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Date: Fri, 13 Mar 2015 11:38:21 -1000 From: Matthew Garrett <matthew.garrett@...ula.com> To: linux-security-module@...r.kernel.org Cc: james.l.morris@...cle.com, serge@...lyn.com, linux-kernel@...r.kernel.org, keescook@...omium.org, hpa@...or.com, gnomes@...rguk.ukuu.org.uk, Matthew Garrett <matthew.garrett@...ula.com> Subject: [PATCH 05/12] Restrict /dev/mem and /dev/kmem when trusted_kernel is true Allowing users to write to address space provides mechanisms that may permit modification of the kernel at runtime. Prevent this if trusted_kernel is true. Signed-off-by: Matthew Garrett <matthew.garrett@...ula.com> --- drivers/char/mem.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 74227cd..91e7409 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -164,6 +164,9 @@ static ssize_t write_mem(struct file *file, const char __user *buf, unsigned long copied; void *ptr; + if (get_trusted_kernel()) + return -EPERM; + if (p != *ppos) return -EFBIG; @@ -513,6 +516,9 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; + if (get_trusted_kernel()) + return -EPERM; + if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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