From df1dab1a1a7900650ad4be157fea1a002048cc49 Mon Sep 17 00:00:00 2001 From: Olivier Bal-Petre Date: Tue, 4 Mar 2025 14:37:02 +0100 Subject: [PATCH ] pam-namespace-rebase Refresh the pam-namespace. Upstream-Status: Backport [https://github.com/linux-pam/linux-pam/commit/a8b4dce7b53d73de372e150028c970ee0a2a2e97] Signed-off-by: Hitendra Prajapati --- modules/pam_namespace/pam_namespace.c | 444 +++++++++++++------------- modules/pam_namespace/pam_namespace.h | 7 +- 2 files changed, 224 insertions(+), 227 deletions(-) diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c index b026861..166bfce 100644 --- a/modules/pam_namespace/pam_namespace.c +++ b/modules/pam_namespace/pam_namespace.c @@ -41,7 +41,7 @@ #include "pam_namespace.h" #include "argv_parse.h" -/* --- evaluting all files in VENDORDIR/security/namespace.d and /etc/security/namespace.d --- */ +/* --- evaluating all files in VENDORDIR/security/namespace.d and /etc/security/namespace.d --- */ static const char *base_name(const char *path) { const char *base = strrchr(path, '/'); @@ -55,6 +55,155 @@ compare_filename(const void *a, const void *b) base_name(* (char * const *) b)); } +static void close_fds_pre_exec(struct instance_data *idata) +{ + if (pam_modutil_sanitize_helper_fds(idata->pamh, PAM_MODUTIL_IGNORE_FD, + PAM_MODUTIL_IGNORE_FD, PAM_MODUTIL_IGNORE_FD) < 0) { + _exit(1); + } +} + +static void +strip_trailing_slashes(char *str) +{ + char *p = str + strlen(str); + + while (--p > str && *p == '/') + *p = '\0'; +} + +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; + } + + if (pam_sprintf(tmpbuf, "/proc/self/fd/%d", dfd) < 0) + return -1; + + dir = calloc(1, sizeof(*dir)); + + if (dir == NULL) { + return -1; + } + + dir->dir = strdup(path); + + if (dir->dir == NULL) { + free(dir); + return -1; + } + + 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 | O_DIRECTORY; + int rv = -1; + struct stat st; + + if (p == NULL) { + return -1; + } + + 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 (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 && dfd >= 0) + close(dfd); + errno = save_errno; + + return rv; +} + /* Evaluating a list of files which have to be parsed in the right order: * * - If etc/security/namespace.d/@filename@.conf exists, then @@ -129,6 +278,7 @@ static char **read_namespace_dir(struct instance_data *idata) return file_list; } + /* * Adds an entry for a polyinstantiated directory to the linked list of * polyinstantiated directories. It is called from process_line() while @@ -198,7 +348,7 @@ static void cleanup_protect_data(pam_handle_t *pamh UNUSED , void *data, int err unprotect_dirs(data); } -static char *expand_variables(const char *orig, const char *var_names[], const char *var_values[]) +static char *expand_variables(const char *orig, const char *const var_names[], const char *var_values[]) { const char *src = orig; char *dst; @@ -209,7 +359,7 @@ static char *expand_variables(const char *orig, const char *var_names[], const c if (*src == '$') { int i; for (i = 0; var_names[i]; i++) { - int namelen = strlen(var_names[i]); + size_t namelen = strlen(var_names[i]); if (strncmp(var_names[i], src+1, namelen) == 0) { dstlen += strlen(var_values[i]) - 1; /* $ */ src += namelen; @@ -227,7 +377,7 @@ static char *expand_variables(const char *orig, const char *var_names[], const c if (c == '$') { int i; for (i = 0; var_names[i]; i++) { - int namelen = strlen(var_names[i]); + size_t namelen = strlen(var_names[i]); if (strncmp(var_names[i], src+1, namelen) == 0) { dst = stpcpy(dst, var_values[i]); --dst; @@ -311,8 +461,7 @@ static int parse_iscript_params(char *params, struct polydir_s *poly) if (*params != '\0') { if (*params != '/') { /* path is relative to NAMESPACE_D_DIR */ - if (asprintf(&poly->init_script, "%s%s", NAMESPACE_D_DIR, params) == -1) - return -1; + poly->init_script = pam_asprintf("%s%s", NAMESPACE_D_DIR, params); } else { poly->init_script = strdup(params); } @@ -394,9 +543,9 @@ static int parse_method(char *method, struct polydir_s *poly, { enum polymethod pm; char *sptr = NULL; - static const char *method_names[] = { "user", "context", "level", "tmpdir", + static const char *const method_names[] = { "user", "context", "level", "tmpdir", "tmpfs", NULL }; - static const char *flag_names[] = { "create", "noinit", "iscript", + static const char *const flag_names[] = { "create", "noinit", "iscript", "shared", "mntopts", NULL }; static const unsigned int flag_values[] = { POLYDIR_CREATE, POLYDIR_NOINIT, POLYDIR_ISCRIPT, POLYDIR_SHARED, POLYDIR_MNTOPTS }; @@ -421,7 +570,7 @@ static int parse_method(char *method, struct polydir_s *poly, while ((flag=strtok_r(NULL, ":", &sptr)) != NULL) { for (i = 0; flag_names[i]; i++) { - int namelen = strlen(flag_names[i]); + size_t namelen = strlen(flag_names[i]); if (strncmp(flag, flag_names[i], namelen) == 0) { poly->flags |= flag_values[i]; @@ -467,27 +616,27 @@ static int parse_method(char *method, struct polydir_s *poly, * of the namespace configuration file. It skips over comments and incomplete * or malformed lines. It processes a valid line with information on * polyinstantiating a directory by populating appropriate fields of a - * polyinstatiated directory structure and then calling add_polydir_entry to + * polyinstantiated directory structure and then calling add_polydir_entry to * add that entry to the linked list of polyinstantiated directories. */ static int process_line(char *line, const char *home, const char *rhome, struct instance_data *idata) { char *dir = NULL, *instance_prefix = NULL, *rdir = NULL; + const char *config_dir, *config_instance_prefix; char *method, *uids; char *tptr; struct polydir_s *poly; int retval = 0; char **config_options = NULL; - static const char *var_names[] = {"HOME", "USER", NULL}; + static const char *const var_names[] = {"HOME", "USER", NULL}; const char *var_values[] = {home, idata->user}; const char *rvar_values[] = {rhome, idata->ruser}; - int len; /* * skip the leading white space */ - while (*line && isspace(*line)) + while (*line && isspace((unsigned char)*line)) line++; /* @@ -523,22 +672,19 @@ static int process_line(char *line, const char *home, const char *rhome, goto erralloc; } - dir = config_options[0]; - if (dir == NULL) { + config_dir = config_options[0]; + if (config_dir == NULL) { pam_syslog(idata->pamh, LOG_NOTICE, "Invalid line missing polydir"); goto skipping; } - instance_prefix = config_options[1]; - if (instance_prefix == NULL) { + config_instance_prefix = config_options[1]; + if (config_instance_prefix == NULL) { pam_syslog(idata->pamh, LOG_NOTICE, "Invalid line missing instance_prefix"); - instance_prefix = NULL; goto skipping; } method = config_options[2]; if (method == NULL) { pam_syslog(idata->pamh, LOG_NOTICE, "Invalid line missing method"); - instance_prefix = NULL; - dir = NULL; goto skipping; } @@ -553,19 +699,16 @@ static int process_line(char *line, const char *home, const char *rhome, /* * Expand $HOME and $USER in poly dir and instance dir prefix */ - if ((rdir=expand_variables(dir, var_names, rvar_values)) == NULL) { - instance_prefix = NULL; - dir = NULL; + if ((rdir = expand_variables(config_dir, var_names, rvar_values)) == NULL) { goto erralloc; } - if ((dir=expand_variables(dir, var_names, var_values)) == NULL) { - instance_prefix = NULL; + if ((dir = expand_variables(config_dir, var_names, var_values)) == NULL) { goto erralloc; } - if ((instance_prefix=expand_variables(instance_prefix, var_names, var_values)) - == NULL) { + if ((instance_prefix = expand_variables(config_instance_prefix, + var_names, var_values)) == NULL) { goto erralloc; } @@ -575,15 +718,8 @@ static int process_line(char *line, const char *home, const char *rhome, pam_syslog(idata->pamh, LOG_DEBUG, "Expanded instance prefix: '%s'", instance_prefix); } - len = strlen(dir); - if (len > 0 && dir[len-1] == '/') { - dir[len-1] = '\0'; - } - - len = strlen(rdir); - if (len > 0 && rdir[len-1] == '/') { - rdir[len-1] = '\0'; - } + strip_trailing_slashes(dir); + strip_trailing_slashes(rdir); if (dir[0] == '\0' || rdir[0] == '\0') { pam_syslog(idata->pamh, LOG_NOTICE, "Invalid polydir"); @@ -594,26 +730,19 @@ static int process_line(char *line, const char *home, const char *rhome, * Populate polyinstantiated directory structure with appropriate * pathnames and the method with which to polyinstantiate. */ - if (strlen(dir) >= sizeof(poly->dir) - || strlen(rdir) >= sizeof(poly->rdir) - || strlen(instance_prefix) >= sizeof(poly->instance_prefix)) { - pam_syslog(idata->pamh, LOG_NOTICE, "Pathnames too long"); - goto skipping; - } - strcpy(poly->dir, dir); - strcpy(poly->rdir, rdir); - strcpy(poly->instance_prefix, instance_prefix); - if (parse_method(method, poly, idata) != 0) { goto skipping; } - if (poly->method == TMPDIR) { - if (sizeof(poly->instance_prefix) - strlen(poly->instance_prefix) < 7) { - pam_syslog(idata->pamh, LOG_NOTICE, "Pathnames too long"); - goto skipping; - } - strcat(poly->instance_prefix, "XXXXXX"); +#define COPY_STR(dst, src, apd) \ + pam_sprintf((dst), "%s%s", (src), (apd)) + + if (COPY_STR(poly->dir, dir, "") < 0 + || COPY_STR(poly->rdir, rdir, "") < 0 + || COPY_STR(poly->instance_prefix, instance_prefix, + poly->method == TMPDIR ? "XXXXXX" : "") < 0) { + pam_syslog(idata->pamh, LOG_NOTICE, "Pathnames too long"); + goto skipping; } /* @@ -637,7 +766,7 @@ static int process_line(char *line, const char *home, const char *rhome, if (uids) { uid_t *uidptr; const char *ustr, *sstr; - int count, i; + size_t count, i; if (*uids == '~') { poly->flags |= POLYDIR_EXCLUSIVE; @@ -646,8 +775,13 @@ static int process_line(char *line, const char *home, const char *rhome, for (count = 0, ustr = sstr = uids; sstr; ustr = sstr + 1, count++) sstr = strchr(ustr, ','); + if (count > UINT_MAX || count > SIZE_MAX / sizeof(uid_t)) { + pam_syslog(idata->pamh, LOG_ERR, "Too many uids encountered in configuration"); + goto skipping; + } + poly->num_uids = count; - poly->uid = (uid_t *) malloc(count * sizeof (uid_t)); + poly->uid = malloc(count * sizeof (uid_t)); uidptr = poly->uid; if (uidptr == NULL) { goto erralloc; @@ -996,6 +1130,7 @@ static int form_context(const struct polydir_s *polyptr, return rc; } /* Should never get here */ + freecon(scon); return PAM_SUCCESS; } #endif @@ -1057,10 +1192,8 @@ static int poly_name(const struct polydir_s *polyptr, char **i_name, switch (pm) { case USER: - if (asprintf(i_name, "%s", idata->user) < 0) { - *i_name = NULL; + if ((*i_name = strdup(idata->user)) == NULL) goto fail; - } break; #ifdef WITH_SELINUX @@ -1070,17 +1203,12 @@ static int poly_name(const struct polydir_s *polyptr, char **i_name, pam_syslog(idata->pamh, LOG_ERR, "Error translating directory context"); goto fail; } - if (polyptr->flags & POLYDIR_SHARED) { - if (asprintf(i_name, "%s", rawcon) < 0) { - *i_name = NULL; - goto fail; - } - } else { - if (asprintf(i_name, "%s_%s", rawcon, idata->user) < 0) { - *i_name = NULL; - goto fail; - } - } + if (polyptr->flags & POLYDIR_SHARED) + *i_name = strdup(rawcon); + else + *i_name = pam_asprintf("%s_%s", rawcon, idata->user); + if (*i_name == NULL) + goto fail; break; #endif /* WITH_SELINUX */ @@ -1110,11 +1238,12 @@ static int poly_name(const struct polydir_s *polyptr, char **i_name, *i_name = hash; hash = NULL; } else { - char *newname; - if (asprintf(&newname, "%.*s_%s", NAMESPACE_MAX_DIR_LEN-1-(int)strlen(hash), - *i_name, hash) < 0) { + char *newname = + pam_asprintf("%.*s_%s", + NAMESPACE_MAX_DIR_LEN - 1 - (int)strlen(hash), + *i_name, hash); + if (newname == NULL) goto fail; - } free(*i_name); *i_name = newname; } @@ -1139,137 +1268,6 @@ 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 | O_DIRECTORY; - 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 (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 && dfd >= 0) - close(dfd); - errno = save_errno; - - return rv; -} - static int check_inst_parent(char *ipath, struct instance_data *idata) { struct stat instpbuf; @@ -1281,13 +1279,12 @@ static int check_inst_parent(char *ipath, struct instance_data *idata) * admin explicitly instructs to ignore the instance parent * mode by the "ignore_instance_parent_mode" argument). */ - inst_parent = (char *) malloc(strlen(ipath)+1); + inst_parent = strdup(ipath); if (!inst_parent) { pam_syslog(idata->pamh, LOG_CRIT, "Error allocating pathname string"); return PAM_SESSION_ERR; } - strcpy(inst_parent, ipath); trailing_slash = strrchr(inst_parent, '/'); if (trailing_slash) *trailing_slash = '\0'; @@ -1371,9 +1368,10 @@ static int inst_init(const struct polydir_s *polyptr, const char *ipath, if (setuid(geteuid()) < 0) { /* ignore failures, they don't matter */ } + close_fds_pre_exec(idata); - if (execle(init_script, init_script, - polyptr->dir, ipath, newdir?"1":"0", idata->user, NULL, envp) < 0) + execle(init_script, init_script, + polyptr->dir, ipath, newdir?"1":"0", idata->user, NULL, envp); _exit(1); } else if (pid > 0) { while (((rc = waitpid(pid, &status, 0)) == (pid_t)-1) && @@ -1424,7 +1422,9 @@ static int create_polydir(struct polydir_s *polyptr, #ifdef WITH_SELINUX if (idata->flags & PAMNS_SELINUX_ENABLED) { - getfscreatecon_raw(&oldcon_raw); + if (getfscreatecon_raw(&oldcon_raw) != 0) + pam_syslog(idata->pamh, LOG_NOTICE, + "Error retrieving fs create context: %m"); label_handle = selabel_open(SELABEL_CTX_FILE, NULL, 0); if (!label_handle) { @@ -1453,6 +1453,9 @@ static int create_polydir(struct polydir_s *polyptr, if (rc == -1) { pam_syslog(idata->pamh, LOG_ERR, "Error creating directory %s: %m", dir); +#ifdef WITH_SELINUX + freecon(oldcon_raw); +#endif return PAM_SESSION_ERR; } @@ -1640,16 +1643,14 @@ static int ns_setup(struct polydir_s *polyptr, retval = protect_dir(polyptr->dir, 0, 0, idata); - if (retval < 0 && errno != ENOENT) { - pam_syslog(idata->pamh, LOG_ERR, "Polydir %s access error: %m", - polyptr->dir); - return PAM_SESSION_ERR; - } - if (retval < 0) { - if ((polyptr->flags & POLYDIR_CREATE) && - create_polydir(polyptr, idata) != PAM_SUCCESS) - return PAM_SESSION_ERR; + if (errno != ENOENT || !(polyptr->flags & POLYDIR_CREATE)) { + pam_syslog(idata->pamh, LOG_ERR, "Polydir %s access error: %m", + polyptr->dir); + return PAM_SESSION_ERR; + } + if (create_polydir(polyptr, idata) != PAM_SUCCESS) + return PAM_SESSION_ERR; } else { close(retval); } @@ -1698,7 +1699,7 @@ static int ns_setup(struct polydir_s *polyptr, #endif } - if (asprintf(&inst_dir, "%s%s", polyptr->instance_prefix, instname) < 0) + if ((inst_dir = pam_asprintf("%s%s", polyptr->instance_prefix, instname)) == NULL) goto error_out; if (idata->flags & PAMNS_DEBUG) @@ -1810,8 +1811,9 @@ static int cleanup_tmpdirs(struct instance_data *idata) _exit(1); } #endif - if (execle("/bin/rm", "/bin/rm", "-rf", pptr->instance_prefix, NULL, envp) < 0) - _exit(1); + close_fds_pre_exec(idata); + execle("/bin/rm", "/bin/rm", "-rf", pptr->instance_prefix, NULL, envp); + _exit(1); } else if (pid > 0) { while (((rc = waitpid(pid, &status, 0)) == (pid_t)-1) && (errno == EINTR)); @@ -1826,7 +1828,7 @@ static int cleanup_tmpdirs(struct instance_data *idata) } } else if (pid < 0) { pam_syslog(idata->pamh, LOG_ERR, - "Cannot fork to run namespace init script, %m"); + "Cannot fork to cleanup temporary directory, %m"); rc = PAM_SESSION_ERR; goto out; } diff --git a/modules/pam_namespace/pam_namespace.h b/modules/pam_namespace/pam_namespace.h index a991b4c..180e042 100644 --- a/modules/pam_namespace/pam_namespace.h +++ b/modules/pam_namespace/pam_namespace.h @@ -44,21 +44,17 @@ #include #include #include -#include -#include #include #include #include #include #include -#include #include #include #include #include #include #include -#include #include "security/pam_modules.h" #include "security/pam_modutil.h" #include "security/pam_ext.h" @@ -114,7 +109,7 @@ #define PAMNS_MOUNT_PRIVATE 0x00080000 /* Make the polydir mounts private */ /* polydir flags */ -#define POLYDIR_EXCLUSIVE 0x00000001 /* polyinstatiate exclusively for override uids */ +#define POLYDIR_EXCLUSIVE 0x00000001 /* polyinstantiate exclusively for override uids */ #define POLYDIR_CREATE 0x00000002 /* create the polydir */ #define POLYDIR_NOINIT 0x00000004 /* no init script */ #define POLYDIR_SHARED 0x00000008 /* share context/level instances among users */ -- 2.49.0