[apparmor] [PATCH v2 4/6] utils: Add the --namespace option to C based aa-exec

John Johansen john.johansen at canonical.com
Thu Dec 17 22:30:58 UTC 2015


On 12/16/2015 07:25 PM, Tyler Hicks wrote:
> Switch to the policy in the namespace specified by the --namespace
> option.
> 
> Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
> ---
>  binutils/aa_exec.c | 55 +++++++++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 46 insertions(+), 9 deletions(-)
> 
> diff --git a/binutils/aa_exec.c b/binutils/aa_exec.c
> index 9bcd62f..a57b4ec 100644
> --- a/binutils/aa_exec.c
> +++ b/binutils/aa_exec.c
> @@ -19,6 +19,7 @@
>  #include <errno.h>
>  #include <getopt.h>
>  #include <libintl.h>
> +#include <limits.h>
>  #include <stdio.h>
>  #include <stdarg.h>
>  #include <stdlib.h>
> @@ -28,6 +29,7 @@
>  #define _(s) gettext(s)
>  
>  static const char *opt_profile = NULL;
> +static const char *opt_namespace = NULL;
>  static bool opt_debug = false;
>  static bool opt_immediate = false;
>  static bool opt_verbose = false;
> @@ -49,6 +51,7 @@ static void usage(const char *name, bool error)
>  		"\n"
>  		"OPTIONS:\n"
>  		"  -p PROFILE, --profile=PROFILE		PROFILE to confine <prog> with\n"
> +		"  -n NAMESPACE, --namespace=NAMESPACE	NAMESPACE to confine <prog> in\n"
>  		"  -d, --debug				show messages with debugging information\n"
>  		"  -i, --immediate			change profile immediately instead of at exec\n"
>  		"  -v, --verbose				show messages with stats\n"
> @@ -112,11 +115,12 @@ static char **parse_args(int argc, char **argv)
>  		{"debug", no_argument, 0, 'd'},
>  		{"help", no_argument, 0, 'h'},
>  		{"profile", required_argument, 0, 'p'},
> +		{"namespace", required_argument, 0, 'n'},
>  		{"immediate", no_argument, 0, 'i'},
>  		{"verbose", no_argument, 0, 'v'},
>  	};
>  
> -	while ((opt = getopt_long(argc, argv, "+dhp:iv", long_opts, NULL)) != -1) {
> +	while ((opt = getopt_long(argc, argv, "+dhp:n:iv", long_opts, NULL)) != -1) {
>  		switch (opt) {
>  		case 'd':
>  			opt_debug = true;
> @@ -127,6 +131,9 @@ static char **parse_args(int argc, char **argv)
>  		case 'p':
>  			opt_profile = optarg;
>  			break;
> +		case 'n':
> +			opt_namespace = optarg;
> +			break;
>  		case 'i':
>  			opt_immediate = true;
>  			break;
> @@ -145,28 +152,58 @@ static char **parse_args(int argc, char **argv)
>  	return argv + optind;
>  }
>  
> +static void build_name(char *name, size_t name_len,
> +		       const char *namespace, const char *profile)
> +{
> +	size_t required_len = 1; /* reserve 1 byte for NUL-terminator */
> +
> +	if (namespace)
> +		required_len += 1 + strlen(namespace) + 1; /* :<NAMESPACE>: */
> +
> +	if (profile)
> +		required_len += strlen(profile);
> +
> +	if (required_len > name_len)
> +		error("name too long (%zu > %zu)", required_len, name_len);
> +
> +	name[0] = '\0';
> +
> +	if (namespace) {
> +		strcat(name, ":");
> +		strcat(name, namespace);
> +		strcat(name, ":");
> +	}
> +
while this does work, the interface accepts
  :<namespace name>:<profile name>
and
  :<namespace name>://<profile name>

if there is an error we are exposing this to the user instead of the more standard
  :<namespace name>://

I'm not sure it is worth changing, I like the shorter form for the kernel but I
think in generally anything exposed to the user should probably try to be
consistent, and probably stick with the :// syntax as that is what is used
beyond apparmor

also I smell an opportunity for a library fn

> +	if (profile)
> +		strcat(name, profile);
> +}
> +
>  int main(int argc, char **argv)
>  {
> +	char name[PATH_MAX];
>  	int rc = 0;
>  
>  	argv = parse_args(argc, argv);
>  
> -	if (!opt_profile)
> +	if (opt_namespace || opt_profile)
> +		build_name(name, sizeof(name), opt_namespace, opt_profile);
> +	else
>  		goto exec;
>  
>  	if (opt_immediate) {
> -		verbose("aa_change_profile(\"%s\")", opt_profile);
> -		rc = aa_change_profile(opt_profile);
> -		debug("%d = aa_change_profile(\"%s\")", rc, opt_profile);
> +		verbose("aa_change_profile(\"%s\")", name);
> +		rc = aa_change_profile(name);
> +		debug("%d = aa_change_profile(\"%s\")", rc, name);
>  	} else {
> -		verbose("aa_change_onexec(\"%s\")", opt_profile);
> -		rc = aa_change_onexec(opt_profile);
> -		debug("%d = aa_change_onexec(\"%s\")", rc, opt_profile);
> +		verbose("aa_change_onexec(\"%s\")", name);
> +		rc = aa_change_onexec(name);
> +		debug("%d = aa_change_onexec(\"%s\")", rc, name);
>  	}
>  
>  	if (rc) {
>  		if (errno == ENOENT || errno == EACCES) {
> -			error("profile '%s' does not exist", opt_profile);
> +			error("%s '%s' does not exist\n",
> +			      opt_profile ? "profile" : "namespace", name);

this is where we expose it to the user

>  		} else if (errno == EINVAL) {
>  			error("AppArmor interface not available");
>  		} else {
> 




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