| Message ID | 20200116022049.164659-1-syq@debian.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] binfmt_misc: pass info about P flag by AT_FLAGS | expand |
Le 16/01/2020 à 03:20, YunQiang Su a écrit : > From: YunQiang Su <ysu@wavecomp.com> > > Currently program invoked by binfmt_misc cannot be aware about whether > P flag, aka preserve path is enabled. > > Some applications like qemu need to know since it has 2 use case: > 1. call by hand, like: qemu-mipsel-static test.app OPTION > so, qemu have to assume that P option is not enabled. > 2. call by binfmt_misc. If qemu cannot know about whether P flag is > enabled, distribution's have to set qemu without P flag, and > binfmt_misc call qemu like: > qemu-mipsel-static /absolute/path/to/test.app OPTION > even test.app is not called by absoulute path, like > ./relative/path/to/test.app > > This patch passes this information by the 3rd bits of unused AT_FLAGS. > Then, in qemu, we can get this info by: > getauxval(AT_FLAGS) & (1<<3) > > v1->v2: > not enable kdebug > > See: https://bugs.launchpad.net/qemu/+bug/1818483 > Signed-off-by: YunQiang Su <ysu@wavecomp.com> > --- > fs/binfmt_elf.c | 6 +++++- > fs/binfmt_elf_fdpic.c | 6 +++++- > fs/binfmt_misc.c | 2 ++ > include/linux/binfmts.h | 4 ++++ > 4 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index f4713ea76e82..d33ee07d7f57 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -178,6 +178,7 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, > unsigned char k_rand_bytes[16]; > int items; > elf_addr_t *elf_info; > + elf_addr_t flags = 0; > int ei_index; > const struct cred *cred = current_cred(); > struct vm_area_struct *vma; > @@ -252,7 +253,10 @@ 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 |= BINPRM_FLAGS_PRESERVE_ARGV0; > + } Perhaps we also need a different flag in AT_FLAG than in interp_flag as BINPRM_FLAGS_PRESERVE_ARGV0 is also part of the internal ABI? Al? Thanks, Laurent
Laurent Vivier <laurent@vivier.eu> 于2020年1月16日周四 下午4:07写道： > > Le 16/01/2020 à 03:20, YunQiang Su a écrit : > > From: YunQiang Su <ysu@wavecomp.com> > > > > Currently program invoked by binfmt_misc cannot be aware about whether > > P flag, aka preserve path is enabled. > > > > Some applications like qemu need to know since it has 2 use case: > > 1. call by hand, like: qemu-mipsel-static test.app OPTION > > so, qemu have to assume that P option is not enabled. > > 2. call by binfmt_misc. If qemu cannot know about whether P flag is > > enabled, distribution's have to set qemu without P flag, and > > binfmt_misc call qemu like: > > qemu-mipsel-static /absolute/path/to/test.app OPTION > > even test.app is not called by absoulute path, like > > ./relative/path/to/test.app > > > > This patch passes this information by the 3rd bits of unused AT_FLAGS. > > Then, in qemu, we can get this info by: > > getauxval(AT_FLAGS) & (1<<3) > > > > v1->v2: > > not enable kdebug > > > > See: https://bugs.launchpad.net/qemu/+bug/1818483 > > Signed-off-by: YunQiang Su <ysu@wavecomp.com> > > --- > > fs/binfmt_elf.c | 6 +++++- > > fs/binfmt_elf_fdpic.c | 6 +++++- > > fs/binfmt_misc.c | 2 ++ > > include/linux/binfmts.h | 4 ++++ > > 4 files changed, 16 insertions(+), 2 deletions(-) > > > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > > index f4713ea76e82..d33ee07d7f57 100644 > > --- a/fs/binfmt_elf.c > > +++ b/fs/binfmt_elf.c > > @@ -178,6 +178,7 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, > > unsigned char k_rand_bytes[16]; > > int items; > > elf_addr_t *elf_info; > > + elf_addr_t flags = 0; > > int ei_index; > > const struct cred *cred = current_cred(); > > struct vm_area_struct *vma; > > @@ -252,7 +253,10 @@ 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 |= BINPRM_FLAGS_PRESERVE_ARGV0; > > + } > > Perhaps we also need a different flag in AT_FLAG than in interp_flag as > BINPRM_FLAGS_PRESERVE_ARGV0 is also part of the internal ABI? yep. It may be really a problem. So, should we define a set of new macros for AT_FLAGS? > > Al? > > Thanks, > Laurent >
Le 16/01/2020 à 09:17, YunQiang Su a écrit : > Laurent Vivier <laurent@vivier.eu> 于2020年1月16日周四 下午4:07写道： >> >> Le 16/01/2020 à 03:20, YunQiang Su a écrit : >>> From: YunQiang Su <ysu@wavecomp.com> >>> >>> Currently program invoked by binfmt_misc cannot be aware about whether >>> P flag, aka preserve path is enabled. >>> >>> Some applications like qemu need to know since it has 2 use case: >>> 1. call by hand, like: qemu-mipsel-static test.app OPTION >>> so, qemu have to assume that P option is not enabled. >>> 2. call by binfmt_misc. If qemu cannot know about whether P flag is >>> enabled, distribution's have to set qemu without P flag, and >>> binfmt_misc call qemu like: >>> qemu-mipsel-static /absolute/path/to/test.app OPTION >>> even test.app is not called by absoulute path, like >>> ./relative/path/to/test.app >>> >>> This patch passes this information by the 3rd bits of unused AT_FLAGS. >>> Then, in qemu, we can get this info by: >>> getauxval(AT_FLAGS) & (1<<3) >>> >>> v1->v2: >>> not enable kdebug >>> >>> See: https://bugs.launchpad.net/qemu/+bug/1818483 >>> Signed-off-by: YunQiang Su <ysu@wavecomp.com> >>> --- >>> fs/binfmt_elf.c | 6 +++++- >>> fs/binfmt_elf_fdpic.c | 6 +++++- >>> fs/binfmt_misc.c | 2 ++ >>> include/linux/binfmts.h | 4 ++++ >>> 4 files changed, 16 insertions(+), 2 deletions(-) >>> >>> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c >>> index f4713ea76e82..d33ee07d7f57 100644 >>> --- a/fs/binfmt_elf.c >>> +++ b/fs/binfmt_elf.c >>> @@ -178,6 +178,7 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, >>> unsigned char k_rand_bytes[16]; >>> int items; >>> elf_addr_t *elf_info; >>> + elf_addr_t flags = 0; >>> int ei_index; >>> const struct cred *cred = current_cred(); >>> struct vm_area_struct *vma; >>> @@ -252,7 +253,10 @@ 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 |= BINPRM_FLAGS_PRESERVE_ARGV0; >>> + } >> >> Perhaps we also need a different flag in AT_FLAG than in interp_flag as >> BINPRM_FLAGS_PRESERVE_ARGV0 is also part of the internal ABI? > > yep. It may be really a problem. > So, should we define a set of new macros for AT_FLAGS? Yes, I think. Thanks, Laurent
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index f4713ea76e82..d33ee07d7f57 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -178,6 +178,7 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, unsigned char k_rand_bytes[16]; int items; elf_addr_t *elf_info; + elf_addr_t flags = 0; int ei_index; const struct cred *cred = current_cred(); struct vm_area_struct *vma; @@ -252,7 +253,10 @@ 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 |= BINPRM_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..5ad8fdb3babe 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 +648,10 @@ 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 |= BINPRM_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..3f41b667b241 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -158,6 +158,8 @@ static int load_misc_binary(struct linux_binprm *bprm) retval = remove_arg_zero(bprm); if (retval) goto ret; + } else { + bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0; } if (fmt->flags & MISC_FMT_OPEN_BINARY) { 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;