[PATCH] AUDIT_FD_PAIR

Provide an audit record of the descriptor pair returned by pipe() and
socketpair().  Rewritten from the original posted to linux-audit by
John D. Ramsdell <ramsdell@mitre.org>

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

fs/pipe.c

@@ -16,6 +16,7 @@
 #include <linux/uio.h>
 #include <linux/highmem.h>
 #include <linux/pagemap.h>
+#include <linux/audit.h>
 
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
@@ -985,6 +986,10 @@ int do_pipe(int *fd)
 		goto err_fdr;
 	fdw = error;
 
+	error = audit_fd_pair(fdr, fdw);
+	if (error < 0)
+		goto err_fdw;
+
 	fd_install(fdr, fr);
 	fd_install(fdw, fw);
 	fd[0] = fdr;
@@ -992,6 +997,8 @@ int do_pipe(int *fd)
 
 	return 0;
 
+ err_fdw:
+	put_unused_fd(fdw);
  err_fdr:
 	put_unused_fd(fdr);
  err_read_pipe:

include/linux/audit.h

@@ -89,6 +89,7 @@
 #define AUDIT_MQ_NOTIFY		1314	/* POSIX MQ notify record type */
 #define AUDIT_MQ_GETSETATTR	1315	/* POSIX MQ get/set attribute record type */
 #define AUDIT_KERNEL_OTHER	1316	/* For use by 3rd party modules */
+#define AUDIT_FD_PAIR		1317    /* audit record for pipe/socketpair */
 
 #define AUDIT_AVC		1400	/* SE Linux avc denial or grant */
 #define AUDIT_SELINUX_ERR	1401	/* Internal SE Linux Errors */
@@ -387,6 +388,7 @@ extern int __audit_ipc_set_perm(unsigned long qbytes, uid_t uid, gid_t gid, mode
 extern int audit_bprm(struct linux_binprm *bprm);
 extern int audit_socketcall(int nargs, unsigned long *args);
 extern int audit_sockaddr(int len, void *addr);
+extern int __audit_fd_pair(int fd1, int fd2);
 extern int audit_avc_path(struct dentry *dentry, struct vfsmount *mnt);
 extern int audit_set_macxattr(const char *name);
 extern int __audit_mq_open(int oflag, mode_t mode, struct mq_attr __user *u_attr);
@@ -401,6 +403,12 @@ static inline int audit_ipc_obj(struct kern_ipc_perm *ipcp)
 		return __audit_ipc_obj(ipcp);
 	return 0;
 }
+static inline int audit_fd_pair(int fd1, int fd2)
+{
+	if (unlikely(!audit_dummy_context()))
+		return __audit_fd_pair(fd1, fd2);
+	return 0;
+}
 static inline int audit_ipc_set_perm(unsigned long qbytes, uid_t uid, gid_t gid, mode_t mode)
 {
 	if (unlikely(!audit_dummy_context()))
@@ -459,6 +467,7 @@ extern int audit_n_rules;
 #define audit_ipc_set_perm(q,u,g,m) ({ 0; })
 #define audit_bprm(p) ({ 0; })
 #define audit_socketcall(n,a) ({ 0; })
+#define audit_fd_pair(n,a) ({ 0; })
 #define audit_sockaddr(len, addr) ({ 0; })
 #define audit_avc_path(dentry, mnt) ({ 0; })
 #define audit_set_macxattr(n) do { ; } while (0)

kernel/auditsc.c

@@ -170,6 +170,11 @@ struct audit_aux_data_sockaddr {
 	char			a[0];
 };
 
+struct audit_aux_data_fd_pair {
+	struct	audit_aux_data d;
+	int	fd[2];
+};
+
 struct audit_aux_data_path {
 	struct audit_aux_data	d;
 	struct dentry		*dentry;
@@ -961,6 +966,11 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
 			audit_log_d_path(ab, "path=", axi->dentry, axi->mnt);
 			break; }
 
+		case AUDIT_FD_PAIR: {
+			struct audit_aux_data_fd_pair *axs = (void *)aux;
+			audit_log_format(ab, "fd0=%d fd1=%d", axs->fd[0], axs->fd[1]);
+			break; }
+
 		}
 		audit_log_end(ab);
 	}
@@ -1814,6 +1824,36 @@ int audit_socketcall(int nargs, unsigned long *args)
 	return 0;
 }
 
+/**
+ * __audit_fd_pair - record audit data for pipe and socketpair
+ * @fd1: the first file descriptor
+ * @fd2: the second file descriptor
+ *
+ * Returns 0 for success or NULL context or < 0 on error.
+ */
+int __audit_fd_pair(int fd1, int fd2)
+{
+	struct audit_context *context = current->audit_context;
+	struct audit_aux_data_fd_pair *ax;
+
+	if (likely(!context)) {
+		return 0;
+	}
+
+	ax = kmalloc(sizeof(*ax), GFP_KERNEL);
+	if (!ax) {
+		return -ENOMEM;
+	}
+
+	ax->fd[0] = fd1;
+	ax->fd[1] = fd2;
+
+	ax->d.type = AUDIT_FD_PAIR;
+	ax->d.next = context->aux;
+	context->aux = (void *)ax;
+	return 0;
+}
+
 /**
  * audit_sockaddr - record audit data for sys_bind, sys_connect, sys_sendto
  * @len: data length in user space

net/socket.c

@@ -1194,6 +1194,7 @@ asmlinkage long sys_socketpair(int family, int type, int protocol,
 {
 	struct socket *sock1, *sock2;
 	int fd1, fd2, err;
+	struct file *newfile1, *newfile2;
 
 	/*
 	 * Obtain the first socket and check if the underlying protocol
@@ -1212,18 +1213,37 @@ asmlinkage long sys_socketpair(int family, int type, int protocol,
 	if (err < 0)
 		goto out_release_both;
 
-	fd1 = fd2 = -1;
-
-	err = sock_map_fd(sock1);
-	if (err < 0)
+	fd1 = sock_alloc_fd(&newfile1);
+	if (unlikely(fd1 < 0))
 		goto out_release_both;
-	fd1 = err;
 
-	err = sock_map_fd(sock2);
-	if (err < 0)
-		goto out_close_1;
-	fd2 = err;
+	fd2 = sock_alloc_fd(&newfile2);
+	if (unlikely(fd2 < 0)) {
+		put_filp(newfile1);
+		put_unused_fd(fd1);
+		goto out_release_both;
+	}
 
+	err = sock_attach_fd(sock1, newfile1);
+	if (unlikely(err < 0)) {
+		goto out_fd2;
+	}
+
+	err = sock_attach_fd(sock2, newfile2);
+	if (unlikely(err < 0)) {
+		fput(newfile1);
+		goto out_fd1;
+	}
+
+	err = audit_fd_pair(fd1, fd2);
+	if (err < 0) {
+		fput(newfile1);
+		fput(newfile2);
+		goto out_fd;
+	}
+
+	fd_install(fd1, newfile1);
+	fd_install(fd2, newfile2);
 	/* fd1 and fd2 may be already another descriptors.
 	 * Not kernel problem.
 	 */
@@ -1238,17 +1258,23 @@ asmlinkage long sys_socketpair(int family, int type, int protocol,
 	sys_close(fd1);
 	return err;
 
-out_close_1:
-	sock_release(sock2);
-	sys_close(fd1);
-	return err;
-
 out_release_both:
 	sock_release(sock2);
 out_release_1:
 	sock_release(sock1);
 out:
 	return err;
+
+out_fd2:
+	put_filp(newfile1);
+	sock_release(sock1);
+out_fd1:
+	put_filp(newfile2);
+	sock_release(sock2);
+out_fd:
+	put_unused_fd(fd1);
+	put_unused_fd(fd2);
+	goto out;
 }
 
 /*