sysctl: fix write access to dmesg_restrict/kptr_restrict

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@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 52b3a06..4ab1187 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -170,7 +170,7 @@ static int proc_taint(struct ctl_table *table, int write,
 #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
 
@@ -703,7 +703,7 @@ 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,
        },
@@ -712,7 +712,7 @@ 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,
        },
@@ -1943,7 +1943,7 @@ static int proc_taint(struct ctl_table *table, int write,
 }
 
 #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))