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LSM: hide struct security_mnt_opts from any generic code 

Keep void * instead, allocate on demand (in parse_str_opts, at the
moment).  Eventually both selinux and smack will be better off
with private structures with several strings in those, rather than
this "counter and two pointers to dynamically allocated arrays"
ugliness.  This commit allows to do that at leisure, without
disrupting anything outside of given module.

Changes:
	* instead of struct security_mnt_opt use an opaque pointer
initialized to NULL.
	* security_sb_eat_lsm_opts(), security_sb_parse_opts_str() and
security_free_mnt_opts() take it as var argument (i.e. as void **);
call sites are unchanged.
	* security_sb_set_mnt_opts() and security_sb_remount() take
it by value (i.e. as void *).
	* new method: ->sb_free_mnt_opts().  Takes void *, does
whatever freeing that needs to be done.
	* ->sb_set_mnt_opts() and ->sb_remount() might get NULL as
mnt_opts argument, meaning "empty".

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-12-13 13:41:47 -05:00
parent e3489f8974
commit 204cc0ccf1
10 changed files with 118 additions and 92 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
fs/btrfs/super.c
View File

@ -1472,14 +1472,13 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
struct btrfs_device *device = NULL;
struct btrfs_fs_devices *fs_devices = NULL;
struct btrfs_fs_info *fs_info = NULL;
struct security_mnt_opts new_sec_opts;
void *new_sec_opts = NULL;
fmode_t mode = FMODE_READ;
int error = 0;
if (!(flags & SB_RDONLY))
mode |= FMODE_WRITE;
security_init_mnt_opts(&new_sec_opts);
if (data) {
error = security_sb_eat_lsm_opts(data, &new_sec_opts);
if (error)
@ -1551,7 +1550,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
error = btrfs_fill_super(s, fs_devices, data);
}
if (!error)
error = security_sb_set_mnt_opts(s, &new_sec_opts, 0, NULL);
error = security_sb_set_mnt_opts(s, new_sec_opts, 0, NULL);
security_free_mnt_opts(&new_sec_opts);
if (error) {
deactivate_locked_super(s);
@ -1724,12 +1723,11 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
btrfs_remount_prepare(fs_info);
if (data) {
struct security_mnt_opts new_sec_opts;
void *new_sec_opts = NULL;
security_init_mnt_opts(&new_sec_opts);
ret = security_sb_eat_lsm_opts(data, &new_sec_opts);
if (!ret)
ret = security_sb_remount(sb, &new_sec_opts);
ret = security_sb_remount(sb, new_sec_opts);
security_free_mnt_opts(&new_sec_opts);
if (ret)
goto restore;

9
fs/namespace.c
View File

@ -2299,7 +2299,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
int err;
struct super_block *sb = path->mnt->mnt_sb;
struct mount *mnt = real_mount(path->mnt);
struct security_mnt_opts opts;
void *sec_opts = NULL;
if (!check_mnt(mnt))
return -EINVAL;
@ -2310,14 +2310,13 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
if (!can_change_locked_flags(mnt, mnt_flags))
return -EPERM;
security_init_mnt_opts(&opts);
if (data && !(sb->s_type->fs_flags & FS_BINARY_MOUNTDATA)) {
err = security_sb_eat_lsm_opts(data, &opts);
err = security_sb_eat_lsm_opts(data, &sec_opts);
if (err)
return err;
}
err = security_sb_remount(sb, &opts);
security_free_mnt_opts(&opts);
err = security_sb_remount(sb, sec_opts);
security_free_mnt_opts(&sec_opts);
if (err)
return err;

2
fs/nfs/internal.h
View File

@ -123,7 +123,7 @@ struct nfs_parsed_mount_data {
unsigned short protocol;
} nfs_server;
struct security_mnt_opts lsm_opts;
void *lsm_opts;
struct net *net;
};

6
fs/nfs/super.c
View File

@ -929,7 +929,7 @@ static struct nfs_parsed_mount_data *nfs_alloc_parsed_mount_data(void)
data->minorversion = 0;
data->need_mount = true;
data->net = current->nsproxy->net_ns;
security_init_mnt_opts(&data->lsm_opts);
data->lsm_opts = NULL;
}
return data;
}
@ -2294,7 +2294,7 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
/* compare new mount options with old ones */
error = nfs_compare_remount_data(nfss, data);
if (!error)
error = security_sb_remount(sb, &data->lsm_opts);
error = security_sb_remount(sb, data->lsm_opts);
out:
nfs_free_parsed_mount_data(data);
return error;
@ -2534,7 +2534,7 @@ int nfs_set_sb_security(struct super_block *s, struct dentry *mntroot,
if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL)
kflags |= SECURITY_LSM_NATIVE_LABELS;
error = security_sb_set_mnt_opts(s, &mount_info->parsed->lsm_opts,
error = security_sb_set_mnt_opts(s, mount_info->parsed->lsm_opts,
kflags, &kflags_out);
if (error)
goto err;

12
fs/super.c
View File

@ -1247,12 +1247,10 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
struct dentry *root;
struct super_block *sb;
int error = -ENOMEM;
struct security_mnt_opts opts;
security_init_mnt_opts(&opts);
void *sec_opts = NULL;
if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
error = security_sb_eat_lsm_opts(data, &opts);
error = security_sb_eat_lsm_opts(data, &sec_opts);
if (error)
return ERR_PTR(error);
}
@ -1275,7 +1273,7 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
smp_wmb();
sb->s_flags |= SB_BORN;
error = security_sb_set_mnt_opts(sb, &opts, 0, NULL);
error = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
if (error)
goto out_sb;
@ -1295,13 +1293,13 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
"negative value (%lld)\n", type->name, sb->s_maxbytes);
up_write(&sb->s_umount);
security_free_mnt_opts(&opts);
security_free_mnt_opts(&sec_opts);
return root;
out_sb:
dput(root);
deactivate_locked_super(sb);
out_free_secdata:
security_free_mnt_opts(&opts);
security_free_mnt_opts(&sec_opts);
return ERR_PTR(error);
}

11
include/linux/lsm_hooks.h
View File

@ -1461,9 +1461,9 @@ union security_list_options {
int (*sb_alloc_security)(struct super_block *sb);
void (*sb_free_security)(struct super_block *sb);
int (*sb_eat_lsm_opts)(char *orig, struct security_mnt_opts *opts);
int (*sb_remount)(struct super_block *sb,
struct security_mnt_opts *opts);
void (*sb_free_mnt_opts)(void *mnt_opts);
int (*sb_eat_lsm_opts)(char *orig, void **mnt_opts);
int (*sb_remount)(struct super_block *sb, void *mnt_opts);
int (*sb_kern_mount)(struct super_block *sb);
int (*sb_show_options)(struct seq_file *m, struct super_block *sb);
int (*sb_statfs)(struct dentry *dentry);
@ -1472,14 +1472,14 @@ union security_list_options {
int (*sb_umount)(struct vfsmount *mnt, int flags);
int (*sb_pivotroot)(const struct path *old_path, const struct path *new_path);
int (*sb_set_mnt_opts)(struct super_block *sb,
struct security_mnt_opts *opts,
void *mnt_opts,
unsigned long kern_flags,
unsigned long *set_kern_flags);
int (*sb_clone_mnt_opts)(const struct super_block *oldsb,
struct super_block *newsb,
unsigned long kern_flags,
unsigned long *set_kern_flags);
int (*sb_parse_opts_str)(char *options, struct security_mnt_opts *opts);
int (*sb_parse_opts_str)(char *options, void **mnt_opts);
int (*dentry_init_security)(struct dentry *dentry, int mode,
const struct qstr *name, void **ctx,
u32 *ctxlen);
@ -1801,6 +1801,7 @@ struct security_hook_heads {
struct hlist_head bprm_committed_creds;
struct hlist_head sb_alloc_security;
struct hlist_head sb_free_security;
struct hlist_head sb_free_mnt_opts;
struct hlist_head sb_eat_lsm_opts;
struct hlist_head sb_remount;
struct hlist_head sb_kern_mount;

43
include/linux/security.h
View File

@ -192,26 +192,6 @@ int call_lsm_notifier(enum lsm_event event, void *data);
int register_lsm_notifier(struct notifier_block *nb);
int unregister_lsm_notifier(struct notifier_block *nb);
static inline void security_init_mnt_opts(struct security_mnt_opts *opts)
{
opts->mnt_opts = NULL;
opts->mnt_opts_flags = NULL;
opts->num_mnt_opts = 0;
}
static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
{
int i;
if (opts->mnt_opts)
for (i = 0; i < opts->num_mnt_opts; i++)
kfree(opts->mnt_opts[i]);
kfree(opts->mnt_opts);
opts->mnt_opts = NULL;
kfree(opts->mnt_opts_flags);
opts->mnt_opts_flags = NULL;
opts->num_mnt_opts = 0;
}
/* prototypes */
extern int security_init(void);
@ -248,8 +228,9 @@ void security_bprm_committing_creds(struct linux_binprm *bprm);
void security_bprm_committed_creds(struct linux_binprm *bprm);
int security_sb_alloc(struct super_block *sb);
void security_sb_free(struct super_block *sb);
int security_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts);
int security_sb_remount(struct super_block *sb, struct security_mnt_opts *opts);
void security_free_mnt_opts(void **mnt_opts);
int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
int security_sb_remount(struct super_block *sb, void *mnt_opts);
int security_sb_kern_mount(struct super_block *sb);
int security_sb_show_options(struct seq_file *m, struct super_block *sb);
int security_sb_statfs(struct dentry *dentry);
@ -258,14 +239,14 @@ int security_sb_mount(const char *dev_name, const struct path *path,
int security_sb_umount(struct vfsmount *mnt, int flags);
int security_sb_pivotroot(const struct path *old_path, const struct path *new_path);
int security_sb_set_mnt_opts(struct super_block *sb,
struct security_mnt_opts *opts,
void *mnt_opts,
unsigned long kern_flags,
unsigned long *set_kern_flags);
int security_sb_clone_mnt_opts(const struct super_block *oldsb,
struct super_block *newsb,
unsigned long kern_flags,
unsigned long *set_kern_flags);
int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts);
int security_sb_parse_opts_str(char *options, void **mnt_opts);
int security_dentry_init_security(struct dentry *dentry, int mode,
const struct qstr *name, void **ctx,
u32 *ctxlen);
@ -421,11 +402,7 @@ static inline int unregister_lsm_notifier(struct notifier_block *nb)
return 0;
}
static inline void security_init_mnt_opts(struct security_mnt_opts *opts)
{
}
static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
static inline void security_free_mnt_opts(void **mnt_opts)
{
}
@ -556,13 +533,13 @@ static inline void security_sb_free(struct super_block *sb)
{ }
static inline int security_sb_eat_lsm_opts(char *options,
struct security_mnt_opts *opts)
void **mnt_opts)
{
return 0;
}
static inline int security_sb_remount(struct super_block *sb,
struct security_mnt_opts *opts)
void *mnt_opts)
{
return 0;
}
@ -602,7 +579,7 @@ static inline int security_sb_pivotroot(const struct path *old_path,
}
static inline int security_sb_set_mnt_opts(struct super_block *sb,
struct security_mnt_opts *opts,
void *mnt_opts,
unsigned long kern_flags,
unsigned long *set_kern_flags)
{
@ -617,7 +594,7 @@ static inline int security_sb_clone_mnt_opts(const struct super_block *oldsb,
return 0;
}
static inline int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts)
static inline int security_sb_parse_opts_str(char *options, void **mnt_opts)
{
return 0;
}

27
security/security.c
View File

@ -384,16 +384,25 @@ void security_sb_free(struct super_block *sb)
call_void_hook(sb_free_security, sb);
}
int security_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts)
void security_free_mnt_opts(void **mnt_opts)
{
return call_int_hook(sb_eat_lsm_opts, 0, options, opts);
if (!*mnt_opts)
return;
call_void_hook(sb_free_mnt_opts, *mnt_opts);
*mnt_opts = NULL;
}
EXPORT_SYMBOL(security_free_mnt_opts);
int security_sb_eat_lsm_opts(char *options, void **mnt_opts)
{
return call_int_hook(sb_eat_lsm_opts, 0, options, mnt_opts);
}
EXPORT_SYMBOL(security_sb_eat_lsm_opts);
int security_sb_remount(struct super_block *sb,
struct security_mnt_opts *opts)
void *mnt_opts)
{
return call_int_hook(sb_remount, 0, sb, opts);
return call_int_hook(sb_remount, 0, sb, mnt_opts);
}
EXPORT_SYMBOL(security_sb_remount);
@ -429,13 +438,13 @@ int security_sb_pivotroot(const struct path *old_path, const struct path *new_pa
}
int security_sb_set_mnt_opts(struct super_block *sb,
struct security_mnt_opts *opts,
void *mnt_opts,
unsigned long kern_flags,
unsigned long *set_kern_flags)
{
return call_int_hook(sb_set_mnt_opts,
opts->num_mnt_opts ? -EOPNOTSUPP : 0, sb,
opts, kern_flags, set_kern_flags);
mnt_opts ? -EOPNOTSUPP : 0, sb,
mnt_opts, kern_flags, set_kern_flags);
}
EXPORT_SYMBOL(security_sb_set_mnt_opts);
@ -449,9 +458,9 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb,
}
EXPORT_SYMBOL(security_sb_clone_mnt_opts);
int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts)
int security_sb_parse_opts_str(char *options, void **mnt_opts)
{
return call_int_hook(sb_parse_opts_str, 0, options, opts);
return call_int_hook(sb_parse_opts_str, 0, options, mnt_opts);
}
EXPORT_SYMBOL(security_sb_parse_opts_str);

52
security/selinux/hooks.c
View File

@ -433,6 +433,19 @@ static void superblock_free_security(struct super_block *sb)
kfree(sbsec);
}
static void selinux_free_mnt_opts(void *mnt_opts)
{
struct security_mnt_opts *opts = mnt_opts;
int i;
if (opts->mnt_opts)
for (i = 0; i < opts->num_mnt_opts; i++)
kfree(opts->mnt_opts[i]);
kfree(opts->mnt_opts);
kfree(opts->mnt_opts_flags);
kfree(opts);
}
static inline int inode_doinit(struct inode *inode)
{
return inode_doinit_with_dentry(inode, NULL);
@ -616,7 +629,7 @@ static int bad_option(struct superblock_security_struct *sbsec, char flag,
* labeling information.
*/
static int selinux_set_mnt_opts(struct super_block *sb,
struct security_mnt_opts *opts,
void *mnt_opts,
unsigned long kern_flags,
unsigned long *set_kern_flags)
{
@ -628,9 +641,10 @@ static int selinux_set_mnt_opts(struct super_block *sb,
struct inode_security_struct *root_isec;
u32 fscontext_sid = 0, context_sid = 0, rootcontext_sid = 0;
u32 defcontext_sid = 0;
char **mount_options = opts->mnt_opts;
int *flags = opts->mnt_opts_flags;
int num_opts = opts->num_mnt_opts;
struct security_mnt_opts *opts = mnt_opts;
char **mount_options = opts ? opts->mnt_opts : NULL;
int *flags = opts ? opts->mnt_opts_flags : NULL;
int num_opts = opts ? opts->num_mnt_opts : 0;
mutex_lock(&sbsec->lock);
@ -982,12 +996,20 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
}
static int selinux_parse_opts_str(char *options,
struct security_mnt_opts *opts)
void **mnt_opts)
{
char *p;
char *context = NULL, *defcontext = NULL;
char *fscontext = NULL, *rootcontext = NULL;
int rc, num_mnt_opts = 0;
struct security_mnt_opts *opts = *mnt_opts;
if (!opts) {
opts = kzalloc(sizeof(struct security_mnt_opts), GFP_KERNEL);
*mnt_opts = opts;
if (!opts)
return -ENOMEM;
}
opts->num_mnt_opts = 0;
@ -1094,7 +1116,7 @@ static int selinux_parse_opts_str(char *options,
return 0;
out_err:
security_free_mnt_opts(opts);
security_free_mnt_opts(mnt_opts);
kfree(context);
kfree(defcontext);
kfree(fscontext);
@ -2714,7 +2736,7 @@ static int selinux_sb_copy_data(char *orig, char *copy)
return rc;
}
static int selinux_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts)
static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
{
char *s = (char *)get_zeroed_page(GFP_KERNEL);
int err;
@ -2723,14 +2745,14 @@ static int selinux_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts
return -ENOMEM;
err = selinux_sb_copy_data(options, s);
if (!err)
err = selinux_parse_opts_str(s, opts);
err = selinux_parse_opts_str(s, mnt_opts);
free_page((unsigned long)s);
return err;
}
static int selinux_sb_remount(struct super_block *sb,
struct security_mnt_opts *opts)
static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
{
struct security_mnt_opts *opts = mnt_opts;
int i, *flags;
char **mount_options;
struct superblock_security_struct *sbsec = sb->s_security;
@ -2738,6 +2760,9 @@ static int selinux_sb_remount(struct super_block *sb,
if (!(sbsec->flags & SE_SBINITIALIZED))
return 0;
if (!opts)
return 0;
mount_options = opts->mnt_opts;
flags = opts->mnt_opts_flags;
@ -6782,6 +6807,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_alloc_security, selinux_sb_alloc_security),
LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
LSM_HOOK_INIT(sb_eat_lsm_opts, selinux_sb_eat_lsm_opts),
LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),
@ -7051,11 +7077,7 @@ static __init int selinux_init(void)
static void delayed_superblock_init(struct super_block *sb, void *unused)
{
struct security_mnt_opts opts;
security_init_mnt_opts(&opts);
selinux_set_mnt_opts(sb, &opts, 0, NULL);
security_free_mnt_opts(&opts);
selinux_set_mnt_opts(sb, NULL, 0, NULL);
}
void selinux_complete_init(void)

38
security/smack/smack_lsm.c
View File

@ -567,6 +567,19 @@ static void smack_sb_free_security(struct super_block *sb)
sb->s_security = NULL;
}
static void smack_free_mnt_opts(void *mnt_opts)
{
struct security_mnt_opts *opts = mnt_opts;
int i;
if (opts->mnt_opts)
for (i = 0; i < opts->num_mnt_opts; i++)
kfree(opts->mnt_opts[i]);
kfree(opts->mnt_opts);
kfree(opts->mnt_opts_flags);
kfree(opts);
}
/**
* smack_sb_copy_data - copy mount options data for processing
* @orig: where to start
@ -624,8 +637,9 @@ static int smack_sb_copy_data(char *orig, char *smackopts)
* converts Smack specific mount options to generic security option format
*/
static int smack_parse_opts_str(char *options,
struct security_mnt_opts *opts)
void **mnt_opts)
{
struct security_mnt_opts *opts = *mnt_opts;
char *p;
char *fsdefault = NULL;
char *fsfloor = NULL;
@ -636,11 +650,17 @@ static int smack_parse_opts_str(char *options,
int num_mnt_opts = 0;
int token;
opts->num_mnt_opts = 0;
if (!options)
return 0;
if (!opts) {
opts = kzalloc(sizeof(struct security_mnt_opts), GFP_KERNEL);
*mnt_opts = opts;
if (!opts)
return -ENOMEM;
}
opts->num_mnt_opts = 0;
while ((p = strsep(&options, ",")) != NULL) {
substring_t args[MAX_OPT_ARGS];
@ -735,11 +755,11 @@ static int smack_parse_opts_str(char *options,
kfree(fshat);
kfree(fsroot);
kfree(fstransmute);
security_free_mnt_opts(opts);
security_free_mnt_opts(mnt_opts);
return rc;
}
static int smack_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts)
static int smack_sb_eat_lsm_opts(char *options, void **mnt_opts)
{
char *s = (char *)get_zeroed_page(GFP_KERNEL);
int err;
@ -748,7 +768,7 @@ static int smack_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts)
return -ENOMEM;
err = smack_sb_copy_data(options, s);
if (!err)
err = smack_parse_opts_str(s, opts);
err = smack_parse_opts_str(s, mnt_opts);
free_page((unsigned long)s);
return err;
}
@ -766,7 +786,7 @@ static int smack_sb_eat_lsm_opts(char *options, struct security_mnt_opts *opts)
* labels.
*/
static int smack_set_mnt_opts(struct super_block *sb,
struct security_mnt_opts *opts,
void *mnt_opts,
unsigned long kern_flags,
unsigned long *set_kern_flags)
{
@ -776,7 +796,8 @@ static int smack_set_mnt_opts(struct super_block *sb,
struct inode_smack *isp;
struct smack_known *skp;
int i;
int num_opts = opts->num_mnt_opts;
struct security_mnt_opts *opts = mnt_opts;
int num_opts = opts ? opts->num_mnt_opts : 0;
int transmute = 0;
if (sp->smk_flags & SMK_SB_INITIALIZED)
@ -4651,6 +4672,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_alloc_security, smack_sb_alloc_security),
LSM_HOOK_INIT(sb_free_security, smack_sb_free_security),
LSM_HOOK_INIT(sb_free_mnt_opts, smack_free_mnt_opts),
LSM_HOOK_INIT(sb_eat_lsm_opts, smack_sb_eat_lsm_opts),
LSM_HOOK_INIT(sb_statfs, smack_sb_statfs),
LSM_HOOK_INIT(sb_set_mnt_opts, smack_set_mnt_opts),