Commit 855b7717 authored by Kanchan Joshi's avatar Kanchan Joshi Committed by Christoph Hellwig
Browse files

nvme: fine-granular CAP_SYS_ADMIN for nvme io commands 



Currently both io and admin commands are kept under a
coarse-granular CAP_SYS_ADMIN check, disregarding file mode completely.

$ ls -l /dev/ng*
crw-rw-rw- 1 root root 242, 0 Sep  9 19:20 /dev/ng0n1
crw------- 1 root root 242, 1 Sep  9 19:20 /dev/ng0n2

In the example above, ng0n1 appears as if it may allow unprivileged
read/write operation but it does not and behaves same as ng0n2.

This patch implements a shift from CAP_SYS_ADMIN to more fine-granular
control for io-commands.
If CAP_SYS_ADMIN is present, nothing else is checked as before.
Otherwise, following rules are in place
- any admin-cmd is not allowed
- vendor-specific and fabric commmand are not allowed
- io-commands that can write are allowed if matching FMODE_WRITE
permission is present
- io-commands that read are allowed

Add a helper nvme_cmd_allowed that implements above policy.
Change all the callers of CAP_SYS_ADMIN to go through nvme_cmd_allowed
for any decision making.
Since file open mode is counted for any approval/denial, change at
various places to keep file-mode information handy.

Signed-off-by: default avatarKanchan Joshi <joshi.k@samsung.com>
Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Reviewed-by: default avatarKeith Busch <kbusch@kernel.org>
Reviewed-by: default avatarChaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent cf3d0084

drivers/nvme/host/ioctl.c

+69 −33
Original line number Diff line number Diff line
@@ -8,6 +8,34 @@ 
#include <linux/io_uring.h>

#include "nvme.h"



static bool nvme_cmd_allowed(struct nvme_ns *ns, struct nvme_command *c,

		fmode_t mode)

{

	if (capable(CAP_SYS_ADMIN))

		return true;



	/*

	 * Do not allow unprivileged processes to send vendor specific or fabrics

	 * commands as we can't be sure about their effects.

	 */

	if (c->common.opcode >= nvme_cmd_vendor_start ||

	    c->common.opcode == nvme_fabrics_command)

		return false;



	/* do not allow unprivileged admin commands */

	if (!ns)

		return false;



	/*

	 * Only allow I/O commands that transfer data to the controller if the

	 * special file is open for writing, but always allow I/O commands that

	 * transfer data from the controller.

	 */

	if (nvme_is_write(c))

		return mode & FMODE_WRITE;

	return true;

}



/*

 * Convert integer values from ioctl structures to user pointers, silently

 * ignoring the upper bits in the compat case to match behaviour of 32-bit
@@ -261,7 +289,7 @@ static bool nvme_validate_passthru_nsid(struct nvme_ctrl *ctrl, 
}



static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns,

			struct nvme_passthru_cmd __user *ucmd)

			struct nvme_passthru_cmd __user *ucmd, fmode_t mode)

{

	struct nvme_passthru_cmd cmd;

	struct nvme_command c;
@@ -269,8 +297,6 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns, 
	u64 result;

	int status;



	if (!capable(CAP_SYS_ADMIN))

		return -EACCES;

	if (copy_from_user(&cmd, ucmd, sizeof(cmd)))

		return -EFAULT;

	if (cmd.flags)
@@ -291,6 +317,9 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns, 
	c.common.cdw14 = cpu_to_le32(cmd.cdw14);

	c.common.cdw15 = cpu_to_le32(cmd.cdw15);



	if (!nvme_cmd_allowed(ns, &c, mode))

		return -EACCES;



	if (cmd.timeout_ms)

		timeout = msecs_to_jiffies(cmd.timeout_ms);
@@ -308,15 +337,14 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns, 
}



static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns,

			struct nvme_passthru_cmd64 __user *ucmd, bool vec)

			struct nvme_passthru_cmd64 __user *ucmd, bool vec,

			fmode_t mode)

{

	struct nvme_passthru_cmd64 cmd;

	struct nvme_command c;

	unsigned timeout = 0;

	int status;



	if (!capable(CAP_SYS_ADMIN))

		return -EACCES;

	if (copy_from_user(&cmd, ucmd, sizeof(cmd)))

		return -EFAULT;

	if (cmd.flags)
@@ -337,6 +365,9 @@ static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns, 
	c.common.cdw14 = cpu_to_le32(cmd.cdw14);

	c.common.cdw15 = cpu_to_le32(cmd.cdw15);



	if (!nvme_cmd_allowed(ns, &c, mode))

		return -EACCES;



	if (cmd.timeout_ms)

		timeout = msecs_to_jiffies(cmd.timeout_ms);
@@ -483,9 +514,6 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns, 
	void *meta = NULL;

	int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EACCES;



	c.common.opcode = READ_ONCE(cmd->opcode);

	c.common.flags = READ_ONCE(cmd->flags);

	if (c.common.flags)
@@ -507,6 +535,9 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns, 
	c.common.cdw14 = cpu_to_le32(READ_ONCE(cmd->cdw14));

	c.common.cdw15 = cpu_to_le32(READ_ONCE(cmd->cdw15));



	if (!nvme_cmd_allowed(ns, &c, ioucmd->file->f_mode))

		return -EACCES;



	d.metadata = READ_ONCE(cmd->metadata);

	d.addr = READ_ONCE(cmd->addr);

	d.data_len = READ_ONCE(cmd->data_len);
@@ -570,13 +601,13 @@ static bool is_ctrl_ioctl(unsigned int cmd) 
}



static int nvme_ctrl_ioctl(struct nvme_ctrl *ctrl, unsigned int cmd,

		void __user *argp)

		void __user *argp, fmode_t mode)

{

	switch (cmd) {

	case NVME_IOCTL_ADMIN_CMD:

		return nvme_user_cmd(ctrl, NULL, argp);

		return nvme_user_cmd(ctrl, NULL, argp, mode);

	case NVME_IOCTL_ADMIN64_CMD:

		return nvme_user_cmd64(ctrl, NULL, argp, false);

		return nvme_user_cmd64(ctrl, NULL, argp, false, mode);

	default:

		return sed_ioctl(ctrl->opal_dev, cmd, argp);

	}
@@ -601,14 +632,14 @@ struct nvme_user_io32 { 
#endif /* COMPAT_FOR_U64_ALIGNMENT */



static int nvme_ns_ioctl(struct nvme_ns *ns, unsigned int cmd,

		void __user *argp)

		void __user *argp, fmode_t mode)

{

	switch (cmd) {

	case NVME_IOCTL_ID:

		force_successful_syscall_return();

		return ns->head->ns_id;

	case NVME_IOCTL_IO_CMD:

		return nvme_user_cmd(ns->ctrl, ns, argp);

		return nvme_user_cmd(ns->ctrl, ns, argp, mode);

	/*

	 * struct nvme_user_io can have different padding on some 32-bit ABIs.

	 * Just accept the compat version as all fields that are used are the
@@ -620,19 +651,20 @@ static int nvme_ns_ioctl(struct nvme_ns *ns, unsigned int cmd, 
	case NVME_IOCTL_SUBMIT_IO:

		return nvme_submit_io(ns, argp);

	case NVME_IOCTL_IO64_CMD:

		return nvme_user_cmd64(ns->ctrl, ns, argp, false);

		return nvme_user_cmd64(ns->ctrl, ns, argp, false, mode);

	case NVME_IOCTL_IO64_CMD_VEC:

		return nvme_user_cmd64(ns->ctrl, ns, argp, true);

		return nvme_user_cmd64(ns->ctrl, ns, argp, true, mode);

	default:

		return -ENOTTY;

	}

}



static int __nvme_ioctl(struct nvme_ns *ns, unsigned int cmd, void __user *arg)

static int __nvme_ioctl(struct nvme_ns *ns, unsigned int cmd, void __user *arg,

			fmode_t mode)

{

	if (is_ctrl_ioctl(cmd))

               return nvme_ctrl_ioctl(ns->ctrl, cmd, arg);

       return nvme_ns_ioctl(ns, cmd, arg);

		return nvme_ctrl_ioctl(ns->ctrl, cmd, arg, mode);

	return nvme_ns_ioctl(ns, cmd, arg, mode);

}



int nvme_ioctl(struct block_device *bdev, fmode_t mode,
@@ -640,7 +672,7 @@ int nvme_ioctl(struct block_device *bdev, fmode_t mode, 
{

	struct nvme_ns *ns = bdev->bd_disk->private_data;



	return __nvme_ioctl(ns, cmd, (void __user *)arg);

	return __nvme_ioctl(ns, cmd, (void __user *)arg, mode);

}



long nvme_ns_chr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
@@ -648,7 +680,7 @@ long nvme_ns_chr_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
	struct nvme_ns *ns =

		container_of(file_inode(file)->i_cdev, struct nvme_ns, cdev);



	return __nvme_ioctl(ns, cmd, (void __user *)arg);

	return __nvme_ioctl(ns, cmd, (void __user *)arg, file->f_mode);

}



static int nvme_uring_cmd_checks(unsigned int issue_flags)
@@ -716,7 +748,8 @@ int nvme_ns_chr_uring_cmd_iopoll(struct io_uring_cmd *ioucmd, 
}

#ifdef CONFIG_NVME_MULTIPATH

static int nvme_ns_head_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,

		void __user *argp, struct nvme_ns_head *head, int srcu_idx)

		void __user *argp, struct nvme_ns_head *head, int srcu_idx,

		fmode_t mode)

	__releases(&head->srcu)

{

	struct nvme_ctrl *ctrl = ns->ctrl;
@@ -724,7 +757,7 @@ static int nvme_ns_head_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd, 


	nvme_get_ctrl(ns->ctrl);

	srcu_read_unlock(&head->srcu, srcu_idx);

	ret = nvme_ctrl_ioctl(ns->ctrl, cmd, argp);

	ret = nvme_ctrl_ioctl(ns->ctrl, cmd, argp, mode);



	nvme_put_ctrl(ctrl);

	return ret;
@@ -749,9 +782,10 @@ int nvme_ns_head_ioctl(struct block_device *bdev, fmode_t mode, 
	 * deadlock when deleting namespaces using the passthrough interface.

	 */

	if (is_ctrl_ioctl(cmd))

		return nvme_ns_head_ctrl_ioctl(ns, cmd, argp, head, srcu_idx);

		return nvme_ns_head_ctrl_ioctl(ns, cmd, argp, head, srcu_idx,

					mode);



	ret = nvme_ns_ioctl(ns, cmd, argp);

	ret = nvme_ns_ioctl(ns, cmd, argp, mode);

out_unlock:

	srcu_read_unlock(&head->srcu, srcu_idx);

	return ret;
@@ -773,9 +807,10 @@ long nvme_ns_head_chr_ioctl(struct file *file, unsigned int cmd, 
		goto out_unlock;



	if (is_ctrl_ioctl(cmd))

		return nvme_ns_head_ctrl_ioctl(ns, cmd, argp, head, srcu_idx);

		return nvme_ns_head_ctrl_ioctl(ns, cmd, argp, head, srcu_idx,

				file->f_mode);



	ret = nvme_ns_ioctl(ns, cmd, argp);

	ret = nvme_ns_ioctl(ns, cmd, argp, file->f_mode);

out_unlock:

	srcu_read_unlock(&head->srcu, srcu_idx);

	return ret;
@@ -849,7 +884,8 @@ int nvme_dev_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags) 
	return ret;

}



static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp)

static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp,

		fmode_t mode)

{

	struct nvme_ns *ns;

	int ret;
@@ -873,7 +909,7 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp) 
	kref_get(&ns->kref);

	up_read(&ctrl->namespaces_rwsem);



	ret = nvme_user_cmd(ctrl, ns, argp);

	ret = nvme_user_cmd(ctrl, ns, argp, mode);

	nvme_put_ns(ns);

	return ret;
@@ -890,11 +926,11 @@ long nvme_dev_ioctl(struct file *file, unsigned int cmd, 


	switch (cmd) {

	case NVME_IOCTL_ADMIN_CMD:

		return nvme_user_cmd(ctrl, NULL, argp);

		return nvme_user_cmd(ctrl, NULL, argp, file->f_mode);

	case NVME_IOCTL_ADMIN64_CMD:

		return nvme_user_cmd64(ctrl, NULL, argp, false);

		return nvme_user_cmd64(ctrl, NULL, argp, false, file->f_mode);

	case NVME_IOCTL_IO_CMD:

		return nvme_dev_user_cmd(ctrl, argp);

		return nvme_dev_user_cmd(ctrl, argp, file->f_mode);

	case NVME_IOCTL_RESET:

		if (!capable(CAP_SYS_ADMIN))

			return -EACCES;

include/linux/nvme.h

+1 −0
Original line number Diff line number Diff line
@@ -797,6 +797,7 @@ enum nvme_opcode { 
	nvme_cmd_zone_mgmt_send	= 0x79,

	nvme_cmd_zone_mgmt_recv	= 0x7a,

	nvme_cmd_zone_append	= 0x7d,

	nvme_cmd_vendor_start	= 0x80,

};



#define nvme_opcode_name(opcode)	{ opcode, #opcode }