[RFC PATCH] audit: Add generic compat syscall support

[AKASHI Takahiro]

To: Eric, Al

Could you please give me your comments on my patch below?
I don't think this patch breaks anything on existing architectures
which support audit.

If you don't prefer the way, I'm going to keep the code
arm64-specific to support audit on AArch64(arm64) as in
my old patch series.:
https://www.redhat.com/archives/linux-audit/2013-November/msg00040.html

Thank you,
-Takahiro AKASHI

On 11/19/2013 04:33 PM, AKASHI Takahiro wrote:
> lib/audit.c provides a generic definition for auditing system calls.
> lib/compat_audit.c similarly adds compat syscall support for
> bi-architectures (32/64-bit).
>
> Each architecture must define audit_is_compat() in asm/audit.h.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
>   include/linux/audit.h |    3 +++
>   lib/Makefile          |    3 +++
>   lib/audit.c           |   10 ++++++++
>   lib/compat_audit.c    |   64 +++++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 80 insertions(+)
>   create mode 100644 lib/compat_audit.c
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 729a4d1..f6c8d18 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -75,6 +75,9 @@ struct audit_field {
>
>   extern int __init audit_register_class(int class, unsigned *list);
>   extern int audit_classify_syscall(int abi, unsigned syscall);
> +#ifdef CONFIG_COMPAT
> +extern int audit_classify_compat_syscall(int abi, unsigned syscall);
> +#endif
>   extern int audit_classify_arch(int arch);
>
>   /* audit_names->type values */
> diff --git a/lib/Makefile b/lib/Makefile
> index f3bb2cb..5bb185a 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -96,6 +96,9 @@ obj-$(CONFIG_TEXTSEARCH_BM) += ts_bm.o
>   obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o
>   obj-$(CONFIG_SMP) += percpu_counter.o
>   obj-$(CONFIG_AUDIT_GENERIC) += audit.o
> +ifeq ($(CONFIG_COMPAT),y)
> +obj-$(CONFIG_AUDIT_GENERIC) += compat_audit.o
> +endif
>
>   obj-$(CONFIG_SWIOTLB) += swiotlb.o
>   obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
> diff --git a/lib/audit.c b/lib/audit.c
> index 76bbed4..fa373bd 100644
> --- a/lib/audit.c
> +++ b/lib/audit.c
> @@ -1,6 +1,7 @@
>   #include <linux/init.h>
>   #include <linux/types.h>
>   #include <linux/audit.h>
> +#include <asm/audit.h>
>   #include <asm/unistd.h>
>
>   static unsigned dir_class[] = {
> @@ -30,11 +31,20 @@ static unsigned signal_class[] = {
>
>   int audit_classify_arch(int arch)
>   {
> +#ifdef CONFIG_COMPAT
> +	if (audit_is_compat(arch))
> +		return 1;
> +#endif
>   	return 0;
>   }
>
>   int audit_classify_syscall(int abi, unsigned syscall)
>   {
> +#ifdef CONFIG_COMPAT
> +	if (audit_is_compat(abi))
> +		return audit_classify_compat_syscall(abi, syscall);
> +#endif
> +
>   	switch(syscall) {
>   #ifdef __NR_open
>   	case __NR_open:
> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
> new file mode 100644
> index 0000000..837a6e6
> --- /dev/null
> +++ b/lib/compat_audit.c
> @@ -0,0 +1,64 @@
> +#include <linux/init.h>
> +#include <linux/types.h>
> +#include <linux/audit.h>
> +/* FIXME: this might be architecture dependent */
> +#include <asm/unistd_32.h>
> +
> +static unsigned compat_dir_class[] = {
> +#include <asm-generic/audit_dir_write.h>
> +~0U
> +};
> +
> +static unsigned compat_read_class[] = {
> +#include <asm-generic/audit_read.h>
> +~0U
> +};
> +
> +static unsigned compat_write_class[] = {
> +#include <asm-generic/audit_write.h>
> +~0U
> +};
> +
> +static unsigned compat_chattr_class[] = {
> +#include <asm-generic/audit_change_attr.h>
> +~0U
> +};
> +
> +static unsigned compat_signal_class[] = {
> +#include <asm-generic/audit_signal.h>
> +~0U
> +};
> +
> +int audit_classify_compat_syscall(int abi, unsigned syscall)
> +{
> +	switch(syscall) {
> +#ifdef __NR_open
> +	case __NR_open:
> +		return 2;
> +#endif
> +#ifdef __NR_openat
> +	case __NR_openat:
> +		return 3;
> +#endif
> +#ifdef __NR_socketcall
> +	case __NR_socketcall:
> +		return 4;
> +#endif
> +	case __NR_execve:
> +		return 5;
> +	default:
> +		return 1;
> +	}
> +}
> +
> +static int __init audit_compat_classes_init(void)
> +{
> +	audit_register_class(AUDIT_CLASS_WRITE, compat_write_class);
> +	audit_register_class(AUDIT_CLASS_READ, compat_read_class);
> +	audit_register_class(AUDIT_CLASS_DIR_WRITE, compat_dir_class);
> +	audit_register_class(AUDIT_CLASS_CHATTR, compat_chattr_class);
> +	audit_register_class(AUDIT_CLASS_SIGNAL, compat_signal_class);
> +	return 0;
> +}
> +
> +__initcall(audit_compat_classes_init);
>