add rpath $ORIGIN processing to dynamic linker

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 8c5b962..6f23fa5 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -72,8 +72,9 @@ struct dso {
        signed char global;
        char relocated;
        char constructed;
+       char kernel_mapped;
        struct dso **deps, *needed_by;
-       char *rpath;
+       char *rpath_orig, *rpath;
        void *tls_image;
        size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
        void **new_dtv;
@@ -448,6 +449,58 @@ static int path_open(const char *name, const char *s, char *buf, size_t buf_size
        }
 }
 
+static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
+{
+       size_t n, l;
+       const char *s, *t, *origin;
+       char *d;
+       if (p->rpath) return 0;
+       if (!p->rpath_orig) return -1;
+       if (!strchr(p->rpath_orig, '$')) {
+               p->rpath = p->rpath_orig;
+               return 0;
+       }
+       n = 0;
+       s = p->rpath_orig;
+       while ((t=strstr(s, "$ORIGIN")) || (t=strstr(s, "${ORIGIN}"))) {
+               s = t+1;
+               n++;
+       }
+       if (n > SSIZE_MAX/PATH_MAX) return -1;
+
+       if (p->kernel_mapped) {
+               /* $ORIGIN searches cannot be performed for the main program
+                * when it is suid/sgid/AT_SECURE. This is because the
+                * pathname is under the control of the caller of execve.
+                * For libraries, however, $ORIGIN can be processed safely
+                * since the library's pathname came from a trusted source
+                * (either system paths or a call to dlopen). */
+               if (libc.secure)
+                       return -1;
+               if (readlink("/proc/self/exe", buf, buf_size) >= buf_size)
+                       return -1;
+               origin = buf;
+       } else {
+               origin = p->name;
+       }
+       t = strrchr(origin, '/');
+       l = t ? t-origin : 0;
+       p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
+       if (!p->rpath) return -1;
+
+       d = p->rpath;
+       s = p->rpath_orig;
+       while ((t=strstr(s, "$ORIGIN")) || (t=strstr(s, "${ORIGIN}"))) {
+               memcpy(d, s, t-s);
+               d += t-s;
+               memcpy(d, origin, l);
+               d += l;
+               s = t + 7 + 2*(t[1]=='{');
+       }
+       strcpy(d, s);
+       return 0;
+}
+
 static void decode_dyn(struct dso *p)
 {
        size_t dyn[DYN_CNT] = {0};
@@ -457,7 +510,7 @@ static void decode_dyn(struct dso *p)
        if (dyn[0]&(1<<DT_HASH))
                p->hashtab = (void *)(p->base + dyn[DT_HASH]);
        if (dyn[0]&(1<<DT_RPATH))
-               p->rpath = (void *)(p->strings + dyn[DT_RPATH]);
+               p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
        if (search_vec(p->dynv, dyn, DT_GNU_HASH))
                p->ghashtab = (void *)(p->base + *dyn);
        if (search_vec(p->dynv, dyn, DT_VERSYM))
@@ -525,7 +578,7 @@ static struct dso *load_library(const char *name, struct dso *needed_by)
                fd = -1;
                if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
                for (p=needed_by; fd < 0 && p; p=p->needed_by)
-                       if (p->rpath)
+                       if (!fixup_rpath(p, buf, sizeof buf))
                                fd = path_open(name, p->rpath, buf, sizeof buf);
                if (fd < 0) {
                        if (!sys_path) {
@@ -917,6 +970,7 @@ void *__dynlink(int argc, char **argv)
          || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
                env_path = 0;
                env_preload = 0;
+               libc.secure = 1;
        }
 
        /* If the dynamic linker was invoked as a program itself, AT_BASE
@@ -933,6 +987,7 @@ void *__dynlink(int argc, char **argv)
        lib->base = (void *)aux[AT_BASE];
        lib->name = lib->shortname = "libc.so";
        lib->global = 1;
+       lib->kernel_mapped = 1;
        ehdr = (void *)lib->base;
        lib->phnum = ehdr->e_phnum;
        lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
@@ -962,6 +1017,7 @@ void *__dynlink(int argc, char **argv)
                if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
                if (interp_off) lib->name = (char *)app->base + interp_off;
                app->name = argv[0];
+               app->kernel_mapped = 1;
                app->dynv = (void *)(app->base + find_dyn(
                        (void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
                find_map_range((void *)aux[AT_PHDR],