linux-kernel - [PATCH x86/mm 4/6] x86-64 ptrace get/putreg current task

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20071129004118.D317B26F8E7@magilla.localdomain>
Date:	Wed, 28 Nov 2007 16:41:18 -0800 (PST)
From:	Roland McGrath <roland@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH x86/mm 4/6] x86-64 ptrace get/putreg current task


This generalizes the getreg and putreg functions so they can be used on the
current task, as well as on a task stopped in TASK_TRACED and switched off.
This lays the groundwork to share this code for all kinds of user-mode
machine state access, not just ptrace.

Signed-off-by: Roland McGrath <roland@...hat.com>
---
 arch/x86/kernel/ptrace_64.c |   36 ++++++++++++++++++++++++++++++++++--
 1 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ptrace_64.c b/arch/x86/kernel/ptrace_64.c
index 2427548..5979dbe 100644
--- a/arch/x86/kernel/ptrace_64.c
+++ b/arch/x86/kernel/ptrace_64.c
@@ -67,21 +67,29 @@ static int putreg(struct task_struct *child,
 		if (value && (value & 3) != 3)
 			return -EIO;
 		child->thread.fsindex = value & 0xffff;
+		if (child == current)
+			loadsegment(fs, child->thread.fsindex);
 		return 0;
 	case offsetof(struct user_regs_struct,gs):
 		if (value && (value & 3) != 3)
 			return -EIO;
 		child->thread.gsindex = value & 0xffff;
+		if (child == current)
+			load_gs_index(child->thread.gsindex);
 		return 0;
 	case offsetof(struct user_regs_struct,ds):
 		if (value && (value & 3) != 3)
 			return -EIO;
 		child->thread.ds = value & 0xffff;
+		if (child == current)
+			loadsegment(ds, child->thread.ds);
 		return 0;
 	case offsetof(struct user_regs_struct,es):
 		if (value && (value & 3) != 3)
 			return -EIO;
 		child->thread.es = value & 0xffff;
+		if (child == current)
+			loadsegment(es, child->thread.es);
 		return 0;
 	case offsetof(struct user_regs_struct,ss):
 		if ((value & 3) != 3)
@@ -135,14 +143,32 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
 {
 	struct pt_regs *regs = task_pt_regs(child);
 	unsigned long val;
+	unsigned int seg;
 	switch (regno) {
 	case offsetof(struct user_regs_struct, fs):
+		if (child == current) {
+			/* Older gas can't assemble movq %?s,%r?? */
+			asm("movl %%fs,%0" : "=r" (seg));
+			return seg;
+		}
 		return child->thread.fsindex;
 	case offsetof(struct user_regs_struct, gs):
+		if (child == current) {
+			asm("movl %%gs,%0" : "=r" (seg));
+			return seg;
+		}
 		return child->thread.gsindex;
 	case offsetof(struct user_regs_struct, ds):
+		if (child == current) {
+			asm("movl %%ds,%0" : "=r" (seg));
+			return seg;
+		}
 		return child->thread.ds;
 	case offsetof(struct user_regs_struct, es):
+		if (child == current) {
+			asm("movl %%es,%0" : "=r" (seg));
+			return seg;
+		}
 		return child->thread.es;
 	case offsetof(struct user_regs_struct, fs_base):
 		/*
@@ -152,7 +178,10 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
 		 */
 		if (child->thread.fs != 0)
 			return child->thread.fs;
-		if (child->thread.fsindex != FS_TLS_SEL)
+		seg = child->thread.fsindex;
+		if (child == current)
+			asm("movl %%fs,%0" : "=r" (seg));
+		if (seg != FS_TLS_SEL)
 			return 0;
 		return get_desc_base(&child->thread.tls_array[FS_TLS]);
 	case offsetof(struct user_regs_struct, gs_base):
@@ -161,7 +190,10 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
 		 */
 		if (child->thread.gs != 0)
 			return child->thread.gs;
-		if (child->thread.gsindex != GS_TLS_SEL)
+		seg = child->thread.gsindex;
+		if (child == current)
+			asm("movl %%gs,%0" : "=r" (seg));
+		if (seg != GS_TLS_SEL)
 			return 0;
 		return get_desc_base(&child->thread.tls_array[GS_TLS]);
 	case offsetof(struct user_regs_struct, flags):
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/