diff options
Diffstat (limited to 'security/apparmor/file.c')
| -rw-r--r-- | security/apparmor/file.c | 752 |
1 files changed, 511 insertions, 241 deletions
diff --git a/security/apparmor/file.c b/security/apparmor/file.c index fdaa50cb1876..c75820402878 100644 --- a/security/apparmor/file.c +++ b/security/apparmor/file.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * AppArmor security module * @@ -5,56 +6,35 @@ * * Copyright (C) 1998-2008 Novell/SUSE * Copyright 2009-2010 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/tty.h> +#include <linux/fdtable.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/mount.h> + +#include "include/af_unix.h" #include "include/apparmor.h" #include "include/audit.h" +#include "include/cred.h" #include "include/file.h" #include "include/match.h" +#include "include/net.h" #include "include/path.h" #include "include/policy.h" +#include "include/label.h" -struct file_perms nullperms; - - -/** - * audit_file_mask - convert mask to permission string - * @buffer: buffer to write string to (NOT NULL) - * @mask: permission mask to convert - */ -static void audit_file_mask(struct audit_buffer *ab, u32 mask) +static u32 map_mask_to_chr_mask(u32 mask) { - char str[10]; + u32 m = mask & PERMS_CHRS_MASK; + + if (mask & AA_MAY_GETATTR) + m |= MAY_READ; + if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN)) + m |= MAY_WRITE; - char *m = str; - - if (mask & AA_EXEC_MMAP) - *m++ = 'm'; - if (mask & (MAY_READ | AA_MAY_META_READ)) - *m++ = 'r'; - if (mask & (MAY_WRITE | AA_MAY_META_WRITE | AA_MAY_CHMOD | - AA_MAY_CHOWN)) - *m++ = 'w'; - else if (mask & MAY_APPEND) - *m++ = 'a'; - if (mask & AA_MAY_CREATE) - *m++ = 'c'; - if (mask & AA_MAY_DELETE) - *m++ = 'd'; - if (mask & AA_MAY_LINK) - *m++ = 'l'; - if (mask & AA_MAY_LOCK) - *m++ = 'k'; - if (mask & MAY_EXEC) - *m++ = 'x'; - *m = '\0'; - - audit_log_string(ab, str); + return m; } /** @@ -65,209 +45,226 @@ static void audit_file_mask(struct audit_buffer *ab, u32 mask) static void file_audit_cb(struct audit_buffer *ab, void *va) { struct common_audit_data *sa = va; - kuid_t fsuid = current_fsuid(); + struct apparmor_audit_data *ad = aad(sa); + kuid_t fsuid = ad->subj_cred ? ad->subj_cred->fsuid : current_fsuid(); + char str[10]; - if (sa->aad->fs.request & AA_AUDIT_FILE_MASK) { - audit_log_format(ab, " requested_mask="); - audit_file_mask(ab, sa->aad->fs.request); + if (ad->request & AA_AUDIT_FILE_MASK) { + aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs, + map_mask_to_chr_mask(ad->request)); + audit_log_format(ab, " requested_mask=\"%s\"", str); } - if (sa->aad->fs.denied & AA_AUDIT_FILE_MASK) { - audit_log_format(ab, " denied_mask="); - audit_file_mask(ab, sa->aad->fs.denied); + if (ad->denied & AA_AUDIT_FILE_MASK) { + aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs, + map_mask_to_chr_mask(ad->denied)); + audit_log_format(ab, " denied_mask=\"%s\"", str); } - if (sa->aad->fs.request & AA_AUDIT_FILE_MASK) { + if (ad->request & AA_AUDIT_FILE_MASK) { audit_log_format(ab, " fsuid=%d", from_kuid(&init_user_ns, fsuid)); audit_log_format(ab, " ouid=%d", - from_kuid(&init_user_ns, sa->aad->fs.ouid)); + from_kuid(&init_user_ns, ad->fs.ouid)); } - if (sa->aad->fs.target) { + if (ad->peer) { + audit_log_format(ab, " target="); + aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer, + FLAG_VIEW_SUBNS, GFP_KERNEL); + } else if (ad->fs.target) { audit_log_format(ab, " target="); - audit_log_untrustedstring(ab, sa->aad->fs.target); + audit_log_untrustedstring(ab, ad->fs.target); } } /** * aa_audit_file - handle the auditing of file operations + * @subj_cred: cred of the subject * @profile: the profile being enforced (NOT NULL) * @perms: the permissions computed for the request (NOT NULL) - * @gfp: allocation flags * @op: operation being mediated * @request: permissions requested * @name: name of object being mediated (MAYBE NULL) * @target: name of target (MAYBE NULL) + * @tlabel: target label (MAY BE NULL) * @ouid: object uid * @info: extra information message (MAYBE NULL) * @error: 0 if operation allowed else failure error code * * Returns: %0 or error on failure */ -int aa_audit_file(struct aa_profile *profile, struct file_perms *perms, - gfp_t gfp, int op, u32 request, const char *name, - const char *target, kuid_t ouid, const char *info, int error) +int aa_audit_file(const struct cred *subj_cred, + struct aa_profile *profile, struct aa_perms *perms, + const char *op, u32 request, const char *name, + const char *target, struct aa_label *tlabel, + kuid_t ouid, const char *info, int error) { int type = AUDIT_APPARMOR_AUTO; - struct common_audit_data sa; - struct apparmor_audit_data aad = {0,}; - sa.type = LSM_AUDIT_DATA_NONE; - sa.aad = &aad; - aad.op = op, - aad.fs.request = request; - aad.name = name; - aad.fs.target = target; - aad.fs.ouid = ouid; - aad.info = info; - aad.error = error; - - if (likely(!sa.aad->error)) { + DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_TASK, AA_CLASS_FILE, op); + + ad.subj_cred = subj_cred; + ad.request = request; + ad.name = name; + ad.fs.target = target; + ad.peer = tlabel; + ad.fs.ouid = ouid; + ad.info = info; + ad.error = error; + ad.common.u.tsk = NULL; + + if (likely(!ad.error)) { u32 mask = perms->audit; if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL)) mask = 0xffff; /* mask off perms that are not being force audited */ - sa.aad->fs.request &= mask; + ad.request &= mask; - if (likely(!sa.aad->fs.request)) + if (likely(!ad.request)) return 0; type = AUDIT_APPARMOR_AUDIT; } else { /* only report permissions that were denied */ - sa.aad->fs.request = sa.aad->fs.request & ~perms->allow; + ad.request = ad.request & ~perms->allow; + AA_BUG(!ad.request); - if (sa.aad->fs.request & perms->kill) + if (ad.request & perms->kill) type = AUDIT_APPARMOR_KILL; /* quiet known rejects, assumes quiet and kill do not overlap */ - if ((sa.aad->fs.request & perms->quiet) && + if ((ad.request & perms->quiet) && AUDIT_MODE(profile) != AUDIT_NOQUIET && AUDIT_MODE(profile) != AUDIT_ALL) - sa.aad->fs.request &= ~perms->quiet; + ad.request &= ~perms->quiet; - if (!sa.aad->fs.request) - return COMPLAIN_MODE(profile) ? 0 : sa.aad->error; + if (!ad.request) + return ad.error; } - sa.aad->fs.denied = sa.aad->fs.request & ~perms->allow; - return aa_audit(type, profile, gfp, &sa, file_audit_cb); + ad.denied = ad.request & ~perms->allow; + return aa_audit(type, profile, &ad, file_audit_cb); } -/** - * map_old_perms - map old file perms layout to the new layout - * @old: permission set in old mapping - * - * Returns: new permission mapping - */ -static u32 map_old_perms(u32 old) +static int path_name(const char *op, const struct cred *subj_cred, + struct aa_label *label, + const struct path *path, int flags, char *buffer, + const char **name, struct path_cond *cond, u32 request) { - u32 new = old & 0xf; - if (old & MAY_READ) - new |= AA_MAY_META_READ; - if (old & MAY_WRITE) - new |= AA_MAY_META_WRITE | AA_MAY_CREATE | AA_MAY_DELETE | - AA_MAY_CHMOD | AA_MAY_CHOWN; - if (old & 0x10) - new |= AA_MAY_LINK; - /* the old mapping lock and link_subset flags where overlaid - * and use was determined by part of a pair that they were in - */ - if (old & 0x20) - new |= AA_MAY_LOCK | AA_LINK_SUBSET; - if (old & 0x40) /* AA_EXEC_MMAP */ - new |= AA_EXEC_MMAP; + struct aa_profile *profile; + const char *info = NULL; + int error; - return new; + error = aa_path_name(path, flags, buffer, name, &info, + labels_profile(label)->disconnected); + if (error) { + fn_for_each_confined(label, profile, + aa_audit_file(subj_cred, + profile, &nullperms, op, request, *name, + NULL, NULL, cond->uid, info, error)); + return error; + } + + return 0; } +struct aa_perms default_perms = {}; /** - * compute_perms - convert dfa compressed perms to internal perms - * @dfa: dfa to compute perms for (NOT NULL) + * aa_lookup_condperms - convert dfa compressed perms to internal perms + * @subj_uid: uid to use for subject owner test + * @rules: the aa_policydb to lookup perms for (NOT NULL) * @state: state in dfa * @cond: conditions to consider (NOT NULL) * - * TODO: convert from dfa + state to permission entry, do computation conversion - * at load time. + * TODO: convert from dfa + state to permission entry * - * Returns: computed permission set + * Returns: a pointer to a file permission set */ -static struct file_perms compute_perms(struct aa_dfa *dfa, unsigned int state, - struct path_cond *cond) +struct aa_perms *aa_lookup_condperms(kuid_t subj_uid, struct aa_policydb *rules, + aa_state_t state, struct path_cond *cond) { - struct file_perms perms; + unsigned int index = ACCEPT_TABLE(rules->dfa)[state]; - /* FIXME: change over to new dfa format - * currently file perms are encoded in the dfa, new format - * splits the permissions from the dfa. This mapping can be - * done at profile load - */ - perms.kill = 0; + if (!(rules->perms)) + return &default_perms; - if (uid_eq(current_fsuid(), cond->uid)) { - perms.allow = map_old_perms(dfa_user_allow(dfa, state)); - perms.audit = map_old_perms(dfa_user_audit(dfa, state)); - perms.quiet = map_old_perms(dfa_user_quiet(dfa, state)); - perms.xindex = dfa_user_xindex(dfa, state); - } else { - perms.allow = map_old_perms(dfa_other_allow(dfa, state)); - perms.audit = map_old_perms(dfa_other_audit(dfa, state)); - perms.quiet = map_old_perms(dfa_other_quiet(dfa, state)); - perms.xindex = dfa_other_xindex(dfa, state); + if ((ACCEPT_TABLE2(rules->dfa)[state] & ACCEPT_FLAG_OWNER)) { + if (uid_eq(subj_uid, cond->uid)) + return &(rules->perms[index]); + return &(rules->perms[index + 1]); } - perms.allow |= AA_MAY_META_READ; - - /* change_profile wasn't determined by ownership in old mapping */ - if (ACCEPT_TABLE(dfa)[state] & 0x80000000) - perms.allow |= AA_MAY_CHANGE_PROFILE; - if (ACCEPT_TABLE(dfa)[state] & 0x40000000) - perms.allow |= AA_MAY_ONEXEC; - return perms; + return &(rules->perms[index]); } /** * aa_str_perms - find permission that match @name - * @dfa: to match against (MAYBE NULL) - * @state: state to start matching in + * @file_rules: the aa_policydb to match against (NOT NULL) + * @start: state to start matching in * @name: string to match against dfa (NOT NULL) * @cond: conditions to consider for permission set computation (NOT NULL) * @perms: Returns - the permissions found when matching @name * * Returns: the final state in @dfa when beginning @start and walking @name */ -unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start, - const char *name, struct path_cond *cond, - struct file_perms *perms) +aa_state_t aa_str_perms(struct aa_policydb *file_rules, aa_state_t start, + const char *name, struct path_cond *cond, + struct aa_perms *perms) { - unsigned int state; - if (!dfa) { - *perms = nullperms; - return DFA_NOMATCH; - } - - state = aa_dfa_match(dfa, start, name); - *perms = compute_perms(dfa, state, cond); + aa_state_t state; + state = aa_dfa_match(file_rules->dfa, start, name); + *perms = *(aa_lookup_condperms(current_fsuid(), file_rules, state, + cond)); return state; } -/** - * is_deleted - test if a file has been completely unlinked - * @dentry: dentry of file to test for deletion (NOT NULL) - * - * Returns: %1 if deleted else %0 - */ -static inline bool is_deleted(struct dentry *dentry) +int __aa_path_perm(const char *op, const struct cred *subj_cred, + struct aa_profile *profile, const char *name, + u32 request, struct path_cond *cond, int flags, + struct aa_perms *perms) { - if (d_unlinked(dentry) && dentry->d_inode->i_nlink == 0) - return 1; - return 0; + struct aa_ruleset *rules = profile->label.rules[0]; + int e = 0; + + if (profile_unconfined(profile) || + ((flags & PATH_SOCK_COND) && !RULE_MEDIATES_v9NET(rules))) + return 0; + aa_str_perms(rules->file, rules->file->start[AA_CLASS_FILE], + name, cond, perms); + if (request & ~perms->allow) + e = -EACCES; + return aa_audit_file(subj_cred, + profile, perms, op, request, name, NULL, NULL, + cond->uid, NULL, e); +} + + +static int profile_path_perm(const char *op, const struct cred *subj_cred, + struct aa_profile *profile, + const struct path *path, char *buffer, u32 request, + struct path_cond *cond, int flags, + struct aa_perms *perms) +{ + const char *name; + int error; + + if (profile_unconfined(profile)) + return 0; + + error = path_name(op, subj_cred, &profile->label, path, + flags | profile->path_flags, buffer, &name, cond, + request); + if (error) + return error; + return __aa_path_perm(op, subj_cred, profile, name, request, cond, + flags, perms); } /** * aa_path_perm - do permissions check & audit for @path * @op: operation being checked - * @profile: profile being enforced (NOT NULL) + * @subj_cred: subject cred + * @label: profile being enforced (NOT NULL) * @path: path to check permissions of (NOT NULL) * @flags: any additional path flags beyond what the profile specifies * @request: requested permissions @@ -275,34 +272,26 @@ static inline bool is_deleted(struct dentry *dentry) * * Returns: %0 else error if access denied or other error */ -int aa_path_perm(int op, struct aa_profile *profile, struct path *path, - int flags, u32 request, struct path_cond *cond) +int aa_path_perm(const char *op, const struct cred *subj_cred, + struct aa_label *label, + const struct path *path, int flags, u32 request, + struct path_cond *cond) { + struct aa_perms perms = {}; + struct aa_profile *profile; char *buffer = NULL; - struct file_perms perms = {}; - const char *name, *info = NULL; int error; - flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0); - error = aa_path_name(path, flags, &buffer, &name, &info); - if (error) { - if (error == -ENOENT && is_deleted(path->dentry)) { - /* Access to open files that are deleted are - * give a pass (implicit delegation) - */ - error = 0; - info = NULL; - perms.allow = request; - } - } else { - aa_str_perms(profile->file.dfa, profile->file.start, name, cond, - &perms); - if (request & ~perms.allow) - error = -EACCES; - } - error = aa_audit_file(profile, &perms, GFP_KERNEL, op, request, name, - NULL, cond->uid, info, error); - kfree(buffer); + flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR : + 0); + buffer = aa_get_buffer(false); + if (!buffer) + return -ENOMEM; + error = fn_for_each_confined(label, profile, + profile_path_perm(op, subj_cred, profile, path, buffer, + request, cond, flags, &perms)); + + aa_put_buffer(buffer); return error; } @@ -316,76 +305,56 @@ int aa_path_perm(int op, struct aa_profile *profile, struct path *path, * this is done as part of the subset test, where a hardlink must have * a subset of permissions that the target has. * - * Returns: %1 if subset else %0 + * Returns: true if subset else false */ static inline bool xindex_is_subset(u32 link, u32 target) { if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) || ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE))) - return 0; + return false; - return 1; + return true; } -/** - * aa_path_link - Handle hard link permission check - * @profile: the profile being enforced (NOT NULL) - * @old_dentry: the target dentry (NOT NULL) - * @new_dir: directory the new link will be created in (NOT NULL) - * @new_dentry: the link being created (NOT NULL) - * - * Handle the permission test for a link & target pair. Permission - * is encoded as a pair where the link permission is determined - * first, and if allowed, the target is tested. The target test - * is done from the point of the link match (not start of DFA) - * making the target permission dependent on the link permission match. - * - * The subset test if required forces that permissions granted - * on link are a subset of the permission granted to target. - * - * Returns: %0 if allowed else error - */ -int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry, - struct path *new_dir, struct dentry *new_dentry) +static int profile_path_link(const struct cred *subj_cred, + struct aa_profile *profile, + const struct path *link, char *buffer, + const struct path *target, char *buffer2, + struct path_cond *cond) { - struct path link = { new_dir->mnt, new_dentry }; - struct path target = { new_dir->mnt, old_dentry }; - struct path_cond cond = { - old_dentry->d_inode->i_uid, - old_dentry->d_inode->i_mode - }; - char *buffer = NULL, *buffer2 = NULL; - const char *lname, *tname = NULL, *info = NULL; - struct file_perms lperms, perms; + struct aa_ruleset *rules = profile->label.rules[0]; + const char *lname, *tname = NULL; + struct aa_perms lperms = {}, perms; + const char *info = NULL; u32 request = AA_MAY_LINK; - unsigned int state; + aa_state_t state; int error; - lperms = nullperms; - - /* buffer freed below, lname is pointer in buffer */ - error = aa_path_name(&link, profile->path_flags, &buffer, &lname, - &info); + error = path_name(OP_LINK, subj_cred, &profile->label, link, + profile->path_flags, + buffer, &lname, cond, AA_MAY_LINK); if (error) goto audit; /* buffer2 freed below, tname is pointer in buffer2 */ - error = aa_path_name(&target, profile->path_flags, &buffer2, &tname, - &info); + error = path_name(OP_LINK, subj_cred, &profile->label, target, + profile->path_flags, + buffer2, &tname, cond, AA_MAY_LINK); if (error) goto audit; error = -EACCES; /* aa_str_perms - handles the case of the dfa being NULL */ - state = aa_str_perms(profile->file.dfa, profile->file.start, lname, - &cond, &lperms); + state = aa_str_perms(rules->file, + rules->file->start[AA_CLASS_FILE], lname, + cond, &lperms); if (!(lperms.allow & AA_MAY_LINK)) goto audit; /* test to see if target can be paired with link */ - state = aa_dfa_null_transition(profile->file.dfa, state); - aa_str_perms(profile->file.dfa, state, tname, &cond, &perms); + state = aa_dfa_null_transition(rules->file->dfa, state); + aa_str_perms(rules->file, state, tname, cond, &perms); /* force audit/quiet masks for link are stored in the second entry * in the link pair. @@ -396,6 +365,7 @@ int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry, if (!(perms.allow & AA_MAY_LINK)) { info = "target restricted"; + lperms = perms; goto audit; } @@ -403,11 +373,11 @@ int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry, if (!(perms.allow & AA_LINK_SUBSET)) goto done_tests; - /* Do link perm subset test requiring allowed permission on link are a - * subset of the allowed permissions on target. + /* Do link perm subset test requiring allowed permission on link are + * a subset of the allowed permissions on target. */ - aa_str_perms(profile->file.dfa, profile->file.start, tname, &cond, - &perms); + aa_str_perms(rules->file, rules->file->start[AA_CLASS_FILE], + tname, cond, &perms); /* AA_MAY_LINK is not considered in the subset test */ request = lperms.allow & ~AA_MAY_LINK; @@ -428,31 +398,331 @@ done_tests: error = 0; audit: - error = aa_audit_file(profile, &lperms, GFP_KERNEL, OP_LINK, request, - lname, tname, cond.uid, info, error); - kfree(buffer); - kfree(buffer2); + return aa_audit_file(subj_cred, + profile, &lperms, OP_LINK, request, lname, tname, + NULL, cond->uid, info, error); +} + +/** + * aa_path_link - Handle hard link permission check + * @subj_cred: subject cred + * @label: the label being enforced (NOT NULL) + * @old_dentry: the target dentry (NOT NULL) + * @new_dir: directory the new link will be created in (NOT NULL) + * @new_dentry: the link being created (NOT NULL) + * + * Handle the permission test for a link & target pair. Permission + * is encoded as a pair where the link permission is determined + * first, and if allowed, the target is tested. The target test + * is done from the point of the link match (not start of DFA) + * making the target permission dependent on the link permission match. + * + * The subset test if required forces that permissions granted + * on link are a subset of the permission granted to target. + * + * Returns: %0 if allowed else error + */ +int aa_path_link(const struct cred *subj_cred, + struct aa_label *label, struct dentry *old_dentry, + const struct path *new_dir, struct dentry *new_dentry) +{ + struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry }; + struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry }; + struct inode *inode = d_backing_inode(old_dentry); + vfsuid_t vfsuid = i_uid_into_vfsuid(mnt_idmap(target.mnt), inode); + struct path_cond cond = { + .uid = vfsuid_into_kuid(vfsuid), + .mode = inode->i_mode, + }; + char *buffer = NULL, *buffer2 = NULL; + struct aa_profile *profile; + int error; + + /* buffer freed below, lname is pointer in buffer */ + buffer = aa_get_buffer(false); + buffer2 = aa_get_buffer(false); + error = -ENOMEM; + if (!buffer || !buffer2) + goto out; + + error = fn_for_each_confined(label, profile, + profile_path_link(subj_cred, profile, &link, buffer, + &target, buffer2, &cond)); +out: + aa_put_buffer(buffer); + aa_put_buffer(buffer2); + return error; +} + +static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label, + u32 request) +{ + struct aa_label *l, *old; + + /* update caching of label on file_ctx */ + spin_lock(&fctx->lock); + old = rcu_dereference_protected(fctx->label, + lockdep_is_held(&fctx->lock)); + l = aa_label_merge(old, label, GFP_ATOMIC); + if (l) { + if (l != old) { + rcu_assign_pointer(fctx->label, l); + aa_put_label(old); + } else + aa_put_label(l); + fctx->allow |= request; + } + spin_unlock(&fctx->lock); +} + +static int __file_path_perm(const char *op, const struct cred *subj_cred, + struct aa_label *label, + struct aa_label *flabel, struct file *file, + u32 request, u32 denied, bool in_atomic) +{ + struct aa_profile *profile; + struct aa_perms perms = {}; + vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(file), + file_inode(file)); + struct path_cond cond = { + .uid = vfsuid_into_kuid(vfsuid), + .mode = file_inode(file)->i_mode + }; + char *buffer; + int flags, error; + + /* revalidation due to label out of date. No revocation at this time */ + if (!denied && aa_label_is_subset(flabel, label)) + /* TODO: check for revocation on stale profiles */ + return 0; + + flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0); + buffer = aa_get_buffer(in_atomic); + if (!buffer) + return -ENOMEM; + + /* check every profile in task label not in current cache */ + error = fn_for_each_not_in_set(flabel, label, profile, + profile_path_perm(op, subj_cred, profile, + &file->f_path, buffer, + request, &cond, flags, &perms)); + if (denied && !error) { + /* + * check every profile in file label that was not tested + * in the initial check above. + * + * TODO: cache full perms so this only happens because of + * conditionals + * TODO: don't audit here + */ + if (label == flabel) + error = fn_for_each(label, profile, + profile_path_perm(op, subj_cred, + profile, &file->f_path, + buffer, request, &cond, flags, + &perms)); + else + error = fn_for_each_not_in_set(label, flabel, profile, + profile_path_perm(op, subj_cred, + profile, &file->f_path, + buffer, request, &cond, flags, + &perms)); + } + if (!error) + update_file_ctx(file_ctx(file), label, request); + + aa_put_buffer(buffer); return error; } +static int __file_sock_perm(const char *op, const struct cred *subj_cred, + struct aa_label *label, + struct aa_label *flabel, struct file *file, + u32 request, u32 denied) +{ + int error; + + /* revalidation due to label out of date. No revocation at this time */ + if (!denied && aa_label_is_subset(flabel, label)) + return 0; + + /* TODO: improve to skip profiles cached in flabel */ + error = aa_sock_file_perm(subj_cred, label, op, request, file); + if (denied) { + /* TODO: improve to skip profiles checked above */ + /* check every profile in file label to is cached */ + last_error(error, aa_sock_file_perm(subj_cred, flabel, op, + request, file)); + } + if (!error) + update_file_ctx(file_ctx(file), label, request); + + return error; +} + +/* for now separate fn to indicate semantics of the check */ +static bool __file_is_delegated(struct aa_label *obj_label) +{ + return unconfined(obj_label); +} + +static bool __unix_needs_revalidation(struct file *file, struct aa_label *label, + u32 request) +{ + struct socket *sock = (struct socket *) file->private_data; + + lockdep_assert_in_rcu_read_lock(); + + if (!S_ISSOCK(file_inode(file)->i_mode)) + return false; + if (request & NET_PEER_MASK) + return false; + if (sock->sk->sk_family == PF_UNIX) { + struct aa_sk_ctx *ctx = aa_sock(sock->sk); + + if (rcu_access_pointer(ctx->peer) != + rcu_access_pointer(ctx->peer_lastupdate)) + return true; + return !__aa_subj_label_is_cached(rcu_dereference(ctx->label), + label); + } + return false; +} + /** * aa_file_perm - do permission revalidation check & audit for @file * @op: operation being checked - * @profile: profile being enforced (NOT NULL) + * @subj_cred: subject cred + * @label: label being enforced (NOT NULL) * @file: file to revalidate access permissions on (NOT NULL) * @request: requested permissions + * @in_atomic: whether allocations need to be done in atomic context * * Returns: %0 if access allowed else error */ -int aa_file_perm(int op, struct aa_profile *profile, struct file *file, - u32 request) +int aa_file_perm(const char *op, const struct cred *subj_cred, + struct aa_label *label, struct file *file, + u32 request, bool in_atomic) { - struct path_cond cond = { - .uid = file_inode(file)->i_uid, - .mode = file_inode(file)->i_mode - }; + struct aa_file_ctx *fctx; + struct aa_label *flabel; + u32 denied; + int error = 0; + + AA_BUG(!label); + AA_BUG(!file); + + fctx = file_ctx(file); + + rcu_read_lock(); + flabel = rcu_dereference(fctx->label); + AA_BUG(!flabel); + + /* revalidate access, if task is unconfined, or the cached cred + * doesn't match or if the request is for more permissions than + * was granted. + * + * Note: the test for !unconfined(flabel) is to handle file + * delegation from unconfined tasks + */ + denied = request & ~fctx->allow; + if (unconfined(label) || __file_is_delegated(flabel) || + __unix_needs_revalidation(file, label, request) || + (!denied && __aa_subj_label_is_cached(label, flabel))) { + rcu_read_unlock(); + goto done; + } + + /* slow path - revalidate access */ + flabel = aa_get_newest_label(flabel); + rcu_read_unlock(); + + if (path_mediated_fs(file->f_path.dentry)) + error = __file_path_perm(op, subj_cred, label, flabel, file, + request, denied, in_atomic); - return aa_path_perm(op, profile, &file->f_path, PATH_DELEGATE_DELETED, - request, &cond); + else if (S_ISSOCK(file_inode(file)->i_mode)) + error = __file_sock_perm(op, subj_cred, label, flabel, file, + request, denied); + aa_put_label(flabel); + +done: + return error; +} + +static void revalidate_tty(const struct cred *subj_cred, struct aa_label *label) +{ + struct tty_struct *tty; + int drop_tty = 0; + + tty = get_current_tty(); + if (!tty) + return; + + spin_lock(&tty->files_lock); + if (!list_empty(&tty->tty_files)) { + struct tty_file_private *file_priv; + struct file *file; + /* TODO: Revalidate access to controlling tty. */ + file_priv = list_first_entry(&tty->tty_files, + struct tty_file_private, list); + file = file_priv->file; + + if (aa_file_perm(OP_INHERIT, subj_cred, label, file, + MAY_READ | MAY_WRITE, IN_ATOMIC)) + drop_tty = 1; + } + spin_unlock(&tty->files_lock); + tty_kref_put(tty); + + if (drop_tty) + no_tty(); +} + +struct cred_label { + const struct cred *cred; + struct aa_label *label; +}; + +static int match_file(const void *p, struct file *file, unsigned int fd) +{ + struct cred_label *cl = (struct cred_label *)p; + + if (aa_file_perm(OP_INHERIT, cl->cred, cl->label, file, + aa_map_file_to_perms(file), IN_ATOMIC)) + return fd + 1; + return 0; +} + + +/* based on selinux's flush_unauthorized_files */ +void aa_inherit_files(const struct cred *cred, struct files_struct *files) +{ + struct aa_label *label = aa_get_newest_cred_label(cred); + struct cred_label cl = { + .cred = cred, + .label = label, + }; + struct file *devnull = NULL; + unsigned int n; + + revalidate_tty(cred, label); + + /* Revalidate access to inherited open files. */ + n = iterate_fd(files, 0, match_file, &cl); + if (!n) /* none found? */ + goto out; + + devnull = dentry_open(&aa_null, O_RDWR, cred); + if (IS_ERR(devnull)) + devnull = NULL; + /* replace all the matching ones with this */ + do { + replace_fd(n - 1, devnull, 0); + } while ((n = iterate_fd(files, n, match_file, &cl)) != 0); + if (devnull) + fput(devnull); +out: + aa_put_label(label); } |