32, Ondrej Mosnacek wrote:
> While trying to address a Coverity warning that the dev_name string
> might end up unterminated when strcpy'ing it in
> selinux_ib_endport_manage_subnet(), I realized that it is possible (and
> simpler) to just pass the dev_name pointer directly, rather than copying
> the string to a buffer.
> 
> The ibendport variable goes out of scope at the end of the function
> anyway, so the lifetime of the dev_name pointer will never be shorter
> than that of ibendport, thus we can safely just pass the dev_name
> pointer and be done with it.

Agreed, this is better (other than the unrelated whitespace changes).

> Signed-off-by: Ondrej Mosnacek <omosnace at redhat.com>

Acked-by: Richard Guy Briggs <rgb at redhat.com>

> ---
>  include/linux/lsm_audit.h | 8 ++++----
>  security/selinux/hooks.c  | 2 +-
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> v2: just pass the dev_name pointer and avoid the string copy
> 
> v1:
> https://lore.kernel.org/selinux/20210507130445.145457-1-omosnace@redhat.com/T/
> 
> diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
> index cd23355d2271..17d02eda9538 100644
> --- a/include/linux/lsm_audit.h
> +++ b/include/linux/lsm_audit.h
> @@ -48,13 +48,13 @@ struct lsm_ioctlop_audit {
>  };
>  
>  struct lsm_ibpkey_audit {
> -	u64	subnet_prefix;
> -	u16	pkey;
> +	u64 subnet_prefix;
> +	u16 pkey;
>  };
>  
>  struct lsm_ibendport_audit {
> -	char	dev_name[IB_DEVICE_NAME_MAX];
> -	u8	port;
> +	const char *dev_name;
> +	u8 port;
>  };
>  
>  /* Auxiliary data to use in generating the audit record. */
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 92f909a2e8f7..4d9764dad18f 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6864,7 +6864,7 @@ static int selinux_ib_endport_manage_subnet(void *ib_sec, const char *dev_name,
>  		return err;
>  
>  	ad.type = LSM_AUDIT_DATA_IBENDPORT;
> -	strncpy(ibendport.dev_name, dev_name, sizeof(ibendport.dev_name));
> +	ibendport.dev_name = dev_name;
>  	ibendport.port = port_num;
>  	ad.u.ibendport = &ibendport;
>  	return avc_has_perm(&selinux_state,
> -- 
> 2.31.1
> 
> --
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> Linux-audit at redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-audit

- RGB

--
Richard Guy Briggs <rgb at redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635