Linux: Add memfd_create system call wrapper

The system call is somewhat obscure because it is closely related
to file descriptor sealing.  However, it is also the recommended
way to create alias mappings, which is why it has more general use.

No emulation is provided.  Except for the name of the
/proc/self/fd links, it would be possible to implement an
approximation using O_TMPFILE and tmpfs, but this does not appear
to be worth the added complexity.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>

36 files changed, 249 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index a84f970..04fac09 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2017-11-23  Florian Weimer  <fweimer@redhat.com>
+
+	Linux: Add memfd_create system call wrapper
+	* sysdeps/unix/sysv/linux/Makefile [misc] (tests): Add
+	tst-memfd_create.
+	* sysdeps/unix/sysv/linux/bits/mman-linux.h [__USE_GNU]
+	(MFD_CLOEXEC, MFD_ALLOW_SEALING): Define.
+	[__USE_GNU] (memfd_create): Declare.
+	* sysdeps/unix/sysv/linux/Versions (GLIBC_2.27): Add memfd_create.
+	* sysdeps/unix/sysv/linux/syscalls.list (memfd_create): Add.
+	* sysdeps/unix/sysv/linux/tst-memfd_create.c: New file.
+	* sysdeps/unix/sysv/linux/**.abilist: Update.
+	* manual/llio.texi (Memory-mapped I/O): Document memfd_create.
+
 2017-11-22  Joseph Myers  <joseph@codesourcery.com>
 
 	* localedata/gen-locale.sh: Fix typo in variable name.
diff --git a/NEWS b/NEWS
index 30ff04e..ab14d1e 100644
--- a/NEWS
+++ b/NEWS
@@ -35,6 +35,8 @@ Major new features:
   are the same interfaces added in version 2.26 for some platforms where
   this format is supported but is not the format of long double.
 
+* glibc now implements the memfd_create function on Linux.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * On GNU/Linux, the obsolete Linux constant PTRACE_SEIZE_DEVEL is no longer
diff --git a/manual/llio.texi b/manual/llio.texi
index 41c3e06..8b2f599 100644
--- a/manual/llio.texi
+++ b/manual/llio.texi
@@ -1801,6 +1801,69 @@ the given @var{name} previously created by @code{shm_open}.
 On failure @code{errno} is set.
 @end deftypefn
 
+@deftypefun int memfd_create (const char *@var{name}, unsigned int @var{flags})
+@standards{Linux, sys/mman.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
+The @code{memfd_create} function returns a file descriptor which can be
+used to create memory mappings using the @code{mmap} function.  It is
+similar to the @code{shm_open} function in the sense that these mappings
+are not backed by actual files.  However, the descriptor returned by
+@code{memfd_create} does not correspond to a named object; the
+@var{name} argument is used for debugging purposes only (e.g., will
+appear in @file{/proc}), and separate invocations of @code{memfd_create}
+with the same @var{name} will not return descriptors for the same region
+of memory.  The descriptor can also be used to create alias mappings
+within the same process.
+
+The descriptor initially refers to a zero-length file.  Before mappings
+can be created which are backed by memory, the file size needs to be
+increased with the @code{ftruncate} function.  @xref{File Size}.
+
+The @var{flags} argument can be a combination of the following flags:
+
+@vtable @code
+@item MFD_CLOEXEC
+@standards{Linux, sys/mman.h}
+The descriptor is created with the @code{O_CLOEXEC} flag.
+
+@item MFD_ALLOW_SEALING
+@standards{Linux, sys/mman.h}
+The descriptor supports the addition of seals using the @code{fcntl}
+function.
+
+@item MFD_HUGETLB
+@standards{Linux, sys/mman.h}
+This requests that mappings created using the returned file descriptor
+use a larger page size.  See @code{MAP_HUGETLB} above for details.
+
+This flag is incompatible with @code{MFD_ALLOW_SEALING}.
+@end vtable
+
+@code{memfd_create} returns a file descriptor on success, and @math{-1}
+on failure.
+
+The following @code{errno} error conditions are defined for this
+function:
+
+@table @code
+@item EINVAL
+An invalid combination is specified in @var{flags}, or @var{name} is
+too long.
+
+@item EFAULT
+The @var{name} argument does not point to a string.
+
+@item EMFILE
+The operation would exceed the file descriptor limit for this process.
+
+@item ENFILE
+The operation would exceed the system-wide file descriptor limit.
+
+@item ENOMEM
+There is not enough memory for the operation.
+@end table
+@end deftypefun
+
 @node Waiting for I/O
 @section Waiting for Input or Output
 @cindex waiting for input or output
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index c6675b3..c484d26 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -44,7 +44,7 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
 
 tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
 	 tst-quota tst-sync_file_range tst-sysconf-iov_max tst-ttyname \
-	 test-errno-linux
+	 test-errno-linux tst-memfd_create
 
 # Generate the list of SYS_* macros for the system calls (__NR_*
 # macros).  The file syscall-names.list contains all possible system
diff --git a/sysdeps/unix/sysv/linux/Versions b/sysdeps/unix/sysv/linux/Versions
index d3dbcde..6f2fe51 100644
--- a/sysdeps/unix/sysv/linux/Versions
+++ b/sysdeps/unix/sysv/linux/Versions
@@ -166,6 +166,9 @@ libc {
   GLIBC_2.15 {
     process_vm_readv; process_vm_writev;
   }
+  GLIBC_2.27 {
+    memfd_create;
+  }
   GLIBC_PRIVATE {
     # functions used in other libraries
     __syscall_rt_sigqueueinfo;
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index ed598ae..140ca28 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2106,6 +2106,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index 4e57f36..f698e1b 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2017,6 +2017,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
index 5b70e1b..8a8af3e 100644
--- a/sysdeps/unix/sysv/linux/arm/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
@@ -107,6 +107,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/bits/mman-linux.h b/sysdeps/unix/sysv/linux/bits/mman-linux.h
index 78c07c8..1ffa549 100644
--- a/sysdeps/unix/sysv/linux/bits/mman-linux.h
+++ b/sysdeps/unix/sysv/linux/bits/mman-linux.h
@@ -111,3 +111,19 @@
 # define MCL_ONFAULT	4		/* Lock all pages that are
 					   faulted in.  */
 #endif
+
+#ifdef __USE_GNU
+/* Flags for memfd_create.  */
+# define MFD_CLOEXEC 1U
+# define MFD_ALLOW_SEALING 2U
+# define MFD_HUGETLB 4U
+
+__BEGIN_DECLS
+
+/* Create a new memory file descriptor.  NAME is a name for debugging.
+   FLAGS is a combination of the MFD_* constants.  */
+int memfd_create (const char *__name, unsigned int __flags) __THROW;
+
+__END_DECLS
+
+#endif /* __USE_GNU */
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 6a2500a..5b81a6c 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -1871,6 +1871,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index 9ab4e36..51ead9e 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2036,6 +2036,7 @@ GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index 81bb623..78b4ee8 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -1900,6 +1900,7 @@ GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index 5a33b57..d9c9777 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -108,6 +108,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.4 GLIBC_2.4 A
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0x98
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index 50a86e7..4acbf7e 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -1985,6 +1985,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
index 250ef30..93f02f0 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
@@ -2106,3 +2106,4 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 87a1dc4..795e85d 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -1960,6 +1960,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index f2b35f2..dc71405 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -1958,6 +1958,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index ade654d..ce7bc9b 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -1956,6 +1956,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index 56032c3..3fdd85e 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -1951,6 +1951,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index c599dd9..3e0bcb2 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2147,3 +2147,4 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index 385409a..375c69d 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -1989,6 +1989,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index e99cb45..a88172a 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -1994,6 +1994,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
index 173672a..fa026a3 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
@@ -2201,3 +2201,4 @@ GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
index 8a65443..838f395 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
@@ -108,6 +108,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 _Exit F
 GLIBC_2.3 _IO_2_1_stderr_ D 0xe0
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index dbd411c..41b79c4 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -1989,6 +1989,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index 5617784..68251a0 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -1890,6 +1890,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
index 0f840e6..bc1aae2 100644
--- a/sysdeps/unix/sysv/linux/sh/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
@@ -1875,6 +1875,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index bb7e104..93e6d09 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -1982,6 +1982,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index 4053b0a..b11d676 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -1919,6 +1919,7 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.27 strfromf128 F
 GLIBC_2.27 strtof128 F
 GLIBC_2.27 strtof128_l F
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index 8bfb080..40c4fbb 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -109,3 +109,4 @@ setns		EXTRA	setns		i:ii	setns
 
 process_vm_readv EXTRA	process_vm_readv i:ipipii process_vm_readv
 process_vm_writev EXTRA	process_vm_writev i:ipipii process_vm_writev
+memfd_create    EXTRA	memfd_create	i:si    memfd_create
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
index 38a96d3..e9eb4ff 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
@@ -2113,3 +2113,4 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
index 572b917..8f08e90 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
@@ -2113,3 +2113,4 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
index 38a96d3..e9eb4ff 100644
--- a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
@@ -2113,3 +2113,4 @@ GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/tst-memfd_create.c b/sysdeps/unix/sysv/linux/tst-memfd_create.c
new file mode 100644
index 0000000..fd173ff
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-memfd_create.c
@@ -0,0 +1,121 @@
+/* Test for the memfd_create system call.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+
+/* Return true if the descriptor has the FD_CLOEXEC flag set.  */
+static bool
+is_cloexec (int fd)
+{
+  int flags = fcntl (fd, F_GETFD);
+  TEST_VERIFY (flags >= 0);
+  return flags & FD_CLOEXEC;
+}
+
+/* Return the seals set on FD.  */
+static int
+get_seals (int fd)
+{
+  int flags = fcntl (fd, F_GET_SEALS);
+  TEST_VERIFY (flags >= 0);
+  return flags;
+}
+
+/* Return true if the F_SEAL_SEAL flag is set on the descriptor.  */
+static bool
+is_sealed (int fd)
+{
+  return get_seals (fd) & F_SEAL_SEAL;
+}
+
+static int
+do_test (void)
+{
+  /* Initialized by the first call to memfd_create to 0 (memfd_create
+     unsupported) or 1 (memfd_create is implemented in the kernel).
+     Subsequent iterations check that the success/failure state is
+     consistent.  */
+  int supported = -1;
+
+  for (int do_cloexec = 0; do_cloexec < 2; ++do_cloexec)
+    for (int do_sealing = 0; do_sealing < 2; ++do_sealing)
+      {
+        int flags = 0;
+        if (do_cloexec)
+          flags |= MFD_CLOEXEC;
+        if (do_sealing)
+          flags |= MFD_ALLOW_SEALING;
+        if  (test_verbose > 0)
+          printf ("info: memfd_create with flags=0x%x\n", flags);
+        int fd = memfd_create ("tst-memfd_create", flags);
+        if (fd < 0)
+          {
+            if (errno == ENOSYS)
+              {
+                if (supported < 0)
+                  {
+                    printf ("warning: memfd_create is unsupported\n");
+                    supported = 0;
+                    continue;
+                  }
+                TEST_VERIFY (supported == 0);
+                continue;
+              }
+            else
+              FAIL_EXIT1 ("memfd_create: %m");
+          }
+        if (supported < 0)
+          supported = 1;
+        TEST_VERIFY (supported > 0);
+
+        char *fd_path = xasprintf ("/proc/self/fd/%d", fd);
+        char *link = xreadlink (fd_path);
+        if (test_verbose > 0)
+          printf ("info: memfd link: %s\n", link);
+        TEST_VERIFY (strcmp (link, "memfd:tst-memfd_create (deleted)"));
+        TEST_VERIFY (is_cloexec (fd) == do_cloexec);
+        TEST_VERIFY (is_sealed (fd) == !do_sealing);
+        if (do_sealing)
+          {
+            TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_WRITE) == 0);
+            TEST_VERIFY (!is_sealed (fd));
+            TEST_VERIFY (get_seals (fd) & F_SEAL_WRITE);
+            TEST_VERIFY (fcntl (fd, F_ADD_SEALS, F_SEAL_SEAL) == 0);
+            TEST_VERIFY (is_sealed (fd));
+          }
+        xclose (fd);
+        free (fd_path);
+        free (link);
+      }
+
+  if (supported == 0)
+    return EXIT_UNSUPPORTED;
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index b83d25c..0a4f779 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -1877,6 +1877,7 @@ GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F
 GLIBC_2.3 GLIBC_2.3 A
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index cba1d59..23f6a91 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2120,3 +2120,4 @@ GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
+GLIBC_2.27 memfd_create F