diff --git a/modules/pam_namespace/namespace.conf.5.xml b/modules/pam_namespace/namespace.conf.5.xml index c7698cb..a94b49e 100644 --- a/modules/pam_namespace/namespace.conf.5.xml +++ b/modules/pam_namespace/namespace.conf.5.xml @@ -122,9 +122,14 @@ mntopts=value - value of this flag is passed to the mount call when the tmpfs mount is done. It allows for example the specification of the maximum size of the - tmpfs instance that is created by the mount call. See - mount8 - for details. + tmpfs instance that is created by the mount call. In addition to + options specified in the + tmpfs5 + manual the nosuid, + noexec, and nodev flags + can be used to respectively disable setuid bit effect, disable running + executables, and disable devices to be interpreted on the mounted + tmpfs filesystem. diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c index f541f89..660c7a1 100644 --- a/modules/pam_namespace/pam_namespace.c +++ b/modules/pam_namespace/pam_namespace.c @@ -230,6 +230,73 @@ static int parse_iscript_params(char *params, struct polydir_s *poly) return 0; } +struct mntflag { + const char *name; + size_t len; + unsigned long flag; +}; + +#define LITERAL_AND_LEN(x) x, sizeof(x) - 1 + +static const struct mntflag mntflags[] = { + { LITERAL_AND_LEN("noexec"), MS_NOEXEC }, + { LITERAL_AND_LEN("nosuid"), MS_NOSUID }, + { LITERAL_AND_LEN("nodev"), MS_NODEV } + }; + +static int filter_mntopts(const char *opts, char **filtered, + unsigned long *mountflags) +{ + size_t origlen = strlen(opts); + const char *end; + char *dest; + + dest = *filtered = NULL; + *mountflags = 0; + + if (origlen == 0) + return 0; + + do { + size_t len; + int i; + + end = strchr(opts, ','); + if (end == NULL) { + len = strlen(opts); + } else { + len = end - opts; + } + + for (i = 0; i < (int)(sizeof(mntflags)/sizeof(mntflags[0])); i++) { + if (mntflags[i].len != len) + continue; + if (memcmp(mntflags[i].name, opts, len) == 0) { + *mountflags |= mntflags[i].flag; + opts = end; + break; + } + } + + if (opts != end) { + if (dest != NULL) { + *dest = ','; + ++dest; + } else { + dest = *filtered = calloc(1, origlen + 1); + if (dest == NULL) + return -1; + } + memcpy(dest, opts, len); + dest += len; + } + + opts = end + 1; + } while (end != NULL); + + return 0; +} + static int parse_method(char *method, struct polydir_s *poly, struct instance_data *idata) { @@ -289,7 +356,8 @@ static int parse_method(char *method, struct polydir_s *poly, break; } free(poly->mount_opts); /* if duplicate mntopts specified */ - if ((poly->mount_opts = strdup(flag+namelen+1)) == NULL) { + poly->mount_opts = NULL; + if (filter_mntopts(flag+namelen+1, &poly->mount_opts, &poly->mount_flags) != 0) { pam_syslog(idata->pamh, LOG_CRIT, "Memory allocation error"); return -1; } @@ -1484,7 +1552,7 @@ static int ns_setup(struct polydir_s *polyptr, } if (polyptr->method == TMPFS) { - if (mount("tmpfs", polyptr->dir, "tmpfs", 0, polyptr->mount_opts) < 0) { + if (mount("tmpfs", polyptr->dir, "tmpfs", polyptr->mount_flags, polyptr->mount_opts) < 0) { pam_syslog(idata->pamh, LOG_ERR, "Error mounting tmpfs on %s, %m", polyptr->dir); return PAM_SESSION_ERR; diff --git a/modules/pam_namespace/pam_namespace.h b/modules/pam_namespace/pam_namespace.h index 47ebcc3..1522386 100644 --- a/modules/pam_namespace/pam_namespace.h +++ b/modules/pam_namespace/pam_namespace.h @@ -166,6 +166,7 @@ struct polydir_s { unsigned int flags; /* polydir flags */ char *init_script; /* path to init script */ char *mount_opts; /* mount options for tmpfs mount */ + unsigned long mount_flags; /* mount flags for tmpfs mount */ uid_t owner; /* user which should own the polydir */ gid_t group; /* group which should own the polydir */ mode_t mode; /* mode of the polydir */