[PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"

From: Kees Cook
Date: Thu Aug 10 2017 - 16:36:45 EST


This reverts commit 68c4a4f8abc60c9440ede9cd123d48b78325f7a3, with
various conflict clean-ups.

With the default root directory mode set to 0750 now, the capability
check was redundant.

Suggested-by: Nick Kralevich <nnk@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
fs/pstore/inode.c | 22 ----------------------
include/linux/syslog.h | 9 ---------
kernel/printk/printk.c | 3 +--
3 files changed, 1 insertion(+), 33 deletions(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index f1e88b695090..d814723fb27d 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -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;
diff --git a/include/linux/syslog.h b/include/linux/syslog.h
index c3a7f0cc3a27..e1c3632f4e81 100644
--- a/include/linux/syslog.h
+++ b/include/linux/syslog.h
@@ -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 */
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fc47863f629c..97bda7b0655b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -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)
{
--
2.7.4