make dynamic linker work around MAP_FAILED mmap failure on nommu kernels

[musl] / src / ldso / dynlink.c

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 42930ad..b77c6f6 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -270,6 +270,7 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
        for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
                if (skip_relative && IS_RELATIVE(rel[1])) continue;
                type = R_TYPE(rel[1]);
+               if (type == REL_NONE) continue;
                sym_index = R_SYM(rel[1]);
                reloc_addr = (void *)(base + rel[0]);
                if (sym_index) {
@@ -422,6 +423,28 @@ static void reclaim_gaps(struct dso *dso)
        }
 }
 
+static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
+{
+       char *q = mmap(p, n, prot, flags, fd, off);
+       if (q != MAP_FAILED || errno != EINVAL) return q;
+       /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
+       if (flags & MAP_ANONYMOUS) {
+               memset(p, 0, n);
+               return p;
+       }
+       ssize_t r;
+       if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
+       for (q=p; n; q+=r, off+=r, n-=r) {
+               r = read(fd, q, n);
+               if (r < 0 && errno != EINTR) return MAP_FAILED;
+               if (!r) {
+                       memset(q, 0, n);
+                       break;
+               }
+       }
+       return p;
+}
+
 static void *map_library(int fd, struct dso *dso)
 {
        Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
@@ -523,19 +546,20 @@ static void *map_library(int fd, struct dso *dso)
                prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
                        ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
                        ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
-               if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
+               if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
                        goto error;
                if (ph->p_memsz > ph->p_filesz) {
                        size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
                        size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
                        memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
-                       if (pgbrk-(size_t)base < this_max && mmap((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
+                       if (pgbrk-(size_t)base < this_max && mmap_fixed((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
                                goto error;
                }
        }
        for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
                if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
-                       if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
+                       if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
+                           && errno != ENOSYS)
                                goto error;
                        break;
                }
@@ -926,7 +950,8 @@ static void reloc_all(struct dso *p)
                do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
 
                if (head != &ldso && p->relro_start != p->relro_end &&
-                   mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
+                   mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ)
+                   && errno != ENOSYS) {
                        error("Error relocating %s: RELRO protection failed: %m",
                                p->name);
                        if (runtime) longjmp(*rtld_fail, 1);
@@ -1191,6 +1216,17 @@ _Noreturn void __dls3(size_t *sp)
        char **argv_orig = argv;
        char **envp = argv+argc+1;
 
+       /* Find aux vector just past environ[] and use it to initialize
+        * global data that may be needed before we can make syscalls. */
+       __environ = envp;
+       for (i=argc+1; argv[i]; i++);
+       libc.auxv = auxv = (void *)(argv+i+1);
+       decode_vec(auxv, aux, AUX_CNT);
+       __hwcap = aux[AT_HWCAP];
+       libc.page_size = aux[AT_PAGESZ];
+       libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
+               || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
+
        /* Setup early thread pointer in builtin_tls for ldso/libc itself to
         * use during dynamic linking. If possible it will also serve as the
         * thread pointer at runtime. */
@@ -1199,25 +1235,11 @@ _Noreturn void __dls3(size_t *sp)
                a_crash();
        }
 
-       /* Find aux vector just past environ[] */
-       for (i=argc+1; argv[i]; i++)
-               if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
-                       env_path = argv[i]+16;
-               else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
-                       env_preload = argv[i]+11;
-       auxv = (void *)(argv+i+1);
-
-       decode_vec(auxv, aux, AUX_CNT);
-
        /* 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] || aux[AT_SECURE]) {
-               env_path = 0;
-               env_preload = 0;
-               libc.secure = 1;
+       if (!libc.secure) {
+               env_path = getenv("LD_LIBRARY_PATH");
+               env_preload = getenv("LD_PRELOAD");
        }
-       libc.page_size = aux[AT_PAGESZ];
-       libc.auxv = auxv;
 
        /* If the main program was already loaded by the kernel,
         * AT_PHDR will point to some location other than the dynamic