| Message ID | 20181102231510.15911-1-ebiggers@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KEYS: always initialize keyring_index_key::desc_len | expand |
On Fri, Nov 02, 2018 at 04:15:10PM -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > syzbot hit the 'BUG_ON(index_key->desc_len == 0);' in __key_link_begin() > called from construct_alloc_key() during sys_request_key(), because the > length of the key description was never calculated. > > The problem is that we rely on ->desc_len being initialized by > search_process_keyrings(), specifically by search_nested_keyrings(). > But, if the process isn't subscribed to any keyrings that never happens. > > Fix it by always initializing keyring_index_key::desc_len as soon as the > description is set, like we already do in some places. > > The following program reproduces the BUG_ON() when it's run as root and > no session keyring has been installed. If it doesn't work, try removing > pam_keyinit.so from /etc/pam.d/login and rebooting. > > #include <stdlib.h> > #include <unistd.h> > #include <keyutils.h> > > int main(void) > { > int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING); > > keyctl_setperm(id, KEY_OTH_WRITE); > setreuid(5000, 5000); > request_key("user", "desc", "", id); > } > > Reported-by: syzbot+ec24e95ea483de0a24da@syzkaller.appspotmail.com > Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring") > Cc: <stable@vger.kernel.org> # v3.13+ > Signed-off-by: Eric Biggers <ebiggers@google.com> > --- > security/keys/keyring.c | 4 +--- > security/keys/proc.c | 1 + > security/keys/request_key.c | 1 + > security/keys/request_key_auth.c | 2 +- > 4 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/security/keys/keyring.c b/security/keys/keyring.c > index 41bcf57e96f2..99a55145ddcd 100644 > --- a/security/keys/keyring.c > +++ b/security/keys/keyring.c > @@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring, > BUG_ON((ctx->flags & STATE_CHECKS) == 0 || > (ctx->flags & STATE_CHECKS) == STATE_CHECKS); > > - if (ctx->index_key.description) > - ctx->index_key.desc_len = strlen(ctx->index_key.description); > - > /* Check to see if this top-level keyring is what we are looking for > * and whether it is valid or not. > */ > @@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring, > struct keyring_search_context ctx = { > .index_key.type = type, > .index_key.description = description, > + .index_key.desc_len = strlen(description), > .cred = current_cred(), > .match_data.cmp = key_default_cmp, > .match_data.raw_data = description, > diff --git a/security/keys/proc.c b/security/keys/proc.c > index 5af2934965d8..909f6c5270a1 100644 > --- a/security/keys/proc.c > +++ b/security/keys/proc.c > @@ -168,6 +168,7 @@ static int proc_keys_show(struct seq_file *m, void *v) > struct keyring_search_context ctx = { > .index_key.type = key->type, > .index_key.description = key->description, > + .index_key.desc_len = strlen(key->description), > .cred = m->file->f_cred, > .match_data.cmp = lookup_user_key_possessed, > .match_data.raw_data = key, It's actually possible to just set '.index_key = key->index_key' here. I'll send v2 with that instead. - Eric
diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 41bcf57e96f2..99a55145ddcd 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -661,9 +661,6 @@ static bool search_nested_keyrings(struct key *keyring, BUG_ON((ctx->flags & STATE_CHECKS) == 0 || (ctx->flags & STATE_CHECKS) == STATE_CHECKS); - if (ctx->index_key.description) - ctx->index_key.desc_len = strlen(ctx->index_key.description); - /* Check to see if this top-level keyring is what we are looking for * and whether it is valid or not. */ @@ -914,6 +911,7 @@ key_ref_t keyring_search(key_ref_t keyring, struct keyring_search_context ctx = { .index_key.type = type, .index_key.description = description, + .index_key.desc_len = strlen(description), .cred = current_cred(), .match_data.cmp = key_default_cmp, .match_data.raw_data = description, diff --git a/security/keys/proc.c b/security/keys/proc.c index 5af2934965d8..909f6c5270a1 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -168,6 +168,7 @@ static int proc_keys_show(struct seq_file *m, void *v) struct keyring_search_context ctx = { .index_key.type = key->type, .index_key.description = key->description, + .index_key.desc_len = strlen(key->description), .cred = m->file->f_cred, .match_data.cmp = lookup_user_key_possessed, .match_data.raw_data = key, diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 114f7408feee..738553698649 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -545,6 +545,7 @@ struct key *request_key_and_link(struct key_type *type, struct keyring_search_context ctx = { .index_key.type = type, .index_key.description = description, + .index_key.desc_len = strlen(description), .cred = current_cred(), .match_data.cmp = key_default_cmp, .match_data.raw_data = description, diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index 424e1d90412e..6797843154f0 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -246,7 +246,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id) struct key *authkey; key_ref_t authkey_ref; - sprintf(description, "%x", target_id); + ctx.index_key.desc_len = sprintf(description, "%x", target_id); authkey_ref = search_process_keyrings(&ctx);