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syslog: distinguish between /proc/kmsg and syscalls

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This allows the LSM to distinguish between syslog functions originating
from /proc/kmsg access and direct syscalls.  By default, the commoncaps
will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg
file descriptor.  For example the kernel syslog reader can now drop
privileges after opening /proc/kmsg, instead of staying privileged with
CAP_SYS_ADMIN.  MAC systems that implement security_syslog have unchanged
behavior.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Kees Cook
2010-02-03 15:36:43 -08:00
committed by James Morris
parent 0719aaf5ea
commit 002345925e
8 changed files with 59 additions and 22 deletions
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11
include/linux/security.h
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@@ -76,7 +76,7 @@ extern int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
extern int cap_task_setscheduler(struct task_struct *p, int policy, struct sched_param *lp);
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);
extern int cap_syslog(int type, bool from_file);
extern int cap_vm_enough_memory(struct mm_struct *mm, long pages);
struct msghdr;
@@ -1349,6 +1349,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* logging to the console.
* See the syslog(2) manual page for an explanation of the @type values.
* @type contains the type of action.
* @from_file indicates the context of action (if it came from /proc).
* Return 0 if permission is granted.
* @settime:
* Check permission to change the system time.
@@ -1463,7 +1464,7 @@ struct security_operations {
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);
int (*syslog) (int type, bool from_file);
int (*settime) (struct timespec *ts, struct timezone *tz);
int (*vm_enough_memory) (struct mm_struct *mm, long pages);
@@ -1762,7 +1763,7 @@ int security_acct(struct file *file);
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);
int security_syslog(int type, bool from_file);
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);
@@ -2008,9 +2009,9 @@ static inline int security_quota_on(struct dentry *dentry)
return 0;
}
static inline int security_syslog(int type)
static inline int security_syslog(int type, bool from_file)
{
return cap_syslog(type);
return cap_syslog(type, from_file);
}
static inline int security_settime(struct timespec *ts, struct timezone *tz)