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commit 3ac96c30ccfa802501dd2f4941e4508ea54b0b8a
parent ae5906ceee038ea29ff5162d1bcd18fb50af8b94
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu,  7 Mar 2019 12:12:45 -0800

Merge tag 'selinux-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull SELinux updates from Paul Moore:
 "Nine SELinux patches for v5.1, all bug fixes.

  As far as I'm concerned, nothing really jumps out as risky or special
  to me, but each commit has a decent description so you can judge for
  yourself. As usual, everything passes the selinux-testsuite; please
  merge for v5.1"

* tag 'selinux-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: fix avc audit messages
  selinux: replace BUG_ONs with WARN_ONs in avc.c
  selinux: log invalid contexts in AVCs
  selinux: replace some BUG_ON()s with a WARN_ON()
  selinux: inline some AVC functions used only once
  selinux: do not override context on context mounts
  selinux: never allow relabeling on context mounts
  selinux: stop passing MAY_NOT_BLOCK to the AVC upon follow_link
  selinux: avoid silent denials in permissive mode under RCU walk

Diffstat:
Msecurity/selinux/avc.c | 199++++++++++++++++++++++++++++++++++++++-----------------------------------------
Msecurity/selinux/hooks.c | 58++++++++++++++++++++++++++++++++++++++++++++--------------
Msecurity/selinux/include/avc.h | 6+-----
Msecurity/selinux/include/security.h | 3+++
Msecurity/selinux/ss/services.c | 37++++++++++++++++++++++++++++++++-----
5 files changed, 176 insertions(+), 127 deletions(-)

diff --git a/security/selinux/avc.c b/security/selinux/avc.c @@ -130,75 +130,6 @@ static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) } /** - * avc_dump_av - Display an access vector in human-readable form. - * @tclass: target security class - * @av: access vector - */ -static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) -{ - const char **perms; - int i, perm; - - if (av == 0) { - audit_log_format(ab, " null"); - return; - } - - BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)); - perms = secclass_map[tclass-1].perms; - - audit_log_format(ab, " {"); - i = 0; - perm = 1; - while (i < (sizeof(av) * 8)) { - if ((perm & av) && perms[i]) { - audit_log_format(ab, " %s", perms[i]); - av &= ~perm; - } - i++; - perm <<= 1; - } - - if (av) - audit_log_format(ab, " 0x%x", av); - - audit_log_format(ab, " }"); -} - -/** - * avc_dump_query - Display a SID pair and a class in human-readable form. - * @ssid: source security identifier - * @tsid: target security identifier - * @tclass: target security class - */ -static void avc_dump_query(struct audit_buffer *ab, struct selinux_state *state, - u32 ssid, u32 tsid, u16 tclass) -{ - int rc; - char *scontext; - u32 scontext_len; - - rc = security_sid_to_context(state, ssid, &scontext, &scontext_len); - if (rc) - audit_log_format(ab, "ssid=%d", ssid); - else { - audit_log_format(ab, "scontext=%s", scontext); - kfree(scontext); - } - - rc = security_sid_to_context(state, tsid, &scontext, &scontext_len); - if (rc) - audit_log_format(ab, " tsid=%d", tsid); - else { - audit_log_format(ab, " tcontext=%s", scontext); - kfree(scontext); - } - - BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)); - audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name); -} - -/** * avc_init - Initialize the AVC. * * Initialize the access vector cache. @@ -735,11 +666,36 @@ out: static void avc_audit_pre_callback(struct audit_buffer *ab, void *a) { struct common_audit_data *ad = a; - audit_log_format(ab, "avc: %s ", - ad->selinux_audit_data->denied ? "denied" : "granted"); - avc_dump_av(ab, ad->selinux_audit_data->tclass, - ad->selinux_audit_data->audited); - audit_log_format(ab, " for "); + struct selinux_audit_data *sad = ad->selinux_audit_data; + u32 av = sad->audited; + const char **perms; + int i, perm; + + audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted"); + + if (av == 0) { + audit_log_format(ab, " null"); + return; + } + + perms = secclass_map[sad->tclass-1].perms; + + audit_log_format(ab, " {"); + i = 0; + perm = 1; + while (i < (sizeof(av) * 8)) { + if ((perm & av) && perms[i]) { + audit_log_format(ab, " %s", perms[i]); + av &= ~perm; + } + i++; + perm <<= 1; + } + + if (av) + audit_log_format(ab, " 0x%x", av); + + audit_log_format(ab, " } for "); } /** @@ -751,14 +707,47 @@ static void avc_audit_pre_callback(struct audit_buffer *ab, void *a) static void avc_audit_post_callback(struct audit_buffer *ab, void *a) { struct common_audit_data *ad = a; - audit_log_format(ab, " "); - avc_dump_query(ab, ad->selinux_audit_data->state, - ad->selinux_audit_data->ssid, - ad->selinux_audit_data->tsid, - ad->selinux_audit_data->tclass); - if (ad->selinux_audit_data->denied) { - audit_log_format(ab, " permissive=%u", - ad->selinux_audit_data->result ? 0 : 1); + struct selinux_audit_data *sad = ad->selinux_audit_data; + char *scontext; + u32 scontext_len; + int rc; + + rc = security_sid_to_context(sad->state, sad->ssid, &scontext, + &scontext_len); + if (rc) + audit_log_format(ab, " ssid=%d", sad->ssid); + else { + audit_log_format(ab, " scontext=%s", scontext); + kfree(scontext); + } + + rc = security_sid_to_context(sad->state, sad->tsid, &scontext, + &scontext_len); + if (rc) + audit_log_format(ab, " tsid=%d", sad->tsid); + else { + audit_log_format(ab, " tcontext=%s", scontext); + kfree(scontext); + } + + audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name); + + if (sad->denied) + audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1); + + /* in case of invalid context report also the actual context string */ + rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext, + &scontext_len); + if (!rc && scontext) { + audit_log_format(ab, " srawcon=%s", scontext); + kfree(scontext); + } + + rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext, + &scontext_len); + if (!rc && scontext) { + audit_log_format(ab, " trawcon=%s", scontext); + kfree(scontext); } } @@ -772,6 +761,9 @@ noinline int slow_avc_audit(struct selinux_state *state, struct common_audit_data stack_data; struct selinux_audit_data sad; + if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map))) + return -EINVAL; + if (!a) { a = &stack_data; a->type = LSM_AUDIT_DATA_NONE; @@ -838,6 +830,7 @@ out: * @ssid,@tsid,@tclass : identifier of an AVC entry * @seqno : sequence number when decision was made * @xpd: extended_perms_decision to be added to the node + * @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0. * * if a valid AVC entry doesn't exist,this function returns -ENOENT. * if kmalloc() called internal returns NULL, this function returns -ENOMEM. @@ -856,6 +849,22 @@ static int avc_update_node(struct selinux_avc *avc, struct hlist_head *head; spinlock_t *lock; + /* + * If we are in a non-blocking code path, e.g. VFS RCU walk, + * then we must not add permissions to a cache entry + * because we cannot safely audit the denial. Otherwise, + * during the subsequent blocking retry (e.g. VFS ref walk), we + * will find the permissions already granted in the cache entry + * and won't audit anything at all, leading to silent denials in + * permissive mode that only appear when in enforcing mode. + * + * See the corresponding handling in slow_avc_audit(), and the + * logic in selinux_inode_permission for the MAY_NOT_BLOCK flag, + * which is transliterated into AVC_NONBLOCKING. + */ + if (flags & AVC_NONBLOCKING) + return 0; + node = avc_alloc_node(avc); if (!node) { rc = -ENOMEM; @@ -1050,7 +1059,8 @@ int avc_has_extended_perms(struct selinux_state *state, int rc = 0, rc2; xp_node = &local_xp_node; - BUG_ON(!requested); + if (WARN_ON(!requested)) + return -EACCES; rcu_read_lock(); @@ -1115,7 +1125,7 @@ decision: * @tsid: target security identifier * @tclass: target security class * @requested: requested permissions, interpreted based on @tclass - * @flags: AVC_STRICT or 0 + * @flags: AVC_STRICT, AVC_NONBLOCKING, or 0 * @avd: access vector decisions * * Check the AVC to determine whether the @requested permissions are granted @@ -1140,7 +1150,8 @@ inline int avc_has_perm_noaudit(struct selinux_state *state, int rc = 0; u32 denied; - BUG_ON(!requested); + if (WARN_ON(!requested)) + return -EACCES; rcu_read_lock(); @@ -1191,24 +1202,6 @@ int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass, return rc; } -int avc_has_perm_flags(struct selinux_state *state, - u32 ssid, u32 tsid, u16 tclass, u32 requested, - struct common_audit_data *auditdata, - int flags) -{ - struct av_decision avd; - int rc, rc2; - - rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0, - &avd); - - rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc, - auditdata, flags); - if (rc2) - return rc2; - return rc; -} - u32 avc_policy_seqno(struct selinux_state *state) { return state->avc->avc_cache.latest_notif; diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c @@ -490,16 +490,10 @@ static int may_context_mount_inode_relabel(u32 sid, return rc; } -static int selinux_is_sblabel_mnt(struct super_block *sb) +static int selinux_is_genfs_special_handling(struct super_block *sb) { - struct superblock_security_struct *sbsec = sb->s_security; - - return sbsec->behavior == SECURITY_FS_USE_XATTR || - sbsec->behavior == SECURITY_FS_USE_TRANS || - sbsec->behavior == SECURITY_FS_USE_TASK || - sbsec->behavior == SECURITY_FS_USE_NATIVE || - /* Special handling. Genfs but also in-core setxattr handler */ - !strcmp(sb->s_type->name, "sysfs") || + /* Special handling. Genfs but also in-core setxattr handler */ + return !strcmp(sb->s_type->name, "sysfs") || !strcmp(sb->s_type->name, "pstore") || !strcmp(sb->s_type->name, "debugfs") || !strcmp(sb->s_type->name, "tracefs") || @@ -509,6 +503,34 @@ static int selinux_is_sblabel_mnt(struct super_block *sb) !strcmp(sb->s_type->name, "cgroup2"))); } +static int selinux_is_sblabel_mnt(struct super_block *sb) +{ + struct superblock_security_struct *sbsec = sb->s_security; + + /* + * IMPORTANT: Double-check logic in this function when adding a new + * SECURITY_FS_USE_* definition! + */ + BUILD_BUG_ON(SECURITY_FS_USE_MAX != 7); + + switch (sbsec->behavior) { + case SECURITY_FS_USE_XATTR: + case SECURITY_FS_USE_TRANS: + case SECURITY_FS_USE_TASK: + case SECURITY_FS_USE_NATIVE: + return 1; + + case SECURITY_FS_USE_GENFS: + return selinux_is_genfs_special_handling(sb); + + /* Never allow relabeling on context mounts */ + case SECURITY_FS_USE_MNTPOINT: + case SECURITY_FS_USE_NONE: + default: + return 0; + } +} + static int sb_finish_set_opts(struct super_block *sb) { struct superblock_security_struct *sbsec = sb->s_security; @@ -2881,9 +2903,8 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode, if (IS_ERR(isec)) return PTR_ERR(isec); - return avc_has_perm_flags(&selinux_state, - sid, isec->sid, isec->sclass, FILE__READ, &ad, - rcu ? MAY_NOT_BLOCK : 0); + return avc_has_perm(&selinux_state, + sid, isec->sid, isec->sclass, FILE__READ, &ad); } static noinline int audit_inode_permission(struct inode *inode, @@ -2938,7 +2959,9 @@ static int selinux_inode_permission(struct inode *inode, int mask) return PTR_ERR(isec); rc = avc_has_perm_noaudit(&selinux_state, - sid, isec->sid, isec->sclass, perms, 0, &avd); + sid, isec->sid, isec->sclass, perms, + (flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0, + &avd); audited = avc_audit_required(perms, &avd, rc, from_access ? FILE__AUDIT_ACCESS : 0, &denied); @@ -3197,12 +3220,16 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags) { struct inode_security_struct *isec = inode_security_novalidate(inode); + struct superblock_security_struct *sbsec = inode->i_sb->s_security; u32 newsid; int rc; if (strcmp(name, XATTR_SELINUX_SUFFIX)) return -EOPNOTSUPP; + if (!(sbsec->flags & SBLABEL_MNT)) + return -EOPNOTSUPP; + if (!value || !size) return -EACCES; @@ -6236,7 +6263,10 @@ static void selinux_inode_invalidate_secctx(struct inode *inode) */ static int selinux_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen) { - return selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, ctx, ctxlen, 0); + int rc = selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, + ctx, ctxlen, 0); + /* Do not return error when suppressing label (SBLABEL_MNT not set). */ + return rc == -EOPNOTSUPP ? 0 : rc; } /* diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h @@ -142,6 +142,7 @@ static inline int avc_audit(struct selinux_state *state, #define AVC_STRICT 1 /* Ignore permissive mode. */ #define AVC_EXTENDED_PERMS 2 /* update extended permissions */ +#define AVC_NONBLOCKING 4 /* non blocking */ int avc_has_perm_noaudit(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass, u32 requested, @@ -152,11 +153,6 @@ int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass, u32 requested, struct common_audit_data *auditdata); -int avc_has_perm_flags(struct selinux_state *state, - u32 ssid, u32 tsid, - u16 tclass, u32 requested, - struct common_audit_data *auditdata, - int flags); int avc_has_extended_perms(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass, u32 requested, diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h @@ -255,6 +255,9 @@ int security_sid_to_context(struct selinux_state *state, u32 sid, int security_sid_to_context_force(struct selinux_state *state, u32 sid, char **scontext, u32 *scontext_len); +int security_sid_to_context_inval(struct selinux_state *state, + u32 sid, char **scontext, u32 *scontext_len); + int security_context_to_sid(struct selinux_state *state, const char *scontext, u32 scontext_len, u32 *out_sid, gfp_t gfp); diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c @@ -1280,7 +1280,8 @@ const char *security_get_initial_sid_context(u32 sid) static int security_sid_to_context_core(struct selinux_state *state, u32 sid, char **scontext, - u32 *scontext_len, int force) + u32 *scontext_len, int force, + int only_invalid) { struct policydb *policydb; struct sidtab *sidtab; @@ -1325,8 +1326,14 @@ static int security_sid_to_context_core(struct selinux_state *state, rc = -EINVAL; goto out_unlock; } - rc = context_struct_to_string(policydb, context, scontext, - scontext_len); + if (only_invalid && !context->len) { + scontext = NULL; + scontext_len = 0; + rc = 0; + } else { + rc = context_struct_to_string(policydb, context, scontext, + scontext_len); + } out_unlock: read_unlock(&state->ss->policy_rwlock); out: @@ -1348,14 +1355,34 @@ int security_sid_to_context(struct selinux_state *state, u32 sid, char **scontext, u32 *scontext_len) { return security_sid_to_context_core(state, sid, scontext, - scontext_len, 0); + scontext_len, 0, 0); } int security_sid_to_context_force(struct selinux_state *state, u32 sid, char **scontext, u32 *scontext_len) { return security_sid_to_context_core(state, sid, scontext, - scontext_len, 1); + scontext_len, 1, 0); +} + +/** + * security_sid_to_context_inval - Obtain a context for a given SID if it + * is invalid. + * @sid: security identifier, SID + * @scontext: security context + * @scontext_len: length in bytes + * + * Write the string representation of the context associated with @sid + * into a dynamically allocated string of the correct size, but only if the + * context is invalid in the current policy. Set @scontext to point to + * this string (or NULL if the context is valid) and set @scontext_len to + * the length of the string (or 0 if the context is valid). + */ +int security_sid_to_context_inval(struct selinux_state *state, u32 sid, + char **scontext, u32 *scontext_len) +{ + return security_sid_to_context_core(state, sid, scontext, + scontext_len, 1, 1); } /*