From: YunQiang Su <[email protected]>
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 <[email protected]>
---
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;
+ }
+ 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;
--
2.25.0.rc1
Laurent Vivier <[email protected]> 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 <[email protected]>
> >
> > 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 <[email protected]>
> > ---
> > 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 <[email protected]> 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 <[email protected]>
>>>
>>> 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 <[email protected]>
>>> ---
>>> 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
Le 16/01/2020 à 03:20, YunQiang Su a écrit :
> From: YunQiang Su <[email protected]>
>
> 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 <[email protected]>
> ---
> 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