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

From: Richard Guy Briggs
Date: Sun Mar 16 2014 - 15:14:36 EST

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@xxxxxxxxxx>

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>

> ---
> 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@xxxxxxxxxx>
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
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