load vdso, if present, into the dso list

[musl] / src / ldso / dynlink.c

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 226e174..d8f641a 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -298,7 +298,7 @@ static struct dso *load_library(const char *name)
                                if (!libc->prev) {
                                        tail->next = libc;
                                        libc->prev = tail;
-                                       tail = libc;
+                                       tail = libc->next ? libc->next : libc;
                                }
                                return libc;
                        }
@@ -440,12 +440,15 @@ void *__dynlink(int argc, char **argv, size_t *got)
        size_t *auxv, aux[AUX_CNT] = {0};
        size_t app_dyn[DYN_CNT] = {0};
        size_t lib_dyn[DYN_CNT] = {0};
+       size_t vdso_dyn[DYN_CNT] = {0};
        size_t i;
        Phdr *phdr;
        Ehdr *ehdr;
-       static struct dso builtin_dsos[2];
+       static struct dso builtin_dsos[3];
        struct dso *const app = builtin_dsos+0;
        struct dso *const lib = builtin_dsos+1;
+       struct dso *const vdso = builtin_dsos+2;
+       size_t vdso_base=0;
 
        /* Find aux vector just past environ[] */
        for (i=argc+1; argv[i]; i++)
@@ -455,6 +458,13 @@ void *__dynlink(int argc, char **argv, size_t *got)
 
        decode_vec(auxv, aux, AUX_CNT);
 
+       for (i=0; auxv[i]; i+=2) {
+               if (auxv[i]==AT_SYSINFO_EHDR) {
+                       vdso_base = auxv[i+1];
+                       break;
+               }
+       }
+
        /* Only trust user/env if kernel says we're not suid/sgid */
        if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
          || aux[AT_GID]!=aux[AT_EGID]) {
@@ -495,6 +505,25 @@ void *__dynlink(int argc, char **argv, size_t *got)
                .relocated = 1
        };
 
+       if (vdso_base) {
+               ehdr = (void *)vdso_base;
+               phdr = (void *)(vdso_base + ehdr->e_phoff);
+               for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
+                       if (phdr->p_type == PT_DYNAMIC)
+                               vdso->dynv = (void *)(vdso_base + phdr->p_offset);
+                       if (phdr->p_type == PT_LOAD)
+                               vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
+               }
+               decode_vec(vdso->dynv, vdso_dyn, DYN_CNT);
+               vdso->syms = (void *)(vdso->base + vdso_dyn[DT_SYMTAB]);
+               vdso->hashtab = (void *)(vdso->base + vdso_dyn[DT_HASH]);
+               vdso->strings = (void *)(vdso->base + vdso_dyn[DT_STRTAB]);
+               vdso->name = "linux-gate.so.1";
+
+               vdso->prev = lib;
+               lib->next = vdso;
+       }
+
        /* Relocate the dynamic linker/libc */
        do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]),
                lib_dyn[DT_RELSZ], 2, lib->syms, lib->strings, app);