sysctl: Refactor the binary sysctl handling to remove duplicate code

Read in the binary sysctl path once, instead of reread it from user space each time the code needs to access a path element. The deprecated sysctl warning is moved to do_sysctl so that the compat_sysctl entries syscalls will also warn. The return of -ENOSYS when !CONFIG_SYSCTL_SYSCALL is moved to binary_sysctl. Always leaving a do_sysctl available that handles !CONFIG_SYSCTL_SYSCALL and printing the deprecated sysctl warning allows for a single defitition of the sysctl syscall. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

sysctl: Refactor the binary sysctl handling to remove duplicate code
Read in the binary sysctl path once, instead of reread it from user space each time the code needs to access a path element. The deprecated sysctl warning is moved to do_sysctl so that the compat_sysctl entries syscalls will also warn. The return of -ENOSYS when !CONFIG_SYSCTL_SYSCALL is moved to binary_sysctl. Always leaving a do_sysctl available that handles !CONFIG_SYSCTL_SYSCALL and printing the deprecated sysctl warning allows for a single defitition of the sysctl syscall. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Eric W. Biederman
1 parent afa588b265
Showing 1 changed file with 58 additions and 65 deletions Side-by-side Diff
kernel/sysctl_binary.c
@@ -14,8 +14,6 @@
 #include <linux/ctype.h>
 #include <linux/smp_lock.h>
  
-static int deprecated_sysctl_warning(struct __sysctl_args *args);
-
 #ifdef CONFIG_SYSCTL_SYSCALL
  
 /* Perform the actual read/write of a sysctl table entry. */
@@ -51,7 +49,7 @@
 	return 0;
 }
  
-static int parse_table(int __user *name, int nlen,
+static int parse_table(const int *name, int nlen,
 		       void __user *oldval, size_t __user *oldlenp,
 		       void __user *newval, size_t newlen,
 		       struct ctl_table_root *root,
@@ -61,8 +59,7 @@
 repeat:
 	if (!nlen)
 		return -ENOTDIR;
-	if (get_user(n, name))
-		return -EFAULT;
+	n = *name;
 	for ( ; table->ctl_name || table->procname; table++) {
 		if (!table->ctl_name)
 			continue;
  
  
@@ -85,20 +82,14 @@
 	return -ENOTDIR;
 }
  
-int do_sysctl(int __user *name, int nlen, void __user *oldval, size_t __user *oldlenp,
-	       void __user *newval, size_t newlen)
+static ssize_t binary_sysctl(const int *name, int nlen,
+	void __user *oldval, size_t __user *oldlenp,
+	void __user *newval, size_t newlen)
+
 {
 	struct ctl_table_header *head;
-	int error = -ENOTDIR;
+	ssize_t error = -ENOTDIR;
  
-	if (nlen <= 0 || nlen >= CTL_MAXNAME)
-		return -ENOTDIR;
-	if (oldval) {
-		int old_len;
-		if (!oldlenp || get_user(old_len, oldlenp))
-			return -EFAULT;
-	}
-
 	for (head = sysctl_head_next(NULL); head;
 			head = sysctl_head_next(head)) {
 		error = parse_table(name, nlen, oldval, oldlenp, 
  
  
  
  
  
  
  
  
@@ -112,75 +103,77 @@
 	return error;
 }
  
-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
-{
-	struct __sysctl_args tmp;
-	int error;
-
-	if (copy_from_user(&tmp, args, sizeof(tmp)))
-		return -EFAULT;
-
-	error = deprecated_sysctl_warning(&tmp);
-	if (error)
-		goto out;
-
-	lock_kernel();
-	error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
-			  tmp.newval, tmp.newlen);
-	unlock_kernel();
-out:
-	return error;
-}
-
 #else /* CONFIG_SYSCTL_SYSCALL */
  
-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
+static ssize_t binary_sysctl(const int *ctl_name, int nlen,
+	void __user *oldval, size_t __user *oldlenp,
+	void __user *newval, size_t newlen)
 {
-	struct __sysctl_args tmp;
-	int error;
-
-	if (copy_from_user(&tmp, args, sizeof(tmp)))
-		return -EFAULT;
-
-	error = deprecated_sysctl_warning(&tmp);
-
-	/* If no error reading the parameters then just -ENOSYS ... */
-	if (!error)
-		error = -ENOSYS;
-
-	return error;
+	return -ENOSYS;
 }
  
 #endif /* CONFIG_SYSCTL_SYSCALL */
  
-static int deprecated_sysctl_warning(struct __sysctl_args *args)
+static void deprecated_sysctl_warning(const int *name, int nlen)
 {
 	static int msg_count;
-	int name[CTL_MAXNAME];
 	int i;
  
-	/* Check args->nlen. */
-	if (args->nlen < 0 || args->nlen > CTL_MAXNAME)
-		return -ENOTDIR;
-
-	/* Read in the sysctl name for better debug message logging */
-	for (i = 0; i < args->nlen; i++)
-		if (get_user(name[i], args->name + i))
-			return -EFAULT;
-
 	/* Ignore accesses to kernel.version */
-	if ((args->nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
-		return 0;
+	if ((nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
+		return;
  
 	if (msg_count < 5) {
 		msg_count++;
 		printk(KERN_INFO
 			"warning: process `%s' used the deprecated sysctl "
 			"system call with ", current->comm);
-		for (i = 0; i < args->nlen; i++)
+		for (i = 0; i < nlen; i++)
 			printk("%d.", name[i]);
 		printk("\n");
 	}
-	return 0;
+	return;
+}
+
+int do_sysctl(int __user *args_name, int nlen,
+	void __user *oldval, size_t __user *oldlenp,
+	void __user *newval, size_t newlen)
+{
+	int name[CTL_MAXNAME];
+	size_t oldlen = 0;
+	int i;
+
+	if (nlen <= 0 || nlen >= CTL_MAXNAME)
+		return -ENOTDIR;
+	if (oldval && !oldlenp)
+		return -EFAULT;
+	if (oldlenp && get_user(oldlen, oldlenp))
+		return -EFAULT;
+
+	/* Read in the sysctl name for simplicity */
+	for (i = 0; i < nlen; i++)
+		if (get_user(name[i], args_name + i))
+			return -EFAULT;
+
+	deprecated_sysctl_warning(name, nlen);
+
+	return binary_sysctl(name, nlen, oldval, oldlenp, newval, newlen);
+}
+
+
+SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
+{
+	struct __sysctl_args tmp;
+	int error;
+
+	if (copy_from_user(&tmp, args, sizeof(tmp)))
+		return -EFAULT;
+
+	lock_kernel();
+	error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
+			  tmp.newval, tmp.newlen);
+	unlock_kernel();
+
+	return error;
 }
...	...	@@ -14,8 +14,6 @@
14	14	#include <linux/ctype.h>
15	15	#include <linux/smp_lock.h>
16	16
17		-static int deprecated_sysctl_warning(struct __sysctl_args *args);
18		-
19	17	#ifdef CONFIG_SYSCTL_SYSCALL
20	18
21	19	/* Perform the actual read/write of a sysctl table entry. */
...	...	@@ -51,7 +49,7 @@
51	49	return 0;
52	50	}
53	51
54		-static int parse_table(int __user *name, int nlen,
	52	+static int parse_table(const int *name, int nlen,
55	53	void __user oldval, size_t __user oldlenp,
56	54	void __user *newval, size_t newlen,
57	55	struct ctl_table_root *root,
...	...	@@ -61,8 +59,7 @@
61	59	repeat:
62	60	if (!nlen)
63	61	return -ENOTDIR;
64		- if (get_user(n, name))
65		- return -EFAULT;
	62	+ n = *name;
66	63	for ( ; table->ctl_name \|\| table->procname; table++) {
67	64	if (!table->ctl_name)
68	65	continue;
69	66
70	67
...	...	@@ -85,20 +82,14 @@
85	82	return -ENOTDIR;
86	83	}
87	84
88		-int do_sysctl(int __user name, int nlen, void __user oldval, size_t __user *oldlenp,
89		- void __user *newval, size_t newlen)
	85	+static ssize_t binary_sysctl(const int *name, int nlen,
	86	+ void __user oldval, size_t __user oldlenp,
	87	+ void __user *newval, size_t newlen)
	88	+
90	89	{
91	90	struct ctl_table_header *head;
92		- int error = -ENOTDIR;
	91	+ ssize_t error = -ENOTDIR;
93	92
94		- if (nlen <= 0 \|\| nlen >= CTL_MAXNAME)
95		- return -ENOTDIR;
96		- if (oldval) {
97		- int old_len;
98		- if (!oldlenp \|\| get_user(old_len, oldlenp))
99		- return -EFAULT;
100		- }
101		-
102	93	for (head = sysctl_head_next(NULL); head;
103	94	head = sysctl_head_next(head)) {
104	95	error = parse_table(name, nlen, oldval, oldlenp,
105	96
106	97
107	98
108	99
109	100
110	101
111	102
112	103
...	...	@@ -112,75 +103,77 @@
112	103	return error;
113	104	}
114	105
115		-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
116		-{
117		- struct __sysctl_args tmp;
118		- int error;
119		-
120		- if (copy_from_user(&tmp, args, sizeof(tmp)))
121		- return -EFAULT;
122		-
123		- error = deprecated_sysctl_warning(&tmp);
124		- if (error)
125		- goto out;
126		-
127		- lock_kernel();
128		- error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
129		- tmp.newval, tmp.newlen);
130		- unlock_kernel();
131		-out:
132		- return error;
133		-}
134		-
135	106	#else /* CONFIG_SYSCTL_SYSCALL */
136	107
137		-SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
	108	+static ssize_t binary_sysctl(const int *ctl_name, int nlen,
	109	+ void __user oldval, size_t __user oldlenp,
	110	+ void __user *newval, size_t newlen)
138	111	{
139		- struct __sysctl_args tmp;
140		- int error;
141		-
142		- if (copy_from_user(&tmp, args, sizeof(tmp)))
143		- return -EFAULT;
144		-
145		- error = deprecated_sysctl_warning(&tmp);
146		-
147		- /* If no error reading the parameters then just -ENOSYS ... */
148		- if (!error)
149		- error = -ENOSYS;
150		-
151		- return error;
	112	+ return -ENOSYS;
152	113	}
153	114
154	115	#endif /* CONFIG_SYSCTL_SYSCALL */
155	116
156		-static int deprecated_sysctl_warning(struct __sysctl_args *args)
	117	+static void deprecated_sysctl_warning(const int *name, int nlen)
157	118	{
158	119	static int msg_count;
159		- int name[CTL_MAXNAME];
160	120	int i;
161	121
162		- /* Check args->nlen. */
163		- if (args->nlen < 0 \|\| args->nlen > CTL_MAXNAME)
164		- return -ENOTDIR;
165		-
166		- /* Read in the sysctl name for better debug message logging */
167		- for (i = 0; i < args->nlen; i++)
168		- if (get_user(name[i], args->name + i))
169		- return -EFAULT;
170		-
171	122	/* Ignore accesses to kernel.version */
172		- if ((args->nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
173		- return 0;
	123	+ if ((nlen == 2) && (name[0] == CTL_KERN) && (name[1] == KERN_VERSION))
	124	+ return;
174	125
175	126	if (msg_count < 5) {
176	127	msg_count++;
177	128	printk(KERN_INFO
178	129	"warning: process `%s' used the deprecated sysctl "
179	130	"system call with ", current->comm);
180		- for (i = 0; i < args->nlen; i++)
	131	+ for (i = 0; i < nlen; i++)
181	132	printk("%d.", name[i]);
182	133	printk("\n");
183	134	}
184		- return 0;
	135	+ return;
	136	+}
	137	+
	138	+int do_sysctl(int __user *args_name, int nlen,
	139	+ void __user oldval, size_t __user oldlenp,
	140	+ void __user *newval, size_t newlen)
	141	+{
	142	+ int name[CTL_MAXNAME];
	143	+ size_t oldlen = 0;
	144	+ int i;
	145	+
	146	+ if (nlen <= 0 \|\| nlen >= CTL_MAXNAME)
	147	+ return -ENOTDIR;
	148	+ if (oldval && !oldlenp)
	149	+ return -EFAULT;
	150	+ if (oldlenp && get_user(oldlen, oldlenp))
	151	+ return -EFAULT;
	152	+
	153	+ /* Read in the sysctl name for simplicity */
	154	+ for (i = 0; i < nlen; i++)
	155	+ if (get_user(name[i], args_name + i))
	156	+ return -EFAULT;
	157	+
	158	+ deprecated_sysctl_warning(name, nlen);
	159	+
	160	+ return binary_sysctl(name, nlen, oldval, oldlenp, newval, newlen);
	161	+}
	162	+
	163	+
	164	+SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
	165	+{
	166	+ struct __sysctl_args tmp;
	167	+ int error;
	168	+
	169	+ if (copy_from_user(&tmp, args, sizeof(tmp)))
	170	+ return -EFAULT;
	171	+
	172	+ lock_kernel();
	173	+ error = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,
	174	+ tmp.newval, tmp.newlen);
	175	+ unlock_kernel();
	176	+
	177	+ return error;
185	178	}