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Tue, 22 Jul 2025 05:27:57 -0700 (PDT) Received: from MVIN00016.mvista.com ([43.249.234.224]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23e3b5e2de8sm75446875ad.11.2025.07.22.05.27.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Jul 2025 05:27:56 -0700 (PDT) From: Hitendra Prajapati To: openembedded-core@lists.openembedded.org Cc: Hitendra Prajapati Subject: [scarthgap][PATCH] libpam: fix CVE-2025-6020 Date: Tue, 22 Jul 2025 17:57:29 +0530 Message-ID: <20250722122729.427796-1-hprajapati@mvista.com> X-Mailer: git-send-email 2.49.0 MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Tue, 22 Jul 2025 12:28:03 -0000 X-Groupsio-URL: https://lists.openembedded.org/g/openembedded-core/message/220739 Upstream-Status: Backport from https://github.com/linux-pam/linux-pam/commit/475bd60c552b98c7eddb3270b0b4196847c0072e && https://github.com/linux-pam/linux-pam/commit/592d84e1265d04c3104acee815a503856db503a1 && https://github.com/linux-pam/linux-pam/commit/976c20079358d133514568fc7fd95c02df8b5773 Signed-off-by: Hitendra Prajapati --- .../libpam/0001-pam-inline-pam-asprintf.patch | 101 ++ .../libpam/0002-pam-namespace-rebase.patch | 750 +++++++++++ .../pam/libpam/CVE-2025-6020-01.patch | 1128 +++++++++++++++++ .../pam/libpam/CVE-2025-6020-02.patch | 187 +++ .../pam/libpam/CVE-2025-6020-03.patch | 35 + meta/recipes-extended/pam/libpam_1.5.3.bb | 5 + 6 files changed, 2206 insertions(+) create mode 100644 meta/recipes-extended/pam/libpam/0001-pam-inline-pam-asprintf.patch create mode 100644 meta/recipes-extended/pam/libpam/0002-pam-namespace-rebase.patch create mode 100644 meta/recipes-extended/pam/libpam/CVE-2025-6020-01.patch create mode 100644 meta/recipes-extended/pam/libpam/CVE-2025-6020-02.patch create mode 100644 meta/recipes-extended/pam/libpam/CVE-2025-6020-03.patch diff --git a/meta/recipes-extended/pam/libpam/0001-pam-inline-pam-asprintf.patch b/meta/recipes-extended/pam/libpam/0001-pam-inline-pam-asprintf.patch new file mode 100644 index 0000000000..9d1a0223df --- /dev/null +++ b/meta/recipes-extended/pam/libpam/0001-pam-inline-pam-asprintf.patch @@ -0,0 +1,101 @@ +From 10b80543807e3fc5af5f8bcfd8bb6e219bb3cecc Mon Sep 17 00:00:00 2001 +From: "Dmitry V. Levin" +Date: Tue, 18 Feb 2025 08:00:00 +0000 +Subject: [PATCH] pam_inline: introduce pam_asprintf(), pam_snprintf(), and + pam_sprintf() + +pam_asprintf() is essentially asprintf() with the following semantic +difference: it returns the string itself instead of its length. + +pam_snprintf() is essentially snprintf() with the following semantic +difference: it returns -1 in case of truncation. + +pam_sprintf() is essentially snprintf() but with a check that the buffer +is an array, and with an automatically calculated buffer size. + +Use of these helpers would make error checking simpler. + +(cherry picked from commit 10b80543807e3fc5af5f8bcfd8bb6e219bb3cecc) +Signed-off-by: Dmitry V. Levin + +Upstream-Status: Backport [https://github.com/linux-pam/linux-pam/commit/10b80543807e3fc5af5f8bcfd8bb6e219bb3cecc] +Signed-off-by: Hitendra Prajapati +--- + libpam/include/pam_cc_compat.h | 6 ++++++ + libpam/include/pam_inline.h | 36 ++++++++++++++++++++++++++++++++++ + 2 files changed, 42 insertions(+) + +diff --git a/libpam/include/pam_cc_compat.h b/libpam/include/pam_cc_compat.h +index 0a6e32d..af05428 100644 +--- a/libpam/include/pam_cc_compat.h ++++ b/libpam/include/pam_cc_compat.h +@@ -21,6 +21,12 @@ + # define PAM_ATTRIBUTE_ALIGNED(arg) /* empty */ + #endif + ++#if PAM_GNUC_PREREQ(3, 0) ++# define PAM_ATTRIBUTE_MALLOC __attribute__((__malloc__)) ++#else ++# define PAM_ATTRIBUTE_MALLOC /* empty */ ++#endif ++ + #if PAM_GNUC_PREREQ(4, 6) + # define DIAG_PUSH_IGNORE_CAST_QUAL \ + _Pragma("GCC diagnostic push"); \ +diff --git a/libpam/include/pam_inline.h b/libpam/include/pam_inline.h +index 7721c0b..ec0497c 100644 +--- a/libpam/include/pam_inline.h ++++ b/libpam/include/pam_inline.h +@@ -9,6 +9,8 @@ + #define PAM_INLINE_H + + #include "pam_cc_compat.h" ++#include ++#include + #include + #include + #include +@@ -126,6 +128,40 @@ pam_drop_response(struct pam_response *reply, int replies) + } + + ++static inline char * PAM_FORMAT((printf, 1, 2)) PAM_NONNULL((1)) PAM_ATTRIBUTE_MALLOC ++pam_asprintf(const char *fmt, ...) ++{ ++ int rc; ++ char *res; ++ va_list ap; ++ ++ va_start(ap, fmt); ++ rc = vasprintf(&res, fmt, ap); ++ va_end(ap); ++ ++ return rc < 0 ? NULL : res; ++} ++ ++static inline int PAM_FORMAT((printf, 3, 4)) PAM_NONNULL((3)) ++pam_snprintf(char *str, size_t size, const char *fmt, ...) ++{ ++ int rc; ++ va_list ap; ++ ++ va_start(ap, fmt); ++ rc = vsnprintf(str, size, fmt, ap); ++ va_end(ap); ++ ++ if (rc < 0 || (unsigned int) rc >= size) ++ return -1; ++ return rc; ++} ++ ++#define pam_sprintf(str_, fmt_, ...) \ ++ pam_snprintf((str_), sizeof(str_) + PAM_MUST_BE_ARRAY(str_), (fmt_), \ ++ ##__VA_ARGS__) ++ ++ + static inline int + pam_read_passwords(int fd, int npass, char **passwords) + { +-- +2.49.0 + diff --git a/meta/recipes-extended/pam/libpam/0002-pam-namespace-rebase.patch b/meta/recipes-extended/pam/libpam/0002-pam-namespace-rebase.patch new file mode 100644 index 0000000000..ff5a8a4946 --- /dev/null +++ b/meta/recipes-extended/pam/libpam/0002-pam-namespace-rebase.patch @@ -0,0 +1,750 @@ +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 +44,16 @@ + #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 + diff --git a/meta/recipes-extended/pam/libpam/CVE-2025-6020-01.patch b/meta/recipes-extended/pam/libpam/CVE-2025-6020-01.patch new file mode 100644 index 0000000000..ff0331aa38 --- /dev/null +++ b/meta/recipes-extended/pam/libpam/CVE-2025-6020-01.patch @@ -0,0 +1,1128 @@ +From 475bd60c552b98c7eddb3270b0b4196847c0072e Mon Sep 17 00:00:00 2001 +From: Olivier Bal-Petre +Date: Tue, 4 Mar 2025 14:37:02 +0100 +Subject: [PATCH] pam_namespace: fix potential privilege escalation + +Existing protection provided by protect_dir() and protect_mount() were +bind mounting on themselves all directories part of the to-be-secured +paths. However, this works *only* against attacks executed by processes +in the same mount namespace as the one the mountpoint was created in. +Therefore, a user with an out-of-mount-namespace access, or multiple +users colluding, could exploit multiple race conditions, and, for +instance, elevate their privileges to root. + +This commit keeps the existing protection as a defense in depth +measure, and to keep the existing behavior of the module. However, +it converts all the needed function calls to operate on file +descriptors instead of absolute paths to protect against race +conditions globally. + +Signed-off-by: Olivier Bal-Petre +Signed-off-by: Dmitry V. Levin + +Upstream-Status: Backport [https://github.com/linux-pam/linux-pam/commit/475bd60c552b98c7eddb3270b0b4196847c0072e] +CVE: CVE-2025-6020 +Signed-off-by: Hitendra Prajapati +--- + modules/pam_namespace/pam_namespace.c | 637 ++++++++++++++++++-------- + modules/pam_namespace/pam_namespace.h | 10 + + 2 files changed, 457 insertions(+), 190 deletions(-) + +diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c +index 166bfce..9d993d4 100644 +--- a/modules/pam_namespace/pam_namespace.c ++++ b/modules/pam_namespace/pam_namespace.c +@@ -41,6 +41,8 @@ + #include "pam_namespace.h" + #include "argv_parse.h" + ++#define MAGIC_LNK_FD_SIZE 64 ++ + /* --- evaluating all files in VENDORDIR/security/namespace.d and /etc/security/namespace.d --- */ + static const char *base_name(const char *path) + { +@@ -75,7 +77,7 @@ strip_trailing_slashes(char *str) + static int protect_mount(int dfd, const char *path, struct instance_data *idata) + { + struct protect_dir_s *dir = idata->protect_dirs; +- char tmpbuf[64]; ++ char tmpbuf[MAGIC_LNK_FD_SIZE]; + + while (dir != NULL) { + if (strcmp(path, dir->dir) == 0) { +@@ -121,56 +123,107 @@ static int protect_mount(int dfd, const char *path, struct instance_data *idata) + return 0; + } + +-static int protect_dir(const char *path, mode_t mode, int do_mkdir, ++/* ++ * Returns a fd to the given absolute path, acquired securely. This means: ++ * - iterating on each segment of the path, ++ * - not following user symlinks, ++ * - using race-free operations. ++ * ++ * Takes a bit mask to specify the operation mode: ++ * - SECURE_OPENDIR_PROTECT: call protect_mount() on each unsafe segment of path ++ * - SECURE_OPENDIR_MKDIR: create last segment of path if does not exist ++ * - SECURE_OPENDIR_FULL_FD: open the directory with O_RDONLY instead of O_PATH, ++ * allowing more operations to be done with the returned fd ++ * ++ * Be aware that using SECURE_OPENDIR_PROTECT: ++ * - will modify some external state (global structure...) and should not be ++ * called in cleanup code paths. See wrapper secure_opendir_stateless() ++ * - need a non-NULL idata to call protect_mount() ++ */ ++static int secure_opendir(const char *path, int opm, mode_t mode, + struct instance_data *idata) + { +- char *p = strdup(path); ++ char *p; + char *d; +- char *dir = p; +- int dfd = AT_FDCWD; ++ char *dir; ++ int dfd = -1; + int dfd_next; + int save_errno; +- int flags = O_RDONLY | O_DIRECTORY; ++ int flags = O_DIRECTORY | O_CLOEXEC; + int rv = -1; + struct stat st; + +- if (p == NULL) { ++ if (opm & SECURE_OPENDIR_FULL_FD) ++ flags |= O_RDONLY; ++ else ++ flags |= O_PATH; ++ ++ /* Check for args consistency */ ++ if ((opm & SECURE_OPENDIR_PROTECT) && idata == NULL) + return -1; +- } + +- if (*dir == '/') { +- dfd = open("/", flags); +- if (dfd == -1) { +- goto error; +- } +- dir++; /* assume / is safe */ ++ /* Accept only absolute paths */ ++ if (*path != '/') ++ return -1; ++ ++ dir = p = strdup(path); ++ if (p == NULL) ++ return -1; ++ ++ /* Assume '/' is safe */ ++ dfd = open("/", flags); ++ if (dfd == -1) ++ goto error; ++ ++ /* Needed to not loop too far and call openat() on NULL */ ++ strip_trailing_slashes(p); ++ ++ dir++; ++ ++ /* In case path is '/' */ ++ if (*dir == '\0') { ++ free(p); ++ return dfd; + } + + while ((d=strchr(dir, '/')) != NULL) { + *d = '\0'; ++ + dfd_next = openat(dfd, dir, flags); +- if (dfd_next == -1) { ++ if (dfd_next == -1) + goto error; +- } +- +- if (dfd != AT_FDCWD) +- close(dfd); +- dfd = dfd_next; + +- if (fstat(dfd, &st) != 0) { ++ if (fstat(dfd_next, &st) != 0) { ++ close(dfd_next); + goto error; + } + +- if (flags & O_NOFOLLOW) { ++ if ((flags & O_NOFOLLOW) && (opm & SECURE_OPENDIR_PROTECT)) { + /* we are inside user-owned dir - protect */ +- if (protect_mount(dfd, p, idata) == -1) ++ if (protect_mount(dfd_next, p, idata) == -1) { ++ close(dfd_next); ++ goto error; ++ } ++ /* ++ * Reopen the directory to obtain a new descriptor ++ * after protect_mount(), this is necessary in cases ++ * when another directory is going to be mounted over ++ * the given path. ++ */ ++ close(dfd_next); ++ dfd_next = openat(dfd, dir, flags); ++ if (dfd_next == -1) + goto error; +- } else if (st.st_uid != 0 || st.st_gid != 0 || +- (st.st_mode & S_IWOTH)) { ++ } else if (st.st_uid != 0 ++ || (st.st_gid != 0 && (st.st_mode & S_IWGRP)) ++ || (st.st_mode & S_IWOTH)) { + /* do not follow symlinks on subdirectories */ + flags |= O_NOFOLLOW; + } + ++ close(dfd); ++ dfd = dfd_next; ++ + *d = '/'; + dir = d + 1; + } +@@ -178,13 +231,14 @@ static int protect_dir(const char *path, mode_t mode, int do_mkdir, + rv = openat(dfd, dir, flags); + + if (rv == -1) { +- if (!do_mkdir || mkdirat(dfd, dir, mode) != 0) { ++ if ((opm & SECURE_OPENDIR_MKDIR) && mkdirat(dfd, dir, mode) == 0) ++ rv = openat(dfd, dir, flags); ++ ++ if (rv == -1) + goto error; +- } +- rv = openat(dfd, dir, flags); + } + +- if (flags & O_NOFOLLOW) { ++ if ((flags & O_NOFOLLOW) && (opm & SECURE_OPENDIR_PROTECT)) { + /* we are inside user-owned dir - protect */ + if (protect_mount(rv, p, idata) == -1) { + save_errno = errno; +@@ -192,18 +246,95 @@ static int protect_dir(const char *path, mode_t mode, int do_mkdir, + rv = -1; + errno = save_errno; + } ++ /* ++ * Reopen the directory to obtain a new descriptor after ++ * protect_mount(), this is necessary in cases when another ++ * directory is going to be mounted over the given path. ++ */ ++ close(rv); ++ rv = openat(dfd, dir, flags); + } + + error: + save_errno = errno; + free(p); +- if (dfd != AT_FDCWD && dfd >= 0) ++ if (dfd >= 0) + close(dfd); + errno = save_errno; + + return rv; + } + ++/* ++ * Returns a fd to the given path, acquired securely. ++ * It can be called in all situations, including in cleanup code paths, as ++ * it does not modify external state (no access to global structures...). ++ */ ++static int secure_opendir_stateless(const char *path) ++{ ++ return secure_opendir(path, 0, 0, NULL); ++} ++ ++/* ++ * Umount securely the given path, even if the directories along ++ * the path are under user control. It should protect against ++ * symlinks attacks and race conditions. ++ */ ++static int secure_umount(const char *path) ++{ ++ int save_errno; ++ int rv = -1; ++ int dfd = -1; ++ char s_path[MAGIC_LNK_FD_SIZE]; ++ ++ dfd = secure_opendir_stateless(path); ++ if (dfd == -1) ++ return rv; ++ ++ if (pam_sprintf(s_path, "/proc/self/fd/%d", dfd) < 0) ++ goto error; ++ ++ /* ++ * We still have a fd open to path itself, ++ * so we need to do a lazy umount. ++ */ ++ rv = umount2(s_path, MNT_DETACH); ++ ++error: ++ save_errno = errno; ++ close(dfd); ++ errno = save_errno; ++ return rv; ++} ++ ++/* ++ * Rmdir the given path securely, protecting against symlinks attacks ++ * and race conditions. ++ * This function is currently called only in cleanup code paths where ++ * any errors returned are not handled, so do not handle them either. ++ * Basically, try to rmdir the path on a best-effort basis. ++ */ ++static void secure_try_rmdir(const char *path) ++{ ++ int dfd; ++ char *buf; ++ char *parent; ++ ++ buf = strdup(path); ++ if (buf == NULL) ++ return; ++ ++ parent = dirname(buf); ++ ++ dfd = secure_opendir_stateless(parent); ++ if (dfd >= 0) { ++ unlinkat(dfd, base_name(path), AT_REMOVEDIR); ++ close(dfd); ++ } ++ ++ free(buf); ++} ++ + /* Evaluating a list of files which have to be parsed in the right order: + * + * - If etc/security/namespace.d/@filename@.conf exists, then +@@ -330,7 +461,7 @@ static void unprotect_dirs(struct protect_dir_s *dir) + struct protect_dir_s *next; + + while (dir != NULL) { +- umount(dir->dir); ++ secure_umount(dir->dir); + free(dir->dir); + next = dir->next; + free(dir); +@@ -734,13 +865,9 @@ static int process_line(char *line, const char *home, const char *rhome, + goto skipping; + } + +-#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) { ++ if (pam_sprintf(poly->dir, "%s", dir) < 0 ++ || pam_sprintf(poly->rdir, "%s", rdir) < 0 ++ || pam_sprintf(poly->instance_prefix, "%s", instance_prefix) < 0) { + pam_syslog(idata->pamh, LOG_NOTICE, "Pathnames too long"); + goto skipping; + } +@@ -1023,6 +1150,23 @@ static char *md5hash(const char *instname, struct instance_data *idata) + } + + #ifdef WITH_SELINUX ++static char *secure_getfilecon(pam_handle_t *pamh, const char *dir) ++{ ++ char *ctx = NULL; ++ int dfd = secure_opendir(dir, SECURE_OPENDIR_FULL_FD, 0, NULL); ++ if (dfd < 0) { ++ pam_syslog(pamh, LOG_ERR, "Error getting fd to %s: %m", dir); ++ return NULL; ++ } ++ if (fgetfilecon(dfd, &ctx) < 0) ++ ctx = NULL; ++ if (ctx == NULL) ++ pam_syslog(pamh, LOG_ERR, ++ "Error getting poly dir context for %s: %m", dir); ++ close(dfd); ++ return ctx; ++} ++ + static int form_context(const struct polydir_s *polyptr, + char **i_context, char **origcon, + struct instance_data *idata) +@@ -1034,12 +1178,9 @@ static int form_context(const struct polydir_s *polyptr, + /* + * Get the security context of the directory to polyinstantiate. + */ +- rc = getfilecon(polyptr->dir, origcon); +- if (rc < 0 || *origcon == NULL) { +- pam_syslog(idata->pamh, LOG_ERR, +- "Error getting poly dir context, %m"); ++ *origcon = secure_getfilecon(idata->pamh, polyptr->dir); ++ if (*origcon == NULL) + return PAM_SESSION_ERR; +- } + + if (polyptr->method == USER) return PAM_SUCCESS; + +@@ -1136,29 +1277,52 @@ static int form_context(const struct polydir_s *polyptr, + #endif + + /* +- * poly_name returns the name of the polyinstantiated instance directory ++ * From the instance differentiation string, set in the polyptr structure: ++ * - the absolute path to the instance dir, ++ * - the absolute path to the previous dir (parent), ++ * - the instance name (may be different than the instance differentiation string) ++ */ ++static int set_polydir_paths(struct polydir_s *polyptr, const char *inst_differentiation) ++{ ++ char *tmp; ++ ++ if (pam_sprintf(polyptr->instance_absolute, "%s%s", ++ polyptr->instance_prefix, inst_differentiation) < 0) ++ return -1; ++ ++ polyptr->instname = strrchr(polyptr->instance_absolute, '/') + 1; ++ ++ if (pam_sprintf(polyptr->instance_parent, "%s", polyptr->instance_absolute) < 0) ++ return -1; ++ ++ tmp = strrchr(polyptr->instance_parent, '/') + 1; ++ *tmp = '\0'; ++ ++ return 0; ++} ++ ++/* ++ * Set the name of the polyinstantiated instance directory + * based on the method used for polyinstantiation (user, context or level) + * In addition, the function also returns the security contexts of the + * original directory to polyinstantiate and the polyinstantiated instance + * directory. + */ + #ifdef WITH_SELINUX +-static int poly_name(const struct polydir_s *polyptr, char **i_name, +- char **i_context, char **origcon, +- struct instance_data *idata) ++static int poly_name(struct polydir_s *polyptr, char **i_context, ++ char **origcon, struct instance_data *idata) + #else +-static int poly_name(const struct polydir_s *polyptr, char **i_name, +- struct instance_data *idata) ++static int poly_name(struct polydir_s *polyptr, struct instance_data *idata) + #endif + { + int rc; ++ char *inst_differentiation = NULL; + char *hash = NULL; + enum polymethod pm; + #ifdef WITH_SELINUX + char *rawcon = NULL; + #endif + +- *i_name = NULL; + #ifdef WITH_SELINUX + *i_context = NULL; + *origcon = NULL; +@@ -1192,7 +1356,7 @@ static int poly_name(const struct polydir_s *polyptr, char **i_name, + + switch (pm) { + case USER: +- if ((*i_name = strdup(idata->user)) == NULL) ++ if ((inst_differentiation = strdup(idata->user)) == NULL) + goto fail; + break; + +@@ -1204,20 +1368,24 @@ static int poly_name(const struct polydir_s *polyptr, char **i_name, + goto fail; + } + if (polyptr->flags & POLYDIR_SHARED) +- *i_name = strdup(rawcon); ++ inst_differentiation = strdup(rawcon); + else +- *i_name = pam_asprintf("%s_%s", rawcon, idata->user); +- if (*i_name == NULL) ++ inst_differentiation = pam_asprintf("%s_%s", rawcon, idata->user); ++ if (inst_differentiation == NULL) + goto fail; + break; + + #endif /* WITH_SELINUX */ + + case TMPDIR: ++ if ((inst_differentiation = strdup("XXXXXX")) == NULL) ++ goto fail; ++ goto success; ++ + case TMPFS: +- if ((*i_name=strdup("")) == NULL) ++ if ((inst_differentiation=strdup("")) == NULL) + goto fail; +- return PAM_SUCCESS; ++ goto success; + + default: + if (idata->flags & PAMNS_DEBUG) +@@ -1226,32 +1394,37 @@ static int poly_name(const struct polydir_s *polyptr, char **i_name, + } + + if (idata->flags & PAMNS_DEBUG) +- pam_syslog(idata->pamh, LOG_DEBUG, "poly_name %s", *i_name); ++ pam_syslog(idata->pamh, LOG_DEBUG, "poly_name %s", inst_differentiation); + +- if ((idata->flags & PAMNS_GEN_HASH) || strlen(*i_name) > NAMESPACE_MAX_DIR_LEN) { +- hash = md5hash(*i_name, idata); ++ if ((idata->flags & PAMNS_GEN_HASH) || strlen(inst_differentiation) > NAMESPACE_MAX_DIR_LEN) { ++ hash = md5hash(inst_differentiation, idata); + if (hash == NULL) { + goto fail; + } + if (idata->flags & PAMNS_GEN_HASH) { +- free(*i_name); +- *i_name = hash; ++ free(inst_differentiation); ++ inst_differentiation = hash; + hash = NULL; + } else { + char *newname = + pam_asprintf("%.*s_%s", + NAMESPACE_MAX_DIR_LEN - 1 - (int)strlen(hash), +- *i_name, hash); ++ inst_differentiation, hash); + if (newname == NULL) + goto fail; +- free(*i_name); +- *i_name = newname; ++ free(inst_differentiation); ++ inst_differentiation = newname; + } + } +- rc = PAM_SUCCESS; + ++success: ++ if (set_polydir_paths(polyptr, inst_differentiation) == -1) ++ goto fail; ++ ++ rc = PAM_SUCCESS; + fail: + free(hash); ++ free(inst_differentiation); + #ifdef WITH_SELINUX + freecon(rawcon); + #endif +@@ -1262,55 +1435,35 @@ fail: + freecon(*origcon); + *origcon = NULL; + #endif +- free(*i_name); +- *i_name = NULL; + } + return rc; + } + +-static int check_inst_parent(char *ipath, struct instance_data *idata) ++static int check_inst_parent(int dfd, 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 +- * admin explicitly instructs to ignore the instance parent +- * mode by the "ignore_instance_parent_mode" argument). ++ * Stat the instance parent directory to make sure it's writable by ++ * root only (unless the admin explicitly instructs to ignore the ++ * instance parent mode by the "ignore_instance_parent_mode" argument). + */ +- inst_parent = strdup(ipath); +- if (!inst_parent) { +- pam_syslog(idata->pamh, LOG_CRIT, "Error allocating pathname string"); +- return PAM_SESSION_ERR; +- } + +- trailing_slash = strrchr(inst_parent, '/'); +- if (trailing_slash) +- *trailing_slash = '\0'; +- +- dfd = protect_dir(inst_parent, 0, 1, idata); ++ if (idata->flags & PAMNS_IGN_INST_PARENT_MODE) ++ return PAM_SUCCESS; + +- if (dfd == -1 || fstat(dfd, &instpbuf) < 0) { ++ if (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); ++ "Error accessing instance parent, %m"); + return PAM_SESSION_ERR; + } + +- if ((idata->flags & PAMNS_IGN_INST_PARENT_MODE) == 0) { +- 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; +- } ++ if ((instpbuf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) || instpbuf.st_uid != 0) { ++ pam_syslog(idata->pamh, LOG_ERR, ++ "Mode of inst parent not 000 or owner not root"); ++ return PAM_SESSION_ERR; + } +- close(dfd); +- free(inst_parent); ++ + return PAM_SUCCESS; + } + +@@ -1449,14 +1602,16 @@ static int create_polydir(struct polydir_s *polyptr, + } + #endif + +- rc = protect_dir(dir, mode, 1, idata); ++ rc = secure_opendir(dir, ++ SECURE_OPENDIR_PROTECT | SECURE_OPENDIR_MKDIR | SECURE_OPENDIR_FULL_FD, ++ mode, idata); + 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; ++ return -1; + } + + #ifdef WITH_SELINUX +@@ -1477,9 +1632,9 @@ static int create_polydir(struct polydir_s *polyptr, + 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; ++ secure_umount(dir); /* undo the eventual protection bind mount */ ++ secure_try_rmdir(dir); ++ return -1; + } + } + +@@ -1497,41 +1652,37 @@ static int create_polydir(struct polydir_s *polyptr, + 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; ++ secure_umount(dir); /* undo the eventual protection bind mount */ ++ secure_try_rmdir(dir); ++ return -1; + } + +- close(rc); +- + if (idata->flags & PAMNS_DEBUG) + pam_syslog(idata->pamh, LOG_DEBUG, + "Polydir owner %u group %u", uid, gid); + +- return PAM_SUCCESS; ++ return rc; + } + + /* +- * Create polyinstantiated instance directory (ipath). ++ * Create polyinstantiated instance directory. ++ * To protect against races, changes are done on a fd to the parent of the ++ * instance directory (dfd_iparent) and a relative path (polyptr->instname). ++ * The absolute path (polyptr->instance_absolute) is only updated when creating ++ * a tmpdir and used for logging purposes. + */ + #ifdef WITH_SELINUX +-static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat *statbuf, +- const char *icontext, const char *ocontext, +- struct instance_data *idata) ++static int create_instance(struct polydir_s *polyptr, int dfd_iparent, ++ struct stat *statbuf, const char *icontext, const char *ocontext, ++ struct instance_data *idata) + #else +-static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat *statbuf, +- struct instance_data *idata) ++static int create_instance(struct polydir_s *polyptr, int dfd_iparent, ++ struct stat *statbuf, struct instance_data *idata) + #endif + { + struct stat newstatbuf; + int fd; + +- /* +- * Check to make sure instance parent is valid. +- */ +- if (check_inst_parent(ipath, idata)) +- return PAM_SESSION_ERR; +- + /* + * Create instance directory and set its security context to the context + * returned by the security policy. Set its mode and ownership +@@ -1540,29 +1691,39 @@ static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat * + */ + + if (polyptr->method == TMPDIR) { +- if (mkdtemp(polyptr->instance_prefix) == NULL) { +- pam_syslog(idata->pamh, LOG_ERR, "Error creating temporary instance %s, %m", +- polyptr->instance_prefix); +- polyptr->method = NONE; /* do not clean up! */ +- return PAM_SESSION_ERR; +- } +- /* copy the actual directory name to ipath */ +- strcpy(ipath, polyptr->instance_prefix); +- } else if (mkdir(ipath, S_IRUSR) < 0) { ++ char s_path[PATH_MAX]; ++ /* ++ * Create the template for mkdtemp() as a magic link based on ++ * our existing fd to avoid symlink attacks and races. ++ */ ++ if (pam_sprintf(s_path, "/proc/self/fd/%d/%s", dfd_iparent, polyptr->instname) < 0 ++ || mkdtemp(s_path) == NULL) { ++ pam_syslog(idata->pamh, LOG_ERR, ++ "Error creating temporary instance dir %s, %m", ++ polyptr->instance_absolute); ++ polyptr->method = NONE; /* do not clean up! */ ++ return PAM_SESSION_ERR; ++ } ++ ++ /* Copy the actual directory name to polyptr->instname */ ++ strcpy(polyptr->instname, base_name(s_path)); ++ } else if (mkdirat(dfd_iparent, polyptr->instname, S_IRUSR) < 0) { + if (errno == EEXIST) + return PAM_IGNORE; + else { + pam_syslog(idata->pamh, LOG_ERR, "Error creating %s, %m", +- ipath); ++ polyptr->instance_absolute); + return PAM_SESSION_ERR; + } + } + +- /* Open a descriptor to it to prevent races */ +- fd = open(ipath, O_DIRECTORY | O_RDONLY); ++ /* Open a descriptor to prevent races, based on our existing fd. */ ++ fd = openat(dfd_iparent, polyptr->instname, ++ O_RDONLY | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC); + if (fd < 0) { +- pam_syslog(idata->pamh, LOG_ERR, "Error opening %s, %m", ipath); +- rmdir(ipath); ++ pam_syslog(idata->pamh, LOG_ERR, "Error opening %s, %m", ++ polyptr->instance_absolute); ++ unlinkat(dfd_iparent, polyptr->instname, AT_REMOVEDIR); + return PAM_SESSION_ERR; + } + #ifdef WITH_SELINUX +@@ -1572,17 +1733,19 @@ static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat * + if (icontext) { + if (fsetfilecon(fd, icontext) < 0) { + pam_syslog(idata->pamh, LOG_ERR, +- "Error setting context of %s to %s", ipath, icontext); ++ "Error setting context of %s to %s", ++ polyptr->instance_absolute, icontext); + close(fd); +- rmdir(ipath); ++ unlinkat(dfd_iparent, polyptr->instname, AT_REMOVEDIR); + return PAM_SESSION_ERR; + } + } else { + if (fsetfilecon(fd, ocontext) < 0) { + pam_syslog(idata->pamh, LOG_ERR, +- "Error setting context of %s to %s", ipath, ocontext); ++ "Error setting context of %s to %s", ++ polyptr->instance_absolute, ocontext); + close(fd); +- rmdir(ipath); ++ unlinkat(dfd_iparent, polyptr->instname, AT_REMOVEDIR); + return PAM_SESSION_ERR; + } + } +@@ -1590,9 +1753,9 @@ static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat * + #endif + if (fstat(fd, &newstatbuf) < 0) { + pam_syslog(idata->pamh, LOG_ERR, "Error stating %s, %m", +- ipath); ++ polyptr->instance_absolute); + close(fd); +- rmdir(ipath); ++ unlinkat(dfd_iparent, polyptr->instname, AT_REMOVEDIR); + return PAM_SESSION_ERR; + } + if (newstatbuf.st_uid != statbuf->st_uid || +@@ -1600,17 +1763,17 @@ static int create_instance(struct polydir_s *polyptr, char *ipath, struct stat * + if (fchown(fd, statbuf->st_uid, statbuf->st_gid) < 0) { + pam_syslog(idata->pamh, LOG_ERR, + "Error changing owner for %s, %m", +- ipath); ++ polyptr->instance_absolute); + close(fd); +- rmdir(ipath); ++ unlinkat(dfd_iparent, polyptr->instname, AT_REMOVEDIR); + return PAM_SESSION_ERR; + } + } + if (fchmod(fd, statbuf->st_mode & 07777) < 0) { + pam_syslog(idata->pamh, LOG_ERR, "Error changing mode for %s, %m", +- ipath); ++ polyptr->instance_absolute); + close(fd); +- rmdir(ipath); ++ unlinkat(dfd_iparent, polyptr->instname, AT_REMOVEDIR); + return PAM_SESSION_ERR; + } + close(fd); +@@ -1629,9 +1792,12 @@ static int ns_setup(struct polydir_s *polyptr, + struct instance_data *idata) + { + int retval; ++ int dfd_iparent = -1; ++ int dfd_ipath = -1; ++ int dfd_pptrdir = -1; + int newdir = 1; +- char *inst_dir = NULL; +- char *instname = NULL; ++ char s_ipath[MAGIC_LNK_FD_SIZE]; ++ char s_pptrdir[MAGIC_LNK_FD_SIZE]; + struct stat statbuf; + #ifdef WITH_SELINUX + char *instcontext = NULL, *origcontext = NULL; +@@ -1641,37 +1807,48 @@ static int ns_setup(struct polydir_s *polyptr, + pam_syslog(idata->pamh, LOG_DEBUG, + "Set namespace for directory %s", polyptr->dir); + +- retval = protect_dir(polyptr->dir, 0, 0, idata); ++ dfd_pptrdir = secure_opendir(polyptr->dir, SECURE_OPENDIR_PROTECT, 0, idata); + +- if (retval < 0) { ++ if (dfd_pptrdir < 0) { + 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) ++ dfd_pptrdir = create_polydir(polyptr, idata); ++ if (dfd_pptrdir < 0) + return PAM_SESSION_ERR; +- } else { +- close(retval); + } + + if (polyptr->method == TMPFS) { +- 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; +- } ++ /* ++ * There is no function mount() that operate on a fd, so instead, we ++ * get the magic link corresponding to the fd and give it to mount(). ++ * This protects against potential races exploitable by an unpriv user. ++ */ ++ if (pam_sprintf(s_pptrdir, "/proc/self/fd/%d", dfd_pptrdir) < 0) { ++ pam_syslog(idata->pamh, LOG_ERR, "Error pam_sprintf s_pptrdir"); ++ goto error_out; ++ } + +- if (polyptr->flags & POLYDIR_NOINIT) +- return PAM_SUCCESS; ++ if (mount("tmpfs", s_pptrdir, "tmpfs", polyptr->mount_flags, polyptr->mount_opts) < 0) { ++ pam_syslog(idata->pamh, LOG_ERR, "Error mounting tmpfs on %s, %m", ++ polyptr->dir); ++ goto error_out; ++ } ++ ++ if (polyptr->flags & POLYDIR_NOINIT) { ++ retval = PAM_SUCCESS; ++ goto cleanup; ++ } + +- return inst_init(polyptr, "tmpfs", idata, 1); ++ retval = inst_init(polyptr, "tmpfs", idata, 1); ++ goto cleanup; + } + +- if (stat(polyptr->dir, &statbuf) < 0) { +- pam_syslog(idata->pamh, LOG_ERR, "Error stating %s: %m", +- polyptr->dir); +- return PAM_SESSION_ERR; ++ if (fstat(dfd_pptrdir, &statbuf) < 0) { ++ pam_syslog(idata->pamh, LOG_ERR, "Error stating %s: %m", polyptr->dir); ++ goto error_out; + } + + /* +@@ -1680,15 +1857,16 @@ static int ns_setup(struct polydir_s *polyptr, + * security policy. + */ + #ifdef WITH_SELINUX +- retval = poly_name(polyptr, &instname, &instcontext, +- &origcontext, idata); ++ retval = poly_name(polyptr, &instcontext, &origcontext, idata); + #else +- retval = poly_name(polyptr, &instname, idata); ++ retval = poly_name(polyptr, idata); + #endif + + if (retval != PAM_SUCCESS) { +- if (retval != PAM_IGNORE) ++ if (retval != PAM_IGNORE) { + pam_syslog(idata->pamh, LOG_ERR, "Error getting instance name"); ++ goto error_out; ++ } + goto cleanup; + } else { + #ifdef WITH_SELINUX +@@ -1699,22 +1877,33 @@ static int ns_setup(struct polydir_s *polyptr, + #endif + } + +- if ((inst_dir = pam_asprintf("%s%s", polyptr->instance_prefix, instname)) == NULL) +- goto error_out; +- +- if (idata->flags & PAMNS_DEBUG) +- pam_syslog(idata->pamh, LOG_DEBUG, "instance_dir %s", +- inst_dir); ++ /* ++ * Gets a fd in a secure manner (we may be operating on a path under ++ * user control), and check it's compliant. ++ * Then, we should *always* operate on *this* fd and a relative path ++ * to be protected against race conditions. ++ */ ++ dfd_iparent = secure_opendir(polyptr->instance_parent, ++ SECURE_OPENDIR_PROTECT | SECURE_OPENDIR_MKDIR, 0, idata); ++ if (dfd_iparent == -1) { ++ pam_syslog(idata->pamh, LOG_ERR, ++ "polyptr->instance_parent %s access error", ++ polyptr->instance_parent); ++ goto error_out; ++ } ++ if (check_inst_parent(dfd_iparent, idata)) { ++ goto error_out; ++ } + + /* + * Create instance directory with appropriate security + * contexts, owner, group and mode bits. + */ + #ifdef WITH_SELINUX +- retval = create_instance(polyptr, inst_dir, &statbuf, instcontext, +- origcontext, idata); ++ retval = create_instance(polyptr, dfd_iparent, &statbuf, instcontext, ++ origcontext, idata); + #else +- retval = create_instance(polyptr, inst_dir, &statbuf, idata); ++ retval = create_instance(polyptr, dfd_iparent, &statbuf, idata); + #endif + + if (retval == PAM_IGNORE) { +@@ -1726,19 +1915,48 @@ static int ns_setup(struct polydir_s *polyptr, + goto error_out; + } + ++ /* ++ * Instead of getting a new secure fd, we reuse the fd opened on directory ++ * polyptr->instance_parent to ensure we are working on the same dir as ++ * previously, and thus ensure that previous checks (e.g. check_inst_parent()) ++ * are still relevant. ++ */ ++ dfd_ipath = openat(dfd_iparent, polyptr->instname, ++ O_PATH | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC); ++ if (dfd_ipath == -1) { ++ pam_syslog(idata->pamh, LOG_ERR, "Error openat on %s, %m", ++ polyptr->instname); ++ goto error_out; ++ } ++ ++ if (pam_sprintf(s_ipath, "/proc/self/fd/%d", dfd_ipath) < 0) { ++ pam_syslog(idata->pamh, LOG_ERR, "Error pam_sprintf s_ipath"); ++ goto error_out; ++ } ++ ++ if (pam_sprintf(s_pptrdir, "/proc/self/fd/%d", dfd_pptrdir) < 0) { ++ pam_syslog(idata->pamh, LOG_ERR, "Error pam_sprintf s_pptrdir"); ++ goto error_out; ++ } ++ + /* + * Bind mount instance directory on top of the polyinstantiated + * directory to provide an instance of polyinstantiated directory + * based on polyinstantiated method. ++ * ++ * Operates on magic links created from two fd obtained securely ++ * to protect against race conditions and symlink attacks. Indeed, ++ * the source and destination can be in a user controled path. + */ +- if (mount(inst_dir, polyptr->dir, NULL, MS_BIND, NULL) < 0) { +- pam_syslog(idata->pamh, LOG_ERR, "Error mounting %s on %s, %m", +- inst_dir, polyptr->dir); ++ if(mount(s_ipath, s_pptrdir, NULL, MS_BIND, NULL) < 0) { ++ pam_syslog(idata->pamh, LOG_ERR, ++ "Error mounting %s on %s (%s on %s), %m", ++ s_ipath, s_pptrdir, polyptr->instance_absolute, polyptr->dir); + goto error_out; + } + + if (!(polyptr->flags & POLYDIR_NOINIT)) +- retval = inst_init(polyptr, inst_dir, idata, newdir); ++ retval = inst_init(polyptr, polyptr->instance_absolute, idata, newdir); + + goto cleanup; + +@@ -1750,8 +1968,12 @@ error_out: + retval = PAM_SESSION_ERR; + + cleanup: +- free(inst_dir); +- free(instname); ++ if (dfd_iparent != -1) ++ close(dfd_iparent); ++ if (dfd_ipath != -1) ++ close(dfd_ipath); ++ if (dfd_pptrdir != -1) ++ close(dfd_pptrdir); + #ifdef WITH_SELINUX + freecon(instcontext); + freecon(origcontext); +@@ -1790,6 +2012,7 @@ static int cleanup_tmpdirs(struct instance_data *idata) + { + struct polydir_s *pptr; + pid_t rc, pid; ++ int dfd = -1; + struct sigaction newsa, oldsa; + int status; + +@@ -1801,7 +2024,17 @@ static int cleanup_tmpdirs(struct instance_data *idata) + } + + for (pptr = idata->polydirs_ptr; pptr; pptr = pptr->next) { +- if (pptr->method == TMPDIR && access(pptr->instance_prefix, F_OK) == 0) { ++ if (pptr->method == TMPDIR) { ++ ++ dfd = secure_opendir_stateless(pptr->instance_parent); ++ if (dfd == -1) ++ continue; ++ ++ if (faccessat(dfd, pptr->instname, F_OK, AT_SYMLINK_NOFOLLOW) != 0) { ++ close(dfd); ++ continue; ++ } ++ + pid = fork(); + if (pid == 0) { + static char *envp[] = { NULL }; +@@ -1811,10 +2044,21 @@ static int cleanup_tmpdirs(struct instance_data *idata) + _exit(1); + } + #endif ++ if (fchdir(dfd) == -1) { ++ pam_syslog(idata->pamh, LOG_ERR, "Failed fchdir to %s: %m", ++ pptr->instance_absolute); ++ _exit(1); ++ } ++ + close_fds_pre_exec(idata); +- execle("/bin/rm", "/bin/rm", "-rf", pptr->instance_prefix, NULL, envp); ++ ++ execle("/bin/rm", "/bin/rm", "-rf", pptr->instname, NULL, envp); + _exit(1); + } else if (pid > 0) { ++ ++ if (dfd != -1) ++ close(dfd); ++ + while (((rc = waitpid(pid, &status, 0)) == (pid_t)-1) && + (errno == EINTR)); + if (rc == (pid_t)-1) { +@@ -1827,6 +2071,10 @@ static int cleanup_tmpdirs(struct instance_data *idata) + "Error removing %s", pptr->instance_prefix); + } + } else if (pid < 0) { ++ ++ if (dfd != -1) ++ close(dfd); ++ + pam_syslog(idata->pamh, LOG_ERR, + "Cannot fork to cleanup temporary directory, %m"); + rc = PAM_SESSION_ERR; +@@ -1850,6 +2098,7 @@ out: + static int setup_namespace(struct instance_data *idata, enum unmnt_op unmnt) + { + int retval = 0, need_poly = 0, changing_dir = 0; ++ int dfd = -1; + char *cptr, *fptr, poly_parent[PATH_MAX]; + struct polydir_s *pptr; + +@@ -1965,13 +2214,21 @@ static int setup_namespace(struct instance_data *idata, enum unmnt_op unmnt) + strcpy(poly_parent, "/"); + else if (cptr) + *cptr = '\0'; +- if (chdir(poly_parent) < 0) { ++ ++ dfd = secure_opendir_stateless(poly_parent); ++ if (dfd == -1) { ++ pam_syslog(idata->pamh, LOG_ERR, ++ "Failed opening %s to fchdir: %m", poly_parent); ++ } ++ else if (fchdir(dfd) == -1) { + pam_syslog(idata->pamh, LOG_ERR, +- "Can't chdir to %s, %m", poly_parent); ++ "Failed fchdir to %s: %m", poly_parent); + } ++ if (dfd != -1) ++ close(dfd); + } + +- if (umount(pptr->rdir) < 0) { ++ if (secure_umount(pptr->rdir) < 0) { + int saved_errno = errno; + pam_syslog(idata->pamh, LOG_ERR, "Unmount of %s failed, %m", + pptr->rdir); +@@ -2041,7 +2298,7 @@ static int orig_namespace(struct instance_data *idata) + "Unmounting instance dir for user %d & dir %s", + idata->uid, pptr->dir); + +- if (umount(pptr->dir) < 0) { ++ if (secure_umount(pptr->dir) < 0) { + pam_syslog(idata->pamh, LOG_ERR, "Unmount of %s failed, %m", + pptr->dir); + return PAM_SESSION_ERR; +diff --git a/modules/pam_namespace/pam_namespace.h b/modules/pam_namespace/pam_namespace.h +index 180e042..721d39a 100644 +--- a/modules/pam_namespace/pam_namespace.h ++++ b/modules/pam_namespace/pam_namespace.h +@@ -121,6 +121,13 @@ + #define NAMESPACE_POLYDIR_DATA "pam_namespace:polydir_data" + #define NAMESPACE_PROTECT_DATA "pam_namespace:protect_data" + ++/* ++ * Operation mode for function secure_opendir() ++ */ ++#define SECURE_OPENDIR_PROTECT 0x00000001 ++#define SECURE_OPENDIR_MKDIR 0x00000002 ++#define SECURE_OPENDIR_FULL_FD 0x00000004 ++ + /* + * Polyinstantiation method options, based on user, security context + * or both +@@ -158,6 +165,9 @@ struct polydir_s { + char dir[PATH_MAX]; /* directory to polyinstantiate */ + char rdir[PATH_MAX]; /* directory to unmount (based on RUSER) */ + char instance_prefix[PATH_MAX]; /* prefix for instance dir path name */ ++ char instance_absolute[PATH_MAX]; /* absolute path to the instance dir (instance_parent + instname) */ ++ char instance_parent[PATH_MAX]; /* parent dir of the instance dir */ ++ char *instname; /* last segment of the path to the instance dir */ + enum polymethod method; /* method used to polyinstantiate */ + unsigned int num_uids; /* number of override uids */ + uid_t *uid; /* list of override uids */ +-- +2.49.0 + diff --git a/meta/recipes-extended/pam/libpam/CVE-2025-6020-02.patch b/meta/recipes-extended/pam/libpam/CVE-2025-6020-02.patch new file mode 100644 index 0000000000..18c2a82fb4 --- /dev/null +++ b/meta/recipes-extended/pam/libpam/CVE-2025-6020-02.patch @@ -0,0 +1,187 @@ +From 592d84e1265d04c3104acee815a503856db503a1 Mon Sep 17 00:00:00 2001 +From: Olivier Bal-Petre +Date: Tue, 4 Mar 2025 14:37:02 +0100 +Subject: [PATCH] pam_namespace: add flags to indicate path safety + +Add two flags in the script to indicate if the paths to the polydir +and the instance directories are safe (root owned and writable by +root only). + +Signed-off-by: Olivier Bal-Petre +Signed-off-by: Dmitry V. Levin + +Upstream-Status: Backport [https://github.com/linux-pam/linux-pam/commit/592d84e1265d04c3104acee815a503856db503a1] +CVE: CVE-2025-6020 +Signed-off-by: Hitendra Prajapati +--- + modules/pam_namespace/namespace.init | 56 ++++++++++++------- + modules/pam_namespace/pam_namespace.c | 79 ++++++++++++++++++++++++++- + 2 files changed, 115 insertions(+), 20 deletions(-) + +diff --git a/modules/pam_namespace/namespace.init b/modules/pam_namespace/namespace.init +index d9053a1..8782178 100755 +--- a/modules/pam_namespace/namespace.init ++++ b/modules/pam_namespace/namespace.init +@@ -1,25 +1,43 @@ + #!/bin/sh +-# It receives polydir path as $1, the instance path as $2, +-# a flag whether the instance dir was newly created (0 - no, 1 - yes) in $3, +-# and user name in $4. ++# It receives as arguments: ++# - $1 polydir path (see WARNING below) ++# - $2 instance path (see WARNING below) ++# - $3 flag whether the instance dir was newly created (0 - no, 1 - yes) ++# - $4 user name ++# - $5 flag whether the polydir path ($1) is safe (0 - unsafe, 1 -safe) ++# - $6 flag whether the instance path ($2) is safe (0 - unsafe, 1 - safe) ++# ++# WARNING: This script is invoked with full root privileges. Accessing ++# the polydir ($1) and the instance ($2) directories in this context may be ++# extremely dangerous as those can be under user control. The flags $5 and $6 ++# are provided to let you know if all the segments part of the path (except the ++# last one) are owned by root and are writable by root only. If the path does ++# not meet these criteria, you expose yourself to possible symlink attacks when ++# accessing these path. ++# However, even if the path components are safe, the content of the ++# directories may still be owned/writable by a user, so care must be taken! + # + # The following section will copy the contents of /etc/skel if this is a + # newly created home directory. +-if [ "$3" = 1 ]; then +- # This line will fix the labeling on all newly created directories +- [ -x /sbin/restorecon ] && /sbin/restorecon "$1" +- user="$4" +- passwd=$(getent passwd "$user") +- homedir=$(echo "$passwd" | cut -f6 -d":") +- if [ "$1" = "$homedir" ]; then +- gid=$(echo "$passwd" | cut -f4 -d":") +- cp -rT /etc/skel "$homedir" +- chown -R "$user":"$gid" "$homedir" +- mask=$(awk '/^UMASK/{gsub("#.*$", "", $2); print $2; exit}' /etc/login.defs) +- mode=$(printf "%o" $((0777 & ~mask))) +- chmod ${mode:-700} "$homedir" +- [ -x /sbin/restorecon ] && /sbin/restorecon -R "$homedir" +- fi +-fi + ++# Executes only if the polydir path is safe ++if [ "$5" = 1 ]; then ++ ++ if [ "$3" = 1 ]; then ++ # This line will fix the labeling on all newly created directories ++ [ -x /sbin/restorecon ] && /sbin/restorecon "$1" ++ user="$4" ++ passwd=$(getent passwd "$user") ++ homedir=$(echo "$passwd" | cut -f6 -d":") ++ if [ "$1" = "$homedir" ]; then ++ gid=$(echo "$passwd" | cut -f4 -d":") ++ cp -rT /etc/skel "$homedir" ++ chown -R "$user":"$gid" "$homedir" ++ mask=$(sed -E -n 's/^UMASK[[:space:]]+([^#[:space:]]+).*/\1/p' /etc/login.defs) ++ mode=$(printf "%o" $((0777 & ~mask))) ++ chmod ${mode:-700} "$homedir" ++ [ -x /sbin/restorecon ] && /sbin/restorecon -R "$homedir" ++ fi ++ fi ++fi + exit 0 +diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c +index 9d993d4..4c8153b 100644 +--- a/modules/pam_namespace/pam_namespace.c ++++ b/modules/pam_namespace/pam_namespace.c +@@ -1467,6 +1467,79 @@ static int check_inst_parent(int dfd, struct instance_data *idata) + return PAM_SUCCESS; + } + ++/* ++ * Check for a given absolute path that all segments except the last one are: ++ * 1. a directory owned by root and not writable by group or others ++ * 2. a symlink owned by root and referencing a directory respecting 1. ++ * Returns 0 if safe, -1 is unsafe. ++ * If the path is not accessible (does not exist, hidden under a mount...), ++ * returns -1 (unsafe). ++ */ ++static int check_safe_path(const char *path, struct instance_data *idata) ++{ ++ char *p = strdup(path); ++ char *d; ++ char *dir = p; ++ struct stat st; ++ ++ if (p == NULL) ++ return -1; ++ ++ /* Check path is absolute */ ++ if (p[0] != '/') ++ goto error; ++ ++ strip_trailing_slashes(p); ++ ++ /* Last segment of the path may be owned by the user */ ++ if ((d = strrchr(dir, '/')) != NULL) ++ *d = '\0'; ++ ++ while ((d=strrchr(dir, '/')) != NULL) { ++ ++ /* Do not follow symlinks */ ++ if (lstat(dir, &st) != 0) ++ goto error; ++ ++ if (S_ISLNK(st.st_mode)) { ++ if (st.st_uid != 0) { ++ if (idata->flags & PAMNS_DEBUG) ++ pam_syslog(idata->pamh, LOG_DEBUG, ++ "Path deemed unsafe: Symlink %s should be owned by root", dir); ++ goto error; ++ } ++ ++ /* Follow symlinks */ ++ if (stat(dir, &st) != 0) ++ goto error; ++ } ++ ++ if (!S_ISDIR(st.st_mode)) { ++ if (idata->flags & PAMNS_DEBUG) ++ pam_syslog(idata->pamh, LOG_DEBUG, ++ "Path deemed unsafe: %s is expected to be a directory", dir); ++ goto error; ++ } ++ ++ if (st.st_uid != 0 || ++ ((st.st_mode & (S_IWGRP|S_IWOTH)) && !(st.st_mode & S_ISVTX))) { ++ if (idata->flags & PAMNS_DEBUG) ++ pam_syslog(idata->pamh, LOG_DEBUG, ++ "Path deemed unsafe: %s should be owned by root, and not be writable by group or others", dir); ++ goto error; ++ } ++ ++ *d = '\0'; ++ } ++ ++ free(p); ++ return 0; ++ ++error: ++ free(p); ++ return -1; ++} ++ + /* + * Check to see if there is a namespace initialization script in + * the /etc/security directory. If such a script exists +@@ -1524,7 +1597,11 @@ static int inst_init(const struct polydir_s *polyptr, const char *ipath, + close_fds_pre_exec(idata); + + execle(init_script, init_script, +- polyptr->dir, ipath, newdir?"1":"0", idata->user, NULL, envp); ++ polyptr->dir, ipath, ++ newdir ? "1":"0", idata->user, ++ (check_safe_path(polyptr->dir, idata) == -1) ? "0":"1", ++ (check_safe_path(ipath, idata) == -1) ? "0":"1", ++ NULL, envp); + _exit(1); + } else if (pid > 0) { + while (((rc = waitpid(pid, &status, 0)) == (pid_t)-1) && +-- +2.49.0 + diff --git a/meta/recipes-extended/pam/libpam/CVE-2025-6020-03.patch b/meta/recipes-extended/pam/libpam/CVE-2025-6020-03.patch new file mode 100644 index 0000000000..238bef47ec --- /dev/null +++ b/meta/recipes-extended/pam/libpam/CVE-2025-6020-03.patch @@ -0,0 +1,35 @@ +From 976c20079358d133514568fc7fd95c02df8b5773 Mon Sep 17 00:00:00 2001 +From: "Dmitry V. Levin" +Date: Tue, 27 May 2025 08:00:00 +0000 +Subject: [PATCH] pam_namespace: secure_opendir: do not look at the group + ownership + +When the directory is not group-writable, the group ownership does +not matter, and when it is group-writable, there should not be any +exceptions for the root group as there is no guarantee that the root +group does not include non-root users. + +Upstream-Status: Backport [https://github.com/linux-pam/linux-pam/commit/976c20079358d133514568fc7fd95c02df8b5773] +CVE: CVE-2025-6020 +Signed-off-by: Hitendra Prajapati +--- + modules/pam_namespace/pam_namespace.c | 3 +-- + 1 file changed, 1 insertion(+), 2 deletions(-) + +diff --git a/modules/pam_namespace/pam_namespace.c b/modules/pam_namespace/pam_namespace.c +index 4c8153b..791dd07 100644 +--- a/modules/pam_namespace/pam_namespace.c ++++ b/modules/pam_namespace/pam_namespace.c +@@ -215,8 +215,7 @@ static int secure_opendir(const char *path, int opm, mode_t mode, + if (dfd_next == -1) + goto error; + } else if (st.st_uid != 0 +- || (st.st_gid != 0 && (st.st_mode & S_IWGRP)) +- || (st.st_mode & S_IWOTH)) { ++ || (st.st_mode & (S_IWGRP|S_IWOTH))) { + /* do not follow symlinks on subdirectories */ + flags |= O_NOFOLLOW; + } +-- +2.49.0 + diff --git a/meta/recipes-extended/pam/libpam_1.5.3.bb b/meta/recipes-extended/pam/libpam_1.5.3.bb index 714cdb6552..815085cc82 100644 --- a/meta/recipes-extended/pam/libpam_1.5.3.bb +++ b/meta/recipes-extended/pam/libpam_1.5.3.bb @@ -29,6 +29,11 @@ SRC_URI = "${GITHUB_BASE_URI}/download/v${PV}/Linux-PAM-${PV}.tar.xz \ file://CVE-2024-22365.patch \ file://CVE-2024-10041-1.patch \ file://CVE-2024-10041-2.patch \ + file://0001-pam-inline-pam-asprintf.patch \ + file://0002-pam-namespace-rebase.patch \ + file://CVE-2025-6020-01.patch \ + file://CVE-2025-6020-02.patch \ + file://CVE-2025-6020-03.patch \ " SRC_URI[sha256sum] = "7ac4b50feee004a9fa88f1dfd2d2fa738a82896763050cd773b3c54b0a818283"