[IA64] sysctl option to silence unaligned trap warnings

Allow sysadmin to disable all warnings about userland apps making unaligned accesses by using: # echo 1 > /proc/sys/kernel/ignore-unaligned-usertrap Rather than having to use prctl on a process by process basis. Default behaivour leaves the warnings enabled.

Jes Sorensen committed 20 years ago

Commit d2b176e1 parent c8c16353 files · +43 −3Browse files

Unified · Split

3 files

arch/ia64/kernel/unaligned.c +28 −3
include/linux/sysctl.h +1 −0
kernel/sysctl.c +14 −0

arch/ia64/kernel/unaligned.c+28−3

@@ -52,6 +52,15 @@ dump (const char str, void vp, size_t len) · 51 unmodified lines
52	52	#define IA64_FIRST_ROTATING_FR 32
53	53	#define SIGN_EXT9 0xffffffffffffff00ul
54	54
	55	+/*
	56	+ * sysctl settable hook which tells the kernel whether to honor the
	57	+ * IA64_THREAD_UAC_NOPRINT prctl. Because this is user settable, we want
	58	+ * to allow the super user to enable/disable this for security reasons
	59	+ * (i.e. don't allow attacker to fill up logs with unaligned accesses).
	60	+ */
	61	+int no_unaligned_warning;
	62	+static int noprint_warning;
	63	+
55	64	/*
56	65	* For M-unit:
57	66	*
@@ -1324,8 +1333,9 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs) · 1266 unmodified lines
1324	1333	if ((current->thread.flags & IA64_THREAD_UAC_SIGBUS) != 0)
1325	1334	goto force_sigbus;
1326	1335
1327		− if (!(current->thread.flags & IA64_THREAD_UAC_NOPRINT)
1328		− && within_logging_rate_limit())
	1336	+ if (!no_unaligned_warning &&
	1337	+ !(current->thread.flags & IA64_THREAD_UAC_NOPRINT) &&
	1338	+ within_logging_rate_limit())
1329	1339	{
1330	1340	char buf[200]; /* comm[] is at most 16 bytes... */
1331	1341	size_t len;
@@ -1340,7 +1350,22 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs) · 8 unmodified lines
1340	1350	if (user_mode(regs))
1341	1351	tty_write_message(current->signal->tty, buf);
1342	1352	buf[len-1] = '\0'; /* drop '\r' */
1343		− printk(KERN_WARNING "%s", buf); /* watch for command names containing %s */
	1353	+ /* watch for command names containing %s */
	1354	+ printk(KERN_WARNING "%s", buf);
	1355	+ } else {
	1356	+ if (no_unaligned_warning && !noprint_warning) {
	1357	+ noprint_warning = 1;
	1358	+ printk(KERN_WARNING "%s(%d) encountered an "
	1359	+ "unaligned exception which required\n"
	1360	+ "kernel assistance, which degrades "
	1361	+ "the performance of the application.\n"
	1362	+ "Unaligned exception warnings have "
	1363	+ "been disabled by the system "
	1364	+ "administrator\n"
	1365	+ "echo 0 > /proc/sys/kernel/ignore-"
	1366	+ "unaligned-usertrap to re-enable\n",
	1367	+ current->comm, current->pid);
	1368	+ }
1344	1369	}
1345	1370	} else {
1346	1371	if (within_logging_rate_limit())

include/linux/sysctl.h+1−0

@@ -147,6 +147,7 @@ enum · 146 unmodified lines
147	147	KERN_SETUID_DUMPABLE=69, /* int: behaviour of dumps for setuid core */
148	148	KERN_SPIN_RETRY=70, /* int: number of spinlock retries */
149	149	KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
	150	+ KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */
150	151	};
151	152
152	153

kernel/sysctl.c+14−0

@@ -124,6 +124,10 @@ extern int sysctl_hz_timer; · 123 unmodified lines
124	124	extern int acct_parm[];
125	125	#endif
126	126
	127	+#ifdef CONFIG_IA64
	128	+extern int no_unaligned_warning;
	129	+#endif
	130	+
127	131	static int parse_table(int __user , int, void __user , size_t __user , void __user , size_t,
128	132	ctl_table , void *);
129	133	static int proc_doutsstring(ctl_table table, int write, struct file filp,
@@ -665,6 +669,16 @@ static ctl_table kern_table[] = { · 535 unmodified lines
665	669	.mode = 0644,
666	670	.proc_handler = &proc_dointvec,
667	671	},
	672	+#endif
	673	+#ifdef CONFIG_IA64
	674	+ {
	675	+ .ctl_name = KERN_IA64_UNALIGNED,
	676	+ .procname = "ignore-unaligned-usertrap",
	677	+ .data = &no_unaligned_warning,
	678	+ .maxlen = sizeof (int),
	679	+ .mode = 0644,
	680	+ .proc_handler = &proc_dointvec,
	681	+ },
668	682	#endif
669	683	{ .ctl_name = 0 }
670	684	};