capabilities/syslog: open code cap_syslog logic to fix build failure

The addition of CONFIG_SECURITY_DMESG_RESTRICT resulted in a build failure when CONFIG_PRINTK=n. This is because the capabilities code which used the new option was built even though the variable in question didn't exist. The patch here fixes this by moving the capabilities checks out of the LSM and into the caller. All (known) LSMs should have been calling the capabilities hook already so it actually makes the code organization better to eliminate the hook altogether. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

capabilities/syslog: open code cap_syslog logic to fix build failure
The addition of CONFIG_SECURITY_DMESG_RESTRICT resulted in a build failure when CONFIG_PRINTK=n. This is because the capabilities code which used the new option was built even though the variable in question didn't exist. The patch here fixes this by moving the capabilities checks out of the LSM and into the caller. All (known) LSMs should have been calling the capabilities hook already so it actually makes the code organization better to eliminate the hook altogether. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Paris · Linus Torvalds
1 parent 6800e4c0ea
Showing 7 changed files with 28 additions and 40 deletions Side-by-side Diff
include/linux/security.h
kernel/printk.c
security/capability.c
security/commoncap.c
security/security.c
security/selinux/hooks.c
security/smack/smack_lsm.c
@@ -77,7 +77,6 @@
 extern int cap_task_setscheduler(struct task_struct *p);
 extern int cap_task_setioprio(struct task_struct *p, int ioprio);
 extern int cap_task_setnice(struct task_struct *p, int nice);
-extern int cap_syslog(int type, bool from_file);
 extern int cap_vm_enough_memory(struct mm_struct *mm, long pages);
  
 struct msghdr;
@@ -1388,7 +1387,7 @@
 	int (*sysctl) (struct ctl_table *table, int op);
 	int (*quotactl) (int cmds, int type, int id, struct super_block *sb);
 	int (*quota_on) (struct dentry *dentry);
-	int (*syslog) (int type, bool from_file);
+	int (*syslog) (int type);
 	int (*settime) (struct timespec *ts, struct timezone *tz);
 	int (*vm_enough_memory) (struct mm_struct *mm, long pages);
  
@@ -1671,7 +1670,7 @@
 int security_sysctl(struct ctl_table *table, int op);
 int security_quotactl(int cmds, int type, int id, struct super_block *sb);
 int security_quota_on(struct dentry *dentry);
-int security_syslog(int type, bool from_file);
+int security_syslog(int type);
 int security_settime(struct timespec *ts, struct timezone *tz);
 int security_vm_enough_memory(long pages);
 int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
  
@@ -1901,9 +1900,9 @@
 	return 0;
 }
  
-static inline int security_syslog(int type, bool from_file)
+static inline int security_syslog(int type)
 {
-	return cap_syslog(type, from_file);
+	return 0;
 }
  
 static inline int security_settime(struct timespec *ts, struct timezone *tz)
@@ -274,7 +274,20 @@
 	char c;
 	int error = 0;
  
-	error = security_syslog(type, from_file);
+	/*
+	 * If this is from /proc/kmsg we only do the capabilities checks
+	 * at open time.
+	 */
+	if (type == SYSLOG_ACTION_OPEN || !from_file) {
+		if (dmesg_restrict && !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		if ((type != SYSLOG_ACTION_READ_ALL &&
+		     type != SYSLOG_ACTION_SIZE_BUFFER) &&
+		    !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+	}
+
+	error = security_syslog(type);
 	if (error)
 		return error;
  
@@ -17,6 +17,11 @@
 	return 0;
 }
  
+static int cap_syslog(int type)
+{
+	return 0;
+}
+
 static int cap_quotactl(int cmds, int type, int id, struct super_block *sb)
 {
 	return 0;
@@ -27,7 +27,6 @@
 #include <linux/sched.h>
 #include <linux/prctl.h>
 #include <linux/securebits.h>
-#include <linux/syslog.h>
  
 /*
  * If a non-root user executes a setuid-root binary in
@@ -881,26 +880,6 @@
 error:
 	abort_creds(new);
 	return error;
-}
-
-/**
- * cap_syslog - Determine whether syslog function is permitted
- * @type: Function requested
- * @from_file: Whether this request came from an open file (i.e. /proc)
- *
- * Determine whether the current process is permitted to use a particular
- * syslog function, returning 0 if permission is granted, -ve if not.
- */
-int cap_syslog(int type, bool from_file)
-{
-	if (type != SYSLOG_ACTION_OPEN && from_file)
-		return 0;
-	if (dmesg_restrict && !capable(CAP_SYS_ADMIN))
-		return -EPERM;
-	if ((type != SYSLOG_ACTION_READ_ALL &&
-	     type != SYSLOG_ACTION_SIZE_BUFFER) && !capable(CAP_SYS_ADMIN))
-		return -EPERM;
-	return 0;
 }
  
 /**
@@ -197,9 +197,9 @@
 	return security_ops->quota_on(dentry);
 }
  
-int security_syslog(int type, bool from_file)
+int security_syslog(int type)
 {
-	return security_ops->syslog(type, from_file);
+	return security_ops->syslog(type);
 }
  
 int security_settime(struct timespec *ts, struct timezone *tz)
@@ -1973,13 +1973,9 @@
 	return dentry_has_perm(cred, NULL, dentry, FILE__QUOTAON);
 }
  
-static int selinux_syslog(int type, bool from_file)
+static int selinux_syslog(int type)
 {
 	int rc;
-
-	rc = cap_syslog(type, from_file);
-	if (rc)
-		return rc;
  
 	switch (type) {
 	case SYSLOG_ACTION_READ_ALL:	/* Read last kernel messages */
@@ -157,14 +157,10 @@
  *
  * Returns 0 on success, error code otherwise.
  */
-static int smack_syslog(int type, bool from_file)
+static int smack_syslog(int typefrom_file)
 {
-	int rc;
+	int rc = 0;
 	char *sp = current_security();
-
-	rc = cap_syslog(type, from_file);
-	if (rc != 0)
-		return rc;
  
 	if (capable(CAP_MAC_OVERRIDE))
 		return 0;
...	...	@@ -77,7 +77,6 @@
77	77	extern int cap_task_setscheduler(struct task_struct *p);
78	78	extern int cap_task_setioprio(struct task_struct *p, int ioprio);
79	79	extern int cap_task_setnice(struct task_struct *p, int nice);
80		-extern int cap_syslog(int type, bool from_file);
81	80	extern int cap_vm_enough_memory(struct mm_struct *mm, long pages);
82	81
83	82	struct msghdr;
...	...	@@ -1388,7 +1387,7 @@
1388	1387	int (sysctl) (struct ctl_table table, int op);
1389	1388	int (quotactl) (int cmds, int type, int id, struct super_block sb);
1390	1389	int (quota_on) (struct dentry dentry);
1391		- int (*syslog) (int type, bool from_file);
	1390	+ int (*syslog) (int type);
1392	1391	int (settime) (struct timespec ts, struct timezone *tz);
1393	1392	int (vm_enough_memory) (struct mm_struct mm, long pages);
1394	1393
...	...	@@ -1671,7 +1670,7 @@
1671	1670	int security_sysctl(struct ctl_table *table, int op);
1672	1671	int security_quotactl(int cmds, int type, int id, struct super_block *sb);
1673	1672	int security_quota_on(struct dentry *dentry);
1674		-int security_syslog(int type, bool from_file);
	1673	+int security_syslog(int type);
1675	1674	int security_settime(struct timespec ts, struct timezone tz);
1676	1675	int security_vm_enough_memory(long pages);
1677	1676	int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
1678	1677
...	...	@@ -1901,9 +1900,9 @@
1901	1900	return 0;
1902	1901	}
1903	1902
1904		-static inline int security_syslog(int type, bool from_file)
	1903	+static inline int security_syslog(int type)
1905	1904	{
1906		- return cap_syslog(type, from_file);
	1905	+ return 0;
1907	1906	}
1908	1907
1909	1908	static inline int security_settime(struct timespec ts, struct timezone tz)
...	...	@@ -274,7 +274,20 @@
274	274	char c;
275	275	int error = 0;
276	276
277		- error = security_syslog(type, from_file);
	277	+ /*
	278	+ * If this is from /proc/kmsg we only do the capabilities checks
	279	+ * at open time.
	280	+ */
	281	+ if (type == SYSLOG_ACTION_OPEN \|\| !from_file) {
	282	+ if (dmesg_restrict && !capable(CAP_SYS_ADMIN))
	283	+ return -EPERM;
	284	+ if ((type != SYSLOG_ACTION_READ_ALL &&
	285	+ type != SYSLOG_ACTION_SIZE_BUFFER) &&
	286	+ !capable(CAP_SYS_ADMIN))
	287	+ return -EPERM;
	288	+ }
	289	+
	290	+ error = security_syslog(type);
278	291	if (error)
279	292	return error;
280	293
...	...	@@ -17,6 +17,11 @@
17	17	return 0;
18	18	}
19	19
	20	+static int cap_syslog(int type)
	21	+{
	22	+ return 0;
	23	+}
	24	+
20	25	static int cap_quotactl(int cmds, int type, int id, struct super_block *sb)
21	26	{
22	27	return 0;
...	...	@@ -27,7 +27,6 @@
27	27	#include <linux/sched.h>
28	28	#include <linux/prctl.h>
29	29	#include <linux/securebits.h>
30		-#include <linux/syslog.h>
31	30
32	31	/*
33	32	* If a non-root user executes a setuid-root binary in
...	...	@@ -881,26 +880,6 @@
881	880	error:
882	881	abort_creds(new);
883	882	return error;
884		-}
885		-
886		-/**
887		- * cap_syslog - Determine whether syslog function is permitted
888		- * @type: Function requested
889		- * @from_file: Whether this request came from an open file (i.e. /proc)
890		- *
891		- * Determine whether the current process is permitted to use a particular
892		- * syslog function, returning 0 if permission is granted, -ve if not.
893		- */
894		-int cap_syslog(int type, bool from_file)
895		-{
896		- if (type != SYSLOG_ACTION_OPEN && from_file)
897		- return 0;
898		- if (dmesg_restrict && !capable(CAP_SYS_ADMIN))
899		- return -EPERM;
900		- if ((type != SYSLOG_ACTION_READ_ALL &&
901		- type != SYSLOG_ACTION_SIZE_BUFFER) && !capable(CAP_SYS_ADMIN))
902		- return -EPERM;
903		- return 0;
904	883	}
905	884
906	885	/**
...	...	@@ -197,9 +197,9 @@
197	197	return security_ops->quota_on(dentry);
198	198	}
199	199
200		-int security_syslog(int type, bool from_file)
	200	+int security_syslog(int type)
201	201	{
202		- return security_ops->syslog(type, from_file);
	202	+ return security_ops->syslog(type);
203	203	}
204	204
205	205	int security_settime(struct timespec ts, struct timezone tz)
...	...	@@ -1973,13 +1973,9 @@
1973	1973	return dentry_has_perm(cred, NULL, dentry, FILE__QUOTAON);
1974	1974	}
1975	1975
1976		-static int selinux_syslog(int type, bool from_file)
	1976	+static int selinux_syslog(int type)
1977	1977	{
1978	1978	int rc;
1979		-
1980		- rc = cap_syslog(type, from_file);
1981		- if (rc)
1982		- return rc;
1983	1979
1984	1980	switch (type) {
1985	1981	case SYSLOG_ACTION_READ_ALL: /* Read last kernel messages */
...	...	@@ -157,14 +157,10 @@
157	157	*
158	158	* Returns 0 on success, error code otherwise.
159	159	*/
160		-static int smack_syslog(int type, bool from_file)
	160	+static int smack_syslog(int typefrom_file)
161	161	{
162		- int rc;
	162	+ int rc = 0;
163	163	char *sp = current_security();
164		-
165		- rc = cap_syslog(type, from_file);
166		- if (rc != 0)
167		- return rc;
168	164
169	165	if (capable(CAP_MAC_OVERRIDE))
170	166	return 0;