From fcaaade1db63bb2d6f7611d7824eb50d2f07a546 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Wed, 28 Apr 2010 15:57:57 -0400 Subject: [PATCH] selinux: generalize disabling of execmem for plt-in-heap archs On Tue, 2010-04-27 at 11:47 -0700, David Miller wrote: > From: "Tom \"spot\" Callaway" > Date: Tue, 27 Apr 2010 14:20:21 -0400 > > > [root@apollo ~]$ cat /proc/2174/maps > > 00010000-00014000 r-xp 00000000 fd:00 15466577 > > /sbin/mingetty > > 00022000-00024000 rwxp 00002000 fd:00 15466577 > > /sbin/mingetty > > 00024000-00046000 rwxp 00000000 00:00 0 > > [heap] > > SELINUX probably barfs on the executable heap, the PLT is in the HEAP > just like powerpc32 and that's why VM_DATA_DEFAULT_FLAGS has to set > both executable and writable. > > You also can't remove the CONFIG_PPC32 ifdefs in selinux, since > because of the VM_DATA_DEFAULT_FLAGS setting used still in that arch, > the heap will always have executable permission, just like sparc does. > You have to support those binaries forever, whether you like it or not. > > Let's just replace the CONFIG_PPC32 ifdef in SELINUX with CONFIG_PPC32 > || CONFIG_SPARC as in Tom's original patch and let's be done with > this. > > In fact I would go through all the arch/ header files and check the > VM_DATA_DEFAULT_FLAGS settings and add the necessary new ifdefs to the > SELINUX code so that other platforms don't have the pain of having to > go through this process too. To avoid maintaining per-arch ifdefs, it seems that we could just directly use (VM_DATA_DEFAULT_FLAGS & VM_EXEC) as the basis for deciding whether to enable or disable these checks. VM_DATA_DEFAULT_FLAGS isn't constant on some architectures but instead depends on current->personality, but we want this applied uniformly. So we'll just use the initial task state to determine whether or not to enable these checks. Signed-off-by: Stephen Smalley Acked-by: David S. Miller Signed-off-by: James Morris --- security/selinux/hooks.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index ebee467e2913..a03fd74602b4 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2999,13 +2999,15 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd, return file_has_perm(cred, file, av); } +static int default_noexec; + static int file_map_prot_check(struct file *file, unsigned long prot, int shared) { const struct cred *cred = current_cred(); int rc = 0; -#ifndef CONFIG_PPC32 - if ((prot & PROT_EXEC) && (!file || (!shared && (prot & PROT_WRITE)))) { + if (default_noexec && + (prot & PROT_EXEC) && (!file || (!shared && (prot & PROT_WRITE)))) { /* * We are making executable an anonymous mapping or a * private file mapping that will also be writable. @@ -3015,7 +3017,6 @@ static int file_map_prot_check(struct file *file, unsigned long prot, int shared if (rc) goto error; } -#endif if (file) { /* read access is always possible with a mapping */ @@ -3076,8 +3077,8 @@ static int selinux_file_mprotect(struct vm_area_struct *vma, if (selinux_checkreqprot) prot = reqprot; -#ifndef CONFIG_PPC32 - if ((prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) { + if (default_noexec && + (prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) { int rc = 0; if (vma->vm_start >= vma->vm_mm->start_brk && vma->vm_end <= vma->vm_mm->brk) { @@ -3099,7 +3100,6 @@ static int selinux_file_mprotect(struct vm_area_struct *vma, if (rc) return rc; } -#endif return file_map_prot_check(vma->vm_file, prot, vma->vm_flags&VM_SHARED); } @@ -5662,6 +5662,8 @@ static __init int selinux_init(void) /* Set the security state for the initial task. */ cred_init_security(); + default_noexec = !(VM_DATA_DEFAULT_FLAGS & VM_EXEC); + sel_inode_cache = kmem_cache_create("selinux_inode_security", sizeof(struct inode_security_struct), 0, SLAB_PANIC, NULL);