From 379d9af3f3da2da1bbfa67baf1820c72a080d1f1 Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Tue, 6 Aug 2024 14:51:13 +0800 Subject: selinux: fix potential counting error in avc_add_xperms_decision() The count increases only when a node is successfully added to the linked list. Cc: stable@vger.kernel.org Fixes: fa1aa143ac4a ("selinux: extended permissions for ioctls") Signed-off-by: Zhen Lei Acked-by: Stephen Smalley Signed-off-by: Paul Moore --- security/selinux/avc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/selinux/avc.c b/security/selinux/avc.c index 32eb67fb3e42..7087cd2b802d 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -330,12 +330,12 @@ static int avc_add_xperms_decision(struct avc_node *node, { struct avc_xperms_decision_node *dest_xpd; - node->ae.xp_node->xp.len++; dest_xpd = avc_xperms_decision_alloc(src->used); if (!dest_xpd) return -ENOMEM; avc_copy_xperms_decision(&dest_xpd->xpd, src); list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head); + node->ae.xp_node->xp.len++; return 0; } -- cgit v1.2.3-58-ga151 From 6dd1e4c045afa6a4ba5d46f044c83bd357c593c2 Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Wed, 7 Aug 2024 17:00:56 +0800 Subject: selinux: add the processing of the failure of avc_add_xperms_decision() When avc_add_xperms_decision() fails, the information recorded by the new avc node is incomplete. In this case, the new avc node should be released instead of replacing the old avc node. Cc: stable@vger.kernel.org Fixes: fa1aa143ac4a ("selinux: extended permissions for ioctls") Suggested-by: Stephen Smalley Signed-off-by: Zhen Lei Acked-by: Stephen Smalley Signed-off-by: Paul Moore --- security/selinux/avc.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/security/selinux/avc.c b/security/selinux/avc.c index 7087cd2b802d..b49c44869dc4 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -907,7 +907,11 @@ static int avc_update_node(u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid, node->ae.avd.auditdeny &= ~perms; break; case AVC_CALLBACK_ADD_XPERMS: - avc_add_xperms_decision(node, xpd); + rc = avc_add_xperms_decision(node, xpd); + if (rc) { + avc_node_kill(node); + goto out_unlock; + } break; } avc_node_replace(node, orig); -- cgit v1.2.3-58-ga151 From 05a3d6e9307250a5911d75308e4363466794ab21 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Thu, 8 Aug 2024 11:57:38 -0400 Subject: selinux: revert our use of vma_is_initial_heap() Unfortunately it appears that vma_is_initial_heap() is currently broken for applications that do not currently have any heap allocated, e.g. brk == start_brk. The breakage is such that it will cause SELinux to check for the process/execheap permission on memory regions that cross brk/start_brk even when there is no heap. The proper fix would be to correct vma_is_initial_heap(), but as there are multiple callers I am hesitant to unilaterally modify the helper out of concern that I would end up breaking some other subsystem. The mm developers have been made aware of the situation and hopefully they will have a fix at some point in the future, but we need a fix soon so we are simply going to revert our use of vma_is_initial_heap() in favor of our old logic/code which works as expected, even in the face of a zero size heap. We can return to using vma_is_initial_heap() at some point in the future when it is fixed. Cc: stable@vger.kernel.org Reported-by: Marc Reisner Closes: https://lore.kernel.org/all/ZrPmoLKJEf1wiFmM@marcreisner.com Fixes: 68df1baf158f ("selinux: use vma_is_initial_stack() and vma_is_initial_heap()") Signed-off-by: Paul Moore --- security/selinux/hooks.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 55c78c318ccd..bfa61e005aac 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3852,7 +3852,17 @@ static int selinux_file_mprotect(struct vm_area_struct *vma, if (default_noexec && (prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) { int rc = 0; - if (vma_is_initial_heap(vma)) { + /* + * We don't use the vma_is_initial_heap() helper as it has + * a history of problems and is currently broken on systems + * where there is no heap, e.g. brk == start_brk. Before + * replacing the conditional below with vma_is_initial_heap(), + * or something similar, please ensure that the logic is the + * same as what we have below or you have tested every possible + * corner case you can think to test. + */ + if (vma->vm_start >= vma->vm_mm->start_brk && + vma->vm_end <= vma->vm_mm->brk) { rc = avc_has_perm(sid, sid, SECCLASS_PROCESS, PROCESS__EXECHEAP, NULL); } else if (!vma->vm_file && (vma_is_initial_stack(vma) || -- cgit v1.2.3-58-ga151