lkml.org 
[lkml]   [2020]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [EXTERNAL][PATCH v3] binfmt_misc: pass binfmt_misc flags to the interpreter
    Date
    在 2020-01-28二的 14:25 +0100,Laurent Vivier写道:
    > 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@vivier.eu>

    Reviewed-by: YunQiang Su <ysu@wavecomp.com>

    > ---
    >
    > 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 */

    \
     
     \ /
      Last update: 2020-02-03 13:26    [W:3.829 / U:0.056 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site