IFp4 @208451:

Fix path handling for *at() syscalls.

Before the change directory descriptor was totally ignored,
so the relative path argument was appended to current working
directory path and not to the path provided by descriptor, thus
wrong paths were stored in audit logs.

Now that we use directory descriptor in vfs_lookup, move
AUDIT_ARG_UPATH1() and AUDIT_ARG_UPATH2() calls to the place where
we hold file descriptors table lock, so we are sure paths will
be resolved according to the same directory in audit record and
in actual operation.

Sponsored by:	FreeBSD Foundation (auditdistd)
Reviewed by:	rwatson
MFC after:	2 weeks

5 files changed, 42 insertions, 23 deletions

diff --git a/sys/security/audit/audit.c b/sys/security/audit/audit.c
index 74bfde7..2063c9d 100644
--- a/sys/security/audit/audit.c
+++ b/sys/security/audit/audit.c
@@ -691,7 +691,7 @@ audit_proc_coredump(struct thread *td, char *path, int errcode)
 	if (path != NULL) {
 		pathp = &ar->k_ar.ar_arg_upath1;
 		*pathp = malloc(MAXPATHLEN, M_AUDITPATH, M_WAITOK);
-		audit_canon_path(td, path, *pathp);
+		audit_canon_path(td, AT_FDCWD, path, *pathp);
 		ARG_SET_VALID(ar, ARG_UPATH1);
 	}
 	ar->k_ar.ar_arg_signum = td->td_proc->p_sig;
diff --git a/sys/security/audit/audit.h b/sys/security/audit/audit.h
index dfcd193..69f6c32 100644
--- a/sys/security/audit/audit.h
+++ b/sys/security/audit/audit.h
@@ -99,8 +99,8 @@ void	 audit_arg_sockaddr(struct thread *td, struct sockaddr *sa);
 void	 audit_arg_auid(uid_t auid);
 void	 audit_arg_auditinfo(struct auditinfo *au_info);
 void	 audit_arg_auditinfo_addr(struct auditinfo_addr *au_info);
-void	 audit_arg_upath1(struct thread *td, char *upath);
-void	 audit_arg_upath2(struct thread *td, char *upath);
+void	 audit_arg_upath1(struct thread *td, int dirfd, char *upath);
+void	 audit_arg_upath2(struct thread *td, int dirfd, char *upath);
 void	 audit_arg_vnode1(struct vnode *vp);
 void	 audit_arg_vnode2(struct vnode *vp);
 void	 audit_arg_text(char *text);
@@ -276,14 +276,14 @@ void	 audit_thread_free(struct thread *td);
 		audit_arg_uid((uid));					\
 } while (0)
 
-#define	AUDIT_ARG_UPATH1(td, upath) do {				\
+#define	AUDIT_ARG_UPATH1(td, dirfd, upath) do {				\
 	if (AUDITING_TD(curthread))					\
-		audit_arg_upath1((td), (upath));			\
+		audit_arg_upath1((td), (dirfd), (upath));		\
 } while (0)
 
-#define	AUDIT_ARG_UPATH2(td, upath) do {				\
+#define	AUDIT_ARG_UPATH2(td, dirfd, upath) do {				\
 	if (AUDITING_TD(curthread))					\
-		audit_arg_upath2((td), (upath));			\
+		audit_arg_upath2((td), (dirfd), (upath));		\
 } while (0)
 
 #define	AUDIT_ARG_VALUE(value) do {					\
@@ -356,8 +356,8 @@ void	 audit_thread_free(struct thread *td);
 #define	AUDIT_ARG_SUID(suid)
 #define	AUDIT_ARG_TEXT(text)
 #define	AUDIT_ARG_UID(uid)
-#define	AUDIT_ARG_UPATH1(td, upath)
-#define	AUDIT_ARG_UPATH2(td, upath)
+#define	AUDIT_ARG_UPATH1(td, dirfd, upath)
+#define	AUDIT_ARG_UPATH2(td, dirfd, upath)
 #define	AUDIT_ARG_VALUE(value)
 #define	AUDIT_ARG_VNODE1(vp)
 #define	AUDIT_ARG_VNODE2(vp)
diff --git a/sys/security/audit/audit_arg.c b/sys/security/audit/audit_arg.c
index f19375d..41d6b42 100644
--- a/sys/security/audit/audit_arg.c
+++ b/sys/security/audit/audit_arg.c
@@ -463,7 +463,8 @@ audit_arg_sockaddr(struct thread *td, struct sockaddr *sa)
 		break;
 
 	case AF_UNIX:
-		audit_arg_upath1(td, ((struct sockaddr_un *)sa)->sun_path);
+		audit_arg_upath1(td, AT_FDCWD,
+		    ((struct sockaddr_un *)sa)->sun_path);
 		ARG_SET_VALID(ar, ARG_SADDRUNIX);
 		break;
 	/* XXXAUDIT: default:? */
@@ -707,16 +708,16 @@ audit_arg_file(struct proc *p, struct file *fp)
  * freed when the audit record is freed.
  */
 static void
-audit_arg_upath(struct thread *td, char *upath, char **pathp)
+audit_arg_upath(struct thread *td, int dirfd, char *upath, char **pathp)
 {
 
 	if (*pathp == NULL)
 		*pathp = malloc(MAXPATHLEN, M_AUDITPATH, M_WAITOK);
-	audit_canon_path(td, upath, *pathp);
+	audit_canon_path(td, dirfd, upath, *pathp);
 }
 
 void
-audit_arg_upath1(struct thread *td, char *upath)
+audit_arg_upath1(struct thread *td, int dirfd, char *upath)
 {
 	struct kaudit_record *ar;
 
@@ -724,12 +725,12 @@ audit_arg_upath1(struct thread *td, char *upath)
 	if (ar == NULL)
 		return;
 
-	audit_arg_upath(td, upath, &ar->k_ar.ar_arg_upath1);
+	audit_arg_upath(td, dirfd, upath, &ar->k_ar.ar_arg_upath1);
 	ARG_SET_VALID(ar, ARG_UPATH1);
 }
 
 void
-audit_arg_upath2(struct thread *td, char *upath)
+audit_arg_upath2(struct thread *td, int dirfd, char *upath)
 {
 	struct kaudit_record *ar;
 
@@ -737,7 +738,7 @@ audit_arg_upath2(struct thread *td, char *upath)
 	if (ar == NULL)
 		return;
 
-	audit_arg_upath(td, upath, &ar->k_ar.ar_arg_upath2);
+	audit_arg_upath(td, dirfd, upath, &ar->k_ar.ar_arg_upath2);
 	ARG_SET_VALID(ar, ARG_UPATH2);
 }
 
diff --git a/sys/security/audit/audit_bsm_klib.c b/sys/security/audit/audit_bsm_klib.c
index f26f86c..45cc56a 100644
--- a/sys/security/audit/audit_bsm_klib.c
+++ b/sys/security/audit/audit_bsm_klib.c
@@ -462,13 +462,13 @@ auditon_command_event(int cmd)
  * leave the filename starting with '/' in the audit log in this case.
  */
 void
-audit_canon_path(struct thread *td, char *path, char *cpath)
+audit_canon_path(struct thread *td, int dirfd, char *path, char *cpath)
 {
 	struct vnode *cvnp, *rvnp;
 	char *rbuf, *fbuf, *copy;
 	struct filedesc *fdp;
 	struct sbuf sbf;
-	int error, cwir;
+	int error, needslash, vfslocked;
 
 	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "%s: at %s:%d",
 	    __func__,  __FILE__, __LINE__);
@@ -491,10 +491,27 @@ audit_canon_path(struct thread *td, char *path, char *cpath)
 	 * path.
 	 */
 	if (*path != '/') {
-		cvnp = fdp->fd_cdir;
-		vhold(cvnp);
+		if (dirfd == AT_FDCWD) {
+			cvnp = fdp->fd_cdir;
+			vhold(cvnp);
+		} else {
+			/* XXX: fgetvp() that vhold()s vnode instead of vref()ing it would be better */
+			error = fgetvp(td, dirfd, 0, &cvnp);
+			if (error) {
+				cpath[0] = '\0';
+				if (rvnp != NULL)
+					vdrop(rvnp);
+				return;
+			}
+			vhold(cvnp);
+			vfslocked = VFS_LOCK_GIANT(cvnp->v_mount);
+			vrele(cvnp);
+			VFS_UNLOCK_GIANT(vfslocked);
+		}
+		needslash = (fdp->fd_rdir != cvnp);
+	} else {
+		needslash = 1;
 	}
-	cwir = (fdp->fd_rdir == fdp->fd_cdir);
 	FILEDESC_SUNLOCK(fdp);
 	/*
 	 * NB: We require that the supplied array be at least MAXPATHLEN bytes
@@ -536,7 +553,7 @@ audit_canon_path(struct thread *td, char *path, char *cpath)
 		(void) sbuf_cat(&sbf, rbuf);
 		free(fbuf, M_TEMP);
 	}
-	if (cwir == 0 || (cwir != 0 && cvnp == NULL))
+	if (needslash)
 		(void) sbuf_putc(&sbf, '/');
 	/*
 	 * Now that we have processed any alternate root and relative path
diff --git a/sys/security/audit/audit_private.h b/sys/security/audit/audit_private.h
index 92a0729..ad931c0 100644
--- a/sys/security/audit/audit_private.h
+++ b/sys/security/audit/audit_private.h
@@ -388,7 +388,8 @@ au_event_t	 audit_flags_and_error_to_openevent(int oflags, int error);
 au_event_t	 audit_flags_and_error_to_openatevent(int oflags, int error);
 au_event_t	 audit_msgctl_to_event(int cmd);
 au_event_t	 audit_semctl_to_event(int cmr);
-void		 audit_canon_path(struct thread *td, char *path, char *cpath);
+void		 audit_canon_path(struct thread *td, int dirfd, char *path,
+		    char *cpath);
 au_event_t	 auditon_command_event(int cmd);
 
 /*