Jail and capability mode for shm_rename; add audit support for shm_rename

Co-mingling two things here:

  * Addressing some feedback from Konstantin and Kyle re: jail,
    capability mode, and a few other things
  * Adding audit support as promised.

The audit support change includes a partial refresh of OpenBSM from
upstream, where the change to add shm_rename has already been
accepted. Matthew doesn't plan to work on refreshing anything else to
support audit for those new event types.

Submitted by:	Matthew Bryan <matthew.bryan@isilon.com>
Reviewed by:	kib
Relnotes:	Yes
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D22083

12 files changed, 140 insertions, 93 deletions

diff --git a/contrib/openbsm/etc/audit_event b/contrib/openbsm/etc/audit_event
index 87e778068708..b397674564c6 100644
--- a/contrib/openbsm/etc/audit_event
+++ b/contrib/openbsm/etc/audit_event
@@ -601,6 +601,19 @@
 43238:AUE_SETLOGINCLASS:setloginclass(2):pc
 43239:AUE_POSIX_FADVISE:posix_fadvise(2):no
 43240:AUE_SCTP_GENERIC_SENDMSG_IOV:sctp_generic_sendmsg_iov(2):nt
+43241:AUE_ABORT2:abort(2):pc
+43242:AUE_SEMTIMEDWAIT:sem_timedwait(3):ip
+43243:AUE_SEMDESTROY:sem_destroy(3):ip
+43244:AUE_SEMGETVALUE:sem_getvalue(3):ip
+43245:AUE_SEMINIT:sem_init(3):ip
+43246:AUE_SEMPOST:sem_post(3):ip
+43247:AUE_SEMTRYWAIT:sem_trywait(3):ip
+43258:AUE_SEMWAIT:sem_wait(3):ip
+43259:AUE_FGETUUID:fgetuuid(2):ip
+43260:AUE_GETUUID:getuuid(2):ip
+43261:AUE_LGETUUID:lgetuuid(2):ip
+43262:AUE_EXECVEAT:execveat(2):pc,ex
+43263:AUE_SHMRENAME:shm_rename(2):ip
 #
 # Solaris userspace events.
 #
diff --git a/contrib/openbsm/sys/bsm/audit_kevents.h b/contrib/openbsm/sys/bsm/audit_kevents.h
index a4a3b865a9e2..afa8c0f37a31 100644
--- a/contrib/openbsm/sys/bsm/audit_kevents.h
+++ b/contrib/openbsm/sys/bsm/audit_kevents.h
@@ -640,6 +640,19 @@
 #define	AUE_SETLOGINCLASS	43238	/* FreeBSD-specific. */
 #define	AUE_POSIX_FADVISE	43239	/* FreeBSD-specific. */
 #define	AUE_SCTP_GENERIC_SENDMSG_IOV	43240	/* FreeBSD-specific. */
+#define	AUE_ABORT2		43241	/* FreeBSD-specific. */
+#define	AUE_SEMTIMEDWAIT	43242	/* FreeBSD-specific. */
+#define	AUE_SEMDESTROY		43243	/* FreeBSD-specific. */
+#define	AUE_SEMGETVALUE		43244	/* FreeBSD-specific. */
+#define	AUE_SEMINIT		43245	/* FreeBSD-specific. */
+#define	AUE_SEMPOST		43246	/* FreeBSD-specific. */
+#define	AUE_SEMTRYWAIT		43247	/* FreeBSD-specific. */
+#define	AUE_SEMWAIT		43258	/* FreeBSD-specific. */
+#define	AUE_FGETUUID		43259	/* CADETS. */
+#define	AUE_GETUUID		43260	/* CADETS. */
+#define	AUE_LGETUUID		43261	/* CADETS. */
+#define	AUE_EXECVEAT		43262	/* FreeBSD/Linux. */
+#define	AUE_SHMRENAME		43263	/* FreeBSD-specific. */
 
 /*
  * Darwin BSM uses a number of AUE_O_* definitions, which are aliased to the
@@ -794,12 +807,6 @@
 #define	AUE_REMOVEXATTR		AUE_NULL
 #define	AUE_SBRK		AUE_NULL
 #define	AUE_SELECT		AUE_NULL
-#define	AUE_SEMDESTROY		AUE_NULL
-#define	AUE_SEMGETVALUE		AUE_NULL
-#define	AUE_SEMINIT		AUE_NULL
-#define	AUE_SEMPOST		AUE_NULL
-#define	AUE_SEMTRYWAIT		AUE_NULL
-#define	AUE_SEMWAIT		AUE_NULL
 #define	AUE_SEMWAITSIGNAL	AUE_NULL
 #define	AUE_SETITIMER		AUE_NULL
 #define	AUE_SETSGROUPS		AUE_NULL
diff --git a/sys/bsm/audit_kevents.h b/sys/bsm/audit_kevents.h
index 277e721d0547..195194887db4 100644
--- a/sys/bsm/audit_kevents.h
+++ b/sys/bsm/audit_kevents.h
@@ -644,6 +644,19 @@
 #define	AUE_SETLOGINCLASS	43238	/* FreeBSD-specific. */
 #define	AUE_POSIX_FADVISE	43239	/* FreeBSD-specific. */
 #define	AUE_SCTP_GENERIC_SENDMSG_IOV	43240	/* FreeBSD-specific. */
+#define	AUE_ABORT2		43241	/* FreeBSD-specific. */
+#define	AUE_SEMTIMEDWAIT	43242	/* FreeBSD-specific. */
+#define	AUE_SEMDESTROY		43243	/* FreeBSD-specific. */
+#define	AUE_SEMGETVALUE		43244	/* FreeBSD-specific. */
+#define	AUE_SEMINIT		43245	/* FreeBSD-specific. */
+#define	AUE_SEMPOST		43246	/* FreeBSD-specific. */
+#define	AUE_SEMTRYWAIT		43247	/* FreeBSD-specific. */
+#define	AUE_SEMWAIT		43258	/* FreeBSD-specific. */
+#define	AUE_FGETUUID		43259	/* CADETS. */
+#define	AUE_GETUUID		43260	/* CADETS. */
+#define	AUE_LGETUUID		43261	/* CADETS. */
+#define	AUE_EXECVEAT		43262	/* FreeBSD/Linux. */
+#define	AUE_SHMRENAME		43263	/* FreeBSD-specific. */
 
 /*
  * Darwin BSM uses a number of AUE_O_* definitions, which are aliased to the
@@ -798,12 +811,6 @@
 #define	AUE_REMOVEXATTR		AUE_NULL
 #define	AUE_SBRK		AUE_NULL
 #define	AUE_SELECT		AUE_NULL
-#define	AUE_SEMDESTROY		AUE_NULL
-#define	AUE_SEMGETVALUE		AUE_NULL
-#define	AUE_SEMINIT		AUE_NULL
-#define	AUE_SEMPOST		AUE_NULL
-#define	AUE_SEMTRYWAIT		AUE_NULL
-#define	AUE_SEMWAIT		AUE_NULL
 #define	AUE_SEMWAITSIGNAL	AUE_NULL
 #define	AUE_SETITIMER		AUE_NULL
 #define	AUE_SETSGROUPS		AUE_NULL
diff --git a/sys/compat/freebsd32/freebsd32_sysent.c b/sys/compat/freebsd32/freebsd32_sysent.c
index 5b5e1117d16f..52baae6c02b7 100644
--- a/sys/compat/freebsd32/freebsd32_sysent.c
+++ b/sys/compat/freebsd32/freebsd32_sysent.c
@@ -661,5 +661,5 @@ struct sysent freebsd32_sysent[] = {
 	{ AS(copy_file_range_args), (sy_call_t *)sys_copy_file_range, AUE_NULL, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 569 = copy_file_range */
 	{ AS(freebsd32___sysctlbyname_args), (sy_call_t *)freebsd32___sysctlbyname, AUE_SYSCTL, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 570 = freebsd32___sysctlbyname */
 	{ AS(shm_open2_args), (sy_call_t *)sys_shm_open2, AUE_SHMOPEN, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 571 = shm_open2 */
-	{ AS(shm_rename_args), (sy_call_t *)sys_shm_rename, AUE_NULL, NULL, 0, 0, 0, SY_THR_STATIC },	/* 572 = shm_rename */
+	{ AS(shm_rename_args), (sy_call_t *)sys_shm_rename, AUE_SHMRENAME, NULL, 0, 0, 0, SY_THR_STATIC },	/* 572 = shm_rename */
 };
diff --git a/sys/compat/freebsd32/syscalls.master b/sys/compat/freebsd32/syscalls.master
index b9186ebcf016..b4e58730cc65 100644
--- a/sys/compat/freebsd32/syscalls.master
+++ b/sys/compat/freebsd32/syscalls.master
@@ -1157,7 +1157,7 @@
 571	AUE_SHMOPEN	NOPROTO	{ int shm_open2( \
 				    const char *path, int flags, mode_t mode, \
 				    int shmflags, const char *name); }
-572	AUE_NULL	NOPROTO { int shm_rename(const char *path_from, \
+572	AUE_SHMRENAME	NOPROTO { int shm_rename(const char *path_from, \
 				    const char *path_to, int flags); }
 
 ; vim: syntax=off
diff --git a/sys/kern/init_sysent.c b/sys/kern/init_sysent.c
index 850fbb281ad2..b64105fdea34 100644
--- a/sys/kern/init_sysent.c
+++ b/sys/kern/init_sysent.c
@@ -627,5 +627,5 @@ struct sysent sysent[] = {
 	{ AS(copy_file_range_args), (sy_call_t *)sys_copy_file_range, AUE_NULL, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 569 = copy_file_range */
 	{ AS(__sysctlbyname_args), (sy_call_t *)sys___sysctlbyname, AUE_SYSCTL, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 570 = __sysctlbyname */
 	{ AS(shm_open2_args), (sy_call_t *)sys_shm_open2, AUE_SHMOPEN, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 571 = shm_open2 */
-	{ AS(shm_rename_args), (sy_call_t *)sys_shm_rename, AUE_NULL, NULL, 0, 0, 0, SY_THR_STATIC },	/* 572 = shm_rename */
+	{ AS(shm_rename_args), (sy_call_t *)sys_shm_rename, AUE_SHMRENAME, NULL, 0, 0, 0, SY_THR_STATIC },	/* 572 = shm_rename */
 };
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index 034632c2512c..8c7a3bd06a6c 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -3205,7 +3205,7 @@
 		    _In_z_ const char *name
 		);
 	}
-572	AUE_NULL	STD {
+572	AUE_SHMRENAME	STD {
 		int shm_rename(
 		    _In_z_ const char *path_from,
 		    _In_z_ const char *path_to,
diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c
index e8d1c8f5c40d..1a3325aff0df 100644
--- a/sys/kern/uipc_shm.c
+++ b/sys/kern/uipc_shm.c
@@ -122,6 +122,8 @@ static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
 static int	shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
 static int	shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
     void *rl_cookie);
+static int	shm_copyin_path(struct thread *td, const char *userpath_in,
+    char **path_out);
 
 static fo_rdwr_t	shm_read;
 static fo_rdwr_t	shm_write;
@@ -422,6 +424,44 @@ shm_close(struct file *fp, struct thread *td)
 }
 
 static int
+shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
+	int error;
+	char *path;
+	const char *pr_path;
+	size_t pr_pathlen;
+
+	path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
+	pr_path = td->td_ucred->cr_prison->pr_path;
+
+	/* Construct a full pathname for jailed callers. */
+	pr_pathlen = strcmp(pr_path, "/") ==
+	    0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
+	error = copyinstr(userpath_in, path + pr_pathlen,
+	    MAXPATHLEN - pr_pathlen, NULL);
+	if (error != 0)
+		goto out;
+
+#ifdef KTRACE
+	if (KTRPOINT(curthread, KTR_NAMEI))
+		ktrnamei(path);
+#endif
+
+	/* Require paths to start with a '/' character. */
+	if (path[pr_pathlen] != '/') {
+		error = EINVAL;
+		goto out;
+	}
+
+	*path_out = path;
+
+out:
+	if (error != 0)
+		free(path, M_SHMFD);
+
+	return (error);
+}
+
+static int
 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
 {
 	vm_object_t object;
@@ -707,9 +747,7 @@ kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
 	struct shmfd *shmfd;
 	struct file *fp;
 	char *path;
-	const char *pr_path;
 	void *rl_cookie;
-	size_t pr_pathlen;
 	Fnv32_t fnv;
 	mode_t cmode;
 	int fd, error;
@@ -767,25 +805,10 @@ kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
 		shmfd = shm_alloc(td->td_ucred, cmode);
 		shmfd->shm_seals = initial_seals;
 	} else {
-		path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
-		pr_path = td->td_ucred->cr_prison->pr_path;
-
-		/* Construct a full pathname for jailed callers. */
-		pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
-		    : strlcpy(path, pr_path, MAXPATHLEN);
-		error = copyinstr(userpath, path + pr_pathlen,
-		    MAXPATHLEN - pr_pathlen, NULL);
-#ifdef KTRACE
-		if (error == 0 && KTRPOINT(curthread, KTR_NAMEI))
-			ktrnamei(path);
-#endif
-		/* Require paths to start with a '/' character. */
-		if (error == 0 && path[pr_pathlen] != '/')
-			error = EINVAL;
-		if (error) {
+		error = shm_copyin_path(td, userpath, &path);
+		if (error != 0) {
 			fdclose(td, fp, fd);
 			fdrop(fp, td);
-			free(path, M_SHMFD);
 			return (error);
 		}
 
@@ -918,25 +941,13 @@ int
 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
 {
 	char *path;
-	const char *pr_path;
-	size_t pr_pathlen;
 	Fnv32_t fnv;
 	int error;
 
-	path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
-	pr_path = td->td_ucred->cr_prison->pr_path;
-	pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
-	    : strlcpy(path, pr_path, MAXPATHLEN);
-	error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
-	    NULL);
-	if (error) {
-		free(path, M_TEMP);
+	error = shm_copyin_path(td, uap->path, &path);
+	if (error != 0)
 		return (error);
-	}
-#ifdef KTRACE
-	if (KTRPOINT(curthread, KTR_NAMEI))
-		ktrnamei(path);
-#endif
+
 	AUDIT_ARG_UPATH1_CANON(path);
 	fnv = fnv_32_str(path, FNV1_32_INIT);
 	sx_xlock(&shm_dict_lock);
@@ -958,6 +969,7 @@ sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
 	int flags;
 
 	flags = uap->flags;
+	AUDIT_ARG_FFLAGS(flags);
 
 	/*
 	 * Make sure the user passed only valid flags.
@@ -981,22 +993,25 @@ sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
 		goto out;
 	}
 
-	/*
-	 * Malloc zone M_SHMFD, since this path may end up freed later from
-	 * M_SHMFD if we end up doing an insert.
-	 */
-	path_from = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
-	error = copyinstr(uap->path_from, path_from, MAXPATHLEN, NULL);
-	if (error)
+	/* Renaming to or from anonymous makes no sense */
+	if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
+		error = EINVAL;
 		goto out;
+	}
 
-	path_to = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
-	error = copyinstr(uap->path_to, path_to, MAXPATHLEN, NULL);
-	if (error)
+	error = shm_copyin_path(td, uap->path_from, &path_from);
+	if (error != 0)
 		goto out;
 
+	error = shm_copyin_path(td, uap->path_to, &path_to);
+	if (error != 0)
+		goto out;
+
+	AUDIT_ARG_UPATH1_CANON(path_from);
+	AUDIT_ARG_UPATH2_CANON(path_to);
+
 	/* Rename with from/to equal is a no-op */
-	if (strncmp(path_from, path_to, MAXPATHLEN) == 0)
+	if (strcmp(path_from, path_to) == 0)
 		goto out;
 
 	fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
@@ -1006,16 +1021,14 @@ sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
 
 	fd_from = shm_lookup(path_from, fnv_from);
 	if (fd_from == NULL) {
-		sx_xunlock(&shm_dict_lock);
 		error = ENOENT;
-		goto out;
+		goto out_locked;
 	}
 
 	fd_to = shm_lookup(path_to, fnv_to);
 	if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
-		sx_xunlock(&shm_dict_lock);
 		error = EEXIST;
-		goto out;
+		goto out_locked;
 	}
 
 	/*
@@ -1031,10 +1044,9 @@ sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
 	 */
 	KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
 	    path_from));
-	if (error) {
+	if (error != 0) {
 		shm_drop(fd_from);
-		sx_xunlock(&shm_dict_lock);
-		goto out;
+		goto out_locked;
 	}
 
 	/*
@@ -1057,15 +1069,16 @@ sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
 	 * operation.
 	 */
 	error = shm_remove(path_to, fnv_to, td->td_ucred);
-	if (error && error != ENOENT) {
+	if (error != 0 && error != ENOENT) {
 		shm_insert(path_from, fnv_from, fd_from);
 		shm_drop(fd_from);
 		/* Don't free path_from now, since the hash references it */
 		path_from = NULL;
-		sx_xunlock(&shm_dict_lock);
-		goto out;
+		goto out_locked;
 	}
 
+	error = 0;
+
 	shm_insert(path_to, fnv_to, fd_from);
 
 	/* Don't free path_to now, since the hash references it */
@@ -1073,30 +1086,24 @@ sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
 
 	/* We kept a ref when we removed, and incremented again in insert */
 	shm_drop(fd_from);
-#ifdef DEBUG
 	KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
 	    fd_from->shm_refs));
-#endif
 
 	if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
 		shm_insert(path_from, fnv_from, fd_to);
 		path_from = NULL;
 		shm_drop(fd_to);
-#ifdef DEBUG
 		KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
 		    fd_to->shm_refs));
-#endif
 	}
 
-	error = 0;
+out_locked:
 	sx_xunlock(&shm_dict_lock);
 
 out:
-	if (path_from != NULL)
-		free(path_from, M_SHMFD);
-	if (path_to != NULL)
-		free(path_to, M_SHMFD);
-	return(error);
+	free(path_from, M_SHMFD);
+	free(path_to, M_SHMFD);
+	return (error);
 }
 
 int
diff --git a/sys/security/audit/audit_bsm.c b/sys/security/audit/audit_bsm.c
index fa5589bd2f56..feaae8edce9b 100644
--- a/sys/security/audit/audit_bsm.c
+++ b/sys/security/audit/audit_bsm.c
@@ -1565,6 +1565,16 @@ kaudit_to_bsm(struct kaudit_record *kar, struct au_record **pau)
 		}
 		break;
 
+	/* shm_rename is a non-Posix extension to the Posix shm implementation */
+	case AUE_SHMRENAME:
+		UPATH1_TOKENS;
+		UPATH2_TOKENS;
+		if (ARG_IS_VALID(kar, ARG_FFLAGS)) {
+			tok = au_to_arg32(2, "flags", ar->ar_arg_fflags);
+			kau_write(rec, tok);
+		}
+		break;
+
 	/* AUE_SHMOPEN, AUE_SHMUNLINK, AUE_SEMOPEN, AUE_SEMCLOSE
 	 * and AUE_SEMUNLINK are Posix IPC */
 	case AUE_SHMOPEN:
diff --git a/sys/sys/mman.h b/sys/sys/mman.h
index 7542a1812831..b004b2210441 100644
--- a/sys/sys/mman.h
+++ b/sys/sys/mman.h
@@ -118,6 +118,15 @@
 #define	MAP_ALIGNMENT_SHIFT	24
 #define	MAP_ALIGNMENT_MASK	MAP_ALIGNED(0xff)
 #define	MAP_ALIGNED_SUPER	MAP_ALIGNED(1) /* align on a superpage */
+
+/*
+ * Flags provided to shm_rename
+ */
+/* Don't overwrite dest, if it exists */
+#define SHM_RENAME_NOREPLACE	(1 << 0)
+/* Atomically swap src and dest */
+#define SHM_RENAME_EXCHANGE	(1 << 1)
+
 #endif /* __BSD_VISIBLE */
 
 #if __POSIX_VISIBLE >= 199309
@@ -134,14 +143,6 @@
 #define MAP_FAILED	((void *)-1)
 
 /*
- * Flags provided to shm_rename
- */
-/* Don't overwrite dest, if it exists */
-#define SHM_RENAME_NOREPLACE	(1 << 0)
-/* Atomically swap src and dest */
-#define SHM_RENAME_EXCHANGE	(1 << 1)
-
-/*
  * msync() flags
  */
 #define	MS_SYNC		0x0000	/* msync synchronously */
@@ -321,11 +322,11 @@ int	posix_madvise(void *, size_t, int);
 int	mlockall(int);
 int	munlockall(void);
 int	shm_open(const char *, int, mode_t);
-int	shm_rename(const char *, const char *, int);
 int	shm_unlink(const char *);
 #endif
 #if __BSD_VISIBLE
 int	memfd_create(const char *, unsigned int);
+int	shm_rename(const char *, const char *, int);
 #endif
 __END_DECLS
 
diff --git a/sys/sys/sysproto.h b/sys/sys/sysproto.h
index 941bd1b64c35..f02b2043f832 100644
--- a/sys/sys/sysproto.h
+++ b/sys/sys/sysproto.h
@@ -3129,7 +3129,7 @@ int	freebsd12_shm_open(struct thread *, struct freebsd12_shm_open_args *);
 #define	SYS_AUE_copy_file_range	AUE_NULL
 #define	SYS_AUE___sysctlbyname	AUE_SYSCTL
 #define	SYS_AUE_shm_open2	AUE_SHMOPEN
-#define	SYS_AUE_shm_rename	AUE_NULL
+#define	SYS_AUE_shm_rename	AUE_SHMRENAME
 
 #undef PAD_
 #undef PADL_
diff --git a/tests/sys/posixshm/posixshm_test.c b/tests/sys/posixshm/posixshm_test.c
index c75d9679b994..2bc59807d83f 100644
--- a/tests/sys/posixshm/posixshm_test.c
+++ b/tests/sys/posixshm/posixshm_test.c
@@ -53,7 +53,7 @@ static unsigned int test_path_idx = 0;
 static void
 gen_a_test_path(char *path)
 {
-	snprintf(path, TEST_PATH_LEN, "%s/tmp.XXXXXX%d",
+	snprintf(path, TEST_PATH_LEN, "/%s/tmp.XXXXXX%d",
 	    getenv("TMPDIR") == NULL ? "/tmp" : getenv("TMPDIR"),
 	    test_path_idx);
 
@@ -232,12 +232,14 @@ ATF_TC_BODY(rename_from_nonexisting, tc)
 	int rc;
 
 	gen_test_path();
+	gen_test_path2();
 	rc = shm_rename(test_path, test_path2, 0);
 	if (rc != -1)
 		atf_tc_fail("shm_rename of nonexisting shm succeeded unexpectedly");
 
 	if (errno != ENOENT)
-		atf_tc_fail("Expected ENOENT to rename of nonexistent shm");
+		atf_tc_fail("Expected ENOENT to rename of nonexistent shm; got %d",
+		    errno);
 }
 
 ATF_TC_WITHOUT_HEAD(rename_to_anon);