[PATCH] audit syscall classes

Allow to tie upper bits of syscall bitmap in audit rules to kernel-defined
sets of syscalls.  Infrastructure, a couple of classes (with 32bit counterparts
for biarch targets) and actual tie-in on i386, amd64 and ia64.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/i386/kernel/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_VM86)		+= vm86.o
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_HPET_TIMER) 	+= hpet.o
 obj-$(CONFIG_K8_NB)		+= k8.o
+obj-$(CONFIG_AUDIT)		+= audit.o
 
 EXTRA_AFLAGS   := -traditional
 

arch/i386/kernel/audit.c

+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/audit.h>
+#include <asm/unistd.h>
+
+static unsigned dir_class[] = {
+#include <asm-generic/audit_dir_write.h>
+~0U
+};
+
+static unsigned chattr_class[] = {
+#include <asm-generic/audit_change_attr.h>
+~0U
+};
+
+static int __init audit_classes_init(void)
+{
+	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
+	audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
+	return 0;
+}
+
+__initcall(audit_classes_init);

arch/ia64/ia32/Makefile

@@ -4,6 +4,7 @@
 
 obj-y := ia32_entry.o sys_ia32.o ia32_signal.o \
 	 ia32_support.o ia32_traps.o binfmt_elf32.o ia32_ldt.o
+obj-$(CONFIG_AUDIT) += audit.o
 
 # Don't let GCC uses f16-f31 so that save_ia32_fpstate_live() and
 # restore_ia32_fpstate_live() can be sure the live register contain user-level state.

arch/ia64/ia32/audit.c

+#include <asm-i386/unistd.h>
+
+unsigned ia32_dir_class[] = {
+#include <asm-generic/audit_dir_write.h>
+~0U
+};
+
+unsigned ia32_chattr_class[] = {
+#include <asm-generic/audit_change_attr.h>
+~0U
+};

arch/ia64/kernel/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_CPU_FREQ)		+= cpufreq/
 obj-$(CONFIG_IA64_MCA_RECOVERY)	+= mca_recovery.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o jprobes.o
 obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR)	+= uncached.o
+obj-$(CONFIG_AUDIT)		+= audit.o
 mca_recovery-y			+= mca_drv.o mca_drv_asm.o
 
 # The gate DSO image is built using a special linker script.

arch/ia64/kernel/audit.c

+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/audit.h>
+#include <asm/unistd.h>
+
+static unsigned dir_class[] = {
+#include <asm-generic/audit_dir_write.h>
+~0U
+};
+
+static unsigned chattr_class[] = {
+#include <asm-generic/audit_change_attr.h>
+~0U
+};
+
+static int __init audit_classes_init(void)
+{
+#ifdef CONFIG_IA32_SUPPORT
+	extern __u32 ia32_dir_class[];
+	extern __u32 ia32_chattr_class[];
+	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);
+	audit_register_class(AUDIT_CLASS_CHATTR_32, ia32_chattr_class);
+#endif
+	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
+	audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
+	return 0;
+}
+
+__initcall(audit_classes_init);

arch/x86_64/ia32/Makefile

@@ -11,6 +11,9 @@ obj-$(CONFIG_IA32_EMULATION) += $(sysv-y)
 
 obj-$(CONFIG_IA32_AOUT) += ia32_aout.o
 
+audit-class-$(CONFIG_AUDIT) := audit.o
+obj-$(CONFIG_IA32_EMULATION) += $(audit-class-y)
+
 $(obj)/syscall32_syscall.o: \
 	$(foreach F,sysenter syscall,$(obj)/vsyscall-$F.so)
 

arch/x86_64/ia32/audit.c

+#include <asm-i386/unistd.h>
+
+unsigned ia32_dir_class[] = {
+#include <asm-generic/audit_dir_write.h>
+~0U
+};
+
+unsigned ia32_chattr_class[] = {
+#include <asm-generic/audit_change_attr.h>
+~0U
+};

arch/x86_64/kernel/Makefile

@@ -35,6 +35,7 @@ obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_X86_PM_TIMER)	+= pmtimer.o
 obj-$(CONFIG_X86_VSMP)		+= vsmp.o
 obj-$(CONFIG_K8_NB)		+= k8.o
+obj-$(CONFIG_AUDIT)		+= audit.o
 
 obj-$(CONFIG_MODULES)		+= module.o
 

arch/x86_64/kernel/audit.c

+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/audit.h>
+#include <asm/unistd.h>
+
+static unsigned dir_class[] = {
+#include <asm-generic/audit_dir_write.h>
+~0U
+};
+
+static unsigned chattr_class[] = {
+#include <asm-generic/audit_change_attr.h>
+~0U
+};
+
+static int __init audit_classes_init(void)
+{
+#ifdef CONFIG_IA32_EMULATION
+	extern __u32 ia32_dir_class[];
+	extern __u32 ia32_chattr_class[];
+	audit_register_class(AUDIT_CLASS_DIR_WRITE_32, ia32_dir_class);
+	audit_register_class(AUDIT_CLASS_CHATTR_32, ia32_chattr_class);
+#endif
+	audit_register_class(AUDIT_CLASS_DIR_WRITE, dir_class);
+	audit_register_class(AUDIT_CLASS_CHATTR, chattr_class);
+	return 0;
+}
+
+__initcall(audit_classes_init);

include/asm-generic/audit_change_attr.h

+__NR_chmod,
+__NR_fchmod,
+__NR_chown,
+__NR_fchown,
+__NR_lchown,
+__NR_setxattr,
+__NR_lsetxattr,
+__NR_fsetxattr,
+__NR_removexattr,
+__NR_lremovexattr,
+__NR_fremovexattr,
+__NR_fchownat,
+__NR_fchmodat,
+#ifdef __NR_chown32
+__NR_chown32,
+__NR_fchown32,
+__NR_lchown32,
+#endif

include/asm-generic/audit_dir_write.h

+__NR_rename,
+__NR_mkdir,
+__NR_rmdir,
+__NR_creat,
+__NR_link,
+__NR_unlink,
+__NR_symlink,
+__NR_mknod,
+__NR_mkdirat,
+__NR_mknodat,
+__NR_unlinkat,
+__NR_renameat,
+__NR_linkat,
+__NR_symlinkat,

include/linux/audit.h

@@ -127,6 +127,12 @@
 #define AUDIT_WORD(nr) ((__u32)((nr)/32))
 #define AUDIT_BIT(nr)  (1 << ((nr) - AUDIT_WORD(nr)*32))
 
+#define AUDIT_SYSCALL_CLASSES 16
+#define AUDIT_CLASS_DIR_WRITE 0
+#define AUDIT_CLASS_DIR_WRITE_32 1
+#define AUDIT_CLASS_CHATTR 2
+#define AUDIT_CLASS_CHATTR_32 3
+
 /* This bitmask is used to validate user input.  It represents all bits that
  * are currently used in an audit field constant understood by the kernel.
  * If you are adding a new #define AUDIT_<whatever>, please ensure that
@@ -307,6 +313,7 @@ struct mqstat;
 #define AUDITSC_SUCCESS 1
 #define AUDITSC_FAILURE 2
 #define AUDITSC_RESULT(x) ( ((long)(x))<0?AUDITSC_FAILURE:AUDITSC_SUCCESS )
+extern int __init audit_register_class(int class, unsigned *list);
 #ifdef CONFIG_AUDITSYSCALL
 /* These are defined in auditsc.c */
 				/* Public API */

kernel/auditfilter.c

@@ -279,6 +279,29 @@ static int audit_to_watch(struct audit_krule *krule, char *path, int len,
 	return 0;
 }
 
+static __u32 *classes[AUDIT_SYSCALL_CLASSES];
+
+int __init audit_register_class(int class, unsigned *list)
+{
+	__u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+	while (*list != ~0U) {
+		unsigned n = *list++;
+		if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
+			kfree(p);
+			return -EINVAL;
+		}
+		p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
+	}
+	if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
+		kfree(p);
+		return -EINVAL;
+	}
+	classes[class] = p;
+	return 0;
+}
+
 /* Common user-space to kernel rule translation. */
 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
 {
@@ -322,6 +345,22 @@ static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
 	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
 		entry->rule.mask[i] = rule->mask[i];
 
+	for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
+		int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
+		__u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
+		__u32 *class;
+
+		if (!(*p & AUDIT_BIT(bit)))
+			continue;
+		*p &= ~AUDIT_BIT(bit);
+		class = classes[i];
+		if (class) {
+			int j;
+			for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
+				entry->rule.mask[j] |= class[j];
+		}
+	}
+
 	return entry;
 
 exit_err: