[v2] KEYS: always initialize keyring_index_key::desc_len
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Message ID 20181103015854.7380-1-ebiggers@kernel.org
State New
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Series
  • [v2] KEYS: always initialize keyring_index_key::desc_len
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Commit Message

Eric Biggers Nov. 3, 2018, 1:58 a.m. UTC
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>
---

v2: In proc_keys_show(), assign index_key directly

 security/keys/keyring.c          | 4 +---
 security/keys/proc.c             | 3 +--
 security/keys/request_key.c      | 1 +
 security/keys/request_key_auth.c | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

Comments

Eric Biggers Nov. 28, 2018, 11:19 p.m. UTC | #1
On Fri, Nov 02, 2018 at 06:58:54PM -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>
> ---
> 
> v2: In proc_keys_show(), assign index_key directly
> 
>  security/keys/keyring.c          | 4 +---
>  security/keys/proc.c             | 3 +--
>  security/keys/request_key.c      | 1 +
>  security/keys/request_key_auth.c | 2 +-
>  4 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/security/keys/keyring.c b/security/keys/keyring.c
> index 41bcf57e96f21..99a55145ddcd2 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 5af2934965d80..d38be9db2cc07 100644
> --- a/security/keys/proc.c
> +++ b/security/keys/proc.c
> @@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
>  	int rc;
>  
>  	struct keyring_search_context ctx = {
> -		.index_key.type		= key->type,
> -		.index_key.description	= key->description,
> +		.index_key		= key->index_key,
>  		.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 114f7408feee6..7385536986497 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 424e1d90412ea..6797843154f03 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);
>  
> -- 
> 2.19.1
> 

Ping.  David, are you planning to apply this?

- Eric
Eric Biggers Dec. 6, 2018, 6:26 p.m. UTC | #2
On Wed, Nov 28, 2018 at 03:19:41PM -0800, Eric Biggers wrote:
> On Fri, Nov 02, 2018 at 06:58:54PM -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>
> > ---
> > 
> > v2: In proc_keys_show(), assign index_key directly
> > 
> >  security/keys/keyring.c          | 4 +---
> >  security/keys/proc.c             | 3 +--
> >  security/keys/request_key.c      | 1 +
> >  security/keys/request_key_auth.c | 2 +-
> >  4 files changed, 4 insertions(+), 6 deletions(-)
> > 
> > diff --git a/security/keys/keyring.c b/security/keys/keyring.c
> > index 41bcf57e96f21..99a55145ddcd2 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 5af2934965d80..d38be9db2cc07 100644
> > --- a/security/keys/proc.c
> > +++ b/security/keys/proc.c
> > @@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
> >  	int rc;
> >  
> >  	struct keyring_search_context ctx = {
> > -		.index_key.type		= key->type,
> > -		.index_key.description	= key->description,
> > +		.index_key		= key->index_key,
> >  		.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 114f7408feee6..7385536986497 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 424e1d90412ea..6797843154f03 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);
> >  
> > -- 
> > 2.19.1
> > 
> 
> Ping.  David, are you planning to apply this?
> 
> - Eric
> 

Ping.
Eric Biggers Jan. 10, 2019, 8:27 p.m. UTC | #3
On Wed, Nov 28, 2018 at 03:19:41PM -0800, Eric Biggers wrote:
> On Fri, Nov 02, 2018 at 06:58:54PM -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>
> > ---
> > 
> > v2: In proc_keys_show(), assign index_key directly
> > 
> >  security/keys/keyring.c          | 4 +---
> >  security/keys/proc.c             | 3 +--
> >  security/keys/request_key.c      | 1 +
> >  security/keys/request_key_auth.c | 2 +-
> >  4 files changed, 4 insertions(+), 6 deletions(-)
> > 
> > diff --git a/security/keys/keyring.c b/security/keys/keyring.c
> > index 41bcf57e96f21..99a55145ddcd2 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 5af2934965d80..d38be9db2cc07 100644
> > --- a/security/keys/proc.c
> > +++ b/security/keys/proc.c
> > @@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
> >  	int rc;
> >  
> >  	struct keyring_search_context ctx = {
> > -		.index_key.type		= key->type,
> > -		.index_key.description	= key->description,
> > +		.index_key		= key->index_key,
> >  		.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 114f7408feee6..7385536986497 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 424e1d90412ea..6797843154f03 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);
> >  
> > -- 
> > 2.19.1
> > 
> 
> Ping.  David, are you planning to apply this?
> 
> - Eric
> 
> -- 
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Ping.
Eric Biggers Feb. 7, 2019, 11:35 p.m. UTC | #4
On Thu, Jan 10, 2019 at 12:27:46PM -0800, Eric Biggers wrote:
> On Wed, Nov 28, 2018 at 03:19:41PM -0800, Eric Biggers wrote:
> > On Fri, Nov 02, 2018 at 06:58:54PM -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>
> > > ---
> > > 
> > > v2: In proc_keys_show(), assign index_key directly
> > > 
> > >  security/keys/keyring.c          | 4 +---
> > >  security/keys/proc.c             | 3 +--
> > >  security/keys/request_key.c      | 1 +
> > >  security/keys/request_key_auth.c | 2 +-
> > >  4 files changed, 4 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/security/keys/keyring.c b/security/keys/keyring.c
> > > index 41bcf57e96f21..99a55145ddcd2 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 5af2934965d80..d38be9db2cc07 100644
> > > --- a/security/keys/proc.c
> > > +++ b/security/keys/proc.c
> > > @@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
> > >  	int rc;
> > >  
> > >  	struct keyring_search_context ctx = {
> > > -		.index_key.type		= key->type,
> > > -		.index_key.description	= key->description,
> > > +		.index_key		= key->index_key,
> > >  		.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 114f7408feee6..7385536986497 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 424e1d90412ea..6797843154f03 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);
> > >  
> > > -- 
> > > 2.19.1
> > > 
> > 
> > Ping.  David, are you planning to apply this?
> > 
> > - Eric
> > 
> > -- 
> > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181128231940.GB131170%40gmail.com.
> > For more options, visit https://groups.google.com/d/optout.
> 
> Ping.
> 

Ping.  David, are you planning to apply this?

- Eric
Eric Biggers Feb. 19, 2019, 11:04 p.m. UTC | #5
On Thu, Feb 07, 2019 at 03:35:29PM -0800, Eric Biggers wrote:
> On Thu, Jan 10, 2019 at 12:27:46PM -0800, Eric Biggers wrote:
> > On Wed, Nov 28, 2018 at 03:19:41PM -0800, Eric Biggers wrote:
> > > On Fri, Nov 02, 2018 at 06:58:54PM -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>
> > > > ---
> > > > 
> > > > v2: In proc_keys_show(), assign index_key directly
> > > > 
> > > >  security/keys/keyring.c          | 4 +---
> > > >  security/keys/proc.c             | 3 +--
> > > >  security/keys/request_key.c      | 1 +
> > > >  security/keys/request_key_auth.c | 2 +-
> > > >  4 files changed, 4 insertions(+), 6 deletions(-)
> > > > 
> > > > diff --git a/security/keys/keyring.c b/security/keys/keyring.c
> > > > index 41bcf57e96f21..99a55145ddcd2 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 5af2934965d80..d38be9db2cc07 100644
> > > > --- a/security/keys/proc.c
> > > > +++ b/security/keys/proc.c
> > > > @@ -166,8 +166,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
> > > >  	int rc;
> > > >  
> > > >  	struct keyring_search_context ctx = {
> > > > -		.index_key.type		= key->type,
> > > > -		.index_key.description	= key->description,
> > > > +		.index_key		= key->index_key,
> > > >  		.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 114f7408feee6..7385536986497 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 424e1d90412ea..6797843154f03 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);
> > > >  
> > > > -- 
> > > > 2.19.1
> > > > 
> > > 
> > > Ping.  David, are you planning to apply this?
> > > 
> > > - Eric
> > > 
> > > -- 
> > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181128231940.GB131170%40gmail.com.
> > > For more options, visit https://groups.google.com/d/optout.
> > 
> > Ping.
> > 
> 
> Ping.  David, are you planning to apply this?
> 
> - Eric

Hi James, can you please apply this for v5.1?  This has been ignored by David
for over 3 months with repeated pings.

- Eric

Patch
diff mbox series

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 41bcf57e96f21..99a55145ddcd2 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 5af2934965d80..d38be9db2cc07 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -166,8 +166,7 @@  static int proc_keys_show(struct seq_file *m, void *v)
 	int rc;
 
 	struct keyring_search_context ctx = {
-		.index_key.type		= key->type,
-		.index_key.description	= key->description,
+		.index_key		= key->index_key,
 		.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 114f7408feee6..7385536986497 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 424e1d90412ea..6797843154f03 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);