path: root/security
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authorStephen Smalley <sds@tycho.nsa.gov>2015-07-10 09:40:59 -0400
committerPaul Moore <pmoore@redhat.com>2015-07-10 16:45:29 -0400
commit892e8cac99a71f6254f84fc662068d912e1943bf (patch)
treecae10710e573cd319bdfae8eab3727d91789d787 /security
parentselinux: don't waste ebitmap space when importing NetLabel categories (diff)
selinux: fix mprotect PROT_EXEC regression caused by mm change
commit 66fc13039422ba7df2d01a8ee0873e4ef965b50b ("mm: shmem_zero_setup skip security check and lockdep conflict with XFS") caused a regression for SELinux by disabling any SELinux checking of mprotect PROT_EXEC on shared anonymous mappings. However, even before that regression, the checking on such mprotect PROT_EXEC calls was inconsistent with the checking on a mmap PROT_EXEC call for a shared anonymous mapping. On a mmap, the security hook is passed a NULL file and knows it is dealing with an anonymous mapping and therefore applies an execmem check and no file checks. On a mprotect, the security hook is passed a vma with a non-NULL vm_file (as this was set from the internally-created shmem file during mmap) and therefore applies the file-based execute check and no execmem check. Since the aforementioned commit now marks the shmem zero inode with the S_PRIVATE flag, the file checks are disabled and we have no checking at all on mprotect PROT_EXEC. Add a test to the mprotect hook logic for such private inodes, and apply an execmem check in that case. This makes the mmap and mprotect checking consistent for shared anonymous mappings, as well as for /dev/zero and ashmem. Cc: <stable@vger.kernel.org> # 4.1.x Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Paul Moore <pmoore@redhat.com>
Diffstat (limited to 'security')
1 files changed, 2 insertions, 1 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 312537d48050..692e3cc8ce23 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3271,7 +3271,8 @@ static int file_map_prot_check(struct file *file, unsigned long prot, int shared
int rc = 0;
if (default_noexec &&
- (prot & PROT_EXEC) && (!file || (!shared && (prot & PROT_WRITE)))) {
+ (prot & PROT_EXEC) && (!file || IS_PRIVATE(file_inode(file)) ||
+ (!shared && (prot & PROT_WRITE)))) {
* We are making executable an anonymous mapping or a
* private file mapping that will also be writable.