[PATCH] execve argument logging

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

fs/exec.c

@@ -49,6 +49,7 @@
 #include <linux/rmap.h>
 #include <linux/acct.h>
 #include <linux/cn_proc.h>
+#include <linux/audit.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -1085,6 +1086,11 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 	/* kernel module loader fixup */
 	/* so we don't try to load run modprobe in kernel space. */
 	set_fs(USER_DS);
+
+	retval = audit_bprm(bprm);
+	if (retval)
+		return retval;
+
 	retval = -ENOENT;
 	for (try=0; try<2; try++) {
 		read_lock(&binfmt_lock);

include/linux/audit.h

@@ -83,6 +83,7 @@
 #define AUDIT_CONFIG_CHANGE	1305	/* Audit system configuration change */
 #define AUDIT_SOCKADDR		1306	/* sockaddr copied as syscall arg */
 #define AUDIT_CWD		1307	/* Current working directory */
+#define AUDIT_EXECVE		1309	/* execve arguments */
 #define AUDIT_IPC_SET_PERM	1311	/* IPC new permissions record type */
 
 #define AUDIT_AVC		1400	/* SE Linux avc denial or grant */
@@ -283,6 +284,7 @@ struct audit_buffer;
 struct audit_context;
 struct inode;
 struct netlink_skb_parms;
+struct linux_binprm;
 
 #define AUDITSC_INVALID 0
 #define AUDITSC_SUCCESS 1
@@ -322,6 +324,7 @@ extern int  audit_set_loginuid(struct task_struct *task, uid_t loginuid);
 extern uid_t audit_get_loginuid(struct audit_context *ctx);
 extern int audit_ipc_obj(struct kern_ipc_perm *ipcp);
 extern int audit_ipc_set_perm(unsigned long qbytes, uid_t uid, gid_t gid, mode_t mode, struct kern_ipc_perm *ipcp);
+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_avc_path(struct dentry *dentry, struct vfsmount *mnt);
@@ -342,6 +345,7 @@ extern int audit_set_macxattr(const char *name);
 #define audit_get_loginuid(c) ({ -1; })
 #define audit_ipc_obj(i) ({ 0; })
 #define audit_ipc_set_perm(q,u,g,m,i) ({ 0; })
+#define audit_bprm(p) ({ 0; })
 #define audit_socketcall(n,a) ({ 0; })
 #define audit_sockaddr(len, addr) ({ 0; })
 #define audit_avc_path(dentry, mnt) ({ 0; })
@@ -364,7 +368,7 @@ extern void		    audit_log_end(struct audit_buffer *ab);
 extern void		    audit_log_hex(struct audit_buffer *ab,
 					  const unsigned char *buf,
 					  size_t len);
-extern void		    audit_log_untrustedstring(struct audit_buffer *ab,
+extern const char *	    audit_log_untrustedstring(struct audit_buffer *ab,
 						      const char *string);
 extern void		    audit_log_d_path(struct audit_buffer *ab,
 					     const char *prefix,

kernel/audit.c

@@ -1026,18 +1026,20 @@ void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
  * or a space. Unescaped strings will start and end with a double quote mark.
  * Strings that are escaped are printed in hex (2 digits per char).
  */
-void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
+const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
 {
 	const unsigned char *p = string;
+	size_t len = strlen(string);
 
 	while (*p) {
 		if (*p == '"' || *p < 0x21 || *p > 0x7f) {
-			audit_log_hex(ab, string, strlen(string));
-			return;
+			audit_log_hex(ab, string, len);
+			return string + len + 1;
 		}
 		p++;
 	}
 	audit_log_format(ab, "\"%s\"", string);
+	return p + 1;
 }
 
 /* This is a helper-function to print the escaped d_path */

kernel/auditsc.c

@@ -59,6 +59,7 @@
 #include <linux/list.h>
 #include <linux/tty.h>
 #include <linux/selinux.h>
+#include <linux/binfmts.h>
 
 #include "audit.h"
 
@@ -110,6 +111,13 @@ struct audit_aux_data_ipcctl {
 	u32			osid;
 };
 
+struct audit_aux_data_execve {
+	struct audit_aux_data	d;
+	int argc;
+	int envc;
+	char mem[0];
+};
+
 struct audit_aux_data_socketcall {
 	struct audit_aux_data	d;
 	int			nargs;
@@ -667,6 +675,16 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
 				kfree(ctx);
 			}
 			break; }
+		case AUDIT_EXECVE: {
+			struct audit_aux_data_execve *axi = (void *)aux;
+			int i;
+			const char *p;
+			for (i = 0, p = axi->mem; i < axi->argc; i++) {
+				audit_log_format(ab, "a%d=", i);
+				p = audit_log_untrustedstring(ab, p);
+				audit_log_format(ab, "\n");
+			}
+			break; }
 
 		case AUDIT_SOCKETCALL: {
 			int i;
@@ -1231,6 +1249,39 @@ int audit_ipc_set_perm(unsigned long qbytes, uid_t uid, gid_t gid, mode_t mode,
 	return 0;
 }
 
+int audit_bprm(struct linux_binprm *bprm)
+{
+	struct audit_aux_data_execve *ax;
+	struct audit_context *context = current->audit_context;
+	unsigned long p, next;
+	void *to;
+
+	if (likely(!audit_enabled || !context))
+		return 0;
+
+	ax = kmalloc(sizeof(*ax) + PAGE_SIZE * MAX_ARG_PAGES - bprm->p,
+				GFP_KERNEL);
+	if (!ax)
+		return -ENOMEM;
+
+	ax->argc = bprm->argc;
+	ax->envc = bprm->envc;
+	for (p = bprm->p, to = ax->mem; p < MAX_ARG_PAGES*PAGE_SIZE; p = next) {
+		struct page *page = bprm->page[p / PAGE_SIZE];
+		void *kaddr = kmap(page);
+		next = (p + PAGE_SIZE) & ~(PAGE_SIZE - 1);
+		memcpy(to, kaddr + (p & (PAGE_SIZE - 1)), next - p);
+		to += next - p;
+		kunmap(page);
+	}
+
+	ax->d.type = AUDIT_EXECVE;
+	ax->d.next = context->aux;
+	context->aux = (void *)ax;
+	return 0;
+}
+
+
 /**
  * audit_socketcall - record audit data for sys_socketcall
  * @nargs: number of args