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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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"
static u32 map_mask_to_chr_mask(u32 mask){ 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;
return m;}
/** * file_audit_cb - call back for file specific audit fields * @ab: audit_buffer (NOT NULL) * @va: audit struct to audit values of (NOT NULL) */static void file_audit_cb(struct audit_buffer *ab, void *va){ struct common_audit_data *sa = va; struct apparmor_audit_data *ad = aad(sa); kuid_t fsuid = ad->subj_cred ? ad->subj_cred->fsuid : current_fsuid(); char str[10];
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 (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 (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, ad->fs.ouid)); }
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, 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) * @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(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; DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_TASK, AA_CLASS_FILE, op);
ad.subj_cred = subj_cred; ad.request = request; ad.tags = perms->tag; 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 */ ad.request &= mask;
if (likely(!ad.request)) return 0; type = AUDIT_APPARMOR_AUDIT; } else { /* only report permissions that were denied */ ad.request = ad.request & ~perms->allow; AA_BUG(!ad.request);
if (ad.request & perms->kill) type = AUDIT_APPARMOR_KILL;
/* quiet known rejects, assumes quiet and kill do not overlap */ if ((ad.request & perms->quiet) && AUDIT_MODE(profile) != AUDIT_NOQUIET && AUDIT_MODE(profile) != AUDIT_ALL) ad.request &= ~perms->quiet;
if (!ad.request) return ad.error; }
ad.denied = ad.request & ~perms->allow; return aa_audit(type, profile, &ad, file_audit_cb);}
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){ struct aa_profile *profile; const char *info = NULL; int error;
/* don't reaudit files closed during inheritance */ if (unlikely(path->dentry == aa_null.dentry)) return -EACCES;
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 = {};/** * 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 * * Returns: a pointer to a file permission set */struct aa_perms *aa_lookup_condperms(kuid_t subj_uid, struct aa_policydb *rules, aa_state_t state, struct path_cond *cond){ unsigned int index = ACCEPT_TABLE(rules->dfa)[state];
if (!(rules->perms)) return &default_perms;
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]); }
return &(rules->perms[index]);}
/** * aa_str_perms - find permission that match @name * @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 */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){ 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;}
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){ 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 = NULL; 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 * @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 * @cond: conditional info for this request (NOT NULL) * * Returns: %0 else error if access denied or other error */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; int error;
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;}
/** * xindex_is_subset - helper for aa_path_link * @link: link permission set * @target: target permission set * * test target x permissions are equal OR a subset of link x permissions * this is done as part of the subset test, where a hardlink must have * a subset of permissions that the target has. * * 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 false;
return true;}
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 aa_ruleset *rules = profile->label.rules[0]; const char *lname = NULL, *tname = NULL; struct aa_perms lperms = {}, perms; const char *info = NULL; u32 request = AA_MAY_LINK; aa_state_t state; int error;
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 = 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(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(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. */ lperms.audit = perms.audit; lperms.quiet = perms.quiet; lperms.kill = perms.kill;
if (!(perms.allow & AA_MAY_LINK)) { info = "target restricted"; lperms = perms; goto audit; }
/* done if link subset test is not required */ 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. */ 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; lperms.allow &= perms.allow | AA_MAY_LINK;
request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow); if (request & ~lperms.allow) { goto audit; } else if ((lperms.allow & MAY_EXEC) && !xindex_is_subset(lperms.xindex, perms.xindex)) { lperms.allow &= ~MAY_EXEC; request |= MAY_EXEC; info = "link not subset of target"; goto audit; }
done_tests: error = 0;
audit: 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 __is_unix_file(struct file *file){ struct socket *sock = (struct socket *) file->private_data;
lockdep_assert_in_rcu_read_lock();
if (!S_ISSOCK(file_inode(file)->i_mode)) return false; /* sock and sock->sk can be NULL for sockets being set up or torn down */ if (!sock || !sock->sk) return false; if (sock->sk->sk_family == PF_UNIX) return true; return false;}
static bool __unix_needs_revalidation(struct file *file, struct aa_label *label, u32 request){ struct socket *sock = (struct socket *) file->private_data;
AA_BUG(!__is_unix_file(file)); lockdep_assert_in_rcu_read_lock();
struct aa_sk_ctx *skctx = aa_sock(sock->sk);
if (rcu_access_pointer(skctx->peer) != rcu_access_pointer(skctx->peer_lastupdate)) return true;
return !__aa_subj_label_is_cached(rcu_dereference(skctx->label), label);}
/** * aa_file_perm - do permission revalidation check & audit for @file * @op: operation being checked * @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(const char *op, const struct cred *subj_cred, struct aa_label *label, struct file *file, u32 request, bool in_atomic){ struct aa_file_ctx *fctx; struct aa_label *flabel; u32 denied; int error = 0;
AA_BUG(!label); AA_BUG(!file);
/* don't reaudit files closed during inheritance */ if (unlikely(file->f_path.dentry == aa_null.dentry)) return -EACCES;
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) || (!denied && __is_unix_file(file) && !__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);
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);}