diff options
Diffstat (limited to 'security/apparmor/mount.c')
| -rw-r--r-- | security/apparmor/mount.c | 741 |
1 files changed, 741 insertions, 0 deletions
diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c new file mode 100644 index 000000000..e64f76d34 --- /dev/null +++ b/security/apparmor/mount.c @@ -0,0 +1,741 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * AppArmor security module + * + * This file contains AppArmor mediation of files + * + * Copyright (C) 1998-2008 Novell/SUSE + * Copyright 2009-2017 Canonical Ltd. + */ + +#include <linux/fs.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <uapi/linux/mount.h> + +#include "include/apparmor.h" +#include "include/audit.h" +#include "include/cred.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 independent 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 = { + .allow = dfa_user_allow(dfa, state), + .audit = dfa_user_audit(dfa, state), + .quiet = dfa_user_quiet(dfa, state), + .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", + "failed perms check" +}; + +/* + * 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 perms check, don't confuse with flags match */ + return 6; +} + + +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); + + if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) + return 0; + + 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 (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) + return 0; + + 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; + + buffer = aa_get_buffer(false); + if (!buffer) + return -ENOMEM; + error = fn_for_each_confined(label, profile, + match_mnt(profile, path, buffer, NULL, NULL, NULL, + flags, data, binary)); + aa_put_buffer(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; + + buffer = aa_get_buffer(false); + old_buffer = aa_get_buffer(false); + error = -ENOMEM; + if (!buffer || !old_buffer) + goto out; + + error = fn_for_each_confined(label, profile, + match_mnt(profile, path, buffer, &old_path, old_buffer, + NULL, flags, NULL, false)); +out: + aa_put_buffer(buffer); + aa_put_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); + + buffer = aa_get_buffer(false); + if (!buffer) + return -ENOMEM; + error = fn_for_each_confined(label, profile, + match_mnt(profile, path, buffer, NULL, NULL, NULL, + flags, NULL, false)); + aa_put_buffer(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; + + buffer = aa_get_buffer(false); + old_buffer = aa_get_buffer(false); + error = -ENOMEM; + if (!buffer || !old_buffer) + goto out; + error = fn_for_each_confined(label, profile, + match_mnt(profile, path, buffer, &old_path, old_buffer, + NULL, MS_MOVE, NULL, false)); +out: + aa_put_buffer(buffer); + aa_put_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; + } + } + + buffer = aa_get_buffer(false); + if (!buffer) { + error = -ENOMEM; + goto out; + } + if (dev_path) { + dev_buffer = aa_get_buffer(false); + if (!dev_buffer) { + error = -ENOMEM; + goto out; + } + 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)); + } + +out: + aa_put_buffer(buffer); + aa_put_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); + + if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) + return 0; + + 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); + + buffer = aa_get_buffer(false); + if (!buffer) + return -ENOMEM; + + error = fn_for_each_confined(label, profile, + profile_umount(profile, &path, buffer)); + aa_put_buffer(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) || + !PROFILE_MEDIATES(profile, AA_CLASS_MOUNT)) + 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); + + old_buffer = aa_get_buffer(false); + new_buffer = aa_get_buffer(false); + error = -ENOMEM; + if (!old_buffer || !new_buffer) + goto out; + target = fn_label_build(label, profile, GFP_KERNEL, + 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; + } + aa_put_label(target); + } else + /* already audited error */ + error = PTR_ERR(target); +out: + aa_put_buffer(old_buffer); + aa_put_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; +} |