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credential-cache: respect request capabilities #1842

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@hickford hickford commented Dec 20, 2024

CC: sandals@crustytoothpaste.net

Patch v4 fixes test

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gitgitgadget bot commented Dec 20, 2024

There are issues in commit 945b5c5:
credential-cache: respect request capabilities
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/submit

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gitgitgadget bot commented Dec 20, 2024

Submitted as pull.1842.git.1734729534213.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-1842/hickford/cache-capability-v1

To fetch this version to local tag pr-1842/hickford/cache-capability-v1:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-1842/hickford/cache-capability-v1

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hickford commented Jan 6, 2025

/submit

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gitgitgadget bot commented Jan 6, 2025

Submitted as pull.1842.v2.git.1736193131798.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-1842/hickford/cache-capability-v2

To fetch this version to local tag pr-1842/hickford/cache-capability-v2:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-1842/hickford/cache-capability-v2

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gitgitgadget bot commented Jan 6, 2025

On the Git mailing list, "brian m. carlson" wrote (reply to this):

On 2025-01-06 at 19:52:11, M Hickford via GitGitGadget wrote:
> From: M Hickford <mirth.hickford@gmail.com>
> 
> Previously, credential-cache responded with capability[]=authtype
> regardless of request.

That's the correct behaviour.

> The capabilities in a credential helper response should be a subset of
> the capabilities in the request.

No, it should not.  Otherwise, it's impossible for Git to know whether
the helper does or does not support the capability.  We rely on that
information to correctly pass data back when saving data.

> diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
> index bc22f5c6d24..692216cf83c 100644
> --- a/builtin/credential-cache--daemon.c
> +++ b/builtin/credential-cache--daemon.c
> @@ -134,17 +134,16 @@ static void serve_one_client(FILE *in, FILE *out)
>  	else if (!strcmp(action.buf, "get")) {
>  		struct credential_cache_entry *e = lookup_credential(&c);
>  		if (e) {
> -			e->item.capa_authtype.request_initial = 1;
> -			e->item.capa_authtype.request_helper = 1;
> -
> -			fprintf(out, "capability[]=authtype\n");
> +			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE)) {
> +				fprintf(out, "capability[]=authtype\n");
> +			}

This part is not correct.

>  			if (e->item.username)
>  				fprintf(out, "username=%s\n", e->item.username);
>  			if (e->item.password)
>  				fprintf(out, "password=%s\n", e->item.password);
> -			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.authtype)
> +			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.authtype)
>  				fprintf(out, "authtype=%s\n", e->item.authtype);
> -			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.credential)
> +			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.credential)

This part may very well be correct.

>  				fprintf(out, "credential=%s\n", e->item.credential);
>  			if (e->item.password_expiry_utc != TIME_MAX)
>  				fprintf(out, "password_expiry_utc=%"PRItime"\n",
> diff --git a/t/lib-credential.sh b/t/lib-credential.sh
> index 58b9c740605..324ecc792d5 100644
> --- a/t/lib-credential.sh
> +++ b/t/lib-credential.sh
> @@ -566,6 +566,21 @@ helper_test_authtype() {
>  		EOF
>  	'
>  
> +	test_expect_success "helper ($HELPER) get authtype only if request has authtype capability" '
> +		check fill $HELPER <<-\EOF
> +		protocol=https
> +		host=git.example.com
> +		--
> +		protocol=https
> +		host=git.example.com
> +		username=askpass-username
> +		password=askpass-password
> +		--
> +		askpass: Username for '\''https://git.example.com'\'':
> +		askpass: Password for '\''https://askpass-username@git.example.com'\'':
> +		EOF
> +	'
> +
>  	test_expect_success "helper ($HELPER) stores authtype and credential with username" '
>  		check approve $HELPER <<-\EOF
>  		capability[]=authtype
> 
> base-commit: 92999a42db1c5f43f330e4f2bca4026b5b81576f
> -- 
> gitgitgadget

-- 
brian m. carlson (they/them or he/him)
Toronto, Ontario, CA

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gitgitgadget bot commented Jan 6, 2025

On the Git mailing list, M Hickford wrote (reply to this):

On Mon, 6 Jan 2025 at 22:32, brian m. carlson
<sandals@crustytoothpaste.net> wrote:
>
> On 2025-01-06 at 19:52:11, M Hickford via GitGitGadget wrote:
> > From: M Hickford <mirth.hickford@gmail.com>
> >
> > Previously, credential-cache responded with capability[]=authtype
> > regardless of request.
>
> That's the correct behaviour.
>
> > The capabilities in a credential helper response should be a subset of
> > the capabilities in the request.
>
> No, it should not.  Otherwise, it's impossible for Git to know whether
> the helper does or does not support the capability.  We rely on that
> information to correctly pass data back when saving data.
>
> > diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
> > index bc22f5c6d24..692216cf83c 100644
> > --- a/builtin/credential-cache--daemon.c
> > +++ b/builtin/credential-cache--daemon.c
> > @@ -134,17 +134,16 @@ static void serve_one_client(FILE *in, FILE *out)
> >       else if (!strcmp(action.buf, "get")) {
> >               struct credential_cache_entry *e = lookup_credential(&c);
> >               if (e) {
> > -                     e->item.capa_authtype.request_initial = 1;
> > -                     e->item.capa_authtype.request_helper = 1;
> > -
> > -                     fprintf(out, "capability[]=authtype\n");
> > +                     if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE)) {
> > +                             fprintf(out, "capability[]=authtype\n");
> > +                     }
>
> This part is not correct.

Thanks for the review. I'll revert this part and amend the commit message.

>
> >                       if (e->item.username)
> >                               fprintf(out, "username=%s\n", e->item.username);
> >                       if (e->item.password)
> >                               fprintf(out, "password=%s\n", e->item.password);
> > -                     if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.authtype)
> > +                     if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.authtype)
> >                               fprintf(out, "authtype=%s\n", e->item.authtype);
> > -                     if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.credential)
> > +                     if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.credential)
>
> This part may very well be correct.
>
> >                               fprintf(out, "credential=%s\n", e->item.credential);
> >                       if (e->item.password_expiry_utc != TIME_MAX)
> >                               fprintf(out, "password_expiry_utc=%"PRItime"\n",
> > diff --git a/t/lib-credential.sh b/t/lib-credential.sh
> > index 58b9c740605..324ecc792d5 100644
> > --- a/t/lib-credential.sh
> > +++ b/t/lib-credential.sh
> > @@ -566,6 +566,21 @@ helper_test_authtype() {
> >               EOF
> >       '
> >
> > +     test_expect_success "helper ($HELPER) get authtype only if request has authtype capability" '
> > +             check fill $HELPER <<-\EOF
> > +             protocol=https
> > +             host=git.example.com
> > +             --
> > +             protocol=https
> > +             host=git.example.com
> > +             username=askpass-username
> > +             password=askpass-password
> > +             --
> > +             askpass: Username for '\''https://git.example.com'\'':
> > +             askpass: Password for '\''https://askpass-username@git.example.com'\'':
> > +             EOF
> > +     '
> > +
> >       test_expect_success "helper ($HELPER) stores authtype and credential with username" '
> >               check approve $HELPER <<-\EOF
> >               capability[]=authtype
> >
> > base-commit: 92999a42db1c5f43f330e4f2bca4026b5b81576f
> > --
> > gitgitgadget
>
> --
> brian m. carlson (they/them or he/him)
> Toronto, Ontario, CA

@hickford
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hickford commented Jan 6, 2025

/submit

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gitgitgadget bot commented Jan 6, 2025

Submitted as pull.1842.v3.git.1736204756030.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-1842/hickford/cache-capability-v3

To fetch this version to local tag pr-1842/hickford/cache-capability-v3:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-1842/hickford/cache-capability-v3

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gitgitgadget bot commented Jan 6, 2025

On the Git mailing list, "brian m. carlson" wrote (reply to this):

On 2025-01-06 at 22:57:06, M Hickford wrote:
> On Mon, 6 Jan 2025 at 22:32, brian m. carlson
> <sandals@crustytoothpaste.net> wrote:
> >
> > On 2025-01-06 at 19:52:11, M Hickford via GitGitGadget wrote:
> > > From: M Hickford <mirth.hickford@gmail.com>
> > > diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
> > > index bc22f5c6d24..692216cf83c 100644
> > > --- a/builtin/credential-cache--daemon.c
> > > +++ b/builtin/credential-cache--daemon.c
> > > @@ -134,17 +134,16 @@ static void serve_one_client(FILE *in, FILE *out)
> > >       else if (!strcmp(action.buf, "get")) {
> > >               struct credential_cache_entry *e = lookup_credential(&c);
> > >               if (e) {
> > > -                     e->item.capa_authtype.request_initial = 1;
> > > -                     e->item.capa_authtype.request_helper = 1;
> > > -
> > > -                     fprintf(out, "capability[]=authtype\n");
> > > +                     if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE)) {
> > > +                             fprintf(out, "capability[]=authtype\n");
> > > +                     }
> >
> > This part is not correct.
> 
> Thanks for the review. I'll revert this part and amend the commit message.

I applied this without that change and it does still pass the test,
which I think is good and shows that can be omitted.  If I have some
time, I may send a follow-up patch to add some additional tests.
-- 
brian m. carlson (they/them or he/him)
Toronto, Ontario, CA

Previously, credential-cache populated authtype regardless of request.

Signed-off-by: M Hickford <mirth.hickford@gmail.com>
@hickford
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hickford commented Jan 7, 2025

/submit

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gitgitgadget bot commented Jan 7, 2025

Submitted as pull.1842.v4.git.1736212760709.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-1842/hickford/cache-capability-v4

To fetch this version to local tag pr-1842/hickford/cache-capability-v4:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-1842/hickford/cache-capability-v4

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gitgitgadget bot commented Jan 8, 2025

On the Git mailing list, Junio C Hamano wrote (reply to this):

"M Hickford via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: M Hickford <mirth.hickford@gmail.com>
>
> Previously, credential-cache populated authtype regardless of request.

OK, that may be a correct statement of the fact, but it does not
tell readers any of the following:

 - If it is a bad thing to populate authtype regardless of request,
   and if so why?

 - What is the (negative) consequence of doing so, if any?  What
   breaks because it populates authtype regardless of request?

 - What is the remedy?  Instead of unconditionally populating the
   authtype, how does the new code decide when to populate it and
   with what value?

 - Can there be downsides of fixing this?  Are there use cases where
   this unconditional population of authtype was relied upon?

 - Where did the bug come from and what is its fix?  We used to look
   at OP_HELPER to decide when to emit authtype, but the updated
   code checks OP_RESPONSE, which readers can see in the patch.

   It would be nice if the proposed log message helped them by
   briefly explaining their differences, for example.

which would help future "git log" readers what this fix was about.

Will queue for now, but the log message would want to be a bit more
helpful to the readers.

Thanks.

> Signed-off-by: M Hickford <mirth.hickford@gmail.com>
> ---
>     credential-cache: respect request capabilities
>     
>     CC: sandals@crustytoothpaste.net
>     
>     Patch v4 fixes test
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1842%2Fhickford%2Fcache-capability-v4
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1842/hickford/cache-capability-v4
> Pull-Request: https://github.com/gitgitgadget/git/pull/1842
>
> Range-diff vs v3:
>
>  1:  e9851c5c4ac ! 1:  23942f9fa47 credential-cache: respect request capabilities
>      @@ t/lib-credential.sh: helper_test_authtype() {
>       +		protocol=https
>       +		host=git.example.com
>       +		--
>      -+		capability[]=authtype
>       +		protocol=https
>       +		host=git.example.com
>       +		username=askpass-username
>
>
>  builtin/credential-cache--daemon.c |  4 ++--
>  t/lib-credential.sh                | 15 +++++++++++++++
>  2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
> index bc22f5c6d24..e707618e743 100644
> --- a/builtin/credential-cache--daemon.c
> +++ b/builtin/credential-cache--daemon.c
> @@ -142,9 +142,9 @@ static void serve_one_client(FILE *in, FILE *out)
>  				fprintf(out, "username=%s\n", e->item.username);
>  			if (e->item.password)
>  				fprintf(out, "password=%s\n", e->item.password);
> -			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.authtype)
> +			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.authtype)
>  				fprintf(out, "authtype=%s\n", e->item.authtype);
> -			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.credential)
> +			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.credential)
>  				fprintf(out, "credential=%s\n", e->item.credential);
>  			if (e->item.password_expiry_utc != TIME_MAX)
>  				fprintf(out, "password_expiry_utc=%"PRItime"\n",
> diff --git a/t/lib-credential.sh b/t/lib-credential.sh
> index 58b9c740605..cc6bf9aa5f3 100644
> --- a/t/lib-credential.sh
> +++ b/t/lib-credential.sh
> @@ -566,6 +566,21 @@ helper_test_authtype() {
>  		EOF
>  	'
>  
> +	test_expect_success "helper ($HELPER) gets authtype and credential only if request has authtype capability" '
> +		check fill $HELPER <<-\EOF
> +		protocol=https
> +		host=git.example.com
> +		--
> +		protocol=https
> +		host=git.example.com
> +		username=askpass-username
> +		password=askpass-password
> +		--
> +		askpass: Username for '\''https://git.example.com'\'':
> +		askpass: Password for '\''https://askpass-username@git.example.com'\'':
> +		EOF
> +	'
> +
>  	test_expect_success "helper ($HELPER) stores authtype and credential with username" '
>  		check approve $HELPER <<-\EOF
>  		capability[]=authtype
>
> base-commit: 92999a42db1c5f43f330e4f2bca4026b5b81576f

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gitgitgadget bot commented Jan 8, 2025

This patch series was integrated into seen via git@d970fe7.

@gitgitgadget gitgitgadget bot added the seen label Jan 8, 2025
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gitgitgadget bot commented Jan 8, 2025

This patch series was integrated into seen via git@485116e.

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