security/apparmor/file.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * AppArmor security module
0004  *
0005  * This file contains AppArmor mediation of files
0006  *
0007  * Copyright (C) 1998-2008 Novell/SUSE
0008  * Copyright 2009-2010 Canonical Ltd.
0009  */
0010
0011 #include <linux/tty.h>
0012 #include <linux/fdtable.h>
0013 #include <linux/file.h>
0014 #include <linux/fs.h>
0015 #include <linux/mount.h>
0016
0017 #include "include/apparmor.h"
0018 #include "include/audit.h"
0019 #include "include/cred.h"
0020 #include "include/file.h"
0021 #include "include/match.h"
0022 #include "include/net.h"
0023 #include "include/path.h"
0024 #include "include/policy.h"
0025 #include "include/label.h"
0026
0027 static u32 map_mask_to_chr_mask(u32 mask)
0028 {
0029     u32 m = mask & PERMS_CHRS_MASK;
0030
0031     if (mask & AA_MAY_GETATTR)
0032         m |= MAY_READ;
0033     if (mask & (AA_MAY_SETATTR | AA_MAY_CHMOD | AA_MAY_CHOWN))
0034         m |= MAY_WRITE;
0035
0036     return m;
0037 }
0038
0039 /**
0040  * file_audit_cb - call back for file specific audit fields
0041  * @ab: audit_buffer  (NOT NULL)
0042  * @va: audit struct to audit values of  (NOT NULL)
0043  */
0044 static void file_audit_cb(struct audit_buffer *ab, void *va)
0045 {
0046     struct common_audit_data *sa = va;
0047     kuid_t fsuid = current_fsuid();
0048     char str[10];
0049
0050     if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
0051         aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
0052                     map_mask_to_chr_mask(aad(sa)->request));
0053         audit_log_format(ab, " requested_mask=\"%s\"", str);
0054     }
0055     if (aad(sa)->denied & AA_AUDIT_FILE_MASK) {
0056         aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,
0057                     map_mask_to_chr_mask(aad(sa)->denied));
0058         audit_log_format(ab, " denied_mask=\"%s\"", str);
0059     }
0060     if (aad(sa)->request & AA_AUDIT_FILE_MASK) {
0061         audit_log_format(ab, " fsuid=%d",
0062                  from_kuid(&init_user_ns, fsuid));
0063         audit_log_format(ab, " ouid=%d",
0064                  from_kuid(&init_user_ns, aad(sa)->fs.ouid));
0065     }
0066
0067     if (aad(sa)->peer) {
0068         audit_log_format(ab, " target=");
0069         aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
0070                 FLAG_VIEW_SUBNS, GFP_KERNEL);
0071     } else if (aad(sa)->fs.target) {
0072         audit_log_format(ab, " target=");
0073         audit_log_untrustedstring(ab, aad(sa)->fs.target);
0074     }
0075 }
0076
0077 /**
0078  * aa_audit_file - handle the auditing of file operations
0079  * @profile: the profile being enforced  (NOT NULL)
0080  * @perms: the permissions computed for the request (NOT NULL)
0081  * @op: operation being mediated
0082  * @request: permissions requested
0083  * @name: name of object being mediated (MAYBE NULL)
0084  * @target: name of target (MAYBE NULL)
0085  * @tlabel: target label (MAY BE NULL)
0086  * @ouid: object uid
0087  * @info: extra information message (MAYBE NULL)
0088  * @error: 0 if operation allowed else failure error code
0089  *
0090  * Returns: %0 or error on failure
0091  */
0092 int aa_audit_file(struct aa_profile *profile, struct aa_perms *perms,
0093           const char *op, u32 request, const char *name,
0094           const char *target, struct aa_label *tlabel,
0095           kuid_t ouid, const char *info, int error)
0096 {
0097     int type = AUDIT_APPARMOR_AUTO;
0098     DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_TASK, op);
0099
0100     sa.u.tsk = NULL;
0101     aad(&sa)->request = request;
0102     aad(&sa)->name = name;
0103     aad(&sa)->fs.target = target;
0104     aad(&sa)->peer = tlabel;
0105     aad(&sa)->fs.ouid = ouid;
0106     aad(&sa)->info = info;
0107     aad(&sa)->error = error;
0108     sa.u.tsk = NULL;
0109
0110     if (likely(!aad(&sa)->error)) {
0111         u32 mask = perms->audit;
0112
0113         if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
0114             mask = 0xffff;
0115
0116         /* mask off perms that are not being force audited */
0117         aad(&sa)->request &= mask;
0118
0119         if (likely(!aad(&sa)->request))
0120             return 0;
0121         type = AUDIT_APPARMOR_AUDIT;
0122     } else {
0123         /* only report permissions that were denied */
0124         aad(&sa)->request = aad(&sa)->request & ~perms->allow;
0125         AA_BUG(!aad(&sa)->request);
0126
0127         if (aad(&sa)->request & perms->kill)
0128             type = AUDIT_APPARMOR_KILL;
0129
0130         /* quiet known rejects, assumes quiet and kill do not overlap */
0131         if ((aad(&sa)->request & perms->quiet) &&
0132             AUDIT_MODE(profile) != AUDIT_NOQUIET &&
0133             AUDIT_MODE(profile) != AUDIT_ALL)
0134             aad(&sa)->request &= ~perms->quiet;
0135
0136         if (!aad(&sa)->request)
0137             return aad(&sa)->error;
0138     }
0139
0140     aad(&sa)->denied = aad(&sa)->request & ~perms->allow;
0141     return aa_audit(type, profile, &sa, file_audit_cb);
0142 }
0143
0144 /**
0145  * is_deleted - test if a file has been completely unlinked
0146  * @dentry: dentry of file to test for deletion  (NOT NULL)
0147  *
0148  * Returns: true if deleted else false
0149  */
0150 static inline bool is_deleted(struct dentry *dentry)
0151 {
0152     if (d_unlinked(dentry) && d_backing_inode(dentry)->i_nlink == 0)
0153         return true;
0154     return false;
0155 }
0156
0157 static int path_name(const char *op, struct aa_label *label,
0158              const struct path *path, int flags, char *buffer,
0159              const char **name, struct path_cond *cond, u32 request)
0160 {
0161     struct aa_profile *profile;
0162     const char *info = NULL;
0163     int error;
0164
0165     error = aa_path_name(path, flags, buffer, name, &info,
0166                  labels_profile(label)->disconnected);
0167     if (error) {
0168         fn_for_each_confined(label, profile,
0169             aa_audit_file(profile, &nullperms, op, request, *name,
0170                       NULL, NULL, cond->uid, info, error));
0171         return error;
0172     }
0173
0174     return 0;
0175 }
0176
0177 /**
0178  * map_old_perms - map old file perms layout to the new layout
0179  * @old: permission set in old mapping
0180  *
0181  * Returns: new permission mapping
0182  */
0183 static u32 map_old_perms(u32 old)
0184 {
0185     u32 new = old & 0xf;
0186     if (old & MAY_READ)
0187         new |= AA_MAY_GETATTR | AA_MAY_OPEN;
0188     if (old & MAY_WRITE)
0189         new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
0190                AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
0191     if (old & 0x10)
0192         new |= AA_MAY_LINK;
0193     /* the old mapping lock and link_subset flags where overlaid
0194      * and use was determined by part of a pair that they were in
0195      */
0196     if (old & 0x20)
0197         new |= AA_MAY_LOCK | AA_LINK_SUBSET;
0198     if (old & 0x40) /* AA_EXEC_MMAP */
0199         new |= AA_EXEC_MMAP;
0200
0201     return new;
0202 }
0203
0204 /**
0205  * aa_compute_fperms - convert dfa compressed perms to internal perms
0206  * @dfa: dfa to compute perms for   (NOT NULL)
0207  * @state: state in dfa
0208  * @cond:  conditions to consider  (NOT NULL)
0209  *
0210  * TODO: convert from dfa + state to permission entry, do computation conversion
0211  *       at load time.
0212  *
0213  * Returns: computed permission set
0214  */
0215 struct aa_perms aa_compute_fperms(struct aa_dfa *dfa, unsigned int state,
0216                   struct path_cond *cond)
0217 {
0218     /* FIXME: change over to new dfa format
0219      * currently file perms are encoded in the dfa, new format
0220      * splits the permissions from the dfa.  This mapping can be
0221      * done at profile load
0222      */
0223     struct aa_perms perms = { };
0224
0225     if (uid_eq(current_fsuid(), cond->uid)) {
0226         perms.allow = map_old_perms(dfa_user_allow(dfa, state));
0227         perms.audit = map_old_perms(dfa_user_audit(dfa, state));
0228         perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
0229         perms.xindex = dfa_user_xindex(dfa, state);
0230     } else {
0231         perms.allow = map_old_perms(dfa_other_allow(dfa, state));
0232         perms.audit = map_old_perms(dfa_other_audit(dfa, state));
0233         perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
0234         perms.xindex = dfa_other_xindex(dfa, state);
0235     }
0236     perms.allow |= AA_MAY_GETATTR;
0237
0238     /* change_profile wasn't determined by ownership in old mapping */
0239     if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
0240         perms.allow |= AA_MAY_CHANGE_PROFILE;
0241     if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
0242         perms.allow |= AA_MAY_ONEXEC;
0243
0244     return perms;
0245 }
0246
0247 /**
0248  * aa_str_perms - find permission that match @name
0249  * @dfa: to match against  (MAYBE NULL)
0250  * @state: state to start matching in
0251  * @name: string to match against dfa  (NOT NULL)
0252  * @cond: conditions to consider for permission set computation  (NOT NULL)
0253  * @perms: Returns - the permissions found when matching @name
0254  *
0255  * Returns: the final state in @dfa when beginning @start and walking @name
0256  */
0257 unsigned int aa_str_perms(struct aa_dfa *dfa, unsigned int start,
0258               const char *name, struct path_cond *cond,
0259               struct aa_perms *perms)
0260 {
0261     unsigned int state;
0262     state = aa_dfa_match(dfa, start, name);
0263     *perms = aa_compute_fperms(dfa, state, cond);
0264
0265     return state;
0266 }
0267
0268 int __aa_path_perm(const char *op, struct aa_profile *profile, const char *name,
0269            u32 request, struct path_cond *cond, int flags,
0270            struct aa_perms *perms)
0271 {
0272     int e = 0;
0273
0274     if (profile_unconfined(profile))
0275         return 0;
0276     aa_str_perms(profile->file.dfa, profile->file.start, name, cond, perms);
0277     if (request & ~perms->allow)
0278         e = -EACCES;
0279     return aa_audit_file(profile, perms, op, request, name, NULL, NULL,
0280                  cond->uid, NULL, e);
0281 }
0282
0283
0284 static int profile_path_perm(const char *op, struct aa_profile *profile,
0285                  const struct path *path, char *buffer, u32 request,
0286                  struct path_cond *cond, int flags,
0287                  struct aa_perms *perms)
0288 {
0289     const char *name;
0290     int error;
0291
0292     if (profile_unconfined(profile))
0293         return 0;
0294
0295     error = path_name(op, &profile->label, path,
0296               flags | profile->path_flags, buffer, &name, cond,
0297               request);
0298     if (error)
0299         return error;
0300     return __aa_path_perm(op, profile, name, request, cond, flags,
0301                   perms);
0302 }
0303
0304 /**
0305  * aa_path_perm - do permissions check & audit for @path
0306  * @op: operation being checked
0307  * @label: profile being enforced  (NOT NULL)
0308  * @path: path to check permissions of  (NOT NULL)
0309  * @flags: any additional path flags beyond what the profile specifies
0310  * @request: requested permissions
0311  * @cond: conditional info for this request  (NOT NULL)
0312  *
0313  * Returns: %0 else error if access denied or other error
0314  */
0315 int aa_path_perm(const char *op, struct aa_label *label,
0316          const struct path *path, int flags, u32 request,
0317          struct path_cond *cond)
0318 {
0319     struct aa_perms perms = {};
0320     struct aa_profile *profile;
0321     char *buffer = NULL;
0322     int error;
0323
0324     flags |= PATH_DELEGATE_DELETED | (S_ISDIR(cond->mode) ? PATH_IS_DIR :
0325                                 0);
0326     buffer = aa_get_buffer(false);
0327     if (!buffer)
0328         return -ENOMEM;
0329     error = fn_for_each_confined(label, profile,
0330             profile_path_perm(op, profile, path, buffer, request,
0331                       cond, flags, &perms));
0332
0333     aa_put_buffer(buffer);
0334
0335     return error;
0336 }
0337
0338 /**
0339  * xindex_is_subset - helper for aa_path_link
0340  * @link: link permission set
0341  * @target: target permission set
0342  *
0343  * test target x permissions are equal OR a subset of link x permissions
0344  * this is done as part of the subset test, where a hardlink must have
0345  * a subset of permissions that the target has.
0346  *
0347  * Returns: true if subset else false
0348  */
0349 static inline bool xindex_is_subset(u32 link, u32 target)
0350 {
0351     if (((link & ~AA_X_UNSAFE) != (target & ~AA_X_UNSAFE)) ||
0352         ((link & AA_X_UNSAFE) && !(target & AA_X_UNSAFE)))
0353         return false;
0354
0355     return true;
0356 }
0357
0358 static int profile_path_link(struct aa_profile *profile,
0359                  const struct path *link, char *buffer,
0360                  const struct path *target, char *buffer2,
0361                  struct path_cond *cond)
0362 {
0363     const char *lname, *tname = NULL;
0364     struct aa_perms lperms = {}, perms;
0365     const char *info = NULL;
0366     u32 request = AA_MAY_LINK;
0367     unsigned int state;
0368     int error;
0369
0370     error = path_name(OP_LINK, &profile->label, link, profile->path_flags,
0371               buffer, &lname, cond, AA_MAY_LINK);
0372     if (error)
0373         goto audit;
0374
0375     /* buffer2 freed below, tname is pointer in buffer2 */
0376     error = path_name(OP_LINK, &profile->label, target, profile->path_flags,
0377               buffer2, &tname, cond, AA_MAY_LINK);
0378     if (error)
0379         goto audit;
0380
0381     error = -EACCES;
0382     /* aa_str_perms - handles the case of the dfa being NULL */
0383     state = aa_str_perms(profile->file.dfa, profile->file.start, lname,
0384                  cond, &lperms);
0385
0386     if (!(lperms.allow & AA_MAY_LINK))
0387         goto audit;
0388
0389     /* test to see if target can be paired with link */
0390     state = aa_dfa_null_transition(profile->file.dfa, state);
0391     aa_str_perms(profile->file.dfa, state, tname, cond, &perms);
0392
0393     /* force audit/quiet masks for link are stored in the second entry
0394      * in the link pair.
0395      */
0396     lperms.audit = perms.audit;
0397     lperms.quiet = perms.quiet;
0398     lperms.kill = perms.kill;
0399
0400     if (!(perms.allow & AA_MAY_LINK)) {
0401         info = "target restricted";
0402         lperms = perms;
0403         goto audit;
0404     }
0405
0406     /* done if link subset test is not required */
0407     if (!(perms.allow & AA_LINK_SUBSET))
0408         goto done_tests;
0409
0410     /* Do link perm subset test requiring allowed permission on link are
0411      * a subset of the allowed permissions on target.
0412      */
0413     aa_str_perms(profile->file.dfa, profile->file.start, tname, cond,
0414              &perms);
0415
0416     /* AA_MAY_LINK is not considered in the subset test */
0417     request = lperms.allow & ~AA_MAY_LINK;
0418     lperms.allow &= perms.allow | AA_MAY_LINK;
0419
0420     request |= AA_AUDIT_FILE_MASK & (lperms.allow & ~perms.allow);
0421     if (request & ~lperms.allow) {
0422         goto audit;
0423     } else if ((lperms.allow & MAY_EXEC) &&
0424            !xindex_is_subset(lperms.xindex, perms.xindex)) {
0425         lperms.allow &= ~MAY_EXEC;
0426         request |= MAY_EXEC;
0427         info = "link not subset of target";
0428         goto audit;
0429     }
0430
0431 done_tests:
0432     error = 0;
0433
0434 audit:
0435     return aa_audit_file(profile, &lperms, OP_LINK, request, lname, tname,
0436                  NULL, cond->uid, info, error);
0437 }
0438
0439 /**
0440  * aa_path_link - Handle hard link permission check
0441  * @label: the label being enforced  (NOT NULL)
0442  * @old_dentry: the target dentry  (NOT NULL)
0443  * @new_dir: directory the new link will be created in  (NOT NULL)
0444  * @new_dentry: the link being created  (NOT NULL)
0445  *
0446  * Handle the permission test for a link & target pair.  Permission
0447  * is encoded as a pair where the link permission is determined
0448  * first, and if allowed, the target is tested.  The target test
0449  * is done from the point of the link match (not start of DFA)
0450  * making the target permission dependent on the link permission match.
0451  *
0452  * The subset test if required forces that permissions granted
0453  * on link are a subset of the permission granted to target.
0454  *
0455  * Returns: %0 if allowed else error
0456  */
0457 int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
0458          const struct path *new_dir, struct dentry *new_dentry)
0459 {
0460     struct path link = { .mnt = new_dir->mnt, .dentry = new_dentry };
0461     struct path target = { .mnt = new_dir->mnt, .dentry = old_dentry };
0462     struct path_cond cond = {
0463         d_backing_inode(old_dentry)->i_uid,
0464         d_backing_inode(old_dentry)->i_mode
0465     };
0466     char *buffer = NULL, *buffer2 = NULL;
0467     struct aa_profile *profile;
0468     int error;
0469
0470     /* buffer freed below, lname is pointer in buffer */
0471     buffer = aa_get_buffer(false);
0472     buffer2 = aa_get_buffer(false);
0473     error = -ENOMEM;
0474     if (!buffer || !buffer2)
0475         goto out;
0476
0477     error = fn_for_each_confined(label, profile,
0478             profile_path_link(profile, &link, buffer, &target,
0479                       buffer2, &cond));
0480 out:
0481     aa_put_buffer(buffer);
0482     aa_put_buffer(buffer2);
0483     return error;
0484 }
0485
0486 static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
0487                 u32 request)
0488 {
0489     struct aa_label *l, *old;
0490
0491     /* update caching of label on file_ctx */
0492     spin_lock(&fctx->lock);
0493     old = rcu_dereference_protected(fctx->label,
0494                     lockdep_is_held(&fctx->lock));
0495     l = aa_label_merge(old, label, GFP_ATOMIC);
0496     if (l) {
0497         if (l != old) {
0498             rcu_assign_pointer(fctx->label, l);
0499             aa_put_label(old);
0500         } else
0501             aa_put_label(l);
0502         fctx->allow |= request;
0503     }
0504     spin_unlock(&fctx->lock);
0505 }
0506
0507 static int __file_path_perm(const char *op, struct aa_label *label,
0508                 struct aa_label *flabel, struct file *file,
0509                 u32 request, u32 denied, bool in_atomic)
0510 {
0511     struct aa_profile *profile;
0512     struct aa_perms perms = {};
0513     struct path_cond cond = {
0514         .uid = i_uid_into_mnt(file_mnt_user_ns(file), file_inode(file)),
0515         .mode = file_inode(file)->i_mode
0516     };
0517     char *buffer;
0518     int flags, error;
0519
0520     /* revalidation due to label out of date. No revocation at this time */
0521     if (!denied && aa_label_is_subset(flabel, label))
0522         /* TODO: check for revocation on stale profiles */
0523         return 0;
0524
0525     flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
0526     buffer = aa_get_buffer(in_atomic);
0527     if (!buffer)
0528         return -ENOMEM;
0529
0530     /* check every profile in task label not in current cache */
0531     error = fn_for_each_not_in_set(flabel, label, profile,
0532             profile_path_perm(op, profile, &file->f_path, buffer,
0533                       request, &cond, flags, &perms));
0534     if (denied && !error) {
0535         /*
0536          * check every profile in file label that was not tested
0537          * in the initial check above.
0538          *
0539          * TODO: cache full perms so this only happens because of
0540          * conditionals
0541          * TODO: don't audit here
0542          */
0543         if (label == flabel)
0544             error = fn_for_each(label, profile,
0545                 profile_path_perm(op, profile, &file->f_path,
0546                           buffer, request, &cond, flags,
0547                           &perms));
0548         else
0549             error = fn_for_each_not_in_set(label, flabel, profile,
0550                 profile_path_perm(op, profile, &file->f_path,
0551                           buffer, request, &cond, flags,
0552                           &perms));
0553     }
0554     if (!error)
0555         update_file_ctx(file_ctx(file), label, request);
0556
0557     aa_put_buffer(buffer);
0558
0559     return error;
0560 }
0561
0562 static int __file_sock_perm(const char *op, struct aa_label *label,
0563                 struct aa_label *flabel, struct file *file,
0564                 u32 request, u32 denied)
0565 {
0566     struct socket *sock = (struct socket *) file->private_data;
0567     int error;
0568
0569     AA_BUG(!sock);
0570
0571     /* revalidation due to label out of date. No revocation at this time */
0572     if (!denied && aa_label_is_subset(flabel, label))
0573         return 0;
0574
0575     /* TODO: improve to skip profiles cached in flabel */
0576     error = aa_sock_file_perm(label, op, request, sock);
0577     if (denied) {
0578         /* TODO: improve to skip profiles checked above */
0579         /* check every profile in file label to is cached */
0580         last_error(error, aa_sock_file_perm(flabel, op, request, sock));
0581     }
0582     if (!error)
0583         update_file_ctx(file_ctx(file), label, request);
0584
0585     return error;
0586 }
0587
0588 /**
0589  * aa_file_perm - do permission revalidation check & audit for @file
0590  * @op: operation being checked
0591  * @label: label being enforced   (NOT NULL)
0592  * @file: file to revalidate access permissions on  (NOT NULL)
0593  * @request: requested permissions
0594  * @in_atomic: whether allocations need to be done in atomic context
0595  *
0596  * Returns: %0 if access allowed else error
0597  */
0598 int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
0599          u32 request, bool in_atomic)
0600 {
0601     struct aa_file_ctx *fctx;
0602     struct aa_label *flabel;
0603     u32 denied;
0604     int error = 0;
0605
0606     AA_BUG(!label);
0607     AA_BUG(!file);
0608
0609     fctx = file_ctx(file);
0610
0611     rcu_read_lock();
0612     flabel  = rcu_dereference(fctx->label);
0613     AA_BUG(!flabel);
0614
0615     /* revalidate access, if task is unconfined, or the cached cred
0616      * doesn't match or if the request is for more permissions than
0617      * was granted.
0618      *
0619      * Note: the test for !unconfined(flabel) is to handle file
0620      *       delegation from unconfined tasks
0621      */
0622     denied = request & ~fctx->allow;
0623     if (unconfined(label) || unconfined(flabel) ||
0624         (!denied && aa_label_is_subset(flabel, label))) {
0625         rcu_read_unlock();
0626         goto done;
0627     }
0628
0629     flabel  = aa_get_newest_label(flabel);
0630     rcu_read_unlock();
0631     /* TODO: label cross check */
0632
0633     if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
0634         error = __file_path_perm(op, label, flabel, file, request,
0635                      denied, in_atomic);
0636
0637     else if (S_ISSOCK(file_inode(file)->i_mode))
0638         error = __file_sock_perm(op, label, flabel, file, request,
0639                      denied);
0640     aa_put_label(flabel);
0641
0642 done:
0643     return error;
0644 }
0645
0646 static void revalidate_tty(struct aa_label *label)
0647 {
0648     struct tty_struct *tty;
0649     int drop_tty = 0;
0650
0651     tty = get_current_tty();
0652     if (!tty)
0653         return;
0654
0655     spin_lock(&tty->files_lock);
0656     if (!list_empty(&tty->tty_files)) {
0657         struct tty_file_private *file_priv;
0658         struct file *file;
0659         /* TODO: Revalidate access to controlling tty. */
0660         file_priv = list_first_entry(&tty->tty_files,
0661                          struct tty_file_private, list);
0662         file = file_priv->file;
0663
0664         if (aa_file_perm(OP_INHERIT, label, file, MAY_READ | MAY_WRITE,
0665                  IN_ATOMIC))
0666             drop_tty = 1;
0667     }
0668     spin_unlock(&tty->files_lock);
0669     tty_kref_put(tty);
0670
0671     if (drop_tty)
0672         no_tty();
0673 }
0674
0675 static int match_file(const void *p, struct file *file, unsigned int fd)
0676 {
0677     struct aa_label *label = (struct aa_label *)p;
0678
0679     if (aa_file_perm(OP_INHERIT, label, file, aa_map_file_to_perms(file),
0680              IN_ATOMIC))
0681         return fd + 1;
0682     return 0;
0683 }
0684
0685
0686 /* based on selinux's flush_unauthorized_files */
0687 void aa_inherit_files(const struct cred *cred, struct files_struct *files)
0688 {
0689     struct aa_label *label = aa_get_newest_cred_label(cred);
0690     struct file *devnull = NULL;
0691     unsigned int n;
0692
0693     revalidate_tty(label);
0694
0695     /* Revalidate access to inherited open files. */
0696     n = iterate_fd(files, 0, match_file, label);
0697     if (!n) /* none found? */
0698         goto out;
0699
0700     devnull = dentry_open(&aa_null, O_RDWR, cred);
0701     if (IS_ERR(devnull))
0702         devnull = NULL;
0703     /* replace all the matching ones with this */
0704     do {
0705         replace_fd(n - 1, devnull, 0);
0706     } while ((n = iterate_fd(files, n, match_file, label)) != 0);
0707     if (devnull)
0708         fput(devnull);
0709 out:
0710     aa_put_label(label);
0711 }