should something like:
+ int fd, retval;
+ off_t cur_pos;
+ bool is_execfd = true;
+ char bprm_buf[BPRM_BUF_SIZE];
+
+ fd = qemu_getauxval(AT_EXECFD);
+ if (fd == 0){
+ is_execfd = false;
+ fd = open(path(filename), O_RDONLY);
+ if (fd < 0) {
+ return 0;
+ }
+ }else{
+ cur_pos = lseek(fd, 0, SEEK_CUR);
+ if ((cur_pos < 0) || (lseek(fd, 0, SEEK_SET) != 0)){
+ printf("Error while lseek in %s: %s\n", filename, strerror(errno));
+ _exit(EXIT_FAILURE);
+ }
+ }
+ retval = read(fd, bprm_buf, BPRM_BUF_SIZE);
+ if (!is_execfd)
+ close(fd);
+ else {
+ if (lseek(fd, cur_pos, SEEK_SET) != cur_pos){
+ printf("Error while lseek in %s: %s\n", filename, strerror(errno));
+ _exit(EXIT_FAILURE);
+ }
+ }
+
+ if (retval < 0) {
+ return 0;
+ }
works?
On Sun, Dec 24, 2017 at 12:34 AM, Laurent Vivier <laur...@vivier.eu> wrote:
> Le 19/12/2017 à 12:50, YunQiang Su a écrit :
>> MIPS r6 is not just simple super set for pre-R6,
>> it also drops some instruction and even changes encoding for some.
>> But r6 binary has the same header for binfmt_misc.
>> So here we need to detect the version of binaries and set
>> cpu_model for it.
>> ---
>> include/elf.h | 4 ++++
>> linux-user/elfload.c | 36 ++++++++++++++++++++++++++++++++++++
>> linux-user/main.c | 15 +++++++++++++++
>> linux-user/qemu.h | 1 +
>> 4 files changed, 56 insertions(+)
>>
>> diff --git a/include/elf.h b/include/elf.h
>> index e8a515ce3d..f2104809b1 100644
>> --- a/include/elf.h
>> +++ b/include/elf.h
>> @@ -40,6 +40,10 @@ typedef int64_t Elf64_Sxword;
>> #define EF_MIPS_ARCH_5 0x40000000 /* -mips5 code. */
>> #define EF_MIPS_ARCH_32 0x50000000 /* MIPS32 code. */
>> #define EF_MIPS_ARCH_64 0x60000000 /* MIPS64 code. */
>> +#define EF_MIPS_ARCH_32R2 0x70000000 /* MIPS32r2 code. */
>> +#define EF_MIPS_ARCH_64R2 0x80000000 /* MIPS64r2 code. */
>> +#define EF_MIPS_ARCH_32R6 0x90000000 /* MIPS32r6 code. */
>> +#define EF_MIPS_ARCH_64R6 0xa0000000 /* MIPS64r6 code. */
>>
>> /* The ABI of a file. */
>> #define EF_MIPS_ABI_O32 0x00001000 /* O32 ABI. */
>> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
>> index 20f3d8c2c3..f9b8e028ca 100644
>> --- a/linux-user/elfload.c
>> +++ b/linux-user/elfload.c
>> @@ -2224,6 +2224,42 @@ static void load_elf_interp(const char *filename,
>> struct image_info *info,
>> exit(-1);
>> }
>>
>> +uint32_t get_elf_eflags(const char *filename)
>> +{
>> + int fd, retval;
>> + char bprm_buf[BPRM_BUF_SIZE];
>> +
>> + fd = open(path(filename), O_RDONLY);
>
> You can't do that with binfmt and credential ('C' flag) enabled (it
> implies 'O' flag, open-binary), because in this case the kernel opens
> the file and provides the file descriptor to QEMU. We need the 'C' flags
> to allow to execute binaries with the setuid flag (like "sudo") [1]
>
> See linux-user/main.c:
>
> 4446 execfd = qemu_getauxval(AT_EXECFD);
> 4447 if (execfd == 0) {
> 4448 execfd = open(filename, O_RDONLY);
> 4449 if (execfd < 0) {
> 4450 printf("Error while loading %s: %s\n", filename,
> strerror(errno));
> 4451 _exit(EXIT_FAILURE);
> 4452 }
> 4453 }
>
> Thanks,
> Laurent
> [1]
> https://github.com/torvalds/linux/blob/master/Documentation/admin-guide/binfmt-misc.rst
