Re: [PATCH_v5] audit: Add generic compat syscall support

[Richard Guy Briggs <rgb@redhat.com>]

On 14/03/15, AKASHI Takahiro wrote:
> lib/audit.c provides a generic function for auditing system calls.
> This patch extends it for compat syscall support on bi-architectures
> (32/64-bit) by adding lib/compat_audit.c.
> What is required to support this feature are:
>  * add asm/unistd32.h for compat system call names
>  * select CONFIG_AUDIT_ARCH_COMPAT_GENERIC
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>

> ---
>  include/linux/audit.h      |  8 ++++++++
>  include/uapi/linux/audit.h |  6 ++++++
>  lib/Kconfig                |  9 +++++++++
>  lib/Makefile               |  1 +
>  lib/audit.c                | 15 +++++++++++++-
>  lib/compat_audit.c         | 50 ++++++++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 88 insertions(+), 1 deletion(-)
>  create mode 100644 lib/compat_audit.c
> 
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index aa865a9..85f0503 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -78,6 +78,14 @@ extern int is_audit_feature_set(int which);
>  extern int __init audit_register_class(int class, unsigned *list);
>  extern int audit_classify_syscall(int abi, unsigned syscall);
>  extern int audit_classify_arch(int arch);
> +/* only for compat system calls */
> +extern unsigned compat_write_class[];
> +extern unsigned compat_read_class[];
> +extern unsigned compat_dir_class[];
> +extern unsigned compat_chattr_class[];
> +extern unsigned compat_signal_class[];
> +
> +extern int __weak audit_classify_compat_syscall(int abi, unsigned syscall);
>  
>  /* audit_names->type values */
>  #define	AUDIT_TYPE_UNKNOWN	0	/* we don't know yet */
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index 2d48fe1..624df43 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -361,6 +361,12 @@ enum {
>  #define AUDIT_ARCH_SPARC64	(EM_SPARCV9|__AUDIT_ARCH_64BIT)
>  #define AUDIT_ARCH_X86_64	(EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
>  
> +#ifdef CONFIG_COMPAT
> +#define audit_is_compat(arch)	(!((arch) & __AUDIT_ARCH_64BIT))
> +#else
> +#define audit_is_compat(arch)	false
> +#endif
> +
>  #define AUDIT_PERM_EXEC		1
>  #define AUDIT_PERM_WRITE	2
>  #define AUDIT_PERM_READ		4
> diff --git a/lib/Kconfig b/lib/Kconfig
> index 991c98b..1e80cb3 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -182,6 +182,15 @@ config AUDIT_GENERIC
>  	depends on AUDIT && !AUDIT_ARCH
>  	default y
>  
> +config AUDIT_ARCH_COMPAT_GENERIC
> +	bool
> +	default n
> +
> +config AUDIT_COMPAT_GENERIC
> +	bool
> +	depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
> +	default y
> +
>  config RANDOM32_SELFTEST
>  	bool "PRNG perform self test on init"
>  	default n
> diff --git a/lib/Makefile b/lib/Makefile
> index 48140e3..0cd7b68 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -96,6 +96,7 @@ 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
> +obj-$(CONFIG_AUDIT_COMPAT_GENERIC) += compat_audit.o
>  
>  obj-$(CONFIG_SWIOTLB) += swiotlb.o
>  obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
> diff --git a/lib/audit.c b/lib/audit.c
> index 76bbed4..1d726a2 100644
> --- a/lib/audit.c
> +++ b/lib/audit.c
> @@ -30,11 +30,17 @@ static unsigned signal_class[] = {
>  
>  int audit_classify_arch(int arch)
>  {
> -	return 0;
> +	if (audit_is_compat(arch))
> +		return 1;
> +	else
> +		return 0;
>  }
>  
>  int audit_classify_syscall(int abi, unsigned syscall)
>  {
> +	if (audit_is_compat(abi))
> +		return audit_classify_compat_syscall(abi, syscall);
> +
>  	switch(syscall) {
>  #ifdef __NR_open
>  	case __NR_open:
> @@ -57,6 +63,13 @@ int audit_classify_syscall(int abi, unsigned syscall)
>  
>  static int __init audit_classes_init(void)
>  {
> +#ifdef CONFIG_AUDIT_COMPAT_GENERIC
> +	audit_register_class(AUDIT_CLASS_WRITE_32, compat_write_class);
> +	audit_register_class(AUDIT_CLASS_READ_32, compat_read_class);
> +	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, compat_dir_class);
> +	audit_register_class(AUDIT_CLASS_CHATTR_32, compat_chattr_class);
> +	audit_register_class(AUDIT_CLASS_SIGNAL_32, compat_signal_class);
> +#endif
>  	audit_register_class(AUDIT_CLASS_WRITE, write_class);
>  	audit_register_class(AUDIT_CLASS_READ, read_class);
>  	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
> diff --git a/lib/compat_audit.c b/lib/compat_audit.c
> new file mode 100644
> index 0000000..873f75b
> --- /dev/null
> +++ b/lib/compat_audit.c
> @@ -0,0 +1,50 @@
> +#include <linux/init.h>
> +#include <linux/types.h>
> +#include <asm/unistd32.h>
> +
> +unsigned compat_dir_class[] = {
> +#include <asm-generic/audit_dir_write.h>
> +~0U
> +};
> +
> +unsigned compat_read_class[] = {
> +#include <asm-generic/audit_read.h>
> +~0U
> +};
> +
> +unsigned compat_write_class[] = {
> +#include <asm-generic/audit_write.h>
> +~0U
> +};
> +
> +unsigned compat_chattr_class[] = {
> +#include <asm-generic/audit_change_attr.h>
> +~0U
> +};
> +
> +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;
> +	}
> +}
> -- 
> 1.8.3.2
> 

- RGB

--
Richard Guy Briggs <rbriggs@redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545