Re: [PATCH] Add guards around [nfsidmap] usages of [sysconf].

[Steve Dickson <steved@xxxxxxxxxx>]

On 11/30/24 7:32 AM, Bogdan-Cristian Tătăroiu wrote:
> Hey Steve,
>
> My apologies for dropping this.
>
> I'm a bit confused since the man page for sysconf [1] seems to say it
> returns -1 and sets errno to EINVAL (and indeed the patch I originally
> submitted shows the intended behaviour on my musl system).
>
> The snippet in the newly defined [get_pwnam_buflen] is pretty much
> just what's in the [getpwnam] man page [2] example.
>
> Maybe the thing you're pointing to is that I have [*size_t* buflen =
> sysconf(_SC_GETPW_R_SIZE_MAX)].
> I guess that should technically be [long buflen] and the result could
> be converted to [size_t] upon return, it's just that the implicit
> conversions make it such that the current code behaves as expected.
>
> So something like
>
>       long buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>       if (buflen == -1)
>           buflen = 16384;
>       return (size_t)buflen;
>
> Does that make more sense?
Yes... it does... would mind posting another patch?

I don't have access to a musl system so I can not
test the change in that world.

tia

steved.
> [1] https://www.man7.org/linux/man-pages/man3/sysconf.3.html
> [2] https://www.man7.org/linux/man-pages/man3/getpwnam.3.html
>
> Best,
> Bogdan
>
> On Sat, Nov 9, 2024 at 6:25 PM Steve Dickson <steved@xxxxxxxxxx> wrote:
> > On 6/17/24 2:51 PM, Steve Dickson wrote:
> > > On 5/30/24 2:17 AM, Bogdan-Cristian Tătăroiu wrote:
> > > > sysconf(_SC_GETPW_R_SIZE_MAX) and sysconf(_SC_GETGR_R_SIZE_MAX)
> > > > return -1 on musl, which causes either segmentation faults or ENOMEM
> > > > errors.
> > > Actually sysconf() returns EINVAL not -1 since the return
> > > value is a size_t (unsigned long). So I needed to change
> > >
> > >       size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > >       if (buflen == EINVAL) <<< this from -1 to EINVAL
> > >           buflen = 16384;
> > >       return buflen;
> > >
> > > Good with that? Will this work with musl?
> > Just found this on my todo list... Still
> > interest in  have these patch committed?
> >
> > steved.
> >
> > > steved.
> > >
> > > > Replace all usages of sysconf with dedicated methods that guard against
> > > > a result of -1.
> > > >
> > > > Signed-off-by: Bogdan-Cristian Tătăroiu <b.tataroiu@xxxxxxxxx>
> > > > ---
> > > >    support/nfsidmap/gums.c             |  4 ++--
> > > >    support/nfsidmap/libnfsidmap.c      |  4 ++--
> > > >    support/nfsidmap/nfsidmap_common.c  | 16 ++++++++++++++++
> > > >    support/nfsidmap/nfsidmap_private.h |  2 ++
> > > >    support/nfsidmap/nss.c              |  8 ++++----
> > > >    support/nfsidmap/regex.c            |  9 +++++----
> > > >    support/nfsidmap/static.c           |  5 +++--
> > > >    7 files changed, 34 insertions(+), 14 deletions(-)
> > > >
> > > > diff --git a/support/nfsidmap/gums.c b/support/nfsidmap/gums.c
> > > > index 1d6eb318..e94a4c50 100644
> > > > --- a/support/nfsidmap/gums.c
> > > > +++ b/support/nfsidmap/gums.c
> > > > @@ -475,7 +475,7 @@ static int translate_to_uid(char *local_uid, uid_t
> > > > *uid, uid_t *gid)
> > > >        int ret = -1;
> > > >        struct passwd *pw = NULL;
> > > >        struct pwbuf *buf = NULL;
> > > > -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    size_t buflen = get_pwnam_buflen();
> > > >        buf = malloc(sizeof(*buf) + buflen);
> > > >        if (buf == NULL)
> > > > @@ -501,7 +501,7 @@ static int translate_to_gid(char *local_gid, uid_t
> > > > *gid)
> > > >        struct group *gr = NULL;
> > > >        struct group grbuf;
> > > >        char *buf = NULL;
> > > > -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    size_t buflen = get_grnam_buflen();
> > > >        int ret = -1;
> > > >        do {
> > > > diff --git a/support/nfsidmap/libnfsidmap.c b/support/nfsidmap/
> > > > libnfsidmap.c
> > > > index f8c36480..e1475879 100644
> > > > --- a/support/nfsidmap/libnfsidmap.c
> > > > +++ b/support/nfsidmap/libnfsidmap.c
> > > > @@ -457,7 +457,7 @@ int nfs4_init_name_mapping(char *conffile)
> > > >        nobody_user = conf_get_str("Mapping", "Nobody-User");
> > > >        if (nobody_user) {
> > > > -        size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +        size_t buflen = get_pwnam_buflen();
> > > >            struct passwd *buf;
> > > >            struct passwd *pw = NULL;
> > > >            int err;
> > > > @@ -478,7 +478,7 @@ int nfs4_init_name_mapping(char *conffile)
> > > >        nobody_group = conf_get_str("Mapping", "Nobody-Group");
> > > >        if (nobody_group) {
> > > > -        size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +        size_t buflen = get_grnam_buflen();
> > > >            struct group *buf;
> > > >            struct group *gr = NULL;
> > > >            int err;
> > > > diff --git a/support/nfsidmap/nfsidmap_common.c b/support/nfsidmap/
> > > > nfsidmap_common.c
> > > > index 4d2cb14f..310c68f0 100644
> > > > --- a/support/nfsidmap/nfsidmap_common.c
> > > > +++ b/support/nfsidmap/nfsidmap_common.c
> > > > @@ -116,3 +116,19 @@ int get_reformat_group(void)
> > > >        return reformat_group;
> > > >    }
> > > > +
> > > > +size_t get_pwnam_buflen(void)
> > > > +{
> > > > +    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    if (buflen == -1)
> > > > +        buflen = 16384;
> > > > +    return buflen;
> > > > +}
> > > > +
> > > > +size_t get_grnam_buflen(void)
> > > > +{
> > > > +    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    if (buflen == -1)
> > > > +        buflen = 16384;
> > > > +    return buflen;
> > > > +}
> > > > diff --git a/support/nfsidmap/nfsidmap_private.h b/support/nfsidmap/
> > > > nfsidmap_private.h
> > > > index a5cb6dda..234ca9d4 100644
> > > > --- a/support/nfsidmap/nfsidmap_private.h
> > > > +++ b/support/nfsidmap/nfsidmap_private.h
> > > > @@ -40,6 +40,8 @@ struct conf_list *get_local_realms(void);
> > > >    void free_local_realms(void);
> > > >    int get_nostrip(void);
> > > >    int get_reformat_group(void);
> > > > +size_t get_pwnam_buflen(void);
> > > > +size_t get_grnam_buflen(void);
> > > >    typedef enum {
> > > >        IDTYPE_USER = 1,
> > > > diff --git a/support/nfsidmap/nss.c b/support/nfsidmap/nss.c
> > > > index 0f43076e..3fc045dc 100644
> > > > --- a/support/nfsidmap/nss.c
> > > > +++ b/support/nfsidmap/nss.c
> > > > @@ -91,7 +91,7 @@ static int nss_uid_to_name(uid_t uid, char *domain,
> > > > char *name, size_t len)
> > > >        struct passwd *pw = NULL;
> > > >        struct passwd pwbuf;
> > > >        char *buf;
> > > > -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    size_t buflen = get_pwnam_buflen();
> > > >        int err = -ENOMEM;
> > > >        buf = malloc(buflen);
> > > > @@ -119,7 +119,7 @@ static int nss_gid_to_name(gid_t gid, char
> > > > *domain, char *name, size_t len)
> > > >        struct group *gr = NULL;
> > > >        struct group grbuf;
> > > >        char *buf;
> > > > -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    size_t buflen = get_grnam_buflen();
> > > >        int err;
> > > >        if (domain == NULL)
> > > > @@ -192,7 +192,7 @@ static struct passwd *nss_getpwnam(const char
> > > > *name, const char *domain,
> > > >    {
> > > >        struct passwd *pw;
> > > >        struct pwbuf *buf;
> > > > -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    size_t buflen = get_pwnam_buflen();
> > > >        char *localname;
> > > >        int err = ENOMEM;
> > > > @@ -301,7 +301,7 @@ static int _nss_name_to_gid(char *name, gid_t
> > > > *gid, int dostrip)
> > > >        struct group *gr = NULL;
> > > >        struct group grbuf;
> > > >        char *buf, *domain;
> > > > -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    size_t buflen = get_grnam_buflen();
> > > >        int err = -EINVAL;
> > > >        char *localname = NULL;
> > > >        char *ref_name = NULL;
> > > > diff --git a/support/nfsidmap/regex.c b/support/nfsidmap/regex.c
> > > > index 8424179f..ea094b95 100644
> > > > --- a/support/nfsidmap/regex.c
> > > > +++ b/support/nfsidmap/regex.c
> > > > @@ -46,6 +46,7 @@
> > > >    #include "nfsidmap.h"
> > > >    #include "nfsidmap_plugin.h"
> > > > +#include "nfsidmap_private.h"
> > > >    #define CONFIG_GET_STRING nfsidmap_config_get
> > > >    extern const char *nfsidmap_config_get(const char *, const char *);
> > > > @@ -95,7 +96,7 @@ static struct passwd *regex_getpwnam(const char
> > > > *name, const char *UNUSED(domain
> > > >    {
> > > >        struct passwd *pw;
> > > >        struct pwbuf *buf;
> > > > -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    size_t buflen = get_pwnam_buflen();
> > > >        char *localname;
> > > >        size_t namelen;
> > > >        int err;
> > > > @@ -175,7 +176,7 @@ static struct group *regex_getgrnam(const char
> > > > *name, const char *UNUSED(domain)
> > > >    {
> > > >        struct group *gr;
> > > >        struct grbuf *buf;
> > > > -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    size_t buflen = get_grnam_buflen();
> > > >        char *localgroup;
> > > >        char *groupname;
> > > >        size_t namelen;
> > > > @@ -366,7 +367,7 @@ static int regex_uid_to_name(uid_t uid, char
> > > > *domain, char *name, size_t len)
> > > >        struct passwd *pw = NULL;
> > > >        struct passwd pwbuf;
> > > >        char *buf;
> > > > -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    size_t buflen = get_pwnam_buflen();
> > > >        int err = -ENOMEM;
> > > >        buf = malloc(buflen);
> > > > @@ -392,7 +393,7 @@ static int regex_gid_to_name(gid_t gid, char
> > > > *UNUSED(domain), char *name, size_t
> > > >        struct group grbuf;
> > > >        char *buf;
> > > >        const char *name_prefix;
> > > > -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    size_t buflen = get_grnam_buflen();
> > > >        int err;
> > > >        char * groupname = NULL;
> > > > diff --git a/support/nfsidmap/static.c b/support/nfsidmap/static.c
> > > > index 8ac4a398..395cac06 100644
> > > > --- a/support/nfsidmap/static.c
> > > > +++ b/support/nfsidmap/static.c
> > > > @@ -44,6 +44,7 @@
> > > >    #include "conffile.h"
> > > >    #include "nfsidmap.h"
> > > >    #include "nfsidmap_plugin.h"
> > > > +#include "nfsidmap_private.h"
> > > >    /*
> > > >     * Static Translation Methods
> > > > @@ -98,7 +99,7 @@ static struct passwd *static_getpwnam(const char *name,
> > > >    {
> > > >        struct passwd *pw;
> > > >        struct pwbuf *buf;
> > > > -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> > > > +    size_t buflen = get_pwnam_buflen();
> > > >        char *localname;
> > > >        int err;
> > > > @@ -149,7 +150,7 @@ static struct group *static_getgrnam(const char
> > > > *name,
> > > >    {
> > > >        struct group *gr;
> > > >        struct grbuf *buf;
> > > > -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> > > > +    size_t buflen = get_grnam_buflen();
> > > >        char *localgroup;
> > > >        int err;