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Make pstore permissions more versatile by removing CAP_SYSLOG requirement

Browse source 
and defining more restrictive root directory DAC permissions default
 (0750, which can be adjust after boot unlike the CAP_SYSLOG check).
 Suggested by Nick Kralevich.
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 Version: GnuPG v1
 Comment: Kees Cook <kees@outflux.net>
 
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Merge tag 'pstore-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull pstore update from Kees Cook:
 "Make pstore permissions more versatile by removing CAP_SYSLOG
  requirement and defining more restrictive root directory DAC
  permissions default (0750, which can be adjust after boot unlike the
  CAP_SYSLOG check).

  Suggested by Nick Kralevich"

* tag 'pstore-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"
  pstore: Make default pstorefs root dir perms 0750
This commit is contained in:
Linus Torvalds 2017-09-07 19:58:56 -07:00
commit 21d236bf2b
3 changed files with 2 additions and 34 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
fs/pstore/inode.c
View file

@ -36,7 +36,6 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/syslog.h>
#include "internal.h"
@ -132,18 +131,6 @@ static const struct seq_operations pstore_ftrace_seq_ops = {
.show = pstore_ftrace_seq_show,
};
static int pstore_check_syslog_permissions(struct pstore_private *ps)
{
switch (ps->record->type) {
case PSTORE_TYPE_DMESG:
case PSTORE_TYPE_CONSOLE:
return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
SYSLOG_FROM_READER);
default:
return 0;
}
}
static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
size_t count, loff_t *ppos)
{
@ -163,10 +150,6 @@ static int pstore_file_open(struct inode *inode, struct file *file)
int err;
const struct seq_operations *sops = NULL;
err = pstore_check_syslog_permissions(ps);
if (err)
return err;
if (ps->record->type == PSTORE_TYPE_FTRACE)
sops = &pstore_ftrace_seq_ops;
@ -204,11 +187,6 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry)
{
struct pstore_private *p = d_inode(dentry)->i_private;
struct pstore_record *record = p->record;
int err;
err = pstore_check_syslog_permissions(p);
if (err)
return err;
if (!record->psi->erase)
return -EPERM;
@ -471,7 +449,7 @@ static int pstore_fill_super(struct super_block *sb, void *data, int silent)
inode = pstore_get_inode(sb);
if (inode) {
inode->i_mode = S_IFDIR | 0755;
inode->i_mode = S_IFDIR | 0750;
inode->i_op = &pstore_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inc_nlink(inode);

9
include/linux/syslog.h
View file

@ -49,13 +49,4 @@
int do_syslog(int type, char __user *buf, int count, int source);
#ifdef CONFIG_PRINTK
int check_syslog_permissions(int type, int source);
#else
static inline int check_syslog_permissions(int type, int source)
{
return 0;
}
#endif
#endif /* _LINUX_SYSLOG_H */

3
kernel/printk/printk.c
View file

@ -649,7 +649,7 @@ static int syslog_action_restricted(int type)
type != SYSLOG_ACTION_SIZE_BUFFER;
}
int check_syslog_permissions(int type, int source)
static int check_syslog_permissions(int type, int source)
{
/*
* If this is from /proc/kmsg and we've already opened it, then we've
@ -677,7 +677,6 @@ int check_syslog_permissions(int type, int source)
ok:
return security_syslog(type);
}
EXPORT_SYMBOL_GPL(check_syslog_permissions);
static void append_char(char **pp, char *e, char c)
{