1 files changed, 696 insertions, 0 deletions

diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c
new file mode 100644
index 000000000000..82a64b58041d
--- /dev/null
+++ b/security/apparmor/mount.c
@@ -0,0 +1,696 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor mediation of files
+ *
+ * Copyright (C) 1998-2008 Novell/SUSE
+ * Copyright 2009-2017 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+
+#include "include/apparmor.h"
+#include "include/audit.h"
+#include "include/context.h"
+#include "include/domain.h"
+#include "include/file.h"
+#include "include/match.h"
+#include "include/mount.h"
+#include "include/path.h"
+#include "include/policy.h"
+
+
+static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags)
+{
+        if (flags & MS_RDONLY)
+                audit_log_format(ab, "ro");
+        else
+                audit_log_format(ab, "rw");
+        if (flags & MS_NOSUID)
+                audit_log_format(ab, ", nosuid");
+        if (flags & MS_NODEV)
+                audit_log_format(ab, ", nodev");
+        if (flags & MS_NOEXEC)
+                audit_log_format(ab, ", noexec");
+        if (flags & MS_SYNCHRONOUS)
+                audit_log_format(ab, ", sync");
+        if (flags & MS_REMOUNT)
+                audit_log_format(ab, ", remount");
+        if (flags & MS_MANDLOCK)
+                audit_log_format(ab, ", mand");
+        if (flags & MS_DIRSYNC)
+                audit_log_format(ab, ", dirsync");
+        if (flags & MS_NOATIME)
+                audit_log_format(ab, ", noatime");
+        if (flags & MS_NODIRATIME)
+                audit_log_format(ab, ", nodiratime");
+        if (flags & MS_BIND)
+                audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind");
+        if (flags & MS_MOVE)
+                audit_log_format(ab, ", move");
+        if (flags & MS_SILENT)
+                audit_log_format(ab, ", silent");
+        if (flags & MS_POSIXACL)
+                audit_log_format(ab, ", acl");
+        if (flags & MS_UNBINDABLE)
+                audit_log_format(ab, flags & MS_REC ? ", runbindable" :
+                                 ", unbindable");
+        if (flags & MS_PRIVATE)
+                audit_log_format(ab, flags & MS_REC ? ", rprivate" :
+                                 ", private");
+        if (flags & MS_SLAVE)
+                audit_log_format(ab, flags & MS_REC ? ", rslave" :
+                                 ", slave");
+        if (flags & MS_SHARED)
+                audit_log_format(ab, flags & MS_REC ? ", rshared" :
+                                 ", shared");
+        if (flags & MS_RELATIME)
+                audit_log_format(ab, ", relatime");
+        if (flags & MS_I_VERSION)
+                audit_log_format(ab, ", iversion");
+        if (flags & MS_STRICTATIME)
+                audit_log_format(ab, ", strictatime");
+        if (flags & MS_NOUSER)
+                audit_log_format(ab, ", nouser");
+}
+
+/**
+ * audit_cb - call back for mount specific audit fields
+ * @ab: audit_buffer  (NOT NULL)
+ * @va: audit struct to audit values of  (NOT NULL)
+ */
+static void audit_cb(struct audit_buffer *ab, void *va)
+{
+        struct common_audit_data *sa = va;
+
+        if (aad(sa)->mnt.type) {
+                audit_log_format(ab, " fstype=");
+                audit_log_untrustedstring(ab, aad(sa)->mnt.type);
+        }
+        if (aad(sa)->mnt.src_name) {
+                audit_log_format(ab, " srcname=");
+                audit_log_untrustedstring(ab, aad(sa)->mnt.src_name);
+        }
+        if (aad(sa)->mnt.trans) {
+                audit_log_format(ab, " trans=");
+                audit_log_untrustedstring(ab, aad(sa)->mnt.trans);
+        }
+        if (aad(sa)->mnt.flags) {
+                audit_log_format(ab, " flags=\"");
+                audit_mnt_flags(ab, aad(sa)->mnt.flags);
+                audit_log_format(ab, "\"");
+        }
+        if (aad(sa)->mnt.data) {
+                audit_log_format(ab, " options=");
+                audit_log_untrustedstring(ab, aad(sa)->mnt.data);
+        }
+}
+
+/**
+ * audit_mount - handle the auditing of mount operations
+ * @profile: the profile being enforced  (NOT NULL)
+ * @op: operation being mediated (NOT NULL)
+ * @name: name of object being mediated (MAYBE NULL)
+ * @src_name: src_name of object being mediated (MAYBE_NULL)
+ * @type: type of filesystem (MAYBE_NULL)
+ * @trans: name of trans (MAYBE NULL)
+ * @flags: filesystem idependent mount flags
+ * @data: filesystem mount flags
+ * @request: permissions requested
+ * @perms: the permissions computed for the request (NOT NULL)
+ * @info: extra information message (MAYBE NULL)
+ * @error: 0 if operation allowed else failure error code
+ *
+ * Returns: %0 or error on failure
+ */
+static int audit_mount(struct aa_profile *profile, const char *op,
+                       const char *name, const char *src_name,
+                       const char *type, const char *trans,
+                       unsigned long flags, const void *data, u32 request,
+                       struct aa_perms *perms, const char *info, int error)
+{
+        int audit_type = AUDIT_APPARMOR_AUTO;
+        DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, op);
+
+        if (likely(!error)) {
+                u32 mask = perms->audit;
+
+                if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
+                        mask = 0xffff;
+
+                /* mask off perms that are not being force audited */
+                request &= mask;
+
+                if (likely(!request))
+                        return 0;
+                audit_type = AUDIT_APPARMOR_AUDIT;
+        } else {
+                /* only report permissions that were denied */
+                request = request & ~perms->allow;
+
+                if (request & perms->kill)
+                        audit_type = AUDIT_APPARMOR_KILL;
+
+                /* quiet known rejects, assumes quiet and kill do not overlap */
+                if ((request & perms->quiet) &&
+                    AUDIT_MODE(profile) != AUDIT_NOQUIET &&
+                    AUDIT_MODE(profile) != AUDIT_ALL)
+                        request &= ~perms->quiet;
+
+                if (!request)
+                        return error;
+        }
+
+        aad(&sa)->name = name;
+        aad(&sa)->mnt.src_name = src_name;
+        aad(&sa)->mnt.type = type;
+        aad(&sa)->mnt.trans = trans;
+        aad(&sa)->mnt.flags = flags;
+        if (data && (perms->audit & AA_AUDIT_DATA))
+                aad(&sa)->mnt.data = data;
+        aad(&sa)->info = info;
+        aad(&sa)->error = error;
+
+        return aa_audit(audit_type, profile, &sa, audit_cb);
+}
+
+/**
+ * match_mnt_flags - Do an ordered match on mount flags
+ * @dfa: dfa to match against
+ * @state: state to start in
+ * @flags: mount flags to match against
+ *
+ * Mount flags are encoded as an ordered match. This is done instead of
+ * checking against a simple bitmask, to allow for logical operations
+ * on the flags.
+ *
+ * Returns: next state after flags match
+ */
+static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state,
+                                    unsigned long flags)
+{
+        unsigned int i;
+
+        for (i = 0; i <= 31 ; ++i) {
+                if ((1 << i) & flags)
+                        state = aa_dfa_next(dfa, state, i + 1);
+        }
+
+        return state;
+}
+
+/**
+ * compute_mnt_perms - compute mount permission associated with @state
+ * @dfa: dfa to match against (NOT NULL)
+ * @state: state match finished in
+ *
+ * Returns: mount permissions
+ */
+static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa,
+                                           unsigned int state)
+{
+        struct aa_perms perms;
+
+        perms.kill = 0;
+        perms.allow = dfa_user_allow(dfa, state);
+        perms.audit = dfa_user_audit(dfa, state);
+        perms.quiet = dfa_user_quiet(dfa, state);
+        perms.xindex = dfa_user_xindex(dfa, state);
+
+        return perms;
+}
+
+static const char * const mnt_info_table[] = {
+        "match succeeded",
+        "failed mntpnt match",
+        "failed srcname match",
+        "failed type match",
+        "failed flags match",
+        "failed data match"
+};
+
+/*
+ * Returns 0 on success else element that match failed in, this is the
+ * index into the mnt_info_table above
+ */
+static int do_match_mnt(struct aa_dfa *dfa, unsigned int start,
+                        const char *mntpnt, const char *devname,
+                        const char *type, unsigned long flags,
+                        void *data, bool binary, struct aa_perms *perms)
+{
+        unsigned int state;
+
+        AA_BUG(!dfa);
+        AA_BUG(!perms);
+
+        state = aa_dfa_match(dfa, start, mntpnt);
+        state = aa_dfa_null_transition(dfa, state);
+        if (!state)
+                return 1;
+
+        if (devname)
+                state = aa_dfa_match(dfa, state, devname);
+        state = aa_dfa_null_transition(dfa, state);
+        if (!state)
+                return 2;
+
+        if (type)
+                state = aa_dfa_match(dfa, state, type);
+        state = aa_dfa_null_transition(dfa, state);
+        if (!state)
+                return 3;
+
+        state = match_mnt_flags(dfa, state, flags);
+        if (!state)
+                return 4;
+        *perms = compute_mnt_perms(dfa, state);
+        if (perms->allow & AA_MAY_MOUNT)
+                return 0;
+
+        /* only match data if not binary and the DFA flags data is expected */
+        if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) {
+                state = aa_dfa_null_transition(dfa, state);
+                if (!state)
+                        return 4;
+
+                state = aa_dfa_match(dfa, state, data);
+                if (!state)
+                        return 5;
+                *perms = compute_mnt_perms(dfa, state);
+                if (perms->allow & AA_MAY_MOUNT)
+                        return 0;
+        }
+
+        /* failed at end of flags match */
+        return 4;
+}
+
+
+static int path_flags(struct aa_profile *profile, const struct path *path)
+{
+        AA_BUG(!profile);
+        AA_BUG(!path);
+
+        return profile->path_flags |
+                (S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0);
+}
+
+/**
+ * match_mnt_path_str - handle path matching for mount
+ * @profile: the confining profile
+ * @mntpath: for the mntpnt (NOT NULL)
+ * @buffer: buffer to be used to lookup mntpath
+ * @devnme: string for the devname/src_name (MAY BE NULL OR ERRPTR)
+ * @type: string for the dev type (MAYBE NULL)
+ * @flags: mount flags to match
+ * @data: fs mount data (MAYBE NULL)
+ * @binary: whether @data is binary
+ * @devinfo: error str if (IS_ERR(@devname))
+ *
+ * Returns: 0 on success else error
+ */
+static int match_mnt_path_str(struct aa_profile *profile,
+                              const struct path *mntpath, char *buffer,
+                              const char *devname, const char *type,
+                              unsigned long flags, void *data, bool binary,
+                              const char *devinfo)
+{
+        struct aa_perms perms = { };
+        const char *mntpnt = NULL, *info = NULL;
+        int pos, error;
+
+        AA_BUG(!profile);
+        AA_BUG(!mntpath);
+        AA_BUG(!buffer);
+
+        error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer,
+                             &mntpnt, &info, profile->disconnected);
+        if (error)
+                goto audit;
+        if (IS_ERR(devname)) {
+                error = PTR_ERR(devname);
+                devname = NULL;
+                info = devinfo;
+                goto audit;
+        }
+
+        error = -EACCES;
+        pos = do_match_mnt(profile->policy.dfa,
+                           profile->policy.start[AA_CLASS_MOUNT],
+                           mntpnt, devname, type, flags, data, binary, &perms);
+        if (pos) {
+                info = mnt_info_table[pos];
+                goto audit;
+        }
+        error = 0;
+
+audit:
+        return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL,
+                           flags, data, AA_MAY_MOUNT, &perms, info, error);
+}
+
+/**
+ * match_mnt - handle path matching for mount
+ * @profile: the confining profile
+ * @mntpath: for the mntpnt (NOT NULL)
+ * @buffer: buffer to be used to lookup mntpath
+ * @devpath: path devname/src_name (MAYBE NULL)
+ * @devbuffer: buffer to be used to lookup devname/src_name
+ * @type: string for the dev type (MAYBE NULL)
+ * @flags: mount flags to match
+ * @data: fs mount data (MAYBE NULL)
+ * @binary: whether @data is binary
+ *
+ * Returns: 0 on success else error
+ */
+static int match_mnt(struct aa_profile *profile, const struct path *path,
+                     char *buffer, struct path *devpath, char *devbuffer,
+                     const char *type, unsigned long flags, void *data,
+                     bool binary)
+{
+        const char *devname = NULL, *info = NULL;
+        int error = -EACCES;
+
+        AA_BUG(!profile);
+        AA_BUG(devpath && !devbuffer);
+
+        if (devpath) {
+                error = aa_path_name(devpath, path_flags(profile, devpath),
+                                     devbuffer, &devname, &info,
+                                     profile->disconnected);
+                if (error)
+                        devname = ERR_PTR(error);
+        }
+
+        return match_mnt_path_str(profile, path, buffer, devname, type, flags,
+                                  data, binary, info);
+}
+
+int aa_remount(struct aa_label *label, const struct path *path,
+               unsigned long flags, void *data)
+{
+        struct aa_profile *profile;
+        char *buffer = NULL;
+        bool binary;
+        int error;
+
+        AA_BUG(!label);
+        AA_BUG(!path);
+
+        binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA;
+
+        get_buffers(buffer);
+        error = fn_for_each_confined(label, profile,
+                        match_mnt(profile, path, buffer, NULL, NULL, NULL,
+                                  flags, data, binary));
+        put_buffers(buffer);
+
+        return error;
+}
+
+int aa_bind_mount(struct aa_label *label, const struct path *path,
+                  const char *dev_name, unsigned long flags)
+{
+        struct aa_profile *profile;
+        char *buffer = NULL, *old_buffer = NULL;
+        struct path old_path;
+        int error;
+
+        AA_BUG(!label);
+        AA_BUG(!path);
+
+        if (!dev_name || !*dev_name)
+                return -EINVAL;
+
+        flags &= MS_REC | MS_BIND;
+
+        error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
+        if (error)
+                return error;
+
+        get_buffers(buffer, old_buffer);
+        error = fn_for_each_confined(label, profile,
+                        match_mnt(profile, path, buffer, &old_path, old_buffer,
+                                  NULL, flags, NULL, false));
+        put_buffers(buffer, old_buffer);
+        path_put(&old_path);
+
+        return error;
+}
+
+int aa_mount_change_type(struct aa_label *label, const struct path *path,
+                         unsigned long flags)
+{
+        struct aa_profile *profile;
+        char *buffer = NULL;
+        int error;
+
+        AA_BUG(!label);
+        AA_BUG(!path);
+
+        /* These are the flags allowed by do_change_type() */
+        flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE |
+                  MS_UNBINDABLE);
+
+        get_buffers(buffer);
+        error = fn_for_each_confined(label, profile,
+                        match_mnt(profile, path, buffer, NULL, NULL, NULL,
+                                  flags, NULL, false));
+        put_buffers(buffer);
+
+        return error;
+}
+
+int aa_move_mount(struct aa_label *label, const struct path *path,
+                  const char *orig_name)
+{
+        struct aa_profile *profile;
+        char *buffer = NULL, *old_buffer = NULL;
+        struct path old_path;
+        int error;
+
+        AA_BUG(!label);
+        AA_BUG(!path);
+
+        if (!orig_name || !*orig_name)
+                return -EINVAL;
+
+        error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path);
+        if (error)
+                return error;
+
+        get_buffers(buffer, old_buffer);
+        error = fn_for_each_confined(label, profile,
+                        match_mnt(profile, path, buffer, &old_path, old_buffer,
+                                  NULL, MS_MOVE, NULL, false));
+        put_buffers(buffer, old_buffer);
+        path_put(&old_path);
+
+        return error;
+}
+
+int aa_new_mount(struct aa_label *label, const char *dev_name,
+                 const struct path *path, const char *type, unsigned long flags,
+                 void *data)
+{
+        struct aa_profile *profile;
+        char *buffer = NULL, *dev_buffer = NULL;
+        bool binary = true;
+        int error;
+        int requires_dev = 0;
+        struct path tmp_path, *dev_path = NULL;
+
+        AA_BUG(!label);
+        AA_BUG(!path);
+
+        if (type) {
+                struct file_system_type *fstype;
+
+                fstype = get_fs_type(type);
+                if (!fstype)
+                        return -ENODEV;
+                binary = fstype->fs_flags & FS_BINARY_MOUNTDATA;
+                requires_dev = fstype->fs_flags & FS_REQUIRES_DEV;
+                put_filesystem(fstype);
+
+                if (requires_dev) {
+                        if (!dev_name || !*dev_name)
+                                return -ENOENT;
+
+                        error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path);
+                        if (error)
+                                return error;
+                        dev_path = &tmp_path;
+                }
+        }
+
+        get_buffers(buffer, dev_buffer);
+        if (dev_path) {
+                error = fn_for_each_confined(label, profile,
+                        match_mnt(profile, path, buffer, dev_path, dev_buffer,
+                                  type, flags, data, binary));
+        } else {
+                error = fn_for_each_confined(label, profile,
+                        match_mnt_path_str(profile, path, buffer, dev_name,
+                                           type, flags, data, binary, NULL));
+        }
+        put_buffers(buffer, dev_buffer);
+        if (dev_path)
+                path_put(dev_path);
+
+        return error;
+}
+
+static int profile_umount(struct aa_profile *profile, struct path *path,
+                          char *buffer)
+{
+        struct aa_perms perms = { };
+        const char *name = NULL, *info = NULL;
+        unsigned int state;
+        int error;
+
+        AA_BUG(!profile);
+        AA_BUG(!path);
+
+        error = aa_path_name(path, path_flags(profile, path), buffer, &name,
+                             &info, profile->disconnected);
+        if (error)
+                goto audit;
+
+        state = aa_dfa_match(profile->policy.dfa,
+                             profile->policy.start[AA_CLASS_MOUNT],
+                             name);
+        perms = compute_mnt_perms(profile->policy.dfa, state);
+        if (AA_MAY_UMOUNT & ~perms.allow)
+                error = -EACCES;
+
+audit:
+        return audit_mount(profile, OP_UMOUNT, name, NULL, NULL, NULL, 0, NULL,
+                           AA_MAY_UMOUNT, &perms, info, error);
+}
+
+int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags)
+{
+        struct aa_profile *profile;
+        char *buffer = NULL;
+        int error;
+        struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
+
+        AA_BUG(!label);
+        AA_BUG(!mnt);
+
+        get_buffers(buffer);
+        error = fn_for_each_confined(label, profile,
+                        profile_umount(profile, &path, buffer));
+        put_buffers(buffer);
+
+        return error;
+}
+
+/* helper fn for transition on pivotroot
+ *
+ * Returns: label for transition or ERR_PTR. Does not return NULL
+ */
+static struct aa_label *build_pivotroot(struct aa_profile *profile,
+                                        const struct path *new_path,
+                                        char *new_buffer,
+                                        const struct path *old_path,
+                                        char *old_buffer)
+{
+        const char *old_name, *new_name = NULL, *info = NULL;
+        const char *trans_name = NULL;
+        struct aa_perms perms = { };
+        unsigned int state;
+        int error;
+
+        AA_BUG(!profile);
+        AA_BUG(!new_path);
+        AA_BUG(!old_path);
+
+        if (profile_unconfined(profile))
+                return aa_get_newest_label(&profile->label);
+
+        error = aa_path_name(old_path, path_flags(profile, old_path),
+                             old_buffer, &old_name, &info,
+                             profile->disconnected);
+        if (error)
+                goto audit;
+        error = aa_path_name(new_path, path_flags(profile, new_path),
+                             new_buffer, &new_name, &info,
+                             profile->disconnected);
+        if (error)
+                goto audit;
+
+        error = -EACCES;
+        state = aa_dfa_match(profile->policy.dfa,
+                             profile->policy.start[AA_CLASS_MOUNT],
+                             new_name);
+        state = aa_dfa_null_transition(profile->policy.dfa, state);
+        state = aa_dfa_match(profile->policy.dfa, state, old_name);
+        perms = compute_mnt_perms(profile->policy.dfa, state);
+
+        if (AA_MAY_PIVOTROOT & perms.allow)
+                error = 0;
+
+audit:
+        error = audit_mount(profile, OP_PIVOTROOT, new_name, old_name,
+                            NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT,
+                            &perms, info, error);
+        if (error)
+                return ERR_PTR(error);
+
+        return aa_get_newest_label(&profile->label);
+}
+
+int aa_pivotroot(struct aa_label *label, const struct path *old_path,
+                 const struct path *new_path)
+{
+        struct aa_profile *profile;
+        struct aa_label *target = NULL;
+        char *old_buffer = NULL, *new_buffer = NULL, *info = NULL;
+        int error;
+
+        AA_BUG(!label);
+        AA_BUG(!old_path);
+        AA_BUG(!new_path);
+
+        get_buffers(old_buffer, new_buffer);
+        target = fn_label_build(label, profile, GFP_ATOMIC,
+                        build_pivotroot(profile, new_path, new_buffer,
+                                        old_path, old_buffer));
+        if (!target) {
+                info = "label build failed";
+                error = -ENOMEM;
+                goto fail;
+        } else if (!IS_ERR(target)) {
+                error = aa_replace_current_label(target);
+                if (error) {
+                        /* TODO: audit target */
+                        aa_put_label(target);
+                        goto out;
+                }
+        } else
+                /* already audited error */
+                error = PTR_ERR(target);
+out:
+        put_buffers(old_buffer, new_buffer);
+
+        return error;
+
+fail:
+        /* TODO: add back in auditing of new_name and old_name */
+        error = fn_for_each(label, profile,
+                        audit_mount(profile, OP_PIVOTROOT, NULL /*new_name */,
+                                    NULL /* old_name */,
+                                    NULL, NULL,
+                                    0, NULL, AA_MAY_PIVOTROOT, &nullperms, info,
+                                    error));
+        goto out;
+}