| Message ID | 20190622000358.19895-22-matthewgarrett@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Lockdown as an LSM | expand |
On Fri, Jun 21, 2019 at 05:03:50PM -0700, Matthew Garrett wrote: > From: David Howells <dhowells@redhat.com> > > Disallow access to /proc/kcore when the kernel is locked down to prevent > access to cryptographic data. This is limited to lockdown > confidentiality mode and is still permitted in integrity mode. > > Signed-off-by: David Howells <dhowells@redhat.com> > Signed-off-by: Matthew Garrett <mjg59@google.com> > --- > fs/proc/kcore.c | 5 +++++ > include/linux/security.h | 1 + > security/lockdown/lockdown.c | 1 + > 3 files changed, 7 insertions(+) > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > index d29d869abec1..4e95edb1e282 100644 > --- a/fs/proc/kcore.c > +++ b/fs/proc/kcore.c > @@ -31,6 +31,7 @@ > #include <linux/ioport.h> > #include <linux/memory.h> > #include <linux/sched/task.h> > +#include <linux/security.h> > #include <asm/sections.h> > #include "internal.h" > > @@ -545,6 +546,10 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) > > static int open_kcore(struct inode *inode, struct file *filp) > { > + int ret = security_locked_down(LOCKDOWN_KCORE); > + > + if (ret) > + return ret; > if (!capable(CAP_SYS_RAWIO)) > return -EPERM; Another capable() check ordering fix needed. With that: Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > > diff --git a/include/linux/security.h b/include/linux/security.h > index c649cb91e762..3875f6df2ecc 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -95,6 +95,7 @@ enum lockdown_reason { > LOCKDOWN_MODULE_PARAMETERS, > LOCKDOWN_MMIOTRACE, > LOCKDOWN_INTEGRITY_MAX, > + LOCKDOWN_KCORE, > LOCKDOWN_CONFIDENTIALITY_MAX, > }; > > diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c > index cd86ed9f4d4b..4c9b324dfc55 100644 > --- a/security/lockdown/lockdown.c > +++ b/security/lockdown/lockdown.c > @@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { > [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", > [LOCKDOWN_MMIOTRACE] = "unsafe mmio", > [LOCKDOWN_INTEGRITY_MAX] = "integrity", > + [LOCKDOWN_KCORE] = "/proc/kcore access", > [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", > }; > > -- > 2.22.0.410.gd8fdbe21b5-goog >
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index d29d869abec1..4e95edb1e282 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -31,6 +31,7 @@ #include <linux/ioport.h> #include <linux/memory.h> #include <linux/sched/task.h> +#include <linux/security.h> #include <asm/sections.h> #include "internal.h" @@ -545,6 +546,10 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) static int open_kcore(struct inode *inode, struct file *filp) { + int ret = security_locked_down(LOCKDOWN_KCORE); + + if (ret) + return ret; if (!capable(CAP_SYS_RAWIO)) return -EPERM; diff --git a/include/linux/security.h b/include/linux/security.h index c649cb91e762..3875f6df2ecc 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -95,6 +95,7 @@ enum lockdown_reason { LOCKDOWN_MODULE_PARAMETERS, LOCKDOWN_MMIOTRACE, LOCKDOWN_INTEGRITY_MAX, + LOCKDOWN_KCORE, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index cd86ed9f4d4b..4c9b324dfc55 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", [LOCKDOWN_MMIOTRACE] = "unsafe mmio", [LOCKDOWN_INTEGRITY_MAX] = "integrity", + [LOCKDOWN_KCORE] = "/proc/kcore access", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };