From db4c9641def55d36a6f9df79deb8a949292313ca Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Wed, 1 Feb 2006 03:05:54 -0800 Subject: [PATCH] [PATCH] selinux: fix and cleanup mprotect checks Fix the SELinux mprotect checks on executable mappings so that they are not re-applied when the mapping is already executable as well as cleaning up the code. This avoids a situation where e.g. an application is prevented from removing PROT_WRITE on an already executable mapping previously authorized via execmem permission due to an execmod denial. Signed-off-by: Stephen Smalley Acked-by: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- security/selinux/hooks.c | 50 +++++++++++++++++----------------------- 1 file changed, 21 insertions(+), 29 deletions(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index b9f8d9731c3d5..1bb5eea3b8c12 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2454,35 +2454,27 @@ static int selinux_file_mprotect(struct vm_area_struct *vma, prot = reqprot; #ifndef CONFIG_PPC32 - if ((prot & PROT_EXEC) && !(vma->vm_flags & VM_EXECUTABLE) && - (vma->vm_start >= vma->vm_mm->start_brk && - vma->vm_end <= vma->vm_mm->brk)) { - /* - * We are making an executable mapping in the brk region. - * This has an additional execheap check. - */ - rc = task_has_perm(current, current, PROCESS__EXECHEAP); - if (rc) - return rc; - } - if (vma->vm_file != NULL && vma->anon_vma != NULL && (prot & PROT_EXEC)) { - /* - * We are making executable a file mapping that has - * had some COW done. Since pages might have been written, - * check ability to execute the possibly modified content. - * This typically should only occur for text relocations. - */ - int rc = file_has_perm(current, vma->vm_file, FILE__EXECMOD); - if (rc) - return rc; - } - if (!vma->vm_file && (prot & PROT_EXEC) && - vma->vm_start <= vma->vm_mm->start_stack && - vma->vm_end >= vma->vm_mm->start_stack) { - /* Attempt to make the process stack executable. - * This has an additional execstack check. - */ - rc = task_has_perm(current, current, PROCESS__EXECSTACK); + if ((prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) { + rc = 0; + if (vma->vm_start >= vma->vm_mm->start_brk && + vma->vm_end <= vma->vm_mm->brk) { + rc = task_has_perm(current, current, + PROCESS__EXECHEAP); + } else if (!vma->vm_file && + vma->vm_start <= vma->vm_mm->start_stack && + vma->vm_end >= vma->vm_mm->start_stack) { + rc = task_has_perm(current, current, PROCESS__EXECSTACK); + } else if (vma->vm_file && vma->anon_vma) { + /* + * We are making executable a file mapping that has + * had some COW done. Since pages might have been + * written, check ability to execute the possibly + * modified content. This typically should only + * occur for text relocations. + */ + rc = file_has_perm(current, vma->vm_file, + FILE__EXECMOD); + } if (rc) return rc; }