[ 28/42] sysctl: fix write access to dmesg_restrict/kptr_restrict

From: Greg KH
Date: Wed Apr 11 2012 - 19:29:03 EST


3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Kees Cook <keescook@xxxxxxxxxxxx>

commit 620f6e8e855d6d447688a5f67a4e176944a084e8 upstream.

Commit bfdc0b4 adds code to restrict access to dmesg_restrict,
however, it incorrectly alters kptr_restrict rather than
dmesg_restrict.

The original patch from Richard Weinberger
(https://lkml.org/lkml/2011/3/14/362) alters dmesg_restrict as
expected, and so the patch seems to have been misapplied.

This adds the CAP_SYS_ADMIN check to both dmesg_restrict and
kptr_restrict, since both are sensitive.

Reported-by: Phillip Lougher <plougher@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Acked-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: James Morris <james.l.morris@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
kernel/sysctl.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -172,7 +172,7 @@ static int proc_taint(struct ctl_table *
#endif

#ifdef CONFIG_PRINTK
-static int proc_dmesg_restrict(struct ctl_table *table, int write,
+static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
#endif

@@ -709,7 +709,7 @@ static struct ctl_table kern_table[] = {
.data = &dmesg_restrict,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax_sysadmin,
.extra1 = &zero,
.extra2 = &one,
},
@@ -718,7 +718,7 @@ static struct ctl_table kern_table[] = {
.data = &kptr_restrict,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dmesg_restrict,
+ .proc_handler = proc_dointvec_minmax_sysadmin,
.extra1 = &zero,
.extra2 = &two,
},
@@ -2416,7 +2416,7 @@ static int proc_taint(struct ctl_table *
}

#ifdef CONFIG_PRINTK
-static int proc_dmesg_restrict(struct ctl_table *table, int write,
+static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
if (write && !capable(CAP_SYS_ADMIN))


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