Re: moving audit_free() up into do_exit()

[Alexander Viro <aviro@redhat.com>]

On Fri, Mar 31, 2006 at 03:40:30PM -0500, Steve Grubb wrote:
> On Thursday 30 March 2006 03:56, Alexander Viro wrote:
> > On Thu, Mar 30, 2006 at 03:54:53AM -0500, Alexander Viro wrote:
> > > OK, preliminary patches attached; the first one is minimal "take care of
> >
> > Gah...  Attached to this followup; my apologies.
> 
> In audit-exit.patch
[snip]

Fixed, pushed to kernel.org audit-current, updated patch follows:

diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 506462e..fd7eaf7 100644
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -671,7 +671,7 @@ int do_syscall_trace(struct pt_regs *reg
 
 	if (unlikely(current->audit_context)) {
 		if (entryexit)
-			audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
+			audit_syscall_exit(AUDITSC_RESULT(regs->eax),
 						regs->eax);
 		/* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
 		 * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
@@ -720,14 +720,13 @@ int do_syscall_trace(struct pt_regs *reg
 	ret = is_sysemu;
 out:
 	if (unlikely(current->audit_context) && !entryexit)
-		audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
+		audit_syscall_entry(AUDIT_ARCH_I386, regs->orig_eax,
 				    regs->ebx, regs->ecx, regs->edx, regs->esi);
 	if (ret == 0)
 		return 0;
 
 	regs->orig_eax = -1; /* force skip of syscall restarting */
 	if (unlikely(current->audit_context))
-		audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
-				regs->eax);
+		audit_syscall_exit(AUDITSC_RESULT(regs->eax), regs->eax);
 	return 1;
 }
diff --git a/arch/i386/kernel/vm86.c b/arch/i386/kernel/vm86.c
index aee14fa..00e0118 100644
--- a/arch/i386/kernel/vm86.c
+++ b/arch/i386/kernel/vm86.c
@@ -312,7 +312,7 @@ static void do_sys_vm86(struct kernel_vm
 
 	/*call audit_syscall_exit since we do not exit via the normal paths */
 	if (unlikely(current->audit_context))
-		audit_syscall_exit(current, AUDITSC_RESULT(eax), eax);
+		audit_syscall_exit(AUDITSC_RESULT(eax), eax);
 
 	__asm__ __volatile__(
 		"movl %0,%%esp\n\t"
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 9887c87..e61e15e 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -1644,7 +1644,7 @@ syscall_trace_enter (long arg0, long arg
 			arch = AUDIT_ARCH_IA64;
 		}
 
-		audit_syscall_entry(current, arch, syscall, arg0, arg1, arg2, arg3);
+		audit_syscall_entry(arch, syscall, arg0, arg1, arg2, arg3);
 	}
 
 }
@@ -1662,7 +1662,7 @@ syscall_trace_leave (long arg0, long arg
 
 		if (success != AUDITSC_SUCCESS)
 			result = -result;
-		audit_syscall_exit(current, success, result);
+		audit_syscall_exit(success, result);
 	}
 
 	if (test_thread_flag(TIF_SYSCALL_TRACE)
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index f838b36..26ab8a9 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -469,7 +469,7 @@ static inline int audit_arch(void)
 asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 {
 	if (unlikely(current->audit_context) && entryexit)
-		audit_syscall_exit(current, AUDITSC_RESULT(regs->regs[2]),
+		audit_syscall_exit(AUDITSC_RESULT(regs->regs[2]),
 		                   regs->regs[2]);
 
 	if (!(current->ptrace & PT_PTRACED))
@@ -493,7 +493,7 @@ asmlinkage void do_syscall_trace(struct 
 	}
  out:
 	if (unlikely(current->audit_context) && !entryexit)
-		audit_syscall_entry(current, audit_arch(), regs->regs[2],
+		audit_syscall_entry(audit_arch(), regs->regs[2],
 				    regs->regs[4], regs->regs[5],
 				    regs->regs[6], regs->regs[7]);
 }
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index bcb8357..4a677d1 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -538,7 +538,7 @@ void do_syscall_trace_enter(struct pt_re
 		do_syscall_trace();
 
 	if (unlikely(current->audit_context))
-		audit_syscall_entry(current,
+		audit_syscall_entry(
 #ifdef CONFIG_PPC32
 				    AUDIT_ARCH_PPC,
 #else
@@ -556,8 +556,7 @@ void do_syscall_trace_leave(struct pt_re
 #endif
 
 	if (unlikely(current->audit_context))
-		audit_syscall_exit(current,
-				   (regs->ccr&0x1000)?AUDITSC_FAILURE:AUDITSC_SUCCESS,
+		audit_syscall_exit((regs->ccr&0x1000)?AUDITSC_FAILURE:AUDITSC_SUCCESS,
 				   regs->result);
 
 	if ((test_thread_flag(TIF_SYSCALL_TRACE)
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 37dfe33..8f36504 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -734,7 +734,7 @@ asmlinkage void
 syscall_trace(struct pt_regs *regs, int entryexit)
 {
 	if (unlikely(current->audit_context) && entryexit)
-		audit_syscall_exit(current, AUDITSC_RESULT(regs->gprs[2]), regs->gprs[2]);
+		audit_syscall_exit(AUDITSC_RESULT(regs->gprs[2]), regs->gprs[2]);
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		goto out;
@@ -761,8 +761,7 @@ syscall_trace(struct pt_regs *regs, int 
 	}
  out:
 	if (unlikely(current->audit_context) && !entryexit)
-		audit_syscall_entry(current, 
-				    test_thread_flag(TIF_31BIT)?AUDIT_ARCH_S390:AUDIT_ARCH_S390X,
+		audit_syscall_entry(test_thread_flag(TIF_31BIT)?AUDIT_ARCH_S390:AUDIT_ARCH_S390X,
 				    regs->gprs[2], regs->orig_gpr2, regs->gprs[3],
 				    regs->gprs[4], regs->gprs[5]);
 }
diff --git a/arch/sparc64/kernel/ptrace.c b/arch/sparc64/kernel/ptrace.c
index eb93e9c..bd54daf 100644
--- a/arch/sparc64/kernel/ptrace.c
+++ b/arch/sparc64/kernel/ptrace.c
@@ -630,7 +630,7 @@ asmlinkage void syscall_trace(struct pt_
 		if (unlikely(tstate & (TSTATE_XCARRY | TSTATE_ICARRY)))
 			result = AUDITSC_FAILURE;
 
-		audit_syscall_exit(current, result, regs->u_regs[UREG_I0]);
+		audit_syscall_exit(result, regs->u_regs[UREG_I0]);
 	}
 
 	if (!(current->ptrace & PT_PTRACED))
@@ -654,8 +654,7 @@ asmlinkage void syscall_trace(struct pt_
 
 out:
 	if (unlikely(current->audit_context) && !syscall_exit_p)
-		audit_syscall_entry(current,
-				    (test_thread_flag(TIF_32BIT) ?
+		audit_syscall_entry((test_thread_flag(TIF_32BIT) ?
 				     AUDIT_ARCH_SPARC :
 				     AUDIT_ARCH_SPARC64),
 				    regs->u_regs[UREG_G1],
diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index 98e0939..139c3ac 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -269,15 +269,13 @@ void syscall_trace(union uml_pt_regs *re
 
 	if (unlikely(current->audit_context)) {
 		if (!entryexit)
-			audit_syscall_entry(current,
-                                            HOST_AUDIT_ARCH,
+			audit_syscall_entry(HOST_AUDIT_ARCH,
 					    UPT_SYSCALL_NR(regs),
 					    UPT_SYSCALL_ARG1(regs),
 					    UPT_SYSCALL_ARG2(regs),
 					    UPT_SYSCALL_ARG3(regs),
 					    UPT_SYSCALL_ARG4(regs));
-		else audit_syscall_exit(current,
-                                        AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
+		else audit_syscall_exit(AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
                                         UPT_SYSCALL_RET(regs));
 	}
 
diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index d44b2c1..5ef7aae 100644
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -605,12 +605,12 @@ asmlinkage void syscall_trace_enter(stru
 
 	if (unlikely(current->audit_context)) {
 		if (test_thread_flag(TIF_IA32)) {
-			audit_syscall_entry(current, AUDIT_ARCH_I386,
+			audit_syscall_entry(AUDIT_ARCH_I386,
 					    regs->orig_rax,
 					    regs->rbx, regs->rcx,
 					    regs->rdx, regs->rsi);
 		} else {
-			audit_syscall_entry(current, AUDIT_ARCH_X86_64,
+			audit_syscall_entry(AUDIT_ARCH_X86_64,
 					    regs->orig_rax,
 					    regs->rdi, regs->rsi,
 					    regs->rdx, regs->r10);
@@ -621,7 +621,7 @@ asmlinkage void syscall_trace_enter(stru
 asmlinkage void syscall_trace_leave(struct pt_regs *regs)
 {
 	if (unlikely(current->audit_context))
-		audit_syscall_exit(current, AUDITSC_RESULT(regs->rax), regs->rax);
+		audit_syscall_exit(AUDITSC_RESULT(regs->rax), regs->rax);
 
 	if ((test_thread_flag(TIF_SYSCALL_TRACE)
 	     || test_thread_flag(TIF_SINGLESTEP))
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 1c47c59..39fef6e 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -287,10 +287,10 @@ struct netlink_skb_parms;
 				/* Public API */
 extern int  audit_alloc(struct task_struct *task);
 extern void audit_free(struct task_struct *task);
-extern void audit_syscall_entry(struct task_struct *task, int arch,
+extern void audit_syscall_entry(int arch,
 				int major, unsigned long a0, unsigned long a1,
 				unsigned long a2, unsigned long a3);
-extern void audit_syscall_exit(struct task_struct *task, int failed, long return_code);
+extern void audit_syscall_exit(int failed, long return_code);
 extern void audit_getname(const char *name);
 extern void audit_putname(const char *name);
 extern void __audit_inode(const char *name, const struct inode *inode, unsigned flags);
@@ -323,8 +323,8 @@ extern int audit_set_macxattr(const char
 #else
 #define audit_alloc(t) ({ 0; })
 #define audit_free(t) do { ; } while (0)
-#define audit_syscall_entry(t,ta,a,b,c,d,e) do { ; } while (0)
-#define audit_syscall_exit(t,f,r) do { ; } while (0)
+#define audit_syscall_entry(ta,a,b,c,d,e) do { ; } while (0)
+#define audit_syscall_exit(f,r) do { ; } while (0)
 #define audit_getname(n) do { ; } while (0)
 #define audit_putname(n) do { ; } while (0)
 #define __audit_inode(n,i,f) do { ; } while (0)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4052f0a..8aca4ab 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -329,7 +329,6 @@ static enum audit_state audit_filter_sys
 	return AUDIT_BUILD_CONTEXT;
 }
 
-/* This should be called with task_lock() held. */
 static inline struct audit_context *audit_get_context(struct task_struct *tsk,
 						      int return_valid,
 						      int return_code)
@@ -506,7 +505,7 @@ static inline void audit_free_context(st
 		printk(KERN_ERR "audit: freed %d contexts\n", count);
 }
 
-static void audit_log_task_context(struct audit_buffer *ab, gfp_t gfp_mask)
+static void audit_log_task_context(struct audit_buffer *ab)
 {
 	char *ctx = NULL;
 	ssize_t len = 0;
@@ -518,7 +517,7 @@ static void audit_log_task_context(struc
 		return;
 	}
 
-	ctx = kmalloc(len, gfp_mask);
+	ctx = kmalloc(len, GFP_KERNEL);
 	if (!ctx)
 		goto error_path;
 
@@ -536,47 +535,46 @@ error_path:
 	return;
 }
 
-static void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk, gfp_t gfp_mask)
+static void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
 {
 	char name[sizeof(tsk->comm)];
 	struct mm_struct *mm = tsk->mm;
 	struct vm_area_struct *vma;
 
+	/* tsk == current */
+
 	get_task_comm(name, tsk);
 	audit_log_format(ab, " comm=");
 	audit_log_untrustedstring(ab, name);
 
-	if (!mm)
-		return;
-
-	/*
-	 * this is brittle; all callers that pass GFP_ATOMIC will have
-	 * NULL tsk->mm and we won't get here.
-	 */
-	down_read(&mm->mmap_sem);
-	vma = mm->mmap;
-	while (vma) {
-		if ((vma->vm_flags & VM_EXECUTABLE) &&
-		    vma->vm_file) {
-			audit_log_d_path(ab, "exe=",
-					 vma->vm_file->f_dentry,
-					 vma->vm_file->f_vfsmnt);
-			break;
+	if (mm) {
+		down_read(&mm->mmap_sem);
+		vma = mm->mmap;
+		while (vma) {
+			if ((vma->vm_flags & VM_EXECUTABLE) &&
+			    vma->vm_file) {
+				audit_log_d_path(ab, "exe=",
+						 vma->vm_file->f_dentry,
+						 vma->vm_file->f_vfsmnt);
+				break;
+			}
+			vma = vma->vm_next;
 		}
-		vma = vma->vm_next;
+		up_read(&mm->mmap_sem);
 	}
-	up_read(&mm->mmap_sem);
-	audit_log_task_context(ab, gfp_mask);
+	audit_log_task_context(ab);
 }
 
-static void audit_log_exit(struct audit_context *context, struct task_struct *tsk, gfp_t gfp_mask)
+static void audit_log_exit(struct audit_context *context, struct task_struct *tsk)
 {
 	int i;
 	struct audit_buffer *ab;
 	struct audit_aux_data *aux;
 	const char *tty;
 
-	ab = audit_log_start(context, gfp_mask, AUDIT_SYSCALL);
+	/* tsk == current */
+
+	ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL);
 	if (!ab)
 		return;		/* audit_panic has been called */
 	audit_log_format(ab, "arch=%x syscall=%d",
@@ -607,12 +605,12 @@ static void audit_log_exit(struct audit_
 		  context->gid,
 		  context->euid, context->suid, context->fsuid,
 		  context->egid, context->sgid, context->fsgid, tty);
-	audit_log_task_info(ab, gfp_mask);
+	audit_log_task_info(ab, tsk);
 	audit_log_end(ab);
 
 	for (aux = context->aux; aux; aux = aux->next) {
 
-		ab = audit_log_start(context, gfp_mask, aux->type);
+		ab = audit_log_start(context, GFP_KERNEL, aux->type);
 		if (!ab)
 			continue; /* audit_panic has been called */
 
@@ -649,7 +647,7 @@ static void audit_log_exit(struct audit_
 	}
 
 	if (context->pwd && context->pwdmnt) {
-		ab = audit_log_start(context, gfp_mask, AUDIT_CWD);
+		ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD);
 		if (ab) {
 			audit_log_d_path(ab, "cwd=", context->pwd, context->pwdmnt);
 			audit_log_end(ab);
@@ -659,7 +657,7 @@ static void audit_log_exit(struct audit_
 		unsigned long ino  = context->names[i].ino;
 		unsigned long pino = context->names[i].pino;
 
-		ab = audit_log_start(context, gfp_mask, AUDIT_PATH);
+		ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
 		if (!ab)
 			continue; /* audit_panic has been called */
 
@@ -698,19 +696,12 @@ static void audit_log_exit(struct audit_
  * audit_free - free a per-task audit context
  * @tsk: task whose audit context block to free
  *
- * Called from copy_process and __put_task_struct.
+ * Called from copy_process and do_exit
  */
 void audit_free(struct task_struct *tsk)
 {
 	struct audit_context *context;
 
-	/*
-	 * No need to lock the task - when we execute audit_free()
-	 * then the task has no external references anymore, and
-	 * we are tearing it down. (The locking also confuses
-	 * DEBUG_LOCKDEP - this freeing may occur in softirq
-	 * contexts as well, via RCU.)
-	 */
 	context = audit_get_context(tsk, 0, 0);
 	if (likely(!context))
 		return;
@@ -719,8 +710,9 @@ void audit_free(struct task_struct *tsk)
 	 * function (e.g., exit_group), then free context block. 
 	 * We use GFP_ATOMIC here because we might be doing this 
 	 * in the context of the idle thread */
+	/* that can happen only if we are called from do_exit() */
 	if (context->in_syscall && context->auditable)
-		audit_log_exit(context, tsk, GFP_ATOMIC);
+		audit_log_exit(context, tsk);
 
 	audit_free_context(context);
 }
@@ -743,10 +735,11 @@ void audit_free(struct task_struct *tsk)
  * will only be written if another part of the kernel requests that it
  * be written).
  */
-void audit_syscall_entry(struct task_struct *tsk, int arch, int major,
+void audit_syscall_entry(int arch, int major,
 			 unsigned long a1, unsigned long a2,
 			 unsigned long a3, unsigned long a4)
 {
+	struct task_struct *tsk = current;
 	struct audit_context *context = tsk->audit_context;
 	enum audit_state     state;
 
@@ -824,22 +817,18 @@ void audit_syscall_entry(struct task_str
  * message), then write out the syscall information.  In call cases,
  * free the names stored from getname().
  */
-void audit_syscall_exit(struct task_struct *tsk, int valid, long return_code)
+void audit_syscall_exit(int valid, long return_code)
 {
+	struct task_struct *tsk = current;
 	struct audit_context *context;
 
-	get_task_struct(tsk);
-	task_lock(tsk);
 	context = audit_get_context(tsk, valid, return_code);
-	task_unlock(tsk);
 
-	/* Not having a context here is ok, since the parent may have
-	 * called __put_task_struct. */
 	if (likely(!context))
-		goto out;
+		return;
 
 	if (context->in_syscall && context->auditable)
-		audit_log_exit(context, tsk, GFP_KERNEL);
+		audit_log_exit(context, tsk);
 
 	context->in_syscall = 0;
 	context->auditable  = 0;
@@ -854,8 +843,6 @@ void audit_syscall_exit(struct task_stru
 		audit_free_aux(context);
 		tsk->audit_context = context;
 	}
- out:
-	put_task_struct(tsk);
 }
 
 /**
diff --git a/kernel/exit.c b/kernel/exit.c
index bc0ec67..70bd67b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -34,6 +34,7 @@
 #include <linux/mutex.h>
 #include <linux/futex.h>
 #include <linux/compat.h>
+#include <linux/audit.h> /* for audit_free() */
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -904,6 +905,8 @@ fastcall NORET_TYPE void do_exit(long co
 	if (unlikely(tsk->compat_robust_list))
 		compat_exit_robust_list(tsk);
 #endif
+	if (unlikely(tsk->audit_context))
+		audit_free(tsk);
 	exit_mm(tsk);
 
 	exit_sem(tsk);
diff --git a/kernel/fork.c b/kernel/fork.c
index b3f7a1b..be4a935 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -116,8 +116,6 @@ void __put_task_struct_cb(struct rcu_hea
 	WARN_ON(atomic_read(&tsk->usage));
 	WARN_ON(tsk == current);
 
-	if (unlikely(tsk->audit_context))
-		audit_free(tsk);
 	security_task_free(tsk);
 	free_uid(tsk->user);
 	put_group_info(tsk->group_info);