Helge Deller <deller@xxxxxx> 于2021年2月13日周六 下午3:40写道： > > On 6/5/20 6:20 PM, Laurent Vivier wrote: > > Le 28/01/2020 à 14:25, Laurent Vivier a écrit : > >> 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 <laurent@xxxxxxxxx> > > Acked-by: Helge Deller <deller@xxxxxx> > > If nobody objects, I'd like to take this patch through the > parisc arch git tree. > Thank you. I see this patch has been in linux-next now. @Laurent, I guess it is time to work on to push the patch for qemu? > It fixes a real-world problem with qemu-user which fails to > preserve the argv[0] argument when the callee of an exec is a > qemu-user target. > This problem leads to build errors on multiple Debian buildd servers > which are using qemu-user as emulation for the target machines. > > For details see Debian bug: > http://bugs.debian.org/970460 > > > Helge > > > >> --- > >> > >> Notes: > >> 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 > >> > >> 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 | 5 ++++- > >> 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(+), 3 deletions(-) > >> > >> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > >> index ecd8d2698515..ff918042ceed 100644 > >> --- a/fs/binfmt_elf.c > >> +++ b/fs/binfmt_elf.c > >> @@ -176,6 +176,7 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, > >> unsigned char k_rand_bytes[16]; > >> int items; > >> elf_addr_t *elf_info; > >> + elf_addr_t flags = 0; > >> int ei_index = 0; > >> const struct cred *cred = current_cred(); > >> struct vm_area_struct *vma; > >> @@ -250,7 +251,9 @@ create_elf_tables(struct linux_binprm *bprm, 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, exec->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 */ > >> > > >
