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[4/7] libapparmor: fix available and enabled checks

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Make it easier to separate errors from an actual answer, and ensure
we do a fallback check if there was an error.

Also fix the error code returned from aa_is_enabled() which got
broken by the addition of the private_enabled() check.

Finally make sure the private enabled error code is documented.

Fixes: https://gitlab.com/apparmor/apparmor/-/issues/150
MR: https://gitlab.com/apparmor/apparmor/-/merge_requests/713
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2021-03-17 05:18:05 -07:00
parent 3fb4c4b876
commit d0c4fc7d68
2 changed files with 28 additions and 16 deletions
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4
libraries/libapparmor/doc/aa_find_mountpoint.pod
View File

@ -70,6 +70,10 @@ AppArmor extensions to the system are not available.
AppArmor is available on the system but has been disabled at boot.
=item B<EBUSY>
AppArmor is available but only via private interfaces.
=item B<ENOENT>
AppArmor is available (and maybe even enforcing policy) but the interface is

40
libraries/libapparmor/src/kernel.c
View File

@ -100,18 +100,18 @@ int aa_find_mountpoint(char **mnt)
int rc, fd; \
fd = open("/sys/module/apparmor/parameters/" PARAM, O_RDONLY); \
if (fd == -1) { \
rc = errno; \
rc = -errno; \
} else { \
char buffer[2]; \
int size = read(fd, &buffer, 2); \
rc = errno; \
rc = -errno; \
close(fd); \
errno = rc; \
errno = -rc; \
if (size > 0) { \
if (buffer[0] == 'Y') \
rc = 0; \
rc = 1; \
else \
rc = ECANCELED; \
rc = 0; \
} \
} \
(rc); \
@ -130,14 +130,17 @@ static void param_check_enabled_init_once(void)
static int param_check_enabled()
{
if (pthread_once(&param_enabled_ctl, param_check_enabled_init_once) == 0)
if (pthread_once(&param_enabled_ctl, param_check_enabled_init_once) == 0 && param_enabled >= 0)
return param_enabled;
/* fallback if not initialized OR we recorded an error when
* initializing.
*/
return param_check_base("enabled");
}
static int is_enabled(void)
{
return !param_check_enabled();
return param_check_enabled() == 1;
}
static void param_check_private_enabled_init_once(void)
@ -147,14 +150,17 @@ static void param_check_private_enabled_init_once(void)
static int param_check_private_enabled()
{
if (pthread_once(&param_private_enabled_ctl, param_check_private_enabled_init_once) == 0)
if (pthread_once(&param_private_enabled_ctl, param_check_private_enabled_init_once) == 0 && param_private_enabled >= 0)
return param_private_enabled;
/* fallback if not initialized OR we recorded an error when
* initializing.
*/
return param_check_base("available");
}
static int is_private_enabled(void)
{
return !param_check_private_enabled();
return param_check_private_enabled() == 1;
}
/**
@ -174,15 +180,17 @@ int aa_is_enabled(void)
bool private = false;
rc = param_check_enabled();
if (rc) {
if (rc == ENOENT)
errno = ENOSYS;
else
errno = rc;
if (rc < 1) {
if (!is_private_enabled()) {
if (rc == 0)
errno = ECANCELED;
else if (rc == -ENOENT)
errno = ENOSYS;
else
errno = -rc;
if (!is_private_enabled())
return 0;
}
/* actually available but only on private interfaces */
private = true;
}