svn commit: r352700 - in head/sys: compat/freebsd32 kern sys
Kyle Evans
kevans at FreeBSD.org
Wed Sep 25 17:59:17 UTC 2019
Author: kevans
Date: Wed Sep 25 17:59:15 2019
New Revision: 352700
URL: https://svnweb.freebsd.org/changeset/base/352700
Log:
Add a shm_open2 syscall to support upcoming memfd_create
shm_open2 allows a little more flexibility than the original shm_open.
shm_open2 doesn't enforce CLOEXEC on its callers, and it has a separate
shmflag argument that can be expanded later. Currently the only shmflag is
to allow file sealing on the returned fd.
shm_open and memfd_create will both be implemented in libc to use this new
syscall.
__FreeBSD_version is bumped to indicate the presence.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D21393
Modified:
head/sys/compat/freebsd32/syscalls.master
head/sys/kern/capabilities.conf
head/sys/kern/syscalls.master
head/sys/kern/uipc_shm.c
head/sys/sys/mman.h
head/sys/sys/param.h
head/sys/sys/syscallsubr.h
Modified: head/sys/compat/freebsd32/syscalls.master
==============================================================================
--- head/sys/compat/freebsd32/syscalls.master Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/compat/freebsd32/syscalls.master Wed Sep 25 17:59:15 2019 (r352700)
@@ -1154,5 +1154,8 @@
570 AUE_SYSCTL STD { int freebsd32___sysctlbyname(const char *name, \
size_t namelen, void *old, uint32_t *oldlenp, \
void *new, size_t newlen); }
+571 AUE_SHMOPEN NOPROTO { int shm_open2( \
+ const char *path, int flags, mode_t mode, \
+ int shmflags, const char *name); }
; vim: syntax=off
Modified: head/sys/kern/capabilities.conf
==============================================================================
--- head/sys/kern/capabilities.conf Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/kern/capabilities.conf Wed Sep 25 17:59:15 2019 (r352700)
@@ -655,6 +655,7 @@ setuid
## shm_open(2) is scoped so as to allow only access to new anonymous objects.
##
shm_open
+shm_open2
##
## Allow I/O-related file descriptors, subject to capability rights.
Modified: head/sys/kern/syscalls.master
==============================================================================
--- head/sys/kern/syscalls.master Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/kern/syscalls.master Wed Sep 25 17:59:15 2019 (r352700)
@@ -3195,6 +3195,15 @@
_In_reads_bytes_opt_(newlen) void *new,
size_t newlen);
}
+571 AUE_SHMOPEN STD {
+ int shm_open2(
+ _In_z_ const char *path,
+ int flags,
+ mode_t mode,
+ int shmflags,
+ _In_z_ const char *name
+ );
+ }
; Please copy any additions and changes to the following compatability tables:
; sys/compat/freebsd32/syscalls.master
Modified: head/sys/kern/uipc_shm.c
==============================================================================
--- head/sys/kern/uipc_shm.c Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/kern/uipc_shm.c Wed Sep 25 17:59:15 2019 (r352700)
@@ -1316,3 +1316,36 @@ SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
NULL, 0, sysctl_posix_shm_list, "",
"POSIX SHM list");
+
+int
+kern_shm_open2(struct thread *td, const char *path, int flags, mode_t mode,
+ int shmflags, const char *name __unused)
+{
+ int initial_seals;
+
+ if ((shmflags & ~SHM_ALLOW_SEALING) != 0)
+ return (EINVAL);
+
+ initial_seals = F_SEAL_SEAL;
+ if ((shmflags & SHM_ALLOW_SEALING) != 0)
+ initial_seals &= ~F_SEAL_SEAL;
+ return (kern_shm_open(td, path, flags, 0, NULL, initial_seals));
+}
+
+/*
+ * This version of the shm_open() interface leaves CLOEXEC behavior up to the
+ * caller, and libc will enforce it for the traditional shm_open() call. This
+ * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
+ * interface also includes a 'name' argument that is currently unused, but could
+ * potentially be exported later via some interface for debugging purposes.
+ * From the kernel's perspective, it is optional. Individual consumers like
+ * memfd_create() may require it in order to be compatible with other systems
+ * implementing the same function.
+ */
+int
+sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
+{
+
+ return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
+ uap->shmflags, uap->name));
+}
Modified: head/sys/sys/mman.h
==============================================================================
--- head/sys/sys/mman.h Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/sys/mman.h Wed Sep 25 17:59:15 2019 (r352700)
@@ -176,6 +176,12 @@
* Anonymous object constant for shm_open().
*/
#define SHM_ANON ((char *)1)
+
+/*
+ * shmflags for shm_open2()
+ */
+#define SHM_ALLOW_SEALING 0x00000001
+
#endif /* __BSD_VISIBLE */
/*
Modified: head/sys/sys/param.h
==============================================================================
--- head/sys/sys/param.h Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/sys/param.h Wed Sep 25 17:59:15 2019 (r352700)
@@ -60,7 +60,7 @@
* in the range 5 to 9.
*/
#undef __FreeBSD_version
-#define __FreeBSD_version 1300047 /* Master, propagated to newvers */
+#define __FreeBSD_version 1300048 /* Master, propagated to newvers */
/*
* __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
Modified: head/sys/sys/syscallsubr.h
==============================================================================
--- head/sys/sys/syscallsubr.h Wed Sep 25 17:52:59 2019 (r352699)
+++ head/sys/sys/syscallsubr.h Wed Sep 25 17:59:15 2019 (r352700)
@@ -251,6 +251,8 @@ int kern_settimeofday(struct thread *td, struct timeva
struct timezone *tzp);
int kern_shm_open(struct thread *td, const char *userpath, int flags,
mode_t mode, struct filecaps *fcaps, int initial_seals);
+int kern_shm_open2(struct thread *td, const char *path, int flags,
+ mode_t mode, int shmflags, const char *name);
int kern_shmat(struct thread *td, int shmid, const void *shmaddr,
int shmflg);
int kern_shmctl(struct thread *td, int shmid, int cmd, void *buf,
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