Re: [PATCH] LSM changes for 2.5.62

From: Greg KH (gregat_private)
Date: Wed Feb 19 2003 - 15:43:02 PST

  • Next message: Greg KH: "Re: [PATCH] LSM changes for 2.5.62"

    ChangeSet 1.914.81.3, 2003/02/05 14:37:12+11:00, sdsat_private
    
    [PATCH] LSM: Add LSM syslog hook to 2.5.59
    
    This patch adds the LSM security_syslog hook for controlling the
    syslog(2) interface relative to 2.5.59 plus the previously posted
    security_sysctl patch.  In response to earlier comments by Christoph,
    the existing capability check for syslog(2) is moved into the
    capability security module hook function, and a corresponding dummy
    security module hook function is defined that provides traditional
    superuser behavior.  The LSM hook is placed in do_syslog rather than
    sys_syslog so that it is called when either the system call interface
    or the /proc/kmsg interface is used.  SELinux uses this hook to
    control access to the kernel message ring and to the console log
    level.
    
    
    diff -Nru a/include/linux/security.h b/include/linux/security.h
    --- a/include/linux/security.h	Wed Feb 19 15:38:52 2003
    +++ b/include/linux/security.h	Wed Feb 19 15:38:52 2003
    @@ -47,6 +47,7 @@
     extern int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, int flags);
     extern void cap_task_kmod_set_label (void);
     extern void cap_task_reparent_to_init (struct task_struct *p);
    +extern int cap_syslog (int type);
     
     /*
      * Values used in the task_security_ops calls
    @@ -778,6 +779,12 @@
      *	@tsk contains the task_struct for the process.
      *	@cap contains the capability <include/linux/capability.h>.
      *	Return 0 if the capability is granted for @tsk.
    + * @syslog:
    + *	Check permission before accessing the kernel message ring or changing
    + *	logging to the console.
    + *	See the syslog(2) manual page for an explanation of the @type values.  
    + *	@type contains the type of action.
    + *	Return 0 if permission is granted.
      *
      * @register_security:
      * 	allow module stacking.
    @@ -808,6 +815,7 @@
     	int (*capable) (struct task_struct * tsk, int cap);
     	int (*quotactl) (int cmds, int type, int id, struct super_block * sb);
     	int (*quota_on) (struct file * f);
    +	int (*syslog) (int type);
     
     	int (*bprm_alloc_security) (struct linux_binprm * bprm);
     	void (*bprm_free_security) (struct linux_binprm * bprm);
    @@ -1013,6 +1021,11 @@
     	return security_ops->quota_on (file);
     }
     
    +static inline int security_syslog(int type)
    +{
    +	return security_ops->syslog(type);
    +}
    +
     static inline int security_bprm_alloc (struct linux_binprm *bprm)
     {
     	return security_ops->bprm_alloc_security (bprm);
    @@ -1625,6 +1638,11 @@
     static inline int security_quota_on (struct file * file)
     {
     	return 0;
    +}
    +
    +static inline int security_syslog(int type)
    +{
    +	return cap_syslog(type);
     }
     
     static inline int security_bprm_alloc (struct linux_binprm *bprm)
    diff -Nru a/kernel/printk.c b/kernel/printk.c
    --- a/kernel/printk.c	Wed Feb 19 15:38:52 2003
    +++ b/kernel/printk.c	Wed Feb 19 15:38:52 2003
    @@ -28,6 +28,7 @@
     #include <linux/config.h>
     #include <linux/delay.h>
     #include <linux/smp.h>
    +#include <linux/security.h>
     
     #include <asm/uaccess.h>
     
    @@ -161,6 +162,10 @@
     	char c;
     	int error = 0;
     
    +	error = security_syslog(type);
    +	if (error)
    +		return error;
    +
     	switch (type) {
     	case 0:		/* Close log */
     		break;
    @@ -273,8 +278,6 @@
     
     asmlinkage long sys_syslog(int type, char * buf, int len)
     {
    -	if ((type != 3) && !capable(CAP_SYS_ADMIN))
    -		return -EPERM;
     	return do_syslog(type, buf, len);
     }
     
    diff -Nru a/security/capability.c b/security/capability.c
    --- a/security/capability.c	Wed Feb 19 15:38:52 2003
    +++ b/security/capability.c	Wed Feb 19 15:38:52 2003
    @@ -262,6 +262,13 @@
     	return;
     }
     
    +int cap_syslog (int type)
    +{
    +	if ((type != 3) && !capable(CAP_SYS_ADMIN))
    +		return -EPERM;
    +	return 0;
    +}
    +
     EXPORT_SYMBOL(cap_capable);
     EXPORT_SYMBOL(cap_ptrace);
     EXPORT_SYMBOL(cap_capget);
    @@ -272,6 +279,7 @@
     EXPORT_SYMBOL(cap_task_post_setuid);
     EXPORT_SYMBOL(cap_task_kmod_set_label);
     EXPORT_SYMBOL(cap_task_reparent_to_init);
    +EXPORT_SYMBOL(cap_syslog);
     
     #ifdef CONFIG_SECURITY
     
    @@ -289,6 +297,8 @@
     	.task_post_setuid =		cap_task_post_setuid,
     	.task_kmod_set_label =		cap_task_kmod_set_label,
     	.task_reparent_to_init =	cap_task_reparent_to_init,
    +
    +	.syslog =                       cap_syslog,
     };
     
     #if defined(CONFIG_SECURITY_CAPABILITIES_MODULE)
    diff -Nru a/security/dummy.c b/security/dummy.c
    --- a/security/dummy.c	Wed Feb 19 15:38:52 2003
    +++ b/security/dummy.c	Wed Feb 19 15:38:52 2003
    @@ -90,6 +90,13 @@
     	return 0;
     }
     
    +static int dummy_syslog (int type)
    +{
    +	if ((type != 3) && current->euid)
    +		return -EPERM;
    +	return 0;
    +}
    +
     static int dummy_bprm_alloc_security (struct linux_binprm *bprm)
     {
     	return 0;
    @@ -640,6 +647,7 @@
     	set_to_dummy_if_null(ops, quotactl);
     	set_to_dummy_if_null(ops, quota_on);
     	set_to_dummy_if_null(ops, sysctl);
    +	set_to_dummy_if_null(ops, syslog);
     	set_to_dummy_if_null(ops, bprm_alloc_security);
     	set_to_dummy_if_null(ops, bprm_free_security);
     	set_to_dummy_if_null(ops, bprm_compute_creds);
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