[PATCH v2 17/20] bpf: Use vmalloc special flag

From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, Nadav Amit <nadav.amit@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux_dti@icloud.com, linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org, akpm@linux-foundation.org,
	kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
	will.deacon@arm.com, ard.biesheuvel@linaro.org,
	kristen@linux.intel.com, deneen.t.dock@intel.com,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@kernel.org>
Subject: [PATCH v2 17/20] bpf: Use vmalloc special flag
Date: Mon, 28 Jan 2019 16:34:19 -0800	[thread overview]
Message-ID: <20190129003422.9328-18-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20190129003422.9328-1-rick.p.edgecombe@intel.com>

Use new flag VM_HAS_SPECIAL_PERMS for handling freeing of special
permissioned memory in vmalloc and remove places where memory was set RW
before freeing which is no longer needed. Also we no longer need a bit to
track if the memory is RO because it is tracked in vmalloc.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 include/linux/filter.h | 16 +++-------------
 kernel/bpf/core.c      |  1 -
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9cdfab7f383c..cc9581dd9c58 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -20,6 +20,7 @@
 #include <linux/set_memory.h>
 #include <linux/kallsyms.h>
 #include <linux/if_vlan.h>
+#include <linux/vmalloc.h>
 
 #include <net/sch_generic.h>
 
@@ -483,7 +484,6 @@ struct bpf_prog {
 	u16			pages;		/* Number of allocated pages */
 	u16			jited:1,	/* Is our filter JIT'ed? */
 				jit_requested:1,/* archs need to JIT the prog */
-				undo_set_mem:1,	/* Passed set_memory_ro() checkpoint */
 				gpl_compatible:1, /* Is filter GPL compatible? */
 				cb_access:1,	/* Is control block accessed? */
 				dst_needed:1,	/* Do we need dst entry? */
@@ -681,26 +681,17 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default)
 
 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 {
+	set_vm_special(fp);
 	set_memory_ro((unsigned long)fp, fp->pages);
 }
 
-static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
-{
-	if (fp->undo_set_mem)
-		set_memory_rw((unsigned long)fp, fp->pages);
-}
-
 static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
 {
+	set_vm_special(hdr);
 	set_memory_ro((unsigned long)hdr, hdr->pages);
 	set_memory_x((unsigned long)hdr, hdr->pages);
 }
 
-static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
-{
-	set_memory_rw((unsigned long)hdr, hdr->pages);
-}
-
 static inline struct bpf_binary_header *
 bpf_jit_binary_hdr(const struct bpf_prog *fp)
 {
@@ -735,7 +726,6 @@ void __bpf_prog_free(struct bpf_prog *fp);
 
 static inline void bpf_prog_unlock_free(struct bpf_prog *fp)
 {
-	bpf_prog_unlock_ro(fp);
 	__bpf_prog_free(fp);
 }
 
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 19c49313c709..465c1c3623e8 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -804,7 +804,6 @@ void __weak bpf_jit_free(struct bpf_prog *fp)
 	if (fp->jited) {
 		struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp);
 
-		bpf_jit_binary_unlock_ro(hdr);
 		bpf_jit_binary_free(hdr);
 
 		WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp));
-- 
2.17.1

