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authorTomas Mraz <tm@t8m.info>2008-04-18 12:53:38 +0000
committerTomas Mraz <tm@t8m.info>2008-04-18 12:53:38 +0000
commit902026536a826400014a7508b008e41269d081e6 (patch)
tree90c35614bc4a873845fafcf806385312fc05903f /modules/pam_namespace/pam_namespace.c
parent31a8f873dac892b15d374d8eb33037515678d6af (diff)
Relevant BUGIDs:
Purpose of commit: new feature Commit summary: --------------- 2008-04-18 Tomas Mraz <t8m@centrum.cz> * modules/pam_namespace/pam_namespace.c: New functions unprotect_dirs(), cleanup_protect_data(), protect_mount(), protect_dir() to protect directory by bind mount. (cleanup_data): Renamed to cleanup_polydir_data(). (parse_create_params): Allow missing specification of mode or owner. (check_inst_parent): Call protect_dir() on the instance parent directory. The directory is created when it doesn't exist. (create_polydir): Protect and make the polydir by protect_dir(), remove potential races. (create_dirs): Renamed to create_instance(), remove call to inst_init(). (ns_setup): Call protect_dir() on the polydir if it already exists. Call inst_init() after the polydir is mounted. (setup_namespace): Set the namespace protect data to be cleaned up on pam_close_session()/pam_end(). (pam_sm_open_session): Initialize the protect_dirs. (pam_sm_close_session): Cleanup namespace protect data. * modules/pam_namespace/pam_namespace.h: Define struct for the stack of protected dirs. * modules/pam_namespace/pam_namespace.8.xml: Document when the instance init script is called. * modules/pam_namespace/namespace.conf.5.xml: Likewise.
Diffstat (limited to 'modules/pam_namespace/pam_namespace.c')
-rw-r--r--modules/pam_namespace/pam_namespace.c398
1 files changed, 295 insertions, 103 deletions
diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c
index 80c51443..89bc3686 100644
--- a/modules/pam_namespace/pam_namespace.c
+++ b/modules/pam_namespace/pam_namespace.c
@@ -32,6 +32,8 @@
* DEALINGS IN THE SOFTWARE.
*/
+#define _ATFILE_SOURCE
+
#include "pam_namespace.h"
#include "argv_parse.h"
@@ -78,11 +80,29 @@ static void del_polydir_list(struct polydir_s *polydirs_ptr)
}
}
-static void cleanup_data(pam_handle_t *pamh UNUSED , void *data, int err UNUSED)
+static void unprotect_dirs(struct protect_dir_s *dir)
+{
+ struct protect_dir_s *next;
+
+ while (dir != NULL) {
+ umount(dir->dir);
+ free(dir->dir);
+ next = dir->next;
+ free(dir);
+ dir = next;
+ }
+}
+
+static void cleanup_polydir_data(pam_handle_t *pamh UNUSED , void *data, int err UNUSED)
{
del_polydir_list(data);
}
+static void cleanup_protect_data(pam_handle_t *pamh UNUSED , void *data, int err UNUSED)
+{
+ unprotect_dirs(data);
+}
+
static char *expand_variables(const char *orig, const char *var_names[], const char *var_values[])
{
const char *src = orig;
@@ -132,8 +152,8 @@ static char *expand_variables(const char *orig, const char *var_names[], const c
static int parse_create_params(char *params, struct polydir_s *poly)
{
- char *sptr;
- struct passwd *pwd;
+ char *next;
+ struct passwd *pwd = NULL;
struct group *grp;
poly->mode = (mode_t)ULONG_MAX;
@@ -144,28 +164,40 @@ static int parse_create_params(char *params, struct polydir_s *poly)
return 0;
params++;
- params = strtok_r(params, ",", &sptr);
- if (params == NULL)
- return 0;
+ next = strchr(params, ',');
+ if (next != NULL) {
+ *next = '\0';
+ next++;
+ }
- errno = 0;
- poly->mode = (mode_t)strtoul(params, NULL, 0);
- if (errno != 0) {
- poly->mode = (mode_t)ULONG_MAX;
+ if (*params != '\0') {
+ errno = 0;
+ poly->mode = (mode_t)strtoul(params, NULL, 0);
+ if (errno != 0) {
+ poly->mode = (mode_t)ULONG_MAX;
+ }
}
- params = strtok_r(NULL, ",", &sptr);
+ params = next;
if (params == NULL)
return 0;
+ next = strchr(params, ',');
+ if (next != NULL) {
+ *next = '\0';
+ next++;
+ }
- pwd = getpwnam(params); /* session modules are not reentrant */
- if (pwd == NULL)
- return -1;
- poly->owner = pwd->pw_uid;
-
- params = strtok_r(NULL, ",", &sptr);
- if (params == NULL) {
- poly->group = pwd->pw_gid;
+ if (*params != '\0') {
+ pwd = getpwnam(params); /* session modules are not reentrant */
+ if (pwd == NULL)
+ return -1;
+ poly->owner = pwd->pw_uid;
+ }
+
+ params = next;
+ if (params == NULL || *params == '\0') {
+ if (pwd != NULL)
+ poly->group = pwd->pw_gid;
return 0;
}
grp = getgrnam(params);
@@ -199,7 +231,7 @@ static int parse_method(char *method, struct polydir_s *poly,
struct instance_data *idata)
{
enum polymethod pm;
- char *sptr;
+ char *sptr = NULL;
static const char *method_names[] = { "user", "context", "level", "tmpdir",
"tmpfs", NULL };
static const char *flag_names[] = { "create", "noinit", "iscript",
@@ -921,10 +953,158 @@ fail:
return rc;
}
+static int protect_mount(int dfd, const char *path, struct instance_data *idata)
+{
+ struct protect_dir_s *dir = idata->protect_dirs;
+ char tmpbuf[64];
+
+ while (dir != NULL) {
+ if (strcmp(path, dir->dir) == 0) {
+ return 0;
+ }
+ dir = dir->next;
+ }
+
+ dir = calloc(1, sizeof(*dir));
+
+ if (dir == NULL) {
+ return -1;
+ }
+
+ dir->dir = strdup(path);
+
+ if (dir->dir == NULL) {
+ free(dir);
+ return -1;
+ }
+
+ snprintf(tmpbuf, sizeof(tmpbuf), "/proc/self/fd/%d", dfd);
+
+ if (idata->flags & PAMNS_DEBUG) {
+ pam_syslog(idata->pamh, LOG_INFO,
+ "Protect mount of %s over itself", path);
+ }
+
+ if (mount(tmpbuf, tmpbuf, NULL, MS_BIND, NULL) != 0) {
+ int save_errno = errno;
+ pam_syslog(idata->pamh, LOG_ERR,
+ "Protect mount of %s failed: %m", tmpbuf);
+ free(dir->dir);
+ free(dir);
+ errno = save_errno;
+ return -1;
+ }
+
+ dir->next = idata->protect_dirs;
+ idata->protect_dirs = dir;
+
+ return 0;
+}
+
+static int protect_dir(const char *path, mode_t mode, int do_mkdir,
+ struct instance_data *idata)
+{
+ char *p = strdup(path);
+ char *d;
+ char *dir = p;
+ int dfd = AT_FDCWD;
+ int dfd_next;
+ int save_errno;
+ int flags = O_RDONLY;
+ int rv = -1;
+ struct stat st;
+
+ if (p == NULL) {
+ goto error;
+ }
+
+ if (*dir == '/') {
+ dfd = open("/", flags);
+ if (dfd == -1) {
+ goto error;
+ }
+ dir++; /* assume / is safe */
+ }
+
+ while ((d=strchr(dir, '/')) != NULL) {
+ *d = '\0';
+ dfd_next = openat(dfd, dir, flags);
+ if (dfd_next == -1) {
+ goto error;
+ }
+
+ if (dfd != AT_FDCWD)
+ close(dfd);
+ dfd = dfd_next;
+
+ if (fstat(dfd, &st) != 0) {
+ goto error;
+ }
+
+ if (flags & O_NOFOLLOW) {
+ /* we are inside user-owned dir - protect */
+ if (protect_mount(dfd, p, idata) == -1)
+ goto error;
+ } else if (st.st_uid != 0 || st.st_gid != 0 ||
+ (st.st_mode & S_IWOTH)) {
+ /* do not follow symlinks on subdirectories */
+ flags |= O_NOFOLLOW;
+ }
+
+ *d = '/';
+ dir = d + 1;
+ }
+
+ rv = openat(dfd, dir, flags);
+
+ if (rv == -1) {
+ if (!do_mkdir || mkdirat(dfd, dir, mode) != 0) {
+ goto error;
+ }
+ rv = openat(dfd, dir, flags);
+ }
+
+ if (rv != -1) {
+ if (fstat(rv, &st) != 0) {
+ save_errno = errno;
+ close(rv);
+ rv = -1;
+ errno = save_errno;
+ goto error;
+ }
+ if (!S_ISDIR(st.st_mode)) {
+ close(rv);
+ errno = ENOTDIR;
+ rv = -1;
+ goto error;
+ }
+ }
+
+ if (flags & O_NOFOLLOW) {
+ /* we are inside user-owned dir - protect */
+ if (protect_mount(rv, p, idata) == -1) {
+ save_errno = errno;
+ close(rv);
+ rv = -1;
+ errno = save_errno;
+ }
+ }
+
+error:
+ save_errno = errno;
+ free(p);
+ if (dfd != AT_FDCWD)
+ close(dfd);
+ errno = save_errno;
+
+ return rv;
+}
+
static int check_inst_parent(char *ipath, struct instance_data *idata)
{
struct stat instpbuf;
char *inst_parent, *trailing_slash;
+ int dfd;
/*
* stat the instance parent path to make sure it exists
* and is a directory. Check that its mode is 000 (unless the
@@ -942,30 +1122,27 @@ static int check_inst_parent(char *ipath, struct instance_data *idata)
if (trailing_slash)
*trailing_slash = '\0';
- if (stat(inst_parent, &instpbuf) < 0) {
- pam_syslog(idata->pamh, LOG_ERR, "Error stating %s, %m", inst_parent);
- free(inst_parent);
- return PAM_SESSION_ERR;
- }
+ dfd = protect_dir(inst_parent, 0, 1, idata);
- /*
- * Make sure we are dealing with a directory
- */
- if (!S_ISDIR(instpbuf.st_mode)) {
- pam_syslog(idata->pamh, LOG_ERR, "Instance parent %s is not a dir",
- inst_parent);
+ if (dfd == -1 || fstat(dfd, &instpbuf) < 0) {
+ pam_syslog(idata->pamh, LOG_ERR,
+ "Error creating or accessing instance parent %s, %m", inst_parent);
+ if (dfd != -1)
+ close(dfd);
free(inst_parent);
return PAM_SESSION_ERR;
}
if ((idata->flags & PAMNS_IGN_INST_PARENT_MODE) == 0) {
- if (instpbuf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) {
- pam_syslog(idata->pamh, LOG_ERR, "Mode of inst parent %s not 000",
+ if ((instpbuf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) || instpbuf.st_uid != 0) {
+ pam_syslog(idata->pamh, LOG_ERR, "Mode of inst parent %s not 000 or owner not root",
inst_parent);
+ close(dfd);
free(inst_parent);
return PAM_SESSION_ERR;
}
}
+ close(dfd);
free(inst_parent);
return PAM_SUCCESS;
}
@@ -1051,6 +1228,8 @@ static int create_polydir(struct polydir_s *polyptr,
security_context_t dircon, oldcon = NULL;
#endif
const char *dir = polyptr->dir;
+ uid_t uid;
+ gid_t gid;
if (polyptr->mode != (mode_t)ULONG_MAX)
mode = polyptr->mode;
@@ -1077,8 +1256,8 @@ static int create_polydir(struct polydir_s *polyptr,
}
#endif
- rc = mkdir(dir, mode);
- if (rc != 0) {
+ rc = protect_dir(dir, mode, 1, idata);
+ if (rc == -1) {
pam_syslog(idata->pamh, LOG_ERR,
"Error creating directory %s: %m", dir);
return PAM_SESSION_ERR;
@@ -1098,36 +1277,41 @@ static int create_polydir(struct polydir_s *polyptr,
if (polyptr->mode != (mode_t)ULONG_MAX) {
/* explicit mode requested */
- if (chmod(dir, mode) != 0) {
+ if (fchmod(rc, mode) != 0) {
pam_syslog(idata->pamh, LOG_ERR,
"Error changing mode of directory %s: %m", dir);
+ close(rc);
+ umount(dir); /* undo the eventual protection bind mount */
rmdir(dir);
return PAM_SESSION_ERR;
}
}
- if (polyptr->owner != (uid_t)ULONG_MAX) {
- if (chown(dir, polyptr->owner, polyptr->group) != 0) {
- pam_syslog(idata->pamh, LOG_ERR,
- "Unable to change owner on directory %s: %m", dir);
- rmdir(dir);
- return PAM_SESSION_ERR;
- }
- if (idata->flags & PAMNS_DEBUG)
- pam_syslog(idata->pamh, LOG_DEBUG,
- "Polydir owner %u group %u from configuration", polyptr->owner, polyptr->group);
- } else {
- if (chown(dir, idata->uid, idata->gid) != 0) {
- pam_syslog(idata->pamh, LOG_ERR,
- "Unable to change owner on directory %s: %m", dir);
- rmdir(dir);
- return PAM_SESSION_ERR;
- }
- if (idata->flags & PAMNS_DEBUG)
- pam_syslog(idata->pamh, LOG_DEBUG,
- "Polydir owner %u group %u", idata->uid, idata->gid);
+ if (polyptr->owner != (uid_t)ULONG_MAX)
+ uid = polyptr->owner;
+ else
+ uid = idata->uid;
+
+ if (polyptr->group != (gid_t)ULONG_MAX)
+ gid = polyptr->group;
+ else
+ gid = idata->gid;
+
+ if (fchown(rc, uid, gid) != 0) {
+ pam_syslog(idata->pamh, LOG_ERR,
+ "Unable to change owner on directory %s: %m", dir);
+ close(rc);
+ umount(dir); /* undo the eventual protection bind mount */
+ rmdir(dir);
+ return PAM_SESSION_ERR;
}
+ close(rc);
+
+ if (idata->flags & PAMNS_DEBUG)
+ pam_syslog(idata->pamh, LOG_DEBUG,
+ "Polydir owner %u group %u", uid, gid);
+
return PAM_SUCCESS;
}
@@ -1135,17 +1319,16 @@ static int create_polydir(struct polydir_s *polyptr,
* Create polyinstantiated instance directory (ipath).
*/
#ifdef WITH_SELINUX
-static int create_dirs(struct polydir_s *polyptr, char *ipath, struct stat *statbuf,
+static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat *statbuf,
security_context_t icontext, security_context_t ocontext,
struct instance_data *idata)
#else
-static int create_dirs(struct polydir_s *polyptr, char *ipath, struct stat *statbuf,
+static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat *statbuf,
struct instance_data *idata)
#endif
{
struct stat newstatbuf;
int fd;
- int newdir = 0;
/*
* Check to make sure instance parent is valid.
@@ -1171,7 +1354,7 @@ static int create_dirs(struct polydir_s *polyptr, char *ipath, struct stat *stat
strcpy(ipath, polyptr->instance_prefix);
} else if (mkdir(ipath, S_IRUSR) < 0) {
if (errno == EEXIST)
- goto inst_init;
+ return PAM_IGNORE;
else {
pam_syslog(idata->pamh, LOG_ERR, "Error creating %s, %m",
ipath);
@@ -1179,7 +1362,6 @@ static int create_dirs(struct polydir_s *polyptr, char *ipath, struct stat *stat
}
}
- newdir = 1;
/* Open a descriptor to it to prevent races */
fd = open(ipath, O_DIRECTORY | O_RDONLY);
if (fd < 0) {
@@ -1235,33 +1417,22 @@ static int create_dirs(struct polydir_s *polyptr, char *ipath, struct stat *stat
return PAM_SESSION_ERR;
}
close(fd);
-
- /*
- * Check to see if there is a namespace initialization script in
- * the /etc/security directory. If such a script exists
- * execute it and pass directory to polyinstantiate and instance
- * directory as arguments.
- */
-
-inst_init:
- if (polyptr->flags & POLYDIR_NOINIT)
- return PAM_SUCCESS;
-
- return inst_init(polyptr, ipath, idata, newdir);
+ return PAM_SUCCESS;
}
/*
* This function performs the namespace setup for a particular directory
- * that is being polyinstantiated. It creates an MD5 hash of instance
- * directory, calls create_dirs to create it with appropriate
+ * that is being polyinstantiated. It calls poly_name to create name of instance
+ * directory, calls create_instance to mkdir it with appropriate
* security attributes, and performs bind mount to setup the process
* namespace.
*/
static int ns_setup(struct polydir_s *polyptr,
struct instance_data *idata)
{
- int retval = 0;
+ int retval;
+ int newdir = 1;
char *inst_dir = NULL;
char *instname = NULL;
struct stat statbuf;
@@ -1273,37 +1444,40 @@ static int ns_setup(struct polydir_s *polyptr,
pam_syslog(idata->pamh, LOG_DEBUG,
"Set namespace for directory %s", polyptr->dir);
- while (stat(polyptr->dir, &statbuf) < 0) {
- if (retval || !(polyptr->flags & POLYDIR_CREATE)) {
- pam_syslog(idata->pamh, LOG_ERR, "Error stating %s, %m",
- polyptr->dir);
- return PAM_SESSION_ERR;
- } else {
- if (create_polydir(polyptr, idata) != PAM_SUCCESS)
- return PAM_SESSION_ERR;
- retval = PAM_SESSION_ERR; /* bail out on next failed stat */
- }
- }
+ retval = protect_dir(polyptr->dir, 0, 0, idata);
- /*
- * Make sure we are dealing with a directory
- */
- if (!S_ISDIR(statbuf.st_mode)) {
- pam_syslog(idata->pamh, LOG_ERR, "Polydir %s is not a dir",
+ if (retval < 0 && errno != ENOENT) {
+ pam_syslog(idata->pamh, LOG_ERR, "Polydir %s access error: %m",
polyptr->dir);
- return PAM_SESSION_ERR;
+ return PAM_SESSION_ERR;
}
+ if (retval < 0 && (polyptr->flags & POLYDIR_CREATE)) {
+ if (create_polydir(polyptr, idata) != PAM_SUCCESS)
+ return PAM_SESSION_ERR;
+ } else {
+ close(retval);
+ }
+
if (polyptr->method == TMPFS) {
if (mount("tmpfs", polyptr->dir, "tmpfs", 0, NULL) < 0) {
pam_syslog(idata->pamh, LOG_ERR, "Error mounting tmpfs on %s, %m",
polyptr->dir);
return PAM_SESSION_ERR;
}
- /* we must call inst_init after the mount in this case */
+
+ if (polyptr->flags & POLYDIR_NOINIT)
+ return PAM_SUCCESS;
+
return inst_init(polyptr, "tmpfs", idata, 1);
}
+ if (stat(polyptr->dir, &statbuf) < 0) {
+ pam_syslog(idata->pamh, LOG_ERR, "Error stating %s: %m",
+ polyptr->dir);
+ return PAM_SESSION_ERR;
+ }
+
/*
* Obtain the name of instance pathname based on the
* polyinstantiation method and instance context returned by
@@ -1341,14 +1515,18 @@ static int ns_setup(struct polydir_s *polyptr,
* contexts, owner, group and mode bits.
*/
#ifdef WITH_SELINUX
- retval = create_dirs(polyptr, inst_dir, &statbuf, instcontext,
+ retval = create_instance(polyptr, inst_dir, &statbuf, instcontext,
origcontext, idata);
#else
- retval = create_dirs(polyptr, inst_dir, &statbuf, idata);
+ retval = create_instance(polyptr, inst_dir, &statbuf, idata);
#endif
- if (retval < 0) {
- pam_syslog(idata->pamh, LOG_ERR, "Error creating instance dir");
+ if (retval == PAM_IGNORE) {
+ newdir = 0;
+ retval = PAM_SUCCESS;
+ }
+
+ if (retval != PAM_SUCCESS) {
goto error_out;
}
@@ -1363,6 +1541,9 @@ static int ns_setup(struct polydir_s *polyptr,
goto error_out;
}
+ if (!(polyptr->flags & POLYDIR_NOINIT))
+ retval = inst_init(polyptr, inst_dir, idata, newdir);
+
goto cleanup;
/*
@@ -1600,12 +1781,21 @@ static int setup_namespace(struct instance_data *idata, enum unmnt_op unmnt)
}
}
out:
- if (retval != PAM_SUCCESS)
+ if (retval != PAM_SUCCESS) {
+ cleanup_tmpdirs(idata);
+ unprotect_dirs(idata->protect_dirs);
+ } else if (pam_set_data(idata->pamh, NAMESPACE_PROTECT_DATA, idata->protect_dirs,
+ cleanup_protect_data) != PAM_SUCCESS) {
+ pam_syslog(idata->pamh, LOG_ERR, "Unable to set namespace protect data");
cleanup_tmpdirs(idata);
- else if (pam_set_data(idata->pamh, NAMESPACE_POLYDIR_DATA, idata->polydirs_ptr,
- cleanup_data) != PAM_SUCCESS) {
- pam_syslog(idata->pamh, LOG_ERR, "Unable to set namespace data");
+ unprotect_dirs(idata->protect_dirs);
+ return PAM_SYSTEM_ERR;
+ } else if (pam_set_data(idata->pamh, NAMESPACE_POLYDIR_DATA, idata->polydirs_ptr,
+ cleanup_polydir_data) != PAM_SUCCESS) {
+ pam_syslog(idata->pamh, LOG_ERR, "Unable to set namespace polydir data");
cleanup_tmpdirs(idata);
+ pam_set_data(idata->pamh, NAMESPACE_PROTECT_DATA, NULL, NULL);
+ idata->protect_dirs = NULL;
return PAM_SYSTEM_ERR;
}
return retval;
@@ -1742,6 +1932,7 @@ PAM_EXTERN int pam_sm_open_session(pam_handle_t *pamh, int flags UNUSED,
/* init instance data */
idata.flags = 0;
idata.polydirs_ptr = NULL;
+ idata.protect_dirs = NULL;
idata.pamh = pamh;
#ifdef WITH_SELINUX
if (is_selinux_enabled())
@@ -1893,6 +2084,7 @@ PAM_EXTERN int pam_sm_close_session(pam_handle_t *pamh, int flags UNUSED,
}
pam_set_data(idata.pamh, NAMESPACE_POLYDIR_DATA, NULL, NULL);
+ pam_set_data(idata.pamh, NAMESPACE_PROTECT_DATA, NULL, NULL);
return PAM_SUCCESS;
}