HEADS-UP: libselinux will disallow getpidcon() with pid == 0

[Petr Lautrbach]

Hi,

libselinux upstream plans to disallow to use getpidcon(0, ) in sense of
getpidcon(getpid(), )

This behavior has never been documented and it's implementation is
considered error prone.

There seems to be no such case in Fedora but if your project uses
getpidcon() with pid == 0 to get the context of the current process,
please replace it with getcon().

Thanks,


Petr



-------- Forwarded Message --------
Subject: getpidcon with pid == 0 (Was: Re: [PATCH 2/2] libselinux:
procattr: return einval for <= 0 pid args.)
Date: Wed, 24 Feb 2016 09:49:16 -0500
From: Stephen Smalley <sds(a)tycho.nsa.gov&gt;
Organization: National Security Agency
To: Daniel Cashman <dcashman(a)android.com&gt;, selinux(a)tycho.nsa.gov

On 02/23/2016 03:24 PM, Daniel Cashman wrote:
>  From: dcashman <dcashman(a)android.com&gt;
>
>  getpidcon documentation does not specify that a pid of 0 refers to the
>  current process, and getcon exists specifically to provide this
>  functionality, and getpidcon(getpid()) would provide it as well.
>  Disallow pid values <= 0 that may lead to unintended behavior in
>  userspace object managers. 
I'll try to see if there are any legitimate users of getpidcon with pid
== 0.  If anyone on the list knows of one, please speak up.

>  Signed-off-by: Daniel Cashman <dcashman(a)android.com&gt;
>  ---
>    libselinux/src/procattr.c | 14 ++++++++++++--
>    1 file changed, 12 insertions(+), 2 deletions(-)
>
>  diff --git a/libselinux/src/procattr.c b/libselinux/src/procattr.c
>  index c20f003..eee4612 100644
>  --- a/libselinux/src/procattr.c
>  +++ b/libselinux/src/procattr.c
>  @@ -306,11 +306,21 @@ static int setprocattrcon(const char * context,
>    #define getpidattr_def(fn, attr) \
>    	int get##fn##_raw(pid_t pid, char **c)	\
>    	{ \
>  -		return getprocattrcon_raw(c, pid, #attr); \
>  +		if (pid <= 0) { \
>  +			errno = EINVAL; \
>  +			return -1; \
>  +		} else { \
>  +			return getprocattrcon_raw(c, pid, #attr); \
>  +		} \
>    	} \
>    	int get##fn(pid_t pid, char **c)	\
>    	{ \
>  -		return getprocattrcon(c, pid, #attr); \
>  +		if (pid <= 0) { \
>  +			errno = EINVAL; \
>  +			return -1; \
>  +		} else { \
>  +			return getprocattrcon(c, pid, #attr); \
>  +		} \
>    	}
>
>    all_selfattr_def(con, current)
>