From: Florian Weimer <fw@deneb.enyo.de>
To: "Alexandra Hájková via Libc-alpha" <libc-alpha@sourceware.org>
Cc: "Alexandra Hájková" <alexandra.khirnova@gmail.com>,
"Alexandra Hájková" <ahajkova@redhat.com>
Subject: Re: [PATCH] Linux: Add execveat system call wrapper
Date: Tue, 28 Apr 2020 16:17:16 +0200 [thread overview]
Message-ID: <87lfmfpudv.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <20200428122019.26826-1-ahajkova@redhat.com> ("Alexandra =?iso-8859-1?Q?H=E1jkov=E1?= via Libc-alpha"'s message of "Tue, 28 Apr 2020 14:20:19 +0200")
* Alexandra Hájková via Libc-alpha:
> diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
> index 60696d827f..571c281b06 100644
> --- a/sysdeps/mach/hurd/i386/libc.abilist
> +++ b/sysdeps/mach/hurd/i386/libc.abilist
> @@ -2182,6 +2182,7 @@ GLIBC_2.3.4 xdr_quad_t F
> GLIBC_2.3.4 xdr_u_quad_t F
> GLIBC_2.30 twalk_r F
> GLIBC_2.32 mach_print F
> +GLIBC_2.32 execveat F
> GLIBC_2.32 thrd_current F
> GLIBC_2.32 thrd_equal F
> GLIBC_2.32 thrd_sleep F
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
This is not correct because you are not adding execveat for Hurd. You
can just remove that change.
> diff --git a/sysdeps/unix/sysv/linux/bits/unistd_ext.h b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
> index c315cc5cb8..55225b5447 100644
> --- a/sysdeps/unix/sysv/linux/bits/unistd_ext.h
> +++ b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
> @@ -17,7 +17,7 @@
> <https://www.gnu.org/licenses/>. */
>
> #ifndef _UNISTD_H
> -# error "Never include <bits/unistd_ext.h> directly; use <unistd.h> instead."
> +#error "Never include <bits/unistd_ext.h> directly; use <unistd.h> instead."
> #endif
Spurious change, please remove it.
> diff --git a/sysdeps/unix/sysv/linux/execveat.c b/sysdeps/unix/sysv/linux/execveat.c
> new file mode 100644
> index 0000000000..7ebf397091
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/execveat.c
> @@ -0,0 +1,67 @@
> +/* Copyright (C) 1994-2020 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
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <errno.h>
> +#include <stddef.h>
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <sys/stat.h>
> +
> +#include <sysdep.h>
> +#include <sys/syscall.h>
> +#include <kernel-features.h>
> +#include <fd_to_filename.h>
> +
> +
> +/* Execute the file FD refers to, overlaying the running program image.
> + ARGV and ENVP are passed to the new program, as for `execve'. */
> +int
> +execveat (int dirfd, const char *path, char *const argv[], char *const envp[],
> + int flags)
> +{
> + /* Avoid implicit array coercion in syscall macros. */
> + INLINE_SYSCALL_CALL (execveat, dirfd, path, &argv[0], &envp[0], flags);
> +#ifndef __ASSUME_EXECVEAT
> + if (errno != ENOSYS)
> + return -1;
> +
> + int fd = openat (dirfd, path, flags | O_CLOEXEC);
> + if (fd < 0)
> + return -1;
> +
> + struct fd_to_filename fdfilename;
> + const char *gfilename
> + = path != NULL ? path : __fd_to_filename (fd, &fdfilename);
> +
> + /* We do not need the return value. */
> + __execve (gfilename, argv, envp);
> +
> + int save = errno;
> +
> + /* We come here only if the 'execve' call fails. Determine whether
> + /proc is mounted. If not we return ENOSYS. */
> + struct stat st;
> + if (stat ("/proc/self/fd", &st) != 0 && errno == ENOENT)
> + save = ENOSYS;
> +
> + close (fd);
> + __set_errno (save);
> +#endif
> +
> + return -1;
> +}
I think you should use __openat_nocancel and __close_nocancel (from
<not-cancel.h>) to avoid introducing cancellation points. It will
also fix the elf/check-localplt failures.
> diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> index 6418ace78a..8f4388bf44 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> +++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
> @@ -2061,6 +2061,7 @@ GLIBC_2.30 gettid F
> GLIBC_2.30 tgkill F
> GLIBC_2.30 twalk_r F
> GLIBC_2.32 pthread_sigmask F
> +GLIBC_2.32 execveat F
> GLIBC_2.4 __confstr_chk F
> GLIBC_2.4 __fgets_chk F
> GLIBC_2.4 __fgets_unlocked_chk F
This is quite odd. Did you update the ABI list manually? The order
of pthread_sigmask and execveat is wrong. This is what causes
elf/check-abi-libc failures.
next prev parent reply other threads:[~2020-04-28 14:17 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 12:20 Alexandra Hájková
2020-04-28 14:17 ` Florian Weimer [this message]
2020-04-28 15:03 ` Joseph Myers
2020-04-28 15:03 ` Joseph Myers
2020-04-28 15:08 ` Florian Weimer
2020-04-28 15:29 ` Joseph Myers
2020-04-28 17:15 ` Florian Weimer
2020-04-28 17:19 ` Joseph Myers
2020-04-28 17:44 ` Adhemerval Zanella
2020-04-28 17:50 ` Florian Weimer
2020-04-28 18:31 ` Adhemerval Zanella
2020-04-30 11:15 ` Florian Weimer
2020-04-30 12:28 ` Adhemerval Zanella
2020-04-30 12:55 ` Florian Weimer
2020-04-30 19:03 ` Adhemerval Zanella
2020-04-30 12:32 ` Adhemerval Zanella
2020-11-06 21:03 ` Alexandra Hájková
2020-11-06 22:15 ` Joseph Myers
2020-11-09 18:43 ` Florian Weimer
2020-11-09 21:34 ` Yann Droneaud
2020-11-26 11:31 ` Alexandra Petlanova Hajkova
2020-11-09 20:39 ` Adhemerval Zanella
2020-12-03 13:55 ` Florian Weimer
2020-11-26 21:28 ` Alexandra Hájková
2020-11-27 14:58 ` Adhemerval Zanella
2020-11-27 17:32 ` Florian Weimer
2020-11-27 17:38 ` Adhemerval Zanella
2020-12-03 14:20 ` Alexandra Hájková
2020-12-03 14:37 ` Andreas Schwab
2020-12-08 14:44 ` Adhemerval Zanella
2020-12-08 15:18 ` Florian Weimer
2020-12-08 16:41 ` Adhemerval Zanella
2021-03-15 21:42 ` Alexandra Hájková
2021-03-15 22:12 ` Joseph Myers
2021-03-15 22:17 ` Dmitry V. Levin
2021-03-24 13:54 ` Alexandra Hájková
2021-03-26 20:36 ` Adhemerval Zanella
2021-04-02 12:13 ` Alexandra Hájková
2021-04-02 13:29 ` Adhemerval Zanella
2021-04-05 16:32 ` Alexandra Hájková
2021-04-12 10:26 ` Alexandra Hájková
2021-04-12 11:14 ` Andreas Schwab
2021-04-12 19:26 ` Alexandra Hájková
2021-04-13 19:27 ` Adhemerval Zanella
2021-04-21 18:11 ` Alexandra Hájková
2021-05-03 19:20 ` Adhemerval Zanella
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