[PATCH v4] lib/cobalt: Wrap __open_2/__open64_2 to support _FORTIFY_SOURCE

Jan Kiszka jan.kiszka at siemens.com
Fri Sep 11 12:11:17 CEST 2020


On 11.09.20 11:43, 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.
> 
> If Xenomai itself is not compiled with FORTIFY_SOURCE then the function
> declarations for __open_2() and __open64_2() are not available.
> __STD(__open_2(...)) will not link in this case (would be a very special
> use case anyway?).
> 
> 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..f3fb5d411 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 = __STD(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 = __STD(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..860b26020 100644
> --- a/lib/cobalt/wrappers.c
> +++ b/lib/cobalt/wrappers.c
> @@ -205,6 +205,18 @@ int __real_open64(const char *path, int oflag, ...)
>  }
>  #endif
>  
> +#if __USE_FORTIFY_LEVEL > 0
> +__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);
> +}
> +#endif // __USE_FORTIFY_LEVEL > 0
> +
>  __weak
>  int __real_socket(int protocol_family, int socket_type, int protocol)
>  {
> 

Thanks, applied to next (old one dropped).

Jan

PS: Bonus for adding "From: Jan Leupold <leupold at rsi-elektrotechnik.de>"
at the top of the commit message in any future patches.

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



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