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Re: [PATCH] linux-user: Add AT_EXECFN and AT_EXECFD auxval
From: |
Laurent Vivier |
Subject: |
Re: [PATCH] linux-user: Add AT_EXECFN and AT_EXECFD auxval |
Date: |
Mon, 2 Mar 2020 15:38:56 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 |
Le 21/02/2020 à 21:28, Lirong Yuan a écrit :
> This change adds the support for AT_EXECFN and AT_EXECFD auxval.
Why do we need AT_EXECFD?
AT_EXECFD is normally only used with binfmt_misc so I don't see any use
cases for it with QEMU.
For AT_EXECFN, according to kernel commit
651910874633 execve filename: document and export via auxiliary vector
It sould be like readlink("/proc/self/exe",), and thus I think we should
use realpath() like we have in syscall.c for TARGET_NR_readlink:
8843 case TARGET_NR_readlink:
...
8854 char real[PATH_MAX], *temp;
8855 temp = realpath(exec_path, real);
...
Thanks,
Laurent
>
> Signed-off-by: Lirong Yuan <address@hidden>
> ---
> linux-user/elfload.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index f3080a1635..7e0f3042f1 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -1568,7 +1568,7 @@ struct exec
> ~(abi_ulong)(TARGET_ELF_EXEC_PAGESIZE-1))
> #define TARGET_ELF_PAGEOFFSET(_v) ((_v) & (TARGET_ELF_EXEC_PAGESIZE-1))
>
> -#define DLINFO_ITEMS 15
> +#define DLINFO_ITEMS 17
>
> static inline void memcpy_fromfs(void * to, const void * from, unsigned long
> n)
> {
> @@ -1888,11 +1888,14 @@ static abi_ulong loader_build_fdpic_loadmap(struct
> image_info *info, abi_ulong s
> return sp;
> }
>
> -static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc,
> +static abi_ulong create_elf_tables(struct linux_binprm *bprm,
> struct elfhdr *exec,
> struct image_info *info,
> struct image_info *interp_info)
> {
> + abi_ulong p = bprm->p;
> + int argc = bprm->argc;
> + int envc = bprm->envc;
> abi_ulong sp;
> abi_ulong u_argc, u_argv, u_envp, u_auxv;
> int size;
> @@ -2032,6 +2035,8 @@ static abi_ulong create_elf_tables(abi_ulong p, int
> argc, int envc,
> NEW_AUX_ENT(AT_CLKTCK, (abi_ulong) sysconf(_SC_CLK_TCK));
> NEW_AUX_ENT(AT_RANDOM, (abi_ulong) u_rand_bytes);
> NEW_AUX_ENT(AT_SECURE, (abi_ulong) qemu_getauxval(AT_SECURE));
> + NEW_AUX_ENT(AT_EXECFN, info->file_string);
> + NEW_AUX_ENT(AT_EXECFD, bprm->fd);
>
> #ifdef ELF_HWCAP2
> NEW_AUX_ENT(AT_HWCAP2, (abi_ulong) ELF_HWCAP2);
> @@ -2870,8 +2875,8 @@ int load_elf_binary(struct linux_binprm *bprm, struct
> image_info *info)
> #endif
> }
>
> - bprm->p = create_elf_tables(bprm->p, bprm->argc, bprm->envc, &elf_ex,
> - info, (elf_interpreter ? &interp_info :
> NULL));
> + bprm->p = create_elf_tables(bprm, &elf_ex, info,
> + (elf_interpreter ? &interp_info : NULL));
> info->start_stack = bprm->p;
>
> /* If we have an interpreter, set that as the program's entry point.
>
- Re: [PATCH] linux-user: Add AT_EXECFN and AT_EXECFD auxval,
Laurent Vivier <=