I'd like to have this in the kernel to be able to use it in QEMU (next QEMU release is 28/04, freeze 17/03). Thanks, Laurent Le 14/02/2020 à 13:29, Laurent Vivier a écrit : > Hi, > > any comment? > > I think I've addressed comments on v2. > > Thanks, > Laurent > > 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> >> --- >> >> 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 */ >> >
