audit mmap

Normal syscall audit doesn't catch 5th argument of syscall.  It also
doesn't catch the contents of userland structures pointed to be
syscall argument, so for both old and new mmap(2) ABI it doesn't
record the descriptor we are mapping.  For old one it also misses
flags.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/audit.h

@@ -102,6 +102,7 @@
 #define AUDIT_EOE		1320	/* End of multi-record event */
 #define AUDIT_BPRM_FCAPS	1321	/* Information about fcaps increasing perms */
 #define AUDIT_CAPSET		1322	/* Record showing argument to sys_capset */
+#define AUDIT_MMAP		1323	/* Record showing descriptor and flags in mmap */
 
 #define AUDIT_AVC		1400	/* SE Linux avc denial or grant */
 #define AUDIT_SELINUX_ERR	1401	/* Internal SE Linux Errors */
@@ -478,6 +479,7 @@ extern int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
 				  const struct cred *new,
 				  const struct cred *old);
 extern void __audit_log_capset(pid_t pid, const struct cred *new, const struct cred *old);
+extern void __audit_mmap_fd(int fd, int flags);
 
 static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
 {
@@ -531,6 +533,12 @@ static inline void audit_log_capset(pid_t pid, const struct cred *new,
 		__audit_log_capset(pid, new, old);
 }
 
+static inline void audit_mmap_fd(int fd, int flags)
+{
+	if (unlikely(!audit_dummy_context()))
+		__audit_mmap_fd(fd, flags);
+}
+
 extern int audit_n_rules;
 extern int audit_signals;
 #else
@@ -564,6 +572,7 @@ extern int audit_signals;
 #define audit_mq_getsetattr(d,s) ((void)0)
 #define audit_log_bprm_fcaps(b, ncr, ocr) ({ 0; })
 #define audit_log_capset(pid, ncr, ocr) ((void)0)
+#define audit_mmap_fd(fd, flags) ((void)0)
 #define audit_ptrace(t) ((void)0)
 #define audit_n_rules 0
 #define audit_signals 0

kernel/auditsc.c

@@ -241,6 +241,10 @@ struct audit_context {
 			pid_t			pid;
 			struct audit_cap_data	cap;
 		} capset;
+		struct {
+			int			fd;
+			int			flags;
+		} mmap;
 	};
 	int fds[2];
 
@@ -1305,6 +1309,10 @@ static void show_special(struct audit_context *context, int *call_panic)
 		audit_log_cap(ab, "cap_pp", &context->capset.cap.permitted);
 		audit_log_cap(ab, "cap_pe", &context->capset.cap.effective);
 		break; }
+	case AUDIT_MMAP: {
+		audit_log_format(ab, "fd=%d flags=0x%x", context->mmap.fd,
+				 context->mmap.flags);
+		break; }
 	}
 	audit_log_end(ab);
 }
@@ -2476,6 +2484,14 @@ void __audit_log_capset(pid_t pid,
 	context->type = AUDIT_CAPSET;
 }
 
+void __audit_mmap_fd(int fd, int flags)
+{
+	struct audit_context *context = current->audit_context;
+	context->mmap.fd = fd;
+	context->mmap.flags = flags;
+	context->type = AUDIT_MMAP;
+}
+
 /**
  * audit_core_dumps - record information about processes that end abnormally
  * @signr: signal value

mm/mmap.c

@@ -28,6 +28,7 @@
 #include <linux/rmap.h>
 #include <linux/mmu_notifier.h>
 #include <linux/perf_event.h>
+#include <linux/audit.h>
 
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
@@ -1108,6 +1109,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 	unsigned long retval = -EBADF;
 
 	if (!(flags & MAP_ANONYMOUS)) {
+		audit_mmap_fd(fd, flags);
 		if (unlikely(flags & MAP_HUGETLB))
 			return -EINVAL;
 		file = fget(fd);

mm/nommu.c

@@ -29,6 +29,7 @@
 #include <linux/personality.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
+#include <linux/audit.h>
 
 #include <asm/uaccess.h>
 #include <asm/tlb.h>
@@ -1458,6 +1459,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 	struct file *file = NULL;
 	unsigned long retval = -EBADF;
 
+	audit_mmap_fd(fd, flags);
 	if (!(flags & MAP_ANONYMOUS)) {
 		file = fget(fd);
 		if (!file)