Ping... We really need it. since qemu-user mode have no other choice to get the info about whether P flag is set. > -----Original Message----- > From: Laurent Vivier <laurent@xxxxxxxxx> > Sent: 2019年12月16日 17:22 > To: linux-kernel@xxxxxxxxxxxxxxx > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>; > James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>; Yunqiang Su > <ysu@xxxxxxxxxxxx> > Subject: [EXTERNAL]Re: [RFC v2] binfmt_misc: pass binfmt_misc flags to the > interpreter > > Hi, > > this feature is really needed and requested by several binfmt_misc users. It is > difficult to manage this at user level without this information. > > I've found that someone else tried to address this problem in the past in the > same way: > https://patchwork.kernel.org/patch/10902935/ > > Can a maintainer/reviewer have a look at this and agrees or disagrees? > > I will update getauxval(3) manual page with the new flags in the case one of > these patches is merged. > > Thanks, > Laurent > > > Le 22/11/2019 à 16:08, 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 pass the > > content of the binfmt flags (special flags: P, F, C, O). > > > > Signed-off-by: Laurent Vivier <laurent@xxxxxxxxx> > > --- > > > > Notes: > > v2: only pass special flags (remove Magic and Enabled flags) > > > > fs/binfmt_elf.c | 2 +- > > fs/binfmt_elf_fdpic.c | 2 +- > > fs/binfmt_misc.c | 6 ++++++ > > include/linux/binfmts.h | 2 +- > > 4 files changed, 9 insertions(+), 3 deletions(-) > > > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index > > c5642bcb6b46..7a34c03e5857 100644 > > --- a/fs/binfmt_elf.c > > +++ b/fs/binfmt_elf.c > > @@ -250,7 +250,7 @@ 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); > > + NEW_AUX_ENT(AT_FLAGS, bprm->fmt_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 > > d86ebd0dcc3d..8fe839be125e 100644 > > --- a/fs/binfmt_elf_fdpic.c > > +++ b/fs/binfmt_elf_fdpic.c > > @@ -647,7 +647,7 @@ 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); > > + NEW_AUX_ENT(AT_FLAGS, bprm->fmt_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..25a392f23409 100644 > > --- a/fs/binfmt_misc.c > > +++ b/fs/binfmt_misc.c > > @@ -48,6 +48,9 @@ enum {Enabled, Magic}; #define > MISC_FMT_OPEN_BINARY > > (1 << 30) #define MISC_FMT_CREDENTIALS (1 << 29) #define > > MISC_FMT_OPEN_FILE (1 << 28) > > +#define MISC_FMT_FLAGS_MASK (MISC_FMT_PRESERVE_ARGV0 | > MISC_FMT_OPEN_BINARY | \ > > + MISC_FMT_CREDENTIALS | MISC_FMT_OPEN_FILE) > > + > > > > typedef struct { > > struct list_head list; > > @@ -149,6 +152,9 @@ static int load_misc_binary(struct linux_binprm > *bprm) > > if (!fmt) > > return retval; > > > > + /* pass special flags to the interpreter */ > > + bprm->fmt_flags = fmt->flags & MISC_FMT_FLAGS_MASK; > > + > > /* Need to be able to load the file after exec */ > > retval = -ENOENT; > > if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) diff --git > > a/include/linux/binfmts.h b/include/linux/binfmts.h index > > b40fc633f3be..dae0d0d7b84d 100644 > > --- a/include/linux/binfmts.h > > +++ b/include/linux/binfmts.h > > @@ -60,7 +60,7 @@ struct linux_binprm { > > different for binfmt_{misc,script} */ > > unsigned interp_flags; > > unsigned interp_data; > > - unsigned long loader, exec; > > + unsigned long loader, exec, fmt_flags; > > > > struct rlimit rlim_stack; /* Saved RLIMIT_STACK used during exec. */ > > > >
