79 lines
2.5 KiB
Diff
79 lines
2.5 KiB
Diff
From: David Howells <dhowells@redhat.com>
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Date: Wed, 8 Nov 2017 15:11:36 +0000
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Subject: [22/29] Lock down module params that specify hardware parameters (eg.
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ioport)
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Origin: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit?id=d20a28efda02a7ce70b943c15246ea2f07e780f4
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Provided an annotation for module parameters that specify hardware
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parameters (such as io ports, iomem addresses, irqs, dma channels, fixed
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dma buffers and other types).
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Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
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Signed-off-by: David Howells <dhowells@redhat.com>
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---
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kernel/params.c | 26 +++++++++++++++++++++-----
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1 file changed, 21 insertions(+), 5 deletions(-)
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--- a/kernel/params.c
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+++ b/kernel/params.c
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@@ -108,13 +108,19 @@ bool parameq(const char *a, const char *
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return parameqn(a, b, strlen(a)+1);
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}
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-static void param_check_unsafe(const struct kernel_param *kp)
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+static bool param_check_unsafe(const struct kernel_param *kp,
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+ const char *doing)
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{
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if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
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pr_notice("Setting dangerous option %s - tainting kernel\n",
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kp->name);
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add_taint(TAINT_USER, LOCKDEP_STILL_OK);
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}
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+
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+ if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
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+ kernel_is_locked_down("Command line-specified device addresses, irqs and dma channels"))
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+ return false;
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+ return true;
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}
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static int parse_one(char *param,
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@@ -144,8 +150,10 @@ static int parse_one(char *param,
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pr_debug("handling %s with %p\n", param,
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params[i].ops->set);
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kernel_param_lock(params[i].mod);
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- param_check_unsafe(¶ms[i]);
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- err = params[i].ops->set(val, ¶ms[i]);
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+ if (param_check_unsafe(¶ms[i], doing))
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+ err = params[i].ops->set(val, ¶ms[i]);
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+ else
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+ err = -EPERM;
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kernel_param_unlock(params[i].mod);
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return err;
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}
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@@ -553,6 +561,12 @@ static ssize_t param_attr_show(struct mo
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return count;
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}
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+#ifdef CONFIG_MODULES
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+#define mod_name(mod) (mod)->name
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+#else
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+#define mod_name(mod) "unknown"
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+#endif
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+
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/* sysfs always hands a nul-terminated string in buf. We rely on that. */
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static ssize_t param_attr_store(struct module_attribute *mattr,
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struct module_kobject *mk,
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@@ -565,8 +579,10 @@ static ssize_t param_attr_store(struct m
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return -EPERM;
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kernel_param_lock(mk->mod);
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- param_check_unsafe(attribute->param);
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- err = attribute->param->ops->set(buf, attribute->param);
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+ if (param_check_unsafe(attribute->param, mod_name(mk->mod)))
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+ err = attribute->param->ops->set(buf, attribute->param);
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+ else
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+ err = -EPERM;
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kernel_param_unlock(mk->mod);
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if (!err)
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return len;
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