linux/security
Paul Moore 0909c0ae99 selinux: put the mmap() DAC controls before the MAC controls
It turns out that doing the SELinux MAC checks for mmap() before the
DAC checks was causing users and the SELinux policy folks headaches
as users were seeing a lot of SELinux AVC denials for the
memprotect:mmap_zero permission that would have also been denied by
the normal DAC capability checks (CAP_SYS_RAWIO).

Example:

 # cat mmap_test.c
  #include <stdlib.h>
  #include <stdio.h>
  #include <errno.h>
  #include <sys/mman.h>

  int main(int argc, char *argv[])
  {
        int rc;
        void *mem;

        mem = mmap(0x0, 4096,
                   PROT_READ | PROT_WRITE,
                   MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
        if (mem == MAP_FAILED)
                return errno;
        printf("mem = %p\n", mem);
        munmap(mem, 4096);

        return 0;
  }
 # gcc -g -O0 -o mmap_test mmap_test.c
 # ./mmap_test
 mem = (nil)
 # ausearch -m AVC | grep mmap_zero
 type=AVC msg=audit(...): avc:  denied  { mmap_zero }
   for pid=1025 comm="mmap_test"
   scontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
   tcontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
   tclass=memprotect

This patch corrects things so that when the above example is run by a
user without CAP_SYS_RAWIO the SELinux AVC is no longer generated as
the DAC capability check fails before the SELinux permission check.

Signed-off-by: Paul Moore <pmoore@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
2014-02-28 07:23:24 -05:00
..
apparmor Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2013-11-21 19:46:00 -08:00
integrity ima: properly free ima_template_entry structures 2013-12-02 20:46:56 -05:00
keys security: shmem: implement kernel private shmem inodes 2013-12-02 11:24:19 +00:00
selinux selinux: put the mmap() DAC controls before the MAC controls 2014-02-28 07:23:24 -05:00
smack Smack: Ptrace access check mode 2013-10-28 10:23:36 -07:00
tomoyo Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
yama yama: Better permission check for ptraceme 2013-03-26 13:17:58 -07:00
capability.c Linux 3.12 2013-11-26 17:32:55 -05:00
commoncap.c capabilities: allow nice if we are privileged 2013-08-30 23:44:09 -07:00
device_cgroup.c device_cgroup: remove can_attach 2013-10-24 06:56:56 -04:00
inode.c securityfs: fix object creation races 2012-01-10 10:20:35 -05:00
Kconfig KEYS: Move the key config into security/keys/Kconfig 2012-05-11 10:56:56 +01:00
lsm_audit.c Merge git://git.infradead.org/users/eparis/audit 2013-11-21 19:18:14 -08:00
Makefile security: remove erroneous comment about capabilities.o link ordering 2013-09-24 11:26:28 +10:00
min_addr.c mmap_min_addr check CAP_SYS_RAWIO only for write 2010-04-23 08:56:31 +10:00
security.c Linux 3.12 2013-11-26 17:32:55 -05:00