[libcamera-devel] [PATCH v2 4/4] libcamera: utils: Use internal secure_getenv() implementation

[Kieran Bingham]

Hi Laurent,

On 01/04/2019 21:41, Laurent Pinchart wrote:
> Hi Kieran,
> 
> Thank you for the patch.
> 
> On Mon, Apr 01, 2019 at 06:03:15PM +0700, Kieran Bingham wrote:
>> The secure_getenv() call is not provided by all toolchains. Support
> 
> s/toolchains/C libraries/ ?

Sure. Also changed in the documentation of basename().

>> this feature by implementing our own version.
>>
>> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>> ---
>>  src/libcamera/include/utils.h |  2 ++
>>  src/libcamera/log.cpp         |  4 ++--
>>  src/libcamera/utils.cpp       | 20 ++++++++++++++++++++
>>  3 files changed, 24 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
>> index 1b2a62c0fda7..79038a96feab 100644
>> --- a/src/libcamera/include/utils.h
>> +++ b/src/libcamera/include/utils.h
>> @@ -24,6 +24,8 @@ std::unique_ptr<T> make_unique(Args&&... args)
>>  	return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
>>  }
>>  
>> +char *secure_getenv(const char *name);
>> +
>>  } /* namespace utils */
>>  
>>  } /* namespace libcamera */
>> diff --git a/src/libcamera/log.cpp b/src/libcamera/log.cpp
>> index eb444c31857d..71cfbc422ba0 100644
>> --- a/src/libcamera/log.cpp
>> +++ b/src/libcamera/log.cpp
>> @@ -122,7 +122,7 @@ Logger::Logger()
>>   */
>>  void Logger::parseLogFile()
>>  {
>> -	const char *file = secure_getenv("LIBCAMERA_LOG_FILE");
>> +	const char *file = utils::secure_getenv("LIBCAMERA_LOG_FILE");
>>  	if (!file)
>>  		return;
>>  
>> @@ -140,7 +140,7 @@ void Logger::parseLogFile()
>>   */
>>  void Logger::parseLogLevels()
>>  {
>> -	const char *debug = secure_getenv("LIBCAMERA_LOG_LEVELS");
>> +	const char *debug = utils::secure_getenv("LIBCAMERA_LOG_LEVELS");
>>  	if (!debug)
>>  		return;
>>  
>> diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
>> index 70936e36c5d5..c49e65136514 100644
>> --- a/src/libcamera/utils.cpp
>> +++ b/src/libcamera/utils.cpp
>> @@ -6,6 +6,7 @@
>>   */
>>  
>>  #include <string.h>
>> +#include <sys/auxv.h>
>>  
>>  #include "utils.h"
>>  
>> @@ -35,6 +36,25 @@ const char *basename(const char *path)
>>         return base ? base + 1 : path;
>>  }
>>  
>> +/**
>> + * \brief Get an environment variable
>> + *
>> + * The environment list is searched to find the variable 'name', and returns a
>> + * pointer to the corresponding string.
> 
> The first half of the sentence doesn't seem to provide a subject for
> "returns" in the second half.

Reworded to:


> /**
>  * \brief Get an environment variable
>  * \param[in] name The name of the variable to return
>  *
>  * The environment list is searched to find the variable 'name', and the
>  * corresponding string is returned.
>  *
>  * If 'secure execution' is required then this function always returns NULL to
>  * avoid vulnerabilities that could occur if set-user-ID or set-group-ID
>  * programs accidentally trust the environment.
>  *
>  * \returns A pointer to the value in the environment or NULL if the requested
>  * environment variable doesn't exist or if secure execution is required.
>  */
> char *secure_getenv(const char *name)


which also incorporates the comments below...

> 
>> + * If 'secure execution' is required then this function always returns NULL to
>> + * avoid vulnerabilities that could occur if the set-user-ID or set-group-ID
> 
> s/if the/if/
> 
>> + * programs accidentally trusted the environment.
>> + *
>> + * \returns A pointer to the value in the environment or NULL if the match fails
>> + * or a secure environment is required.
> 
> "..., or NULL if the requested environment variable doesn't exist or if
> secure execution is required." ?
> 
>> + */
>> +char *secure_getenv(const char *name)
>> +{
>> +       if (getauxval(AT_SECURE))
>> +               return NULL;
>> +       else
> 
> You can drop the else.

Done.


> With these small issues fixed,
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
>> +               return getenv(name);
>> +}
>>  
>>  /**
>>   * \fn libcamera::utils::make_unique(Args &&... args)

-- 
Regards
--
Kieran