Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755677AbaF3KbS (ORCPT ); Mon, 30 Jun 2014 06:31:18 -0400 Received: from mail-we0-f202.google.com ([74.125.82.202]:35657 "EHLO mail-we0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755179AbaF3K2q (ORCPT ); Mon, 30 Jun 2014 06:28:46 -0400 From: David Drysdale To: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman Cc: Alexander Viro , Meredydd Luff , Kees Cook , James Morris , linux-api@vger.kernel.org, David Drysdale Subject: [PATCH 09/11] capsicum: implementations of new LSM hooks Date: Mon, 30 Jun 2014 11:28:09 +0100 Message-Id: <1404124096-21445-10-git-send-email-drysdale@google.com> X-Mailer: git-send-email 2.0.0.526.g5318336 In-Reply-To: <1404124096-21445-1-git-send-email-drysdale@google.com> References: <1404124096-21445-1-git-send-email-drysdale@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the LSM does not provide implementations of the .file_lookup and .file_install LSM hooks, always use the Capsicum implementations. The Capsicum implementation of file_lookup checks for a Capsicum capability wrapper file and unwraps to if the appropriate rights are available. The Capsicum implementation of file_install checks whether the file has restricted rights associated with it. If it does, it is replaced with a Capsicum capability wrapper file before installation into the fdtable. Signed-off-by: David Drysdale --- include/linux/capsicum.h | 7 ++ include/uapi/asm-generic/errno.h | 3 + security/Makefile | 2 +- security/capability.c | 17 ++- security/capsicum.c | 257 +++++++++++++++++++++++++++++++++++++++ 5 files changed, 283 insertions(+), 3 deletions(-) create mode 100644 security/capsicum.c diff --git a/include/linux/capsicum.h b/include/linux/capsicum.h index 74f79756097a..a3e7540f15e7 100644 --- a/include/linux/capsicum.h +++ b/include/linux/capsicum.h @@ -13,6 +13,13 @@ struct capsicum_rights { unsigned int *ioctls; }; +/* LSM hook fallback functions */ +struct file *capsicum_file_lookup(struct file *file, + const struct capsicum_rights *required_rights, + const struct capsicum_rights **actual_rights); +struct file *capsicum_file_install(const struct capsicum_rights *base_rights, + struct file *file); + #define CAP_LIST_END 0ULL #ifdef CONFIG_SECURITY_CAPSICUM diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/errno.h index 1e1ea6e6e7a5..550570ed7b9f 100644 --- a/include/uapi/asm-generic/errno.h +++ b/include/uapi/asm-generic/errno.h @@ -110,4 +110,7 @@ #define EHWPOISON 133 /* Memory page has hardware error */ +#define ECAPMODE 134 /* Not permitted in capability mode */ +#define ENOTCAPABLE 135 /* Capability FD rights insufficient */ + #endif diff --git a/security/Makefile b/security/Makefile index c5e1363ae136..e46d014a74b3 100644 --- a/security/Makefile +++ b/security/Makefile @@ -14,7 +14,7 @@ obj-y += commoncap.o obj-$(CONFIG_MMU) += min_addr.o # Object file lists -obj-$(CONFIG_SECURITY) += security.o capability.o capsicum-rights.o +obj-$(CONFIG_SECURITY) += security.o capability.o capsicum.o capsicum-rights.o obj-$(CONFIG_SECURITYFS) += inode.o obj-$(CONFIG_SECURITY_SELINUX) += selinux/ obj-$(CONFIG_SECURITY_SMACK) += smack/ diff --git a/security/capability.c b/security/capability.c index ad0d4de69944..11d5a1bd6e57 100644 --- a/security/capability.c +++ b/security/capability.c @@ -11,6 +11,7 @@ */ #include +#include static int cap_syslog(int type) { @@ -917,9 +918,19 @@ static void cap_audit_rule_free(void *lsmrule) #define set_to_cap_if_null(ops, function) \ do { \ if (!ops->function) { \ - ops->function = cap_##function; \ + ops->function = cap_##function; \ pr_debug("Had to override the " #function \ - " security operation with the default.\n");\ + " security operation with the default "\ + "cap_" #function ".\n"); \ + } \ + } while (0) +#define set_to_capsicum_if_null(ops, function) \ + do { \ + if (!ops->function) { \ + ops->function = capsicum_##function; \ + pr_debug("Had to override the " #function \ + " security operation with the default "\ + "capsicum_" #function ".\n"); \ } \ } while (0) @@ -1007,6 +1018,8 @@ void __init security_fixup_ops(struct security_operations *ops) set_to_cap_if_null(ops, file_send_sigiotask); set_to_cap_if_null(ops, file_receive); set_to_cap_if_null(ops, file_open); + set_to_capsicum_if_null(ops, file_lookup); + set_to_capsicum_if_null(ops, file_install); set_to_cap_if_null(ops, task_create); set_to_cap_if_null(ops, task_free); set_to_cap_if_null(ops, cred_alloc_blank); diff --git a/security/capsicum.c b/security/capsicum.c new file mode 100644 index 000000000000..83677eef3fb6 --- /dev/null +++ b/security/capsicum.c @@ -0,0 +1,257 @@ +/* + * Main implementation of Capsicum, a capability framework for UNIX. + * + * Copyright (C) 2012-2013 The Chromium OS Authors + * + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2, as + * published by the Free Software Foundation. + * + * See Documentation/security/capsicum.txt for information on Capsicum. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "capsicum-rights.h" + +#ifdef CONFIG_SECURITY_CAPSICUM +/* + * Capsicum capability structure, holding the associated rights and underlying + * real file. Capabilities are not stacked, i.e. underlying always points to a + * normal file not another Capsicum capability. Accessed via file->private_data. + */ +struct capsicum_capability { + struct capsicum_rights rights; + struct file *underlying; +}; + +static void capsicum_panic_not_unwrapped(void); +static int capsicum_release(struct inode *i, struct file *capf); +static int capsicum_show_fdinfo(struct seq_file *m, struct file *capf); + +#define panic_ptr ((void *)&capsicum_panic_not_unwrapped) +static const struct file_operations capsicum_file_ops = { + .owner = NULL, + .llseek = panic_ptr, + .read = panic_ptr, + .write = panic_ptr, + .aio_read = panic_ptr, + .aio_write = panic_ptr, + .iterate = panic_ptr, + .poll = panic_ptr, + .unlocked_ioctl = panic_ptr, + .compat_ioctl = panic_ptr, + .mmap = panic_ptr, + .open = panic_ptr, + .flush = NULL, /* This is called on close if implemented. */ + .release = capsicum_release, /* This is the only one we want. */ + .fsync = panic_ptr, + .aio_fsync = panic_ptr, + .fasync = panic_ptr, + .lock = panic_ptr, + .sendpage = panic_ptr, + .get_unmapped_area = panic_ptr, + .check_flags = panic_ptr, + .flock = panic_ptr, + .splice_write = panic_ptr, + .splice_read = panic_ptr, + .setlease = panic_ptr, + .fallocate = panic_ptr, + .show_fdinfo = capsicum_show_fdinfo +}; + +static inline bool capsicum_is_cap(const struct file *file) +{ + return file->f_op == &capsicum_file_ops; +} + +static struct capsicum_rights all_rights = { + .primary = {.cr_rights = {CAP_ALL0, CAP_ALL1} }, + .fcntls = CAP_FCNTL_ALL, + .nioctls = -1, + .ioctls = NULL +}; + +static struct file *capsicum_cap_alloc(const struct capsicum_rights *rights, + bool take_ioctls) +{ + int err; + struct file *capf; + /* memory to be freed on error exit: */ + struct capsicum_capability *cap = NULL; + unsigned int *ioctls = (take_ioctls ? rights->ioctls : NULL); + + BUG_ON((rights->nioctls > 0) != (rights->ioctls != NULL)); + + cap = kmalloc(sizeof(*cap), GFP_KERNEL); + if (!cap) { + err = -ENOMEM; + goto out_err; + } + cap->underlying = NULL; + cap->rights = *rights; + if (!take_ioctls && rights->nioctls > 0) { + cap->rights.ioctls = kmemdup(rights->ioctls, + rights->nioctls * sizeof(unsigned int), + GFP_KERNEL); + if (!cap->rights.ioctls) { + err = -ENOMEM; + goto out_err; + } + ioctls = cap->rights.ioctls; + } + + capf = anon_inode_getfile("[capability]", &capsicum_file_ops, cap, 0); + if (IS_ERR(capf)) { + err = PTR_ERR(capf); + goto out_err; + } + return capf; + +out_err: + kfree(ioctls); + kfree(cap); + return ERR_PTR(err); +} + +/* + * File operations functions. + */ + +/* + * When we release a Capsicum capability, release our reference to the + * underlying (wrapped) file as well. + */ +static int capsicum_release(struct inode *i, struct file *capf) +{ + struct capsicum_capability *cap; + + if (!capsicum_is_cap(capf)) + return -EINVAL; + + cap = capf->private_data; + BUG_ON(!cap); + if (cap->underlying) + fput(cap->underlying); + cap->underlying = NULL; + kfree(cap->rights.ioctls); + kfree(cap); + return 0; +} + +static int capsicum_show_fdinfo(struct seq_file *m, struct file *capf) +{ + int i; + struct capsicum_capability *cap; + + if (!capsicum_is_cap(capf)) + return -EINVAL; + + cap = capf->private_data; + BUG_ON(!cap); + seq_puts(m, "rights:"); + for (i = 0; i < (CAP_RIGHTS_VERSION + 2); i++) + seq_printf(m, "\t%#016llx", cap->rights.primary.cr_rights[i]); + seq_puts(m, "\n"); + seq_printf(m, " fcntls: %#08x\n", cap->rights.fcntls); + if (cap->rights.nioctls > 0) { + seq_puts(m, " ioctls:"); + for (i = 0; i < cap->rights.nioctls; i++) + seq_printf(m, "\t%#08x", cap->rights.ioctls[i]); + seq_puts(m, "\n"); + } + return 0; +} + +static void capsicum_panic_not_unwrapped(void) +{ + /* + * General Capsicum file operations should never be called, because the + * relevant file should always be unwrapped and the underlying real file + * used instead. + */ + panic("Called a file_operations member on a Capsicum wrapper"); +} + +/* + * LSM hook fallback functions. + */ + +/* + * We are looking up a file by its file descriptor. If it is a Capsicum + * capability, and has the required rights, we unwrap it and return the + * underlying file. + */ +struct file *capsicum_file_lookup(struct file *file, + const struct capsicum_rights *required_rights, + const struct capsicum_rights **actual_rights) +{ + struct capsicum_capability *cap; + + /* See if the file in question is a Capsicum capability. */ + if (!capsicum_is_cap(file)) { + if (actual_rights) + *actual_rights = &all_rights; + return file; + } + cap = file->private_data; + if (required_rights && + !cap_rights_contains(&cap->rights, required_rights)) { + return ERR_PTR(-ENOTCAPABLE); + } + if (actual_rights) + *actual_rights = &cap->rights; + return cap->underlying; +} +EXPORT_SYMBOL(capsicum_file_lookup); + +struct file *capsicum_file_install(const struct capsicum_rights *base_rights, + struct file *file) +{ + struct file *capf; + struct capsicum_capability *cap; + if (!base_rights || cap_rights_is_all(base_rights)) + return file; + + capf = capsicum_cap_alloc(base_rights, false); + if (IS_ERR(capf)) + return capf; + + if (!atomic_long_inc_not_zero(&file->f_count)) { + fput(capf); + return ERR_PTR(-EBADF); + } + cap = capf->private_data; + cap->underlying = file; + return capf; +} +EXPORT_SYMBOL(capsicum_file_install); + +#else + +struct file *capsicum_file_lookup(struct file *file, + const struct capsicum_rights *required_rights, + const struct capsicum_rights **actual_rights) +{ + return file; +} + +struct file * +capsicum_file_install(const const struct capsicum_rights *base_rights, + struct file *file) +{ + return file; +} + +#endif -- 2.0.0.526.g5318336 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/