Linux Security Module Development

Based on https://lore.kernel.org/r/20071026073721.618b4778@laptopd505.fenrus.org, a new LSM is accepted into the kernel when its intent (a description of what it tries to protect against and in what cases one would expect to use it) has been appropriately documented in Documentation/admin-guide/LSM/. This allows an LSM's code to be easily compared to its goals, and so that end users and distros can make a more informed decision about which LSMs suit their requirements.

For extensive documentation on the available LSM hook interfaces, please see security/security.c and associated structures:

void security_free_mnt_opts(void **mnt_opts)

Free memory associated with mount options

Parameters

void **mnt_opts

LSM processed mount options

Description

Free memory associated with mnt_ops.

int security_sb_eat_lsm_opts(char *options, void **mnt_opts)

Consume LSM mount options

Parameters

char *options

mount options

void **mnt_opts

LSM processed mount options

Description

Eat (scan options) and save them in mnt_opts.

Return

Returns 0 on success, negative values on failure.

int security_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)

Check if new mount options are allowed

Parameters

struct super_block *sb

filesystem superblock

void *mnt_opts

new mount options

Description

Determine if the new mount options in mnt_opts are allowed given the existing mounted filesystem at sb. sb superblock being compared.

Return

Returns 0 if options are compatible.

int security_sb_remount(struct super_block *sb, void *mnt_opts)

Verify no incompatible mount changes during remount

Parameters

struct super_block *sb

filesystem superblock

void *mnt_opts

(re)mount options

Description

Extracts security system specific mount options and verifies no changes are being made to those options.

Return

Returns 0 if permission is granted.

int security_sb_set_mnt_opts(struct super_block *sb, void *mnt_opts, unsigned long kern_flags, unsigned long *set_kern_flags)

Set the mount options for a filesystem

Parameters

struct super_block *sb

filesystem superblock

void *mnt_opts

binary mount options

unsigned long kern_flags

kernel flags (in)

unsigned long *set_kern_flags

kernel flags (out)

Description

Set the security relevant mount options used for a superblock.

Return

Returns 0 on success, error on failure.

int security_sb_clone_mnt_opts(const struct super_block *oldsb, struct super_block *newsb, unsigned long kern_flags, unsigned long *set_kern_flags)

Duplicate superblock mount options

Parameters

const struct super_block *oldsb

source superblock

struct super_block *newsb

destination superblock

unsigned long kern_flags

kernel flags (in)

unsigned long *set_kern_flags

kernel flags (out)

Description

Copy all security options from a given superblock to another.

Return

Returns 0 on success, error on failure.

int security_dentry_init_security(struct dentry *dentry, int mode, const struct qstr *name, const char **xattr_name, void **ctx, u32 *ctxlen)

Perform dentry initialization

Parameters

struct dentry *dentry

the dentry to initialize

int mode

mode used to determine resource type

const struct qstr *name

name of the last path component

const char **xattr_name

name of the security/LSM xattr

void **ctx

pointer to the resulting LSM context

u32 *ctxlen

length of ctx

Description

Compute a context for a dentry as the inode is not yet available since NFSv4 has no label backed by an EA anyway. It is important to note that xattr_name does not need to be free'd by the caller, it is a static string.

Return

Returns 0 on success, negative values on failure.

int security_dentry_create_files_as(struct dentry *dentry, int mode, struct qstr *name, const struct cred *old, struct cred *new)

Perform dentry initialization

Parameters

struct dentry *dentry

the dentry to initialize

int mode

mode used to determine resource type

struct qstr *name

name of the last path component

const struct cred *old

creds to use for LSM context calculations

struct cred *new

creds to modify

Description

Compute a context for a dentry as the inode is not yet available and set that context in passed in creds so that new files are created using that context. Context is calculated using the passed in creds and not the creds of the caller.

Return

Returns 0 on success, error on failure.

int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data)

Initialize an inode's LSM context

Parameters

struct inode *inode

the inode

struct inode *dir

parent directory

const struct qstr *qstr

last component of the pathname

const initxattrs initxattrs

callback function to write xattrs

void *fs_data

filesystem specific data

Description

Obtain the security attribute name suffix and value to set on a newly created inode and set up the incore security field for the new inode. This hook is called by the fs code as part of the inode creation transaction and provides for atomic labeling of the inode, unlike the post_create/mkdir/... hooks called by the VFS.

The hook function is expected to populate the xattrs array, by calling lsm_get_xattr_slot() to retrieve the slots reserved by the security module with the lbs_xattr_count field of the lsm_blob_sizes structure. For each slot, the hook function should set ->name to the attribute name suffix (e.g. selinux), to allocate ->value (will be freed by the caller) and set it to the attribute value, to set ->value_len to the length of the value. If the security module does not use security attributes or does not wish to put a security attribute on this particular inode, then it should return -EOPNOTSUPP to skip this processing.

Return

Returns 0 if the LSM successfully initialized all of the inode

security attributes that are required, negative values otherwise.

int security_path_mknod(const struct path *dir, struct dentry *dentry, umode_t mode, unsigned int dev)

Check if creating a special file is allowed

Parameters

const struct path *dir

parent directory

struct dentry *dentry

new file

umode_t mode

new file mode

unsigned int dev

device number

Description

Check permissions when creating a file. Note that this hook is called even if mknod operation is being done for a regular file.

Return

Returns 0 if permission is granted.

int security_path_mkdir(const struct path *dir, struct dentry *dentry, umode_t mode)

Check if creating a new directory is allowed

Parameters

const struct path *dir

parent directory

struct dentry *dentry

new directory

umode_t mode

new directory mode

Description

Check permissions to create a new directory in the existing directory.

Return

Returns 0 if permission is granted.

Check if removing a hard link is allowed

Parameters

const struct path *dir

parent directory

struct dentry *dentry

file

Description

Check the permission to remove a hard link to a file.

Return

Returns 0 if permission is granted.

int security_path_rename(const struct path *old_dir, struct dentry *old_dentry, const struct path *new_dir, struct dentry *new_dentry, unsigned int flags)

Check if renaming a file is allowed

Parameters

const struct path *old_dir

parent directory of the old file

struct dentry *old_dentry

the old file

const struct path *new_dir

parent directory of the new file

struct dentry *new_dentry

the new file

unsigned int flags

flags

Description

Check for permission to rename a file or directory.

Return

Returns 0 if permission is granted.

int security_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode)

Check if creating a file is allowed

Parameters

struct inode *dir

the parent directory

struct dentry *dentry

the file being created

umode_t mode

requested file mode

Description

Check permission to create a regular file.

Return

Returns 0 if permission is granted.

int security_inode_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)

Check if creation a new director is allowed

Parameters

struct inode *dir

parent directory

struct dentry *dentry

new directory

umode_t mode

new directory mode

Description

Check permissions to create a new directory in the existing directory associated with inode structure dir.

Return

Returns 0 if permission is granted.

int security_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr)

Check if setting file attributes is allowed

Parameters

struct mnt_idmap *idmap

idmap of the mount

struct dentry *dentry

file

struct iattr *attr

new attributes

Description

Check permission before setting file attributes. Note that the kernel call to notify_change is performed from several locations, whenever file attributes change (such as when a file is truncated, chown/chmod operations, transferring disk quotas, etc).

Return

Returns 0 if permission is granted.

int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)

List the xattr security label names

Parameters

struct inode *inode

inode

char *buffer

buffer

size_t buffer_size

size of buffer

Description

Copy the extended attribute names for the security labels associated with inode into buffer. The maximum size of buffer is specified by buffer_size. buffer may be NULL to request the size of the buffer required.

Return

Returns number of bytes used/required on success.

int security_inode_copy_up(struct dentry *src, struct cred **new)

Create new creds for an overlayfs copy-up op

Parameters

struct dentry *src

union dentry of copy-up file

struct cred **new

newly created creds

Description

A file is about to be copied up from lower layer to upper layer of overlay filesystem. Security module can prepare a set of new creds and modify as need be and return new creds. Caller will switch to new creds temporarily to create new file and release newly allocated creds.

Return

Returns 0 on success or a negative error code on error.

int security_inode_copy_up_xattr(const char *name)

Filter xattrs in an overlayfs copy-up op

Parameters

const char *name

xattr name

Description

Filter the xattrs being copied up when a unioned file is copied up from a lower layer to the union/overlay layer. The caller is responsible for reading and writing the xattrs, this hook is merely a filter.

Return

Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP

if the security module does not know about attribute, or a negative error code to abort the copy up.

int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

Check if an ioctl is allowed

Parameters

struct file *file

associated file

unsigned int cmd

ioctl cmd

unsigned long arg

ioctl arguments

Description

Check permission for an ioctl operation on file. Note that arg sometimes represents a user space pointer; in other cases, it may be a simple integer value. When arg represents a user space pointer, it should never be used by the security module.

Return

Returns 0 if permission is granted.

int security_file_ioctl_compat(struct file *file, unsigned int cmd, unsigned long arg)

Check if an ioctl is allowed in compat mode

Parameters

struct file *file

associated file

unsigned int cmd

ioctl cmd

unsigned long arg

ioctl arguments

Description

Compat version of security_file_ioctl() that correctly handles 32-bit processes running on 64-bit kernels.

Return

Returns 0 if permission is granted.

void security_cred_getsecid(const struct cred *c, u32 *secid)

Get the secid from a set of credentials

Parameters

const struct cred *c

credentials

u32 *secid

secid value

Description

Retrieve the security identifier of the cred structure c. In case of failure, secid will be set to zero.

int security_kernel_read_file(struct file *file, enum kernel_read_file_id id, bool contents)

Read a file specified by userspace

Parameters

struct file *file

file

enum kernel_read_file_id id

file identifier

bool contents

trust if security_kernel_post_read_file() will be called

Description

Read a file specified by userspace.

Return

Returns 0 if permission is granted.

int security_kernel_post_read_file(struct file *file, char *buf, loff_t size, enum kernel_read_file_id id)

Read a file specified by userspace

Parameters

struct file *file

file

char *buf

file contents

loff_t size

size of file contents

enum kernel_read_file_id id

file identifier

Description

Read a file specified by userspace. This must be paired with a prior call to security_kernel_read_file() call that indicated this hook would also be called, see security_kernel_read_file() for more information.

Return

Returns 0 if permission is granted.

int security_kernel_load_data(enum kernel_load_data_id id, bool contents)

Load data provided by userspace

Parameters

enum kernel_load_data_id id

data identifier

bool contents

true if security_kernel_post_load_data() will be called

Description

Load data provided by userspace.

Return

Returns 0 if permission is granted.

int security_kernel_post_load_data(char *buf, loff_t size, enum kernel_load_data_id id, char *description)

Load userspace data from a non-file source

Parameters

char *buf

data

loff_t size

size of data

enum kernel_load_data_id id

data identifier

char *description

text description of data, specific to the id value

Description

Load data provided by a non-file source (usually userspace buffer). This must be paired with a prior security_kernel_load_data() call that indicated this hook would also be called, see security_kernel_load_data() for more information.

Return

Returns 0 if permission is granted.

void security_current_getsecid_subj(u32 *secid)

Get the current task's subjective secid

Parameters

u32 *secid

secid value

Description

Retrieve the subjective security identifier of the current task and return it in secid. In case of failure, secid will be set to zero.

void security_task_getsecid_obj(struct task_struct *p, u32 *secid)

Get a task's objective secid

Parameters

struct task_struct *p

target task

u32 *secid

secid value

Description

Retrieve the objective security identifier of the task_struct in p and return it in secid. In case of failure, secid will be set to zero.

void security_d_instantiate(struct dentry *dentry, struct inode *inode)

Populate an inode's LSM state based on a dentry

Parameters

struct dentry *dentry

dentry

struct inode *inode

inode

Description

Fill in inode security information for a dentry if allowed.

int security_ismaclabel(const char *name)

Check is the named attribute is a MAC label

Parameters

const char *name

full extended attribute name

Description

Check if the extended attribute specified by name represents a MAC label.

Return

Returns 1 if name is a MAC attribute otherwise returns 0.

int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)

Convert a secid to a secctx

Parameters

u32 secid

secid

char **secdata

secctx

u32 *seclen

secctx length

Description

Convert secid to security context. If secdata is NULL the length of the result will be returned in seclen, but no secdata will be returned. This does mean that the length could change between calls to check the length and the next call which actually allocates and returns the secdata.

Return

Return 0 on success, error on failure.

int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)

Convert a secctx to a secid

Parameters

const char *secdata

secctx

u32 seclen

length of secctx

u32 *secid

secid

Description

Convert security context to secid.

Return

Returns 0 on success, error on failure.

void security_release_secctx(char *secdata, u32 seclen)

Free a secctx buffer

Parameters

char *secdata

secctx

u32 seclen

length of secctx

Description

Release the security context.

void security_inode_invalidate_secctx(struct inode *inode)

Invalidate an inode's security label

Parameters

struct inode *inode

inode

Description

Notify the security module that it must revalidate the security context of an inode.

int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)

Notify the LSM of an inode's security label

Parameters

struct inode *inode

inode

void *ctx

secctx

u32 ctxlen

length of secctx

Description

Notify the security module of what the security context of an inode should be. Initializes the incore security context managed by the security module for this inode. Example usage: NFS client invokes this hook to initialize the security context in its incore inode to the value provided by the server for the file when the server returned the file's attributes to the client. Must be called with inode->i_mutex locked.

Return

Returns 0 on success, error on failure.

int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)

Change the security label of an inode

Parameters

struct dentry *dentry

inode

void *ctx

secctx

u32 ctxlen

length of secctx

Description

Change the security context of an inode. Updates the incore security context managed by the security module and invokes the fs code as needed (via __vfs_setxattr_noperm) to update any backing xattrs that represent the context. Example usage: NFS server invokes this hook to change the security context in its incore inode and on the backing filesystem to a value provided by the client on a SETATTR operation. Must be called with inode->i_mutex locked.

Return

Returns 0 on success, error on failure.

int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)

Get the security label of an inode

Parameters

struct inode *inode

inode

void **ctx

secctx

u32 *ctxlen

length of secctx

Description

On success, returns 0 and fills out ctx and ctxlen with the security context for the given inode.

Return

Returns 0 on success, error on failure.

int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk)

Check if a AF_UNIX stream is allowed

Parameters

struct sock *sock

originating sock

struct sock *other

peer sock

struct sock *newsk

new sock

Description

Check permissions before establishing a Unix domain stream connection between sock and other.

The unix_stream_connect and unix_may_send hooks were necessary because Linux provides an alternative to the conventional file name space for Unix domain sockets. Whereas binding and connecting to sockets in the file name space is mediated by the typical file permissions (and caught by the mknod and permission hooks in inode_security_ops), binding and connecting to sockets in the abstract name space is completely unmediated. Sufficient control of Unix domain sockets in the abstract name space isn't possible using only the socket layer hooks, since we need to know the actual target socket, which is not looked up until we are inside the af_unix code.

Return

Returns 0 if permission is granted.

int security_unix_may_send(struct socket *sock, struct socket *other)

Check if AF_UNIX socket can send datagrams

Parameters

struct socket *sock

originating sock

struct socket *other

peer sock

Description

Check permissions before connecting or sending datagrams from sock to other.

The unix_stream_connect and unix_may_send hooks were necessary because Linux provides an alternative to the conventional file name space for Unix domain sockets. Whereas binding and connecting to sockets in the file name space is mediated by the typical file permissions (and caught by the mknod and permission hooks in inode_security_ops), binding and connecting to sockets in the abstract name space is completely unmediated. Sufficient control of Unix domain sockets in the abstract name space isn't possible using only the socket layer hooks, since we need to know the actual target socket, which is not looked up until we are inside the af_unix code.

Return

Returns 0 if permission is granted.

int security_socket_socketpair(struct socket *socka, struct socket *sockb)

Check if creating a socketpair is allowed

Parameters

struct socket *socka

first socket

struct socket *sockb

second socket

Description

Check permissions before creating a fresh pair of sockets.

Return

Returns 0 if permission is granted and the connection was

established.

int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)

Check if an incoming network packet is allowed

Parameters

struct sock *sk

destination sock

struct sk_buff *skb

incoming packet

Description

Check permissions on incoming network packets. This hook is distinct from Netfilter's IP input hooks since it is the first time that the incoming sk_buff skb has been associated with a particular socket, sk. Must not sleep inside this hook because some callers hold spinlocks.

Return

Returns 0 if permission is granted.

int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)

Get the remote peer label

Parameters

struct socket *sock

socket

struct sk_buff *skb

datagram packet

u32 *secid

remote peer label secid

Description

This hook allows the security module to provide peer socket security state for udp sockets on a per-packet basis to userspace via getsockopt SO_GETPEERSEC. The application must first have indicated the IP_PASSSEC option via getsockopt. It can then retrieve the security state returned by this hook for a packet via the SCM_SECURITY ancillary message type.

Return

Returns 0 on success, error on failure.

void security_sk_clone(const struct sock *sk, struct sock *newsk)

Clone a sock's LSM state

Parameters

const struct sock *sk

original sock

struct sock *newsk

target sock

Description

Clone/copy security structure.

void security_sk_classify_flow(const struct sock *sk, struct flowi_common *flic)

Set a flow's secid based on socket

Parameters

const struct sock *sk

original socket

struct flowi_common *flic

target flow

Description

Set the target flow's secid to socket's secid.

void security_req_classify_flow(const struct request_sock *req, struct flowi_common *flic)

Set a flow's secid based on request_sock

Parameters

const struct request_sock *req

request_sock

struct flowi_common *flic

target flow

Description

Sets flic's secid to req's secid.

void security_sock_graft(struct sock *sk, struct socket *parent)

Reconcile LSM state when grafting a sock on a socket

Parameters

struct sock *sk

sock being grafted

struct socket *parent

target parent socket

Description

Sets parent's inode secid to sk's secid and update sk with any necessary LSM state from parent.

int security_inet_conn_request(const struct sock *sk, struct sk_buff *skb, struct request_sock *req)

Set request_sock state using incoming connect

Parameters

const struct sock *sk

parent listening sock

struct sk_buff *skb

incoming connection

struct request_sock *req

new request_sock

Description

Initialize the req LSM state based on sk and the incoming connect in skb.

Return

Returns 0 if permission is granted.

void security_inet_conn_established(struct sock *sk, struct sk_buff *skb)

Update sock's LSM state with connection

Parameters

struct sock *sk

sock

struct sk_buff *skb

connection packet

Description

Update sock's LSM state to represent a new connection from skb.

int security_secmark_relabel_packet(u32 secid)

Check if setting a secmark is allowed

Parameters

u32 secid

new secmark value

Description

Check if the process should be allowed to relabel packets to secid.

Return

Returns 0 if permission is granted.

void security_secmark_refcount_inc(void)

Increment the secmark labeling rule count

Parameters

void

no arguments

Description

Tells the LSM to increment the number of secmark labeling rules loaded.

void security_secmark_refcount_dec(void)

Decrement the secmark labeling rule count

Parameters

void

no arguments

Description

Tells the LSM to decrement the number of secmark labeling rules loaded.

int security_tun_dev_alloc_security(void **security)

Allocate a LSM blob for a TUN device

Parameters

void **security

pointer to the LSM blob

Description

This hook allows a module to allocate a security structure for a TUN device, returning the pointer in security.

Return

Returns a zero on success, negative values on failure.

void security_tun_dev_free_security(void *security)

Free a TUN device LSM blob

Parameters

void *security

LSM blob

Description

This hook allows a module to free the security structure for a TUN device.

int security_tun_dev_create(void)

Check if creating a TUN device is allowed

Parameters

void

no arguments

Description

Check permissions prior to creating a new TUN device.

Return

Returns 0 if permission is granted.

int security_tun_dev_attach_queue(void *security)

Check if attaching a TUN queue is allowed

Parameters

void *security

TUN device LSM blob

Description

Check permissions prior to attaching to a TUN device queue.

Return

Returns 0 if permission is granted.

int security_tun_dev_attach(struct sock *sk, void *security)

Update TUN device LSM state on attach

Parameters

struct sock *sk

associated sock

void *security

TUN device LSM blob

Description

This hook can be used by the module to update any security state associated with the TUN device's sock structure.

Return

Returns 0 if permission is granted.

int security_tun_dev_open(void *security)

Update TUN device LSM state on open

Parameters

void *security

TUN device LSM blob

Description

This hook can be used by the module to update any security state associated with the TUN device's security structure.

Return

Returns 0 if permission is granted.

int security_sctp_assoc_request(struct sctp_association *asoc, struct sk_buff *skb)

Update the LSM on a SCTP association req

Parameters

struct sctp_association *asoc

SCTP association

struct sk_buff *skb

packet requesting the association

Description

Passes the asoc and chunk->skb of the association INIT packet to the LSM.

Return

Returns 0 on success, error on failure.

int security_sctp_bind_connect(struct sock *sk, int optname, struct sockaddr *address, int addrlen)

Validate a list of addrs for a SCTP option

Parameters

struct sock *sk

socket

int optname

SCTP option to validate

struct sockaddr *address

list of IP addresses to validate

int addrlen

length of the address list

Description

Validiate permissions required for each address associated with sock sk. Depending on optname, the addresses will be treated as either a connect or bind service. The addrlen is calculated on each IPv4 and IPv6 address using sizeof(struct sockaddr_in) or sizeof(struct sockaddr_in6).

Return

Returns 0 on success, error on failure.

void security_sctp_sk_clone(struct sctp_association *asoc, struct sock *sk, struct sock *newsk)

Clone a SCTP sock's LSM state

Parameters

struct sctp_association *asoc

SCTP association

struct sock *sk

original sock

struct sock *newsk

target sock

Description

Called whenever a new socket is created by accept(2) (i.e. a TCP style socket) or when a socket is 'peeled off' e.g userspace calls sctp_peeloff(3).

int security_sctp_assoc_established(struct sctp_association *asoc, struct sk_buff *skb)

Update LSM state when assoc established

Parameters

struct sctp_association *asoc

SCTP association

struct sk_buff *skb

packet establishing the association

Description

Passes the asoc and chunk->skb of the association COOKIE_ACK packet to the security module.

Return

Returns 0 if permission is granted.

int security_ib_pkey_access(void *sec, u64 subnet_prefix, u16 pkey)

Check if access to an IB pkey is allowed

Parameters

void *sec

LSM blob

u64 subnet_prefix

subnet prefix of the port

u16 pkey

IB pkey

Description

Check permission to access a pkey when modifying a QP.

Return

Returns 0 if permission is granted.

int security_ib_endport_manage_subnet(void *sec, const char *dev_name, u8 port_num)

Check if SMPs traffic is allowed

Parameters

void *sec

LSM blob

const char *dev_name

IB device name

u8 port_num

port number

Description

Check permissions to send and receive SMPs on a end port.

Return

Returns 0 if permission is granted.

int security_ib_alloc_security(void **sec)

Allocate an Infiniband LSM blob

Parameters

void **sec

LSM blob

Description

Allocate a security structure for Infiniband objects.

Return

Returns 0 on success, non-zero on failure.

void security_ib_free_security(void *sec)

Free an Infiniband LSM blob

Parameters

void *sec

LSM blob

Description

Deallocate an Infiniband security structure.

int security_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, struct xfrm_user_sec_ctx *sec_ctx, gfp_t gfp)

Allocate a xfrm policy LSM blob

Parameters

struct xfrm_sec_ctx **ctxp

xfrm security context being added to the SPD

struct xfrm_user_sec_ctx *sec_ctx

security label provided by userspace

gfp_t gfp

gfp flags

Description

Allocate a security structure to the xp->security field; the security field is initialized to NULL when the xfrm_policy is allocated.

Return

Return 0 if operation was successful.

void security_xfrm_policy_free(struct xfrm_sec_ctx *ctx)

Free a xfrm security context

Parameters

struct xfrm_sec_ctx *ctx

xfrm security context

Description

Free LSM resources associated with ctx.

int security_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *sec_ctx)

Allocate a xfrm state LSM blob

Parameters

struct xfrm_state *x

xfrm state being added to the SAD

struct xfrm_user_sec_ctx *sec_ctx

security label provided by userspace

Description

Allocate a security structure to the x->security field; the security field is initialized to NULL when the xfrm_state is allocated. Set the context to correspond to sec_ctx.

Return

Return 0 if operation was successful.

int security_xfrm_state_delete(struct xfrm_state *x)

Check if deleting a xfrm state is allowed

Parameters

struct xfrm_state *x

xfrm state

Description

Authorize deletion of x->security.

Return

Returns 0 if permission is granted.

int security_locked_down(enum lockdown_reason what)

Check if a kernel feature is allowed

Parameters

enum lockdown_reason what

requested kernel feature

Description

Determine whether a kernel feature that potentially enables arbitrary code execution in kernel space should be permitted.

Return

Returns 0 if permission is granted.