[PATCH] lib/cobalt: Wrap __open_2/__open64_2 to support _FORTIFY_SOURCE

Jan Kiszka jan.kiszka at siemens.com
Thu Sep 10 18:27:04 CEST 2020


On 10.09.20 18:14, Jan Kiszka via Xenomai wrote:
> On 10.09.20 16:46, Jan Leupold via Xenomai wrote:
>> __open_2() and __open64_2() from glibc add runtime precondition tests for the
>> 'oflag' parameter to the functionality of open()/open64(). They may be used when
>> the macro _FORTIFY_SOURCE is defined when compiling the application code. Added
>> these wrappers to cover those cases.
>>
>> Signed-off-by: Jan Leupold <leupold at rsi-elektrotechnik.de>
>> ---
>>  include/cobalt/fcntl.h     |  4 ++++
>>  lib/cobalt/cobalt.wrappers |  2 ++
>>  lib/cobalt/rtdm.c          | 32 ++++++++++++++++++++++++++++++++
>>  lib/cobalt/wrappers.c      | 12 ++++++++++++
>>  4 files changed, 50 insertions(+)
>>
>> diff --git a/include/cobalt/fcntl.h b/include/cobalt/fcntl.h
>> index d54989389..f1052c28d 100644
>> --- a/include/cobalt/fcntl.h
>> +++ b/include/cobalt/fcntl.h
>> @@ -31,6 +31,10 @@ COBALT_DECL(int, open(const char *path, int oflag, ...));
>>  
>>  COBALT_DECL(int, open64(const char *path, int oflag, ...));
>>  
>> +COBALT_DECL(int, __open_2(const char *path, int oflag));
>> +
>> +COBALT_DECL(int, __open64_2(const char *path, int oflag));
>> +
>>  COBALT_DECL(int, fcntl(int fd, int cmd, ...));
>>  
>>  #ifdef __cplusplus
>> diff --git a/lib/cobalt/cobalt.wrappers b/lib/cobalt/cobalt.wrappers
>> index f63a170f8..0e954764d 100644
>> --- a/lib/cobalt/cobalt.wrappers
>> +++ b/lib/cobalt/cobalt.wrappers
>> @@ -54,6 +54,8 @@
>>  --wrap mq_notify
>>  --wrap open
>>  --wrap open64
>> +--wrap __open_2
>> +--wrap __open64_2
>>  --wrap socket
>>  --wrap close
>>  --wrap ioctl
>> diff --git a/lib/cobalt/rtdm.c b/lib/cobalt/rtdm.c
>> index 9f3dcd25f..80d08b18f 100644
>> --- a/lib/cobalt/rtdm.c
>> +++ b/lib/cobalt/rtdm.c
>> @@ -23,6 +23,7 @@
>>  #include <pthread.h>
>>  #include <fcntl.h>
>>  #include <unistd.h>
>> +#include <stdlib.h>
>>  #include <sys/socket.h>
>>  #include <sys/mman.h>
>>  #include <rtdm/rtdm.h>
>> @@ -94,6 +95,37 @@ COBALT_IMPL(int, open64, (const char *path, int oflag, ...))
>>  	return do_open(path, oflag | O_LARGEFILE, mode);
>>  }
>>  
>> +COBALT_IMPL(int, __open_2, (const char *path, int oflag))
>> +{
>> +    /* __open_2() from glibc adds a runtime precondition test for the 'oflag'
>> +     * parameter to the functionality of open(). It may be used when the macro
>> +     * _FORTIFY_SOURCE is defined when compiling the application code.
>> +     */
>> +    if (__OPEN_NEEDS_MODE(oflag)) {
>> +        const char* msg =
>> +            "invalid open call: O_CREAT or O_TMPFILE without mode\n";
>> +        ssize_t n = write(STDERR_FILENO, msg, strlen(msg));
>> +        (void) n;
>> +        abort();
>> +    }
>> +
>> +	return do_open(path, oflag, 0);
>> +}
>> +
>> +COBALT_IMPL(int, __open64_2, (const char *path, int oflag))
>> +{
>> +    /* just like __open_2() and open64() */
>> +    if (__OPEN_NEEDS_MODE(oflag)) {
>> +        const char* msg =
>> +            "invalid open64 call: O_CREAT or O_TMPFILE without mode\n";
>> +        ssize_t n = write(STDERR_FILENO, msg, strlen(msg));
>> +        (void) n;
>> +        abort();
>> +    }
>> +
>> +	return do_open(path, oflag | O_LARGEFILE, 0);
>> +}
>> +
>>  COBALT_IMPL(int, socket, (int protocol_family, int socket_type, int protocol))
>>  {
>>  	int s;
>> diff --git a/lib/cobalt/wrappers.c b/lib/cobalt/wrappers.c
>> index ed8fbaf16..5d86607de 100644
>> --- a/lib/cobalt/wrappers.c
>> +++ b/lib/cobalt/wrappers.c
>> @@ -205,6 +205,18 @@ int __real_open64(const char *path, int oflag, ...)
>>  }
>>  #endif
>>  
>> +__weak
>> +int __real___open_2(const char *path, int oflag)
>> +{
>> +    return __open_2(path, oflag);
>> +}
>> +
>> +__weak
>> +int __real___open64_2(const char *path, int oflag)
>> +{
>> +    return __open64_2(path, oflag);
>> +}
>> +
>>  __weak
>>  int __real_socket(int protocol_family, int socket_type, int protocol)
>>  {
>>
> 
> Thanks, applied to next.
> 

Currently stressing multiple CI infrastructures, and our internal one 
already revealed that you will soon see red lights in some jobs here:

https://gitlab.denx.de/Xenomai/xenomai/-/pipelines/4644

  CC       libcobalt_la-wrappers.lo
wrappers.c: In function '__real___open_2':
wrappers.c:211:12: error: implicit declaration of function '__open_2'; did you mean 'openat'? [-Werror=implicit-function-declaration]
     return __open_2(path, oflag);
            ^~~~~~~~
            openat
wrappers.c: In function '__real___open64_2':
wrappers.c:217:12: error: implicit declaration of function '__open64_2'; did you mean 'open64'? [-Werror=implicit-function-declaration]
     return __open64_2(path, oflag);
            ^~~~~~~~~~
            open64
cc1: all warnings being treated as errors

We need to account for non-fortified setups.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux



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