From patchwork Fri Mar 6 08:09:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: YunQiang Su X-Patchwork-Id: 38445 Received: (qmail 82066 invoked by alias); 6 Mar 2020 08:09:47 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 82048 invoked by uid 89); 6 Mar 2020 08:09:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.1 required=5.0 tests=AWL, BAYES_00, FREEMAIL_FROM, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.1 spammy=H*Ad:D*eu, HX-Google-DKIM-Signature:sender, cred, HX-Spam-Relays-External:209.85.216.66 X-HELO: mail-pj1-f66.google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=7TiOD25ZQuBocGWSYjvqKa3msFH5m2kuVO7nsDjKlwo=; b=NYMTN0wG6q+cq6aqTvrP9llFnl30M4rXTg+zEDw75WgKwGfqHH1odu9d4WDLBoE7TN PwOHuFwovG9TJWp/Hq8kcYY9ZQC3iYdTFjnpb/uc7dQt6+HnCiMG0mHThwgbHJKrPeDc lIT1d+OXgu/TKT7KUckC7Q9CmT/B8I16f5Df49kXmc0uVa6E0p/2rareOGebjILOBdr5 Z12Bgs1bBXUibC/ue4p7pSzIEx7aMftiubqw9WQKH0STVLM2caaWgtVt+HTwWLkcdryH 5k4H4/5qfWQ9CFLX4N6kPOoOLjyEfJzivdHTu8IbGt35LlPmbZGtrEmxZ3f/Dlg47Wyc GOug== Return-Path: From: YunQiang Su To: torvalds@linux-foundation.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, viro@zeniv.linux.org.uk, James.Bottomley@hansenpartnership.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, libc-alpha@sourceware.org, Laurent Vivier , YunQiang Su Subject: [PATCH] binfmt_misc: pass binfmt_misc P flag to the interpreter Date: Fri, 6 Mar 2020 16:09:05 +0800 Message-Id: <20200306080905.173466-1-syq@debian.org> MIME-Version: 1.0 From: Laurent Vivier It can be useful to the interpreter to know which flags are in use. For instance, knowing if the preserve-argv[0] is in use would allow to skip the pathname argument. This patch uses an unused auxiliary vector, AT_FLAGS, to add a flag to inform interpreter if the preserve-argv[0] is enabled. Signed-off-by: Laurent Vivier Signed-off-by: YunQiang Su --- Notes: This patch uses AT_FLAGS, which has never been used. We need to make a decision. since it is about the fundmental API of userland. This can be tested with QEMU from my branch: https://github.com/vivier/qemu/commits/binfmt-argv0 With something like: # cp ..../qemu-ppc /chroot/powerpc/jessie # qemu-binfmt-conf.sh --qemu-path / --systemd ppc --credential yes \ --persistent no --preserve-argv0 yes # systemctl restart systemd-binfmt.service # cat /proc/sys/fs/binfmt_misc/qemu-ppc enabled interpreter //qemu-ppc flags: POC offset 0 magic 7f454c4601020100000000000000000000020014 mask ffffffffffffff00fffffffffffffffffffeffff # chroot /chroot/powerpc/jessie sh -c 'echo $0' sh # qemu-binfmt-conf.sh --qemu-path / --systemd ppc --credential yes \ --persistent no --preserve-argv0 no # systemctl restart systemd-binfmt.service # cat /proc/sys/fs/binfmt_misc/qemu-ppc enabled interpreter //qemu-ppc flags: OC offset 0 magic 7f454c4601020100000000000000000000020014 mask ffffffffffffff00fffffffffffffffffffeffff # chroot /chroot/powerpc/jessie sh -c 'echo $0' /bin/sh v4: Update to merge with linux-next: 20200305. v3: mix my patch with one from YunQiang Su and my comments on it introduce a new flag in the uabi for the AT_FLAGS v2: only pass special flags (remove Magic and Enabled flags) --- fs/binfmt_elf.c | 6 ++++-- fs/binfmt_elf_fdpic.c | 5 ++++- fs/binfmt_misc.c | 4 +++- include/linux/binfmts.h | 4 ++++ include/uapi/linux/binfmts.h | 4 ++++ 5 files changed, 19 insertions(+), 4 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 13f25e241ac4..e9f5d135b847 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -178,7 +178,7 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, const char *k_base_platform = ELF_BASE_PLATFORM; unsigned char k_rand_bytes[16]; int items; - elf_addr_t *elf_info; + elf_addr_t *elf_info, flags = 0; int ei_index; const struct cred *cred = current_cred(); struct vm_area_struct *vma; @@ -253,7 +253,9 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr)); NEW_AUX_ENT(AT_PHNUM, exec->e_phnum); NEW_AUX_ENT(AT_BASE, interp_load_addr); - NEW_AUX_ENT(AT_FLAGS, 0); + if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0) + flags |= AT_FLAGS_PRESERVE_ARGV0; + NEW_AUX_ENT(AT_FLAGS, flags); NEW_AUX_ENT(AT_ENTRY, e_entry); NEW_AUX_ENT(AT_UID, from_kuid_munged(cred->user_ns, cred->uid)); NEW_AUX_ENT(AT_EUID, from_kuid_munged(cred->user_ns, cred->euid)); diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 240f66663543..abb90d82aa58 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -507,6 +507,7 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm, char __user *u_platform, *u_base_platform, *p; int loop; int nr; /* reset for each csp adjustment */ + unsigned long flags = 0; #ifdef CONFIG_MMU /* In some cases (e.g. Hyper-Threading), we want to avoid L1 evictions @@ -647,7 +648,9 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm, NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr)); NEW_AUX_ENT(AT_PHNUM, exec_params->hdr.e_phnum); NEW_AUX_ENT(AT_BASE, interp_params->elfhdr_addr); - NEW_AUX_ENT(AT_FLAGS, 0); + if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0) + flags |= AT_FLAGS_PRESERVE_ARGV0; + NEW_AUX_ENT(AT_FLAGS, flags); NEW_AUX_ENT(AT_ENTRY, exec_params->entry_addr); NEW_AUX_ENT(AT_UID, (elf_addr_t) from_kuid_munged(cred->user_ns, cred->uid)); NEW_AUX_ENT(AT_EUID, (elf_addr_t) from_kuid_munged(cred->user_ns, cred->euid)); diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index cdb45829354d..b9acdd26a654 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -154,7 +154,9 @@ static int load_misc_binary(struct linux_binprm *bprm) if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) goto ret; - if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) { + if (fmt->flags & MISC_FMT_PRESERVE_ARGV0) { + bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0; + } else { retval = remove_arg_zero(bprm); if (retval) goto ret; diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index b40fc633f3be..265b80d5fd6f 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -78,6 +78,10 @@ struct linux_binprm { #define BINPRM_FLAGS_PATH_INACCESSIBLE_BIT 2 #define BINPRM_FLAGS_PATH_INACCESSIBLE (1 << BINPRM_FLAGS_PATH_INACCESSIBLE_BIT) +/* if preserve the argv0 for the interpreter */ +#define BINPRM_FLAGS_PRESERVE_ARGV0_BIT 3 +#define BINPRM_FLAGS_PRESERVE_ARGV0 (1 << BINPRM_FLAGS_PRESERVE_ARGV0_BIT) + /* Function parameter for binfmt->coredump */ struct coredump_params { const kernel_siginfo_t *siginfo; diff --git a/include/uapi/linux/binfmts.h b/include/uapi/linux/binfmts.h index 689025d9c185..a70747416130 100644 --- a/include/uapi/linux/binfmts.h +++ b/include/uapi/linux/binfmts.h @@ -18,4 +18,8 @@ struct pt_regs; /* sizeof(linux_binprm->buf) */ #define BINPRM_BUF_SIZE 256 +/* if preserve the argv0 for the interpreter */ +#define AT_FLAGS_PRESERVE_ARGV0_BIT 0 +#define AT_FLAGS_PRESERVE_ARGV0 (1 << AT_FLAGS_PRESERVE_ARGV0_BIT) + #endif /* _UAPI_LINUX_BINFMTS_H */