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LSM: lift parsing LSM options into the caller of ->sb_kern_mount()
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This paves the way for retaining the LSM options from a common filesystem
mount context during a mount parameter parsing phase to be instituted prior
to actual mount/reconfiguration actions.

Reviewed-by: David Howells <[email protected]>
Signed-off-by: Al Viro <[email protected]>
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Al Viro committed Dec 21, 2018
1 parent 6466f3d commit 6be8750
Showing 6 changed files with 31 additions and 54 deletions.
24 changes: 16 additions & 8 deletions fs/super.c
Original file line number Diff line number Diff line change
@@ -1246,17 +1246,26 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
{
struct dentry *root;
struct super_block *sb;
char *secdata = NULL;
int error = -ENOMEM;
struct security_mnt_opts opts;

security_init_mnt_opts(&opts);

if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
secdata = alloc_secdata();
char *secdata = alloc_secdata();
if (!secdata)
goto out;
return ERR_PTR(-ENOMEM);

error = security_sb_copy_data(data, secdata);
if (error) {
free_secdata(secdata);
return ERR_PTR(error);
}

error = security_sb_parse_opts_str(secdata, &opts);
free_secdata(secdata);
if (error)
goto out_free_secdata;
return ERR_PTR(error);
}

root = type->mount(type, flags, name, data);
@@ -1277,7 +1286,7 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
smp_wmb();
sb->s_flags |= SB_BORN;

error = security_sb_kern_mount(sb, flags, secdata);
error = security_sb_kern_mount(sb, flags, &opts);
if (error)
goto out_sb;

@@ -1291,14 +1300,13 @@ 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);
free_secdata(secdata);
security_free_mnt_opts(&opts);
return root;
out_sb:
dput(root);
deactivate_locked_super(sb);
out_free_secdata:
free_secdata(secdata);
out:
security_free_mnt_opts(&opts);
return ERR_PTR(error);
}

3 changes: 2 additions & 1 deletion include/linux/lsm_hooks.h
Original file line number Diff line number Diff line change
@@ -1463,7 +1463,8 @@ union security_list_options {
void (*sb_free_security)(struct super_block *sb);
int (*sb_copy_data)(char *orig, char *copy);
int (*sb_remount)(struct super_block *sb, void *data);
int (*sb_kern_mount)(struct super_block *sb, int flags, void *data);
int (*sb_kern_mount)(struct super_block *sb, int flags,
struct security_mnt_opts *opts);
int (*sb_show_options)(struct seq_file *m, struct super_block *sb);
int (*sb_statfs)(struct dentry *dentry);
int (*sb_mount)(const char *dev_name, const struct path *path,
6 changes: 4 additions & 2 deletions include/linux/security.h
Original file line number Diff line number Diff line change
@@ -250,7 +250,8 @@ int security_sb_alloc(struct super_block *sb);
void security_sb_free(struct super_block *sb);
int security_sb_copy_data(char *orig, char *copy);
int security_sb_remount(struct super_block *sb, void *data);
int security_sb_kern_mount(struct super_block *sb, int flags, void *data);
int security_sb_kern_mount(struct super_block *sb, int flags,
struct security_mnt_opts *opts);
int security_sb_show_options(struct seq_file *m, struct super_block *sb);
int security_sb_statfs(struct dentry *dentry);
int security_sb_mount(const char *dev_name, const struct path *path,
@@ -565,7 +566,8 @@ static inline int security_sb_remount(struct super_block *sb, void *data)
return 0;
}

static inline int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
static inline int security_sb_kern_mount(struct super_block *sb, int flags,
struct security_mnt_opts *opts)
{
return 0;
}
5 changes: 3 additions & 2 deletions security/security.c
Original file line number Diff line number Diff line change
@@ -395,9 +395,10 @@ int security_sb_remount(struct super_block *sb, void *data)
return call_int_hook(sb_remount, 0, sb, data);
}

int security_sb_kern_mount(struct super_block *sb, int flags, void *data)
int security_sb_kern_mount(struct super_block *sb, int flags,
struct security_mnt_opts *opts)
{
return call_int_hook(sb_kern_mount, 0, sb, flags, data);
return call_int_hook(sb_kern_mount, 0, sb, flags, opts);
}

int security_sb_show_options(struct seq_file *m, struct super_block *sb)
24 changes: 3 additions & 21 deletions security/selinux/hooks.c
Original file line number Diff line number Diff line change
@@ -2897,30 +2897,12 @@ static int selinux_sb_remount(struct super_block *sb, void *data)
goto out_free_opts;
}

static int selinux_sb_kern_mount(struct super_block *sb, int flags, void *data)
static int selinux_sb_kern_mount(struct super_block *sb, int flags,
struct security_mnt_opts *opts)
{
char *options = data;
const struct cred *cred = current_cred();
struct common_audit_data ad;
int rc = 0;
struct security_mnt_opts opts;

security_init_mnt_opts(&opts);

if (!data)
goto out;

BUG_ON(sb->s_type->fs_flags & FS_BINARY_MOUNTDATA);

rc = selinux_parse_opts_str(options, &opts);
if (rc)
goto out_err;

out:
rc = selinux_set_mnt_opts(sb, &opts, 0, NULL);

out_err:
security_free_mnt_opts(&opts);
int rc = selinux_set_mnt_opts(sb, opts, 0, NULL);
if (rc)
return rc;

23 changes: 3 additions & 20 deletions security/smack/smack_lsm.c
Original file line number Diff line number Diff line change
@@ -859,27 +859,10 @@ static int smack_set_mnt_opts(struct super_block *sb,
*
* Returns 0 on success, an error code on failure
*/
static int smack_sb_kern_mount(struct super_block *sb, int flags, void *data)
static int smack_sb_kern_mount(struct super_block *sb, int flags,
struct security_mnt_opts *opts)
{
int rc = 0;
char *options = data;
struct security_mnt_opts opts;

security_init_mnt_opts(&opts);

if (!options)
goto out;

rc = smack_parse_opts_str(options, &opts);
if (rc)
goto out_err;

out:
rc = smack_set_mnt_opts(sb, &opts, 0, NULL);

out_err:
security_free_mnt_opts(&opts);
return rc;
return smack_set_mnt_opts(sb, opts, 0, NULL);
}

/**

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