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>

5 files changed, 10 insertions, 34 deletions

diff --git a/security/capability.c b/security/capability.c
index 30ae00f..c773635 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -17,6 +17,11 @@ static int cap_sysctl(ctl_table *table, int op)
 	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;
diff --git a/security/commoncap.c b/security/commoncap.c
index 04b80f9..64c2ed9 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -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
@@ -884,26 +883,6 @@ 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;
-}
-
-/**
  * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
  * @mm: The VM space in which the new mapping is to be made
  * @pages: The size of the mapping
diff --git a/security/security.c b/security/security.c
index 3ef5e2a..1b798d3 100644
--- a/security/security.c
+++ b/security/security.c
@@ -197,9 +197,9 @@ int security_quota_on(struct dentry *dentry)
 	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)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d9154cf..65fa8bf 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1973,14 +1973,10 @@ static int selinux_quota_on(struct dentry *dentry)
 	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 */
 	case SYSLOG_ACTION_SIZE_BUFFER:	/* Return size of the log buffer */
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index bc39f40..489a85a 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -157,15 +157,11 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
  *
  * 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;