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author | Ondrej Mosnacek <omosnace@redhat.com> | 2021-04-02 10:56:19 +0200 |
---|---|---|
committer | Paul Moore <paul@paul-moore.com> | 2021-04-02 17:46:55 +0200 |
commit | d8f5f0ea5b86300390b026b6c6e7836b7150814a (patch) | |
tree | f1958b4ed857ea6ae8b3c4514db1fe5a3c778bac | |
parent | selinux: make nslot handling in avtab more robust (diff) | |
download | linux-d8f5f0ea5b86300390b026b6c6e7836b7150814a.tar.xz linux-d8f5f0ea5b86300390b026b6c6e7836b7150814a.zip |
selinux: fix cond_list corruption when changing booleans
Currently, duplicate_policydb_cond_list() first copies the whole
conditional avtab and then tries to link to the correct entries in
cond_dup_av_list() using avtab_search(). However, since the conditional
avtab may contain multiple entries with the same key, this approach
often fails to find the right entry, potentially leading to wrong rules
being activated/deactivated when booleans are changed.
To fix this, instead start with an empty conditional avtab and add the
individual entries one-by-one while building the new av_lists. This
approach leads to the correct result, since each entry is present in the
av_lists exactly once.
The issue can be reproduced with Fedora policy as follows:
# sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True
# setsebool ftpd_anon_write=off ftpd_connect_all_unreserved=off ftpd_connect_db=off ftpd_full_access=off
On fixed kernels, the sesearch output is the same after the setsebool
command:
# sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True
While on the broken kernels, it will be different:
# sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A
allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True
While there, also simplify the computation of nslots. This changes the
nslots values for nrules 2 or 3 to just two slots instead of 4, which
makes the sequence more consistent.
Cc: stable@vger.kernel.org
Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
-rw-r--r-- | security/selinux/ss/avtab.c | 88 | ||||
-rw-r--r-- | security/selinux/ss/avtab.h | 2 | ||||
-rw-r--r-- | security/selinux/ss/conditional.c | 12 |
3 files changed, 33 insertions, 69 deletions
diff --git a/security/selinux/ss/avtab.c b/security/selinux/ss/avtab.c index 2aee4c965c25..75df32906055 100644 --- a/security/selinux/ss/avtab.c +++ b/security/selinux/ss/avtab.c @@ -308,24 +308,10 @@ void avtab_init(struct avtab *h) h->mask = 0; } -int avtab_alloc(struct avtab *h, u32 nrules) +static int avtab_alloc_common(struct avtab *h, u32 nslot) { - u32 shift = 0; - u32 work = nrules; - u32 nslot; - - if (nrules == 0) - goto avtab_alloc_out; - - while (work) { - work = work >> 1; - shift++; - } - if (shift > 2) - shift = shift - 2; - nslot = 1 << shift; - if (nslot > MAX_AVTAB_HASH_BUCKETS) - nslot = MAX_AVTAB_HASH_BUCKETS; + if (!nslot) + return 0; h->htable = kvcalloc(nslot, sizeof(void *), GFP_KERNEL); if (!h->htable) @@ -333,59 +319,37 @@ int avtab_alloc(struct avtab *h, u32 nrules) h->nslot = nslot; h->mask = nslot - 1; - -avtab_alloc_out: - pr_debug("SELinux: %d avtab hash slots, %d rules.\n", - h->nslot, nrules); return 0; } -int avtab_duplicate(struct avtab *new, struct avtab *orig) +int avtab_alloc(struct avtab *h, u32 nrules) { - int i; - struct avtab_node *node, *tmp, *tail; - - memset(new, 0, sizeof(*new)); - - new->htable = kvcalloc(orig->nslot, sizeof(void *), GFP_KERNEL); - if (!new->htable) - return -ENOMEM; - new->nslot = orig->nslot; - new->mask = orig->mask; - - for (i = 0; i < orig->nslot; i++) { - tail = NULL; - for (node = orig->htable[i]; node; node = node->next) { - tmp = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL); - if (!tmp) - goto error; - tmp->key = node->key; - if (tmp->key.specified & AVTAB_XPERMS) { - tmp->datum.u.xperms = - kmem_cache_zalloc(avtab_xperms_cachep, - GFP_KERNEL); - if (!tmp->datum.u.xperms) { - kmem_cache_free(avtab_node_cachep, tmp); - goto error; - } - tmp->datum.u.xperms = node->datum.u.xperms; - } else - tmp->datum.u.data = node->datum.u.data; - - if (tail) - tail->next = tmp; - else - new->htable[i] = tmp; - - tail = tmp; - new->nel++; + int rc; + u32 nslot = 0; + + if (nrules != 0) { + u32 shift = 1; + u32 work = nrules >> 3; + while (work) { + work >>= 1; + shift++; } + nslot = 1 << shift; + if (nslot > MAX_AVTAB_HASH_BUCKETS) + nslot = MAX_AVTAB_HASH_BUCKETS; + + rc = avtab_alloc_common(h, nslot); + if (rc) + return rc; } + pr_debug("SELinux: %d avtab hash slots, %d rules.\n", nslot, nrules); return 0; -error: - avtab_destroy(new); - return -ENOMEM; +} + +int avtab_alloc_dup(struct avtab *new, const struct avtab *orig) +{ + return avtab_alloc_common(new, orig->nslot); } void avtab_hash_eval(struct avtab *h, char *tag) diff --git a/security/selinux/ss/avtab.h b/security/selinux/ss/avtab.h index 4c4445ca9118..f2eeb36265d1 100644 --- a/security/selinux/ss/avtab.h +++ b/security/selinux/ss/avtab.h @@ -89,7 +89,7 @@ struct avtab { void avtab_init(struct avtab *h); int avtab_alloc(struct avtab *, u32); -int avtab_duplicate(struct avtab *new, struct avtab *orig); +int avtab_alloc_dup(struct avtab *new, const struct avtab *orig); struct avtab_datum *avtab_search(struct avtab *h, struct avtab_key *k); void avtab_destroy(struct avtab *h); void avtab_hash_eval(struct avtab *h, char *tag); diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c index 0b32f3ab025e..1ef74c085f2b 100644 --- a/security/selinux/ss/conditional.c +++ b/security/selinux/ss/conditional.c @@ -605,7 +605,6 @@ static int cond_dup_av_list(struct cond_av_list *new, struct cond_av_list *orig, struct avtab *avtab) { - struct avtab_node *avnode; u32 i; memset(new, 0, sizeof(*new)); @@ -615,10 +614,11 @@ static int cond_dup_av_list(struct cond_av_list *new, return -ENOMEM; for (i = 0; i < orig->len; i++) { - avnode = avtab_search_node(avtab, &orig->nodes[i]->key); - if (WARN_ON(!avnode)) - return -EINVAL; - new->nodes[i] = avnode; + new->nodes[i] = avtab_insert_nonunique(avtab, + &orig->nodes[i]->key, + &orig->nodes[i]->datum); + if (!new->nodes[i]) + return -ENOMEM; new->len++; } @@ -630,7 +630,7 @@ static int duplicate_policydb_cond_list(struct policydb *newp, { int rc, i, j; - rc = avtab_duplicate(&newp->te_cond_avtab, &origp->te_cond_avtab); + rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab); if (rc) return rc; |