linux-stable/include/linux/lsm_hook_defs.h

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Linux Security Module Hook declarations.
*
* Copyright (C) 2001 WireX Communications, Inc <chris@wirex.com>
* Copyright (C) 2001 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2001 Networks Associates Technology, Inc <ssmalley@nai.com>
* Copyright (C) 2001 James Morris <jmorris@intercode.com.au>
* Copyright (C) 2001 Silicon Graphics, Inc. (Trust Technology Group)
* Copyright (C) 2015 Intel Corporation.
* Copyright (C) 2015 Casey Schaufler <casey@schaufler-ca.com>
* Copyright (C) 2016 Mellanox Techonologies
* Copyright (C) 2020 Google LLC.
*/
/*
* The macro LSM_HOOK is used to define the data structures required by
* the LSM framework using the pattern:
*
* LSM_HOOK(<return_type>, <default_value>, <hook_name>, args...)
*
* struct security_hook_heads {
* #define LSM_HOOK(RET, DEFAULT, NAME, ...) struct hlist_head NAME;
* #include <linux/lsm_hook_defs.h>
* #undef LSM_HOOK
* };
*/
LSM_HOOK(int, 0, binder_set_context_mgr, const struct cred *mgr)
LSM_HOOK(int, 0, binder_transaction, const struct cred *from,
const struct cred *to)
LSM_HOOK(int, 0, binder_transfer_binder, const struct cred *from,
const struct cred *to)
LSM_HOOK(int, 0, binder_transfer_file, const struct cred *from,
const struct cred *to, struct file *file)
LSM_HOOK(int, 0, ptrace_access_check, struct task_struct *child,
unsigned int mode)
LSM_HOOK(int, 0, ptrace_traceme, struct task_struct *parent)
LSM_HOOK(int, 0, capget, struct task_struct *target, kernel_cap_t *effective,
kernel_cap_t *inheritable, kernel_cap_t *permitted)
LSM_HOOK(int, 0, capset, struct cred *new, const struct cred *old,
const kernel_cap_t *effective, const kernel_cap_t *inheritable,
const kernel_cap_t *permitted)
LSM_HOOK(int, 0, capable, const struct cred *cred, struct user_namespace *ns,
int cap, unsigned int opts)
LSM_HOOK(int, 0, quotactl, int cmds, int type, int id, struct super_block *sb)
LSM_HOOK(int, 0, quota_on, struct dentry *dentry)
LSM_HOOK(int, 0, syslog, int type)
LSM_HOOK(int, 0, settime, const struct timespec64 *ts,
const struct timezone *tz)
LSM_HOOK(int, 0, vm_enough_memory, struct mm_struct *mm, long pages)
LSM_HOOK(int, 0, bprm_creds_for_exec, struct linux_binprm *bprm)
exec: Compute file based creds only once Move the computation of creds from prepare_binfmt into begin_new_exec so that the creds need only be computed once. This is just code reorganization no semantic changes of any kind are made. Moving the computation is safe. I have looked through the kernel and verified none of the binfmts look at bprm->cred directly, and that there are no helpers that look at bprm->cred indirectly. Which means that it is not a problem to compute the bprm->cred later in the execution flow as it is not used until it becomes current->cred. A new function bprm_creds_from_file is added to contain the work that needs to be done. bprm_creds_from_file first computes which file bprm->executable or most likely bprm->file that the bprm->creds will be computed from. The funciton bprm_fill_uid is updated to receive the file instead of accessing bprm->file. The now unnecessary work needed to reset the bprm->cred->euid, and bprm->cred->egid is removed from brpm_fill_uid. A small comment to document that bprm_fill_uid now only deals with the work to handle suid and sgid files. The default case is already heandled by prepare_exec_creds. The function security_bprm_repopulate_creds is renamed security_bprm_creds_from_file and now is explicitly passed the file from which to compute the creds. The documentation of the bprm_creds_from_file security hook is updated to explain when the hook is called and what it needs to do. The file is passed from cap_bprm_creds_from_file into get_file_caps so that the caps are computed for the appropriate file. The now unnecessary work in cap_bprm_creds_from_file to reset the ambient capabilites has been removed. A small comment to document that the work of cap_bprm_creds_from_file is to read capabilities from the files secureity attribute and derive capabilities from the fact the user had uid 0 has been added. Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2020-05-30 03:00:54 +00:00
LSM_HOOK(int, 0, bprm_creds_from_file, struct linux_binprm *bprm, struct file *file)
LSM_HOOK(int, 0, bprm_check_security, struct linux_binprm *bprm)
LSM_HOOK(void, LSM_RET_VOID, bprm_committing_creds, struct linux_binprm *bprm)
LSM_HOOK(void, LSM_RET_VOID, bprm_committed_creds, struct linux_binprm *bprm)
LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc,
struct fs_context *src_sc)
LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc,
struct fs_parameter *param)
LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_delete, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
LSM_HOOK(int, 0, sb_mnt_opts_compat, struct super_block *sb, void *mnt_opts)
LSM_HOOK(int, 0, sb_remount, struct super_block *sb, void *mnt_opts)
LSM_HOOK(int, 0, sb_kern_mount, struct super_block *sb)
LSM_HOOK(int, 0, sb_show_options, struct seq_file *m, struct super_block *sb)
LSM_HOOK(int, 0, sb_statfs, struct dentry *dentry)
LSM_HOOK(int, 0, sb_mount, const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data)
LSM_HOOK(int, 0, sb_umount, struct vfsmount *mnt, int flags)
LSM_HOOK(int, 0, sb_pivotroot, const struct path *old_path,
const struct path *new_path)
LSM_HOOK(int, 0, sb_set_mnt_opts, struct super_block *sb, void *mnt_opts,
unsigned long kern_flags, unsigned long *set_kern_flags)
LSM_HOOK(int, 0, sb_clone_mnt_opts, const struct super_block *oldsb,
struct super_block *newsb, unsigned long kern_flags,
unsigned long *set_kern_flags)
LSM_HOOK(int, 0, move_mount, const struct path *from_path,
const struct path *to_path)
security, lsm: dentry_init_security() Handle multi LSM registration A ceph user has reported that ceph is crashing with kernel NULL pointer dereference. Following is the backtrace. /proc/version: Linux version 5.16.2-arch1-1 (linux@archlinux) (gcc (GCC) 11.1.0, GNU ld (GNU Binutils) 2.36.1) #1 SMP PREEMPT Thu, 20 Jan 2022 16:18:29 +0000 distro / arch: Arch Linux / x86_64 SELinux is not enabled ceph cluster version: 16.2.7 (dd0603118f56ab514f133c8d2e3adfc983942503) relevant dmesg output: [ 30.947129] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 30.947206] #PF: supervisor read access in kernel mode [ 30.947258] #PF: error_code(0x0000) - not-present page [ 30.947310] PGD 0 P4D 0 [ 30.947342] Oops: 0000 [#1] PREEMPT SMP PTI [ 30.947388] CPU: 5 PID: 778 Comm: touch Not tainted 5.16.2-arch1-1 #1 86fbf2c313cc37a553d65deb81d98e9dcc2a3659 [ 30.947486] Hardware name: Gigabyte Technology Co., Ltd. B365M DS3H/B365M DS3H, BIOS F5 08/13/2019 [ 30.947569] RIP: 0010:strlen+0x0/0x20 [ 30.947616] Code: b6 07 38 d0 74 16 48 83 c7 01 84 c0 74 05 48 39 f7 75 ec 31 c0 31 d2 89 d6 89 d7 c3 48 89 f8 31 d2 89 d6 89 d7 c3 0 f 1f 40 00 <80> 3f 00 74 12 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 31 ff [ 30.947782] RSP: 0018:ffffa4ed80ffbbb8 EFLAGS: 00010246 [ 30.947836] RAX: 0000000000000000 RBX: ffffa4ed80ffbc60 RCX: 0000000000000000 [ 30.947904] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 30.947971] RBP: ffff94b0d15c0ae0 R08: 0000000000000000 R09: 0000000000000000 [ 30.948040] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 30.948106] R13: 0000000000000001 R14: ffffa4ed80ffbc60 R15: 0000000000000000 [ 30.948174] FS: 00007fc7520f0740(0000) GS:ffff94b7ced40000(0000) knlGS:0000000000000000 [ 30.948252] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.948308] CR2: 0000000000000000 CR3: 0000000104a40001 CR4: 00000000003706e0 [ 30.948376] Call Trace: [ 30.948404] <TASK> [ 30.948431] ceph_security_init_secctx+0x7b/0x240 [ceph 49f9c4b9bf5be8760f19f1747e26da33920bce4b] [ 30.948582] ceph_atomic_open+0x51e/0x8a0 [ceph 49f9c4b9bf5be8760f19f1747e26da33920bce4b] [ 30.948708] ? get_cached_acl+0x4d/0xa0 [ 30.948759] path_openat+0x60d/0x1030 [ 30.948809] do_filp_open+0xa5/0x150 [ 30.948859] do_sys_openat2+0xc4/0x190 [ 30.948904] __x64_sys_openat+0x53/0xa0 [ 30.948948] do_syscall_64+0x5c/0x90 [ 30.948989] ? exc_page_fault+0x72/0x180 [ 30.949034] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 30.949091] RIP: 0033:0x7fc7521e25bb [ 30.950849] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18 00 00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 0 0 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 54 24 28 64 48 2b 14 25 Core of the problem is that ceph checks for return code from security_dentry_init_security() and if return code is 0, it assumes everything is fine and continues to call strlen(name), which crashes. Typically SELinux LSM returns 0 and sets name to "security.selinux" and it is not a problem. Or if selinux is not compiled in or disabled, it returns -EOPNOTSUP and ceph deals with it. But somehow in this configuration, 0 is being returned and "name" is not being initialized and that's creating the problem. Our suspicion is that BPF LSM is registering a hook for dentry_init_security() and returns hook default of 0. LSM_HOOK(int, 0, dentry_init_security, struct dentry *dentry,...) I have not been able to reproduce it just by doing CONFIG_BPF_LSM=y. Stephen has tested the patch though and confirms it solves the problem for him. dentry_init_security() is written in such a way that it expects only one LSM to register the hook. Atleast that's the expectation with current code. If another LSM returns a hook and returns default, it will simply return 0 as of now and that will break ceph. Hence, suggestion is that change semantics of this hook a bit. If there are no LSMs or no LSM is taking ownership and initializing security context, then return -EOPNOTSUP. Also allow at max one LSM to initialize security context. This hook can't deal with multiple LSMs trying to init security context. This patch implements this new behavior. Reported-by: Stephen Muth <smuth4@gmail.com> Tested-by: Stephen Muth <smuth4@gmail.com> Suggested-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Reviewed-by: Serge Hallyn <serge@hallyn.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Paul Moore <paul@paul-moore.com> Cc: <stable@vger.kernel.org> # 5.16.0 Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
2022-01-26 20:35:14 +00:00
LSM_HOOK(int, -EOPNOTSUPP, dentry_init_security, struct dentry *dentry,
int mode, const struct qstr *name, const char **xattr_name,
void **ctx, u32 *ctxlen)
LSM_HOOK(int, 0, dentry_create_files_as, struct dentry *dentry, int mode,
struct qstr *name, const struct cred *old, struct cred *new)
#ifdef CONFIG_SECURITY_PATH
LSM_HOOK(int, 0, path_unlink, const struct path *dir, struct dentry *dentry)
LSM_HOOK(int, 0, path_mkdir, const struct path *dir, struct dentry *dentry,
umode_t mode)
LSM_HOOK(int, 0, path_rmdir, const struct path *dir, struct dentry *dentry)
LSM_HOOK(int, 0, path_mknod, const struct path *dir, struct dentry *dentry,
umode_t mode, unsigned int dev)
LSM_HOOK(int, 0, path_truncate, const struct path *path)
LSM_HOOK(int, 0, path_symlink, const struct path *dir, struct dentry *dentry,
const char *old_name)
LSM_HOOK(int, 0, path_link, struct dentry *old_dentry,
const struct path *new_dir, struct dentry *new_dentry)
LSM_HOOK(int, 0, path_rename, const struct path *old_dir,
struct dentry *old_dentry, const struct path *new_dir,
struct dentry *new_dentry, unsigned int flags)
LSM_HOOK(int, 0, path_chmod, const struct path *path, umode_t mode)
LSM_HOOK(int, 0, path_chown, const struct path *path, kuid_t uid, kgid_t gid)
LSM_HOOK(int, 0, path_chroot, const struct path *path)
#endif /* CONFIG_SECURITY_PATH */
/* Needed for inode based security check */
LSM_HOOK(int, 0, path_notify, const struct path *path, u64 mask,
unsigned int obj_type)
LSM_HOOK(int, 0, inode_alloc_security, struct inode *inode)
LSM_HOOK(void, LSM_RET_VOID, inode_free_security, struct inode *inode)
LSM_HOOK(int, 0, inode_init_security, struct inode *inode,
struct inode *dir, const struct qstr *qstr, const char **name,
void **value, size_t *len)
LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode,
const struct qstr *name, const struct inode *context_inode)
LSM_HOOK(int, 0, inode_create, struct inode *dir, struct dentry *dentry,
umode_t mode)
LSM_HOOK(int, 0, inode_link, struct dentry *old_dentry, struct inode *dir,
struct dentry *new_dentry)
LSM_HOOK(int, 0, inode_unlink, struct inode *dir, struct dentry *dentry)
LSM_HOOK(int, 0, inode_symlink, struct inode *dir, struct dentry *dentry,
const char *old_name)
LSM_HOOK(int, 0, inode_mkdir, struct inode *dir, struct dentry *dentry,
umode_t mode)
LSM_HOOK(int, 0, inode_rmdir, struct inode *dir, struct dentry *dentry)
LSM_HOOK(int, 0, inode_mknod, struct inode *dir, struct dentry *dentry,
umode_t mode, dev_t dev)
LSM_HOOK(int, 0, inode_rename, struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
LSM_HOOK(int, 0, inode_readlink, struct dentry *dentry)
LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode,
bool rcu)
LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask)
LSM_HOOK(int, 0, inode_setattr, struct dentry *dentry, struct iattr *attr)
LSM_HOOK(int, 0, inode_getattr, const struct path *path)
commoncap: handle idmapped mounts When interacting with user namespace and non-user namespace aware filesystem capabilities the vfs will perform various security checks to determine whether or not the filesystem capabilities can be used by the caller, whether they need to be removed and so on. The main infrastructure for this resides in the capability codepaths but they are called through the LSM security infrastructure even though they are not technically an LSM or optional. This extends the existing security hooks security_inode_removexattr(), security_inode_killpriv(), security_inode_getsecurity() to pass down the mount's user namespace and makes them aware of idmapped mounts. In order to actually get filesystem capabilities from disk the capability infrastructure exposes the get_vfs_caps_from_disk() helper. For user namespace aware filesystem capabilities a root uid is stored alongside the capabilities. In order to determine whether the caller can make use of the filesystem capability or whether it needs to be ignored it is translated according to the superblock's user namespace. If it can be translated to uid 0 according to that id mapping the caller can use the filesystem capabilities stored on disk. If we are accessing the inode that holds the filesystem capabilities through an idmapped mount we map the root uid according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts: reading filesystem caps from disk enforces that the root uid associated with the filesystem capability must have a mapping in the superblock's user namespace and that the caller is either in the same user namespace or is a descendant of the superblock's user namespace. For filesystems that are mountable inside user namespace the caller can just mount the filesystem and won't usually need to idmap it. If they do want to idmap it they can create an idmapped mount and mark it with a user namespace they created and which is thus a descendant of s_user_ns. For filesystems that are not mountable inside user namespaces the descendant rule is trivially true because the s_user_ns will be the initial user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-11-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-21 13:19:29 +00:00
LSM_HOOK(int, 0, inode_setxattr, struct user_namespace *mnt_userns,
struct dentry *dentry, const char *name, const void *value,
size_t size, int flags)
LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry,
const char *name, const void *value, size_t size, int flags)
LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
commoncap: handle idmapped mounts When interacting with user namespace and non-user namespace aware filesystem capabilities the vfs will perform various security checks to determine whether or not the filesystem capabilities can be used by the caller, whether they need to be removed and so on. The main infrastructure for this resides in the capability codepaths but they are called through the LSM security infrastructure even though they are not technically an LSM or optional. This extends the existing security hooks security_inode_removexattr(), security_inode_killpriv(), security_inode_getsecurity() to pass down the mount's user namespace and makes them aware of idmapped mounts. In order to actually get filesystem capabilities from disk the capability infrastructure exposes the get_vfs_caps_from_disk() helper. For user namespace aware filesystem capabilities a root uid is stored alongside the capabilities. In order to determine whether the caller can make use of the filesystem capability or whether it needs to be ignored it is translated according to the superblock's user namespace. If it can be translated to uid 0 according to that id mapping the caller can use the filesystem capabilities stored on disk. If we are accessing the inode that holds the filesystem capabilities through an idmapped mount we map the root uid according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts: reading filesystem caps from disk enforces that the root uid associated with the filesystem capability must have a mapping in the superblock's user namespace and that the caller is either in the same user namespace or is a descendant of the superblock's user namespace. For filesystems that are mountable inside user namespace the caller can just mount the filesystem and won't usually need to idmap it. If they do want to idmap it they can create an idmapped mount and mark it with a user namespace they created and which is thus a descendant of s_user_ns. For filesystems that are not mountable inside user namespaces the descendant rule is trivially true because the s_user_ns will be the initial user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-11-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-21 13:19:29 +00:00
LSM_HOOK(int, 0, inode_removexattr, struct user_namespace *mnt_userns,
struct dentry *dentry, const char *name)
LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry)
commoncap: handle idmapped mounts When interacting with user namespace and non-user namespace aware filesystem capabilities the vfs will perform various security checks to determine whether or not the filesystem capabilities can be used by the caller, whether they need to be removed and so on. The main infrastructure for this resides in the capability codepaths but they are called through the LSM security infrastructure even though they are not technically an LSM or optional. This extends the existing security hooks security_inode_removexattr(), security_inode_killpriv(), security_inode_getsecurity() to pass down the mount's user namespace and makes them aware of idmapped mounts. In order to actually get filesystem capabilities from disk the capability infrastructure exposes the get_vfs_caps_from_disk() helper. For user namespace aware filesystem capabilities a root uid is stored alongside the capabilities. In order to determine whether the caller can make use of the filesystem capability or whether it needs to be ignored it is translated according to the superblock's user namespace. If it can be translated to uid 0 according to that id mapping the caller can use the filesystem capabilities stored on disk. If we are accessing the inode that holds the filesystem capabilities through an idmapped mount we map the root uid according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts: reading filesystem caps from disk enforces that the root uid associated with the filesystem capability must have a mapping in the superblock's user namespace and that the caller is either in the same user namespace or is a descendant of the superblock's user namespace. For filesystems that are mountable inside user namespace the caller can just mount the filesystem and won't usually need to idmap it. If they do want to idmap it they can create an idmapped mount and mark it with a user namespace they created and which is thus a descendant of s_user_ns. For filesystems that are not mountable inside user namespaces the descendant rule is trivially true because the s_user_ns will be the initial user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-11-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-21 13:19:29 +00:00
LSM_HOOK(int, 0, inode_killpriv, struct user_namespace *mnt_userns,
struct dentry *dentry)
LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct user_namespace *mnt_userns,
struct inode *inode, const char *name, void **buffer, bool alloc)
LSM_HOOK(int, -EOPNOTSUPP, inode_setsecurity, struct inode *inode,
const char *name, const void *value, size_t size, int flags)
LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer,
size_t buffer_size)
LSM_HOOK(void, LSM_RET_VOID, inode_getsecid, struct inode *inode, u32 *secid)
LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new)
LSM_HOOK(int, -EOPNOTSUPP, inode_copy_up_xattr, const char *name)
LSM_HOOK(int, 0, kernfs_init_security, struct kernfs_node *kn_dir,
struct kernfs_node *kn)
LSM_HOOK(int, 0, file_permission, struct file *file, int mask)
LSM_HOOK(int, 0, file_alloc_security, struct file *file)
LSM_HOOK(void, LSM_RET_VOID, file_free_security, struct file *file)
LSM_HOOK(int, 0, file_ioctl, struct file *file, unsigned int cmd,
unsigned long arg)
LSM_HOOK(int, 0, mmap_addr, unsigned long addr)
LSM_HOOK(int, 0, mmap_file, struct file *file, unsigned long reqprot,
unsigned long prot, unsigned long flags)
LSM_HOOK(int, 0, file_mprotect, struct vm_area_struct *vma,
unsigned long reqprot, unsigned long prot)
LSM_HOOK(int, 0, file_lock, struct file *file, unsigned int cmd)
LSM_HOOK(int, 0, file_fcntl, struct file *file, unsigned int cmd,
unsigned long arg)
LSM_HOOK(void, LSM_RET_VOID, file_set_fowner, struct file *file)
LSM_HOOK(int, 0, file_send_sigiotask, struct task_struct *tsk,
struct fown_struct *fown, int sig)
LSM_HOOK(int, 0, file_receive, struct file *file)
LSM_HOOK(int, 0, file_open, struct file *file)
LSM_HOOK(int, 0, task_alloc, struct task_struct *task,
unsigned long clone_flags)
LSM_HOOK(void, LSM_RET_VOID, task_free, struct task_struct *task)
LSM_HOOK(int, 0, cred_alloc_blank, struct cred *cred, gfp_t gfp)
LSM_HOOK(void, LSM_RET_VOID, cred_free, struct cred *cred)
LSM_HOOK(int, 0, cred_prepare, struct cred *new, const struct cred *old,
gfp_t gfp)
LSM_HOOK(void, LSM_RET_VOID, cred_transfer, struct cred *new,
const struct cred *old)
LSM_HOOK(void, LSM_RET_VOID, cred_getsecid, const struct cred *c, u32 *secid)
LSM_HOOK(int, 0, kernel_act_as, struct cred *new, u32 secid)
LSM_HOOK(int, 0, kernel_create_files_as, struct cred *new, struct inode *inode)
LSM_HOOK(int, 0, kernel_module_request, char *kmod_name)
LSM: Introduce kernel_post_load_data() hook There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-02 17:38:20 +00:00
LSM_HOOK(int, 0, kernel_load_data, enum kernel_load_data_id id, bool contents)
LSM_HOOK(int, 0, kernel_post_load_data, char *buf, loff_t size,
enum kernel_load_data_id id, char *description)
LSM_HOOK(int, 0, kernel_read_file, struct file *file,
enum kernel_read_file_id id, bool contents)
LSM_HOOK(int, 0, kernel_post_read_file, struct file *file, char *buf,
loff_t size, enum kernel_read_file_id id)
LSM_HOOK(int, 0, task_fix_setuid, struct cred *new, const struct cred *old,
int flags)
LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
int flags)
LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
LSM_HOOK(int, 0, task_getsid, struct task_struct *p)
LSM_HOOK(void, LSM_RET_VOID, current_getsecid_subj, u32 *secid)
LSM_HOOK(void, LSM_RET_VOID, task_getsecid_obj,
struct task_struct *p, u32 *secid)
LSM_HOOK(int, 0, task_setnice, struct task_struct *p, int nice)
LSM_HOOK(int, 0, task_setioprio, struct task_struct *p, int ioprio)
LSM_HOOK(int, 0, task_getioprio, struct task_struct *p)
LSM_HOOK(int, 0, task_prlimit, const struct cred *cred,
const struct cred *tcred, unsigned int flags)
LSM_HOOK(int, 0, task_setrlimit, struct task_struct *p, unsigned int resource,
struct rlimit *new_rlim)
LSM_HOOK(int, 0, task_setscheduler, struct task_struct *p)
LSM_HOOK(int, 0, task_getscheduler, struct task_struct *p)
LSM_HOOK(int, 0, task_movememory, struct task_struct *p)
LSM_HOOK(int, 0, task_kill, struct task_struct *p, struct kernel_siginfo *info,
int sig, const struct cred *cred)
LSM_HOOK(int, -ENOSYS, task_prctl, int option, unsigned long arg2,
unsigned long arg3, unsigned long arg4, unsigned long arg5)
LSM_HOOK(void, LSM_RET_VOID, task_to_inode, struct task_struct *p,
struct inode *inode)
LSM_HOOK(int, 0, ipc_permission, struct kern_ipc_perm *ipcp, short flag)
LSM_HOOK(void, LSM_RET_VOID, ipc_getsecid, struct kern_ipc_perm *ipcp,
u32 *secid)
LSM_HOOK(int, 0, msg_msg_alloc_security, struct msg_msg *msg)
LSM_HOOK(void, LSM_RET_VOID, msg_msg_free_security, struct msg_msg *msg)
LSM_HOOK(int, 0, msg_queue_alloc_security, struct kern_ipc_perm *perm)
LSM_HOOK(void, LSM_RET_VOID, msg_queue_free_security,
struct kern_ipc_perm *perm)
LSM_HOOK(int, 0, msg_queue_associate, struct kern_ipc_perm *perm, int msqflg)
LSM_HOOK(int, 0, msg_queue_msgctl, struct kern_ipc_perm *perm, int cmd)
LSM_HOOK(int, 0, msg_queue_msgsnd, struct kern_ipc_perm *perm,
struct msg_msg *msg, int msqflg)
LSM_HOOK(int, 0, msg_queue_msgrcv, struct kern_ipc_perm *perm,
struct msg_msg *msg, struct task_struct *target, long type, int mode)
LSM_HOOK(int, 0, shm_alloc_security, struct kern_ipc_perm *perm)
LSM_HOOK(void, LSM_RET_VOID, shm_free_security, struct kern_ipc_perm *perm)
LSM_HOOK(int, 0, shm_associate, struct kern_ipc_perm *perm, int shmflg)
LSM_HOOK(int, 0, shm_shmctl, struct kern_ipc_perm *perm, int cmd)
LSM_HOOK(int, 0, shm_shmat, struct kern_ipc_perm *perm, char __user *shmaddr,
int shmflg)
LSM_HOOK(int, 0, sem_alloc_security, struct kern_ipc_perm *perm)
LSM_HOOK(void, LSM_RET_VOID, sem_free_security, struct kern_ipc_perm *perm)
LSM_HOOK(int, 0, sem_associate, struct kern_ipc_perm *perm, int semflg)
LSM_HOOK(int, 0, sem_semctl, struct kern_ipc_perm *perm, int cmd)
LSM_HOOK(int, 0, sem_semop, struct kern_ipc_perm *perm, struct sembuf *sops,
unsigned nsops, int alter)
LSM_HOOK(int, 0, netlink_send, struct sock *sk, struct sk_buff *skb)
LSM_HOOK(void, LSM_RET_VOID, d_instantiate, struct dentry *dentry,
struct inode *inode)
LSM_HOOK(int, -EINVAL, getprocattr, struct task_struct *p, char *name,
char **value)
LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size)
LSM_HOOK(int, 0, ismaclabel, const char *name)
security: Fix the default value of secid_to_secctx hook security_secid_to_secctx is called by the bpf_lsm hook and a successful return value (i.e 0) implies that the parameter will be consumed by the LSM framework. The current behaviour return success when the pointer isn't initialized when CONFIG_BPF_LSM is enabled, with the default return from kernel/bpf/bpf_lsm.c. This is the internal error: [ 1229.341488][ T2659] usercopy: Kernel memory exposure attempt detected from null address (offset 0, size 280)! [ 1229.374977][ T2659] ------------[ cut here ]------------ [ 1229.376813][ T2659] kernel BUG at mm/usercopy.c:99! [ 1229.378398][ T2659] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 1229.380348][ T2659] Modules linked in: [ 1229.381654][ T2659] CPU: 0 PID: 2659 Comm: systemd-journal Tainted: G B W 5.7.0-rc5-next-20200511-00019-g864e0c6319b8-dirty #13 [ 1229.385429][ T2659] Hardware name: linux,dummy-virt (DT) [ 1229.387143][ T2659] pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--) [ 1229.389165][ T2659] pc : usercopy_abort+0xc8/0xcc [ 1229.390705][ T2659] lr : usercopy_abort+0xc8/0xcc [ 1229.392225][ T2659] sp : ffff000064247450 [ 1229.393533][ T2659] x29: ffff000064247460 x28: 0000000000000000 [ 1229.395449][ T2659] x27: 0000000000000118 x26: 0000000000000000 [ 1229.397384][ T2659] x25: ffffa000127049e0 x24: ffffa000127049e0 [ 1229.399306][ T2659] x23: ffffa000127048e0 x22: ffffa000127048a0 [ 1229.401241][ T2659] x21: ffffa00012704b80 x20: ffffa000127049e0 [ 1229.403163][ T2659] x19: ffffa00012704820 x18: 0000000000000000 [ 1229.405094][ T2659] x17: 0000000000000000 x16: 0000000000000000 [ 1229.407008][ T2659] x15: 0000000000000000 x14: 003d090000000000 [ 1229.408942][ T2659] x13: ffff80000d5b25b2 x12: 1fffe0000d5b25b1 [ 1229.410859][ T2659] x11: 1fffe0000d5b25b1 x10: ffff80000d5b25b1 [ 1229.412791][ T2659] x9 : ffffa0001034bee0 x8 : ffff00006ad92d8f [ 1229.414707][ T2659] x7 : 0000000000000000 x6 : ffffa00015eacb20 [ 1229.416642][ T2659] x5 : ffff0000693c8040 x4 : 0000000000000000 [ 1229.418558][ T2659] x3 : ffffa0001034befc x2 : d57a7483a01c6300 [ 1229.420610][ T2659] x1 : 0000000000000000 x0 : 0000000000000059 [ 1229.422526][ T2659] Call trace: [ 1229.423631][ T2659] usercopy_abort+0xc8/0xcc [ 1229.425091][ T2659] __check_object_size+0xdc/0x7d4 [ 1229.426729][ T2659] put_cmsg+0xa30/0xa90 [ 1229.428132][ T2659] unix_dgram_recvmsg+0x80c/0x930 [ 1229.429731][ T2659] sock_recvmsg+0x9c/0xc0 [ 1229.431123][ T2659] ____sys_recvmsg+0x1cc/0x5f8 [ 1229.432663][ T2659] ___sys_recvmsg+0x100/0x160 [ 1229.434151][ T2659] __sys_recvmsg+0x110/0x1a8 [ 1229.435623][ T2659] __arm64_sys_recvmsg+0x58/0x70 [ 1229.437218][ T2659] el0_svc_common.constprop.1+0x29c/0x340 [ 1229.438994][ T2659] do_el0_svc+0xe8/0x108 [ 1229.440587][ T2659] el0_svc+0x74/0x88 [ 1229.441917][ T2659] el0_sync_handler+0xe4/0x8b4 [ 1229.443464][ T2659] el0_sync+0x17c/0x180 [ 1229.444920][ T2659] Code: aa1703e2 aa1603e1 910a8260 97ecc860 (d4210000) [ 1229.447070][ T2659] ---[ end trace 400497d91baeaf51 ]--- [ 1229.448791][ T2659] Kernel panic - not syncing: Fatal exception [ 1229.450692][ T2659] Kernel Offset: disabled [ 1229.452061][ T2659] CPU features: 0x240002,20002004 [ 1229.453647][ T2659] Memory Limit: none [ 1229.455015][ T2659] ---[ end Kernel panic - not syncing: Fatal exception ]--- Rework the so the default return value is -EOPNOTSUPP. There are likely other callbacks such as security_inode_getsecctx() that may have the same problem, and that someone that understand the code better needs to audit them. Thank you Arnd for helping me figure out what went wrong. Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: James Morris <jamorris@linux.microsoft.com> Cc: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/bpf/20200512174607.9630-1-anders.roxell@linaro.org
2020-05-12 17:46:07 +00:00
LSM_HOOK(int, -EOPNOTSUPP, secid_to_secctx, u32 secid, char **secdata,
u32 *seclen)
LSM_HOOK(int, 0, secctx_to_secid, const char *secdata, u32 seclen, u32 *secid)
LSM_HOOK(void, LSM_RET_VOID, release_secctx, char *secdata, u32 seclen)
LSM_HOOK(void, LSM_RET_VOID, inode_invalidate_secctx, struct inode *inode)
LSM_HOOK(int, 0, inode_notifysecctx, struct inode *inode, void *ctx, u32 ctxlen)
LSM_HOOK(int, 0, inode_setsecctx, struct dentry *dentry, void *ctx, u32 ctxlen)
LSM_HOOK(int, 0, inode_getsecctx, struct inode *inode, void **ctx,
u32 *ctxlen)
#if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE)
LSM_HOOK(int, 0, post_notification, const struct cred *w_cred,
const struct cred *cred, struct watch_notification *n)
#endif /* CONFIG_SECURITY && CONFIG_WATCH_QUEUE */
#if defined(CONFIG_SECURITY) && defined(CONFIG_KEY_NOTIFICATIONS)
LSM_HOOK(int, 0, watch_key, struct key *key)
#endif /* CONFIG_SECURITY && CONFIG_KEY_NOTIFICATIONS */
#ifdef CONFIG_SECURITY_NETWORK
LSM_HOOK(int, 0, unix_stream_connect, struct sock *sock, struct sock *other,
struct sock *newsk)
LSM_HOOK(int, 0, unix_may_send, struct socket *sock, struct socket *other)
LSM_HOOK(int, 0, socket_create, int family, int type, int protocol, int kern)
LSM_HOOK(int, 0, socket_post_create, struct socket *sock, int family, int type,
int protocol, int kern)
LSM_HOOK(int, 0, socket_socketpair, struct socket *socka, struct socket *sockb)
LSM_HOOK(int, 0, socket_bind, struct socket *sock, struct sockaddr *address,
int addrlen)
LSM_HOOK(int, 0, socket_connect, struct socket *sock, struct sockaddr *address,
int addrlen)
LSM_HOOK(int, 0, socket_listen, struct socket *sock, int backlog)
LSM_HOOK(int, 0, socket_accept, struct socket *sock, struct socket *newsock)
LSM_HOOK(int, 0, socket_sendmsg, struct socket *sock, struct msghdr *msg,
int size)
LSM_HOOK(int, 0, socket_recvmsg, struct socket *sock, struct msghdr *msg,
int size, int flags)
LSM_HOOK(int, 0, socket_getsockname, struct socket *sock)
LSM_HOOK(int, 0, socket_getpeername, struct socket *sock)
LSM_HOOK(int, 0, socket_getsockopt, struct socket *sock, int level, int optname)
LSM_HOOK(int, 0, socket_setsockopt, struct socket *sock, int level, int optname)
LSM_HOOK(int, 0, socket_shutdown, struct socket *sock, int how)
LSM_HOOK(int, 0, socket_sock_rcv_skb, struct sock *sk, struct sk_buff *skb)
LSM_HOOK(int, 0, socket_getpeersec_stream, struct socket *sock,
char __user *optval, int __user *optlen, unsigned len)
LSM_HOOK(int, 0, socket_getpeersec_dgram, struct socket *sock,
struct sk_buff *skb, u32 *secid)
LSM_HOOK(int, 0, sk_alloc_security, struct sock *sk, int family, gfp_t priority)
LSM_HOOK(void, LSM_RET_VOID, sk_free_security, struct sock *sk)
LSM_HOOK(void, LSM_RET_VOID, sk_clone_security, const struct sock *sk,
struct sock *newsk)
LSM_HOOK(void, LSM_RET_VOID, sk_getsecid, struct sock *sk, u32 *secid)
LSM_HOOK(void, LSM_RET_VOID, sock_graft, struct sock *sk, struct socket *parent)
LSM_HOOK(int, 0, inet_conn_request, const struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
LSM_HOOK(void, LSM_RET_VOID, inet_csk_clone, struct sock *newsk,
const struct request_sock *req)
LSM_HOOK(void, LSM_RET_VOID, inet_conn_established, struct sock *sk,
struct sk_buff *skb)
LSM_HOOK(int, 0, secmark_relabel_packet, u32 secid)
LSM_HOOK(void, LSM_RET_VOID, secmark_refcount_inc, void)
LSM_HOOK(void, LSM_RET_VOID, secmark_refcount_dec, void)
LSM_HOOK(void, LSM_RET_VOID, req_classify_flow, const struct request_sock *req,
struct flowi_common *flic)
LSM_HOOK(int, 0, tun_dev_alloc_security, void **security)
LSM_HOOK(void, LSM_RET_VOID, tun_dev_free_security, void *security)
LSM_HOOK(int, 0, tun_dev_create, void)
LSM_HOOK(int, 0, tun_dev_attach_queue, void *security)
LSM_HOOK(int, 0, tun_dev_attach, struct sock *sk, void *security)
LSM_HOOK(int, 0, tun_dev_open, void *security)
LSM_HOOK(int, 0, sctp_assoc_request, struct sctp_association *asoc,
struct sk_buff *skb)
LSM_HOOK(int, 0, sctp_bind_connect, struct sock *sk, int optname,
struct sockaddr *address, int addrlen)
LSM_HOOK(void, LSM_RET_VOID, sctp_sk_clone, struct sctp_association *asoc,
struct sock *sk, struct sock *newsk)
LSM_HOOK(int, 0, sctp_assoc_established, struct sctp_association *asoc,
struct sk_buff *skb)
#endif /* CONFIG_SECURITY_NETWORK */
#ifdef CONFIG_SECURITY_INFINIBAND
LSM_HOOK(int, 0, ib_pkey_access, void *sec, u64 subnet_prefix, u16 pkey)
LSM_HOOK(int, 0, ib_endport_manage_subnet, void *sec, const char *dev_name,
u8 port_num)
LSM_HOOK(int, 0, ib_alloc_security, void **sec)
LSM_HOOK(void, LSM_RET_VOID, ib_free_security, void *sec)
#endif /* CONFIG_SECURITY_INFINIBAND */
#ifdef CONFIG_SECURITY_NETWORK_XFRM
LSM_HOOK(int, 0, xfrm_policy_alloc_security, struct xfrm_sec_ctx **ctxp,
struct xfrm_user_sec_ctx *sec_ctx, gfp_t gfp)
LSM_HOOK(int, 0, xfrm_policy_clone_security, struct xfrm_sec_ctx *old_ctx,
struct xfrm_sec_ctx **new_ctx)
LSM_HOOK(void, LSM_RET_VOID, xfrm_policy_free_security,
struct xfrm_sec_ctx *ctx)
LSM_HOOK(int, 0, xfrm_policy_delete_security, struct xfrm_sec_ctx *ctx)
LSM_HOOK(int, 0, xfrm_state_alloc, struct xfrm_state *x,
struct xfrm_user_sec_ctx *sec_ctx)
LSM_HOOK(int, 0, xfrm_state_alloc_acquire, struct xfrm_state *x,
struct xfrm_sec_ctx *polsec, u32 secid)
LSM_HOOK(void, LSM_RET_VOID, xfrm_state_free_security, struct xfrm_state *x)
LSM_HOOK(int, 0, xfrm_state_delete_security, struct xfrm_state *x)
LSM_HOOK(int, 0, xfrm_policy_lookup, struct xfrm_sec_ctx *ctx, u32 fl_secid)
LSM_HOOK(int, 1, xfrm_state_pol_flow_match, struct xfrm_state *x,
struct xfrm_policy *xp, const struct flowi_common *flic)
LSM_HOOK(int, 0, xfrm_decode_session, struct sk_buff *skb, u32 *secid,
int ckall)
#endif /* CONFIG_SECURITY_NETWORK_XFRM */
/* key management security hooks */
#ifdef CONFIG_KEYS
LSM_HOOK(int, 0, key_alloc, struct key *key, const struct cred *cred,
unsigned long flags)
LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key)
LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred,
enum key_need_perm need_perm)
LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **_buffer)
#endif /* CONFIG_KEYS */
#ifdef CONFIG_AUDIT
LSM_HOOK(int, 0, audit_rule_init, u32 field, u32 op, char *rulestr,
void **lsmrule)
LSM_HOOK(int, 0, audit_rule_known, struct audit_krule *krule)
LSM_HOOK(int, 0, audit_rule_match, u32 secid, u32 field, u32 op, void *lsmrule)
LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule)
#endif /* CONFIG_AUDIT */
#ifdef CONFIG_BPF_SYSCALL
LSM_HOOK(int, 0, bpf, int cmd, union bpf_attr *attr, unsigned int size)
LSM_HOOK(int, 0, bpf_map, struct bpf_map *map, fmode_t fmode)
LSM_HOOK(int, 0, bpf_prog, struct bpf_prog *prog)
LSM_HOOK(int, 0, bpf_map_alloc_security, struct bpf_map *map)
LSM_HOOK(void, LSM_RET_VOID, bpf_map_free_security, struct bpf_map *map)
LSM_HOOK(int, 0, bpf_prog_alloc_security, struct bpf_prog_aux *aux)
LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free_security, struct bpf_prog_aux *aux)
#endif /* CONFIG_BPF_SYSCALL */
LSM_HOOK(int, 0, locked_down, enum lockdown_reason what)
#ifdef CONFIG_PERF_EVENTS
LSM_HOOK(int, 0, perf_event_open, struct perf_event_attr *attr, int type)
LSM_HOOK(int, 0, perf_event_alloc, struct perf_event *event)
LSM_HOOK(void, LSM_RET_VOID, perf_event_free, struct perf_event *event)
LSM_HOOK(int, 0, perf_event_read, struct perf_event *event)
LSM_HOOK(int, 0, perf_event_write, struct perf_event *event)
#endif /* CONFIG_PERF_EVENTS */
lsm,io_uring: add LSM hooks to io_uring A full expalantion of io_uring is beyond the scope of this commit description, but in summary it is an asynchronous I/O mechanism which allows for I/O requests and the resulting data to be queued in memory mapped "rings" which are shared between the kernel and userspace. Optionally, io_uring offers the ability for applications to spawn kernel threads to dequeue I/O requests from the ring and submit the requests in the kernel, helping to minimize the syscall overhead. Rings are accessed in userspace by memory mapping a file descriptor provided by the io_uring_setup(2), and can be shared between applications as one might do with any open file descriptor. Finally, process credentials can be registered with a given ring and any process with access to that ring can submit I/O requests using any of the registered credentials. While the io_uring functionality is widely recognized as offering a vastly improved, and high performing asynchronous I/O mechanism, its ability to allow processes to submit I/O requests with credentials other than its own presents a challenge to LSMs. When a process creates a new io_uring ring the ring's credentials are inhertied from the calling process; if this ring is shared with another process operating with different credentials there is the potential to bypass the LSMs security policy. Similarly, registering credentials with a given ring allows any process with access to that ring to submit I/O requests with those credentials. In an effort to allow LSMs to apply security policy to io_uring I/O operations, this patch adds two new LSM hooks. These hooks, in conjunction with the LSM anonymous inode support previously submitted, allow an LSM to apply access control policy to the sharing of io_uring rings as well as any io_uring credential changes requested by a process. The new LSM hooks are described below: * int security_uring_override_creds(cred) Controls if the current task, executing an io_uring operation, is allowed to override it's credentials with @cred. In cases where the current task is a user application, the current credentials will be those of the user application. In cases where the current task is a kernel thread servicing io_uring requests the current credentials will be those of the io_uring ring (inherited from the process that created the ring). * int security_uring_sqpoll(void) Controls if the current task is allowed to create an io_uring polling thread (IORING_SETUP_SQPOLL). Without a SQPOLL thread in the kernel processes must submit I/O requests via io_uring_enter(2) which allows us to compare any requested credential changes against the application making the request. With a SQPOLL thread, we can no longer compare requested credential changes against the application making the request, the comparison is made against the ring's credentials. Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-02-02 00:56:49 +00:00
#ifdef CONFIG_IO_URING
LSM_HOOK(int, 0, uring_override_creds, const struct cred *new)
LSM_HOOK(int, 0, uring_sqpoll, void)
#endif /* CONFIG_IO_URING */