diff options
Diffstat (limited to 'elf/dl-load.c')
| -rw-r--r-- | elf/dl-load.c | 240 |
1 files changed, 132 insertions, 108 deletions
diff --git a/elf/dl-load.c b/elf/dl-load.c index 12b945a185..b70ba5590a 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -166,6 +166,7 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname) void *file_mapping = NULL; size_t mapping_size = 0; +#define LOSE(s) lose (0, (s)) void lose (int code, const char *msg) { (void) close (fd); @@ -174,6 +175,17 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname) _dl_signal_error (code, l ? l->l_name : name, msg); } + inline caddr_t map_segment (Elf32_Addr mapstart, size_t len, + int prot, int fixed, off_t offset) + { + caddr_t mapat = mmap ((caddr_t) mapstart, len, prot, + fixed|MAP_COPY|MAP_FILE|MAP_INHERIT, + fd, offset); + if (mapat == (caddr_t) -1) + lose (errno, "failed to map segment from shared object"); + return mapat; + } + /* Make sure LOCATION is mapped in. */ void *map (off_t location, size_t size) { @@ -194,6 +206,9 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname) } const Elf32_Ehdr *header; + const Elf32_Phdr *phdr; + const Elf32_Phdr *ph; + int type; /* Look again to see if the real name matched another already loaded. */ for (l = _dl_loaded; l; l = l->l_next) @@ -210,8 +225,6 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname) /* Map in the first page to read the header. */ header = map (0, sizeof *header); -#undef LOSE -#define LOSE(s) lose (0, (s)) /* Check the header for basic validity. */ if (*(Elf32_Word *) &header->e_ident != ((ELFMAG0 << (EI_MAG0 * 8)) | (ELFMAG1 << (EI_MAG1 * 8)) | @@ -242,27 +255,26 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname) _dl_signal_error (errno, NULL, "cannot open zero fill device"); } - { - /* Copy the program header table into stack space so we can then unmap - the headers. */ - Elf32_Phdr phdr[header->e_phnum]; - const Elf32_Phdr *ph; - int anywhere, type; + /* Extract the remaining details we need from the ELF header + and then map in the program header table. */ + l->l_entry = header->e_entry; + type = header->e_type; + l->l_phnum = header->e_phnum; + phdr = map (header->e_phoff, l->l_phnum * sizeof (Elf32_Phdr)); - type = header->e_type; - anywhere = type == ET_DYN || type == ET_REL; - l->l_entry = header->e_entry; - - ph = map (header->e_phoff, header->e_phnum * sizeof (Elf32_Phdr)); - memcpy (phdr, ph, sizeof phdr); - l->l_phnum = header->e_phnum; - - /* We are done reading the file's headers now. Unmap them. */ - munmap (file_mapping, mapping_size); + { + /* Scan the program header table, collecting its load commands. */ + struct loadcmd + { + Elf32_Addr mapstart, mapend, dataend, allocend; + off_t mapoff; + int prot; + } loadcmds[l->l_phnum], *c; + size_t nloadcmds = 0; - /* Scan the program header table, processing its load commands. */ - l->l_addr = 0; l->l_ld = 0; + l->l_phdr = 0; + l->l_addr = 0; for (ph = phdr; ph < &phdr[l->l_phnum]; ++ph) switch (ph->p_type) { @@ -277,114 +289,126 @@ _dl_map_object_from_fd (const char *name, int fd, char *realname) break; case PT_LOAD: - /* A load command tells us to map in part of the file. */ + /* A load command tells us to map in part of the file. + We record the load commands and process them all later. */ if (ph->p_align % pagesize != 0) LOSE ("ELF load command alignment not page-aligned"); if ((ph->p_vaddr - ph->p_offset) % ph->p_align) LOSE ("ELF load command address/offset not properly aligned"); { - Elf32_Addr mapstart = ph->p_vaddr & ~(ph->p_align - 1); - Elf32_Addr mapend = ((ph->p_vaddr + ph->p_filesz + ph->p_align - 1) - & ~(ph->p_align - 1)); - off_t mapoff = ph->p_offset & ~(ph->p_align - 1); - caddr_t mapat; - int prot = 0; + struct loadcmd *c = &loadcmds[nloadcmds++]; + c->mapstart = ph->p_vaddr & ~(ph->p_align - 1); + c->mapend = ((ph->p_vaddr + ph->p_filesz + ph->p_align - 1) + & ~(ph->p_align - 1)); + c->dataend = ph->p_vaddr + ph->p_filesz; + c->allocend = ph->p_vaddr + ph->p_memsz; + c->mapoff = ph->p_offset & ~(ph->p_align - 1); + c->prot = 0; if (ph->p_flags & PF_R) - prot |= PROT_READ; + c->prot |= PROT_READ; if (ph->p_flags & PF_W) - prot |= PROT_WRITE; + c->prot |= PROT_WRITE; if (ph->p_flags & PF_X) - prot |= PROT_EXEC; + c->prot |= PROT_EXEC; + break; + } + } - if (anywhere) - { - /* XXX this loses if the first segment mmap call puts - it someplace where the later segments cannot fit. */ - mapat = mmap ((caddr_t) (l->l_addr + mapstart), - mapend - mapstart, - prot, MAP_COPY|MAP_FILE|MAP_INHERIT | - /* Let the system choose any convenient - location if this is the first segment. - Following segments must be contiguous in - virtual space with the first. */ - (l->l_addr == 0 ? 0 : MAP_FIXED), - fd, mapoff); - if (l->l_addr == 0) - /* This was the first segment mapped, so MAPAT is - the address the system chose for us. Record it. */ - l->l_addr = (Elf32_Addr) mapat - mapstart; - } - else - { - mapat = mmap ((caddr_t) mapstart, mapend - mapstart, - prot, MAP_COPY|MAP_FILE|MAP_INHERIT|MAP_FIXED, - fd, mapoff); - /* This file refers to absolute addresses. So consider its - "load base" to be zero, since that is what we add to the - file's addresses to find them in our memory. */ - l->l_addr = 0; - } - if (mapat == (caddr_t) -1) - lose (errno, "failed to map segment from shared object"); + /* We are done reading the file's headers now. Unmap them. */ + munmap (file_mapping, mapping_size); + + /* Now process the load commands and map segments into memory. */ + c = loadcmds; + + if (type == ET_DYN || type == ET_REL) + { + /* This is a position-independent shared object. We can let the + kernel map it anywhere it likes, but we must have space for all + the segments in their specified positions relative to the first. + So we map the first segment without MAP_FIXED, but with its + extent increased to cover all the segments. Then we unmap the + excess portion, and there is known sufficient space there to map + the later segments. */ + caddr_t mapat; + mapat = map_segment (c->mapstart, + loadcmds[nloadcmds - 1].allocend - c->mapstart, + c->prot, 0, c->mapoff); + l->l_addr = (Elf32_Addr) mapat - c->mapstart; + + /* Unmap the excess portion, and then jump into the normal + segment-mapping loop to handle the portion of the segment past + the end of the file mapping. */ + munmap (mapat + c->mapend, + loadcmds[nloadcmds - 1].allocend - c->mapend); + goto postmap; + } + + while (c < &loadcmds[nloadcmds]) + { + if (c->mapend > c->mapstart) + /* Map the segment contents from the file. */ + map_segment (l->l_addr + c->mapstart, c->mapend - c->mapstart, + c->prot, MAP_FIXED, c->mapoff); + + postmap: + if (c->allocend > c->dataend) + { + /* Extra zero pages should appear at the end of this segment, + after the data mapped from the file. */ + Elf32_Addr zero, zeroend, zeropage; + + zero = l->l_addr + c->dataend; + zeroend = l->l_addr + c->allocend; + zeropage = (zero + pagesize - 1) & ~(pagesize - 1); - if (ph->p_memsz > ph->p_filesz) + if (zeroend < zeropage) + /* All the extra data is in the last page of the segment. + We can just zero it. */ + zeropage = zeroend; + + if (zeropage > zero) { - /* Extra zero pages should appear at the end of this segment, - after the data mapped from the file. */ - caddr_t zero, zeroend, zeropage; - - mapat += ph->p_vaddr - mapstart; - zero = mapat + ph->p_filesz; - zeroend = mapat + ph->p_memsz; - zeropage = (caddr_t) ((Elf32_Addr) (zero + pagesize - 1) - & ~(pagesize - 1)); - - if (zeroend < zeropage) - /* All the extra data is in the last page of the segment. - We can just zero it. */ - zeropage = zeroend; - if (zeropage > zero) + /* Zero the final part of the last page of the segment. */ + if ((c->prot & PROT_WRITE) == 0) { - /* Zero the final part of the last page of the segment. */ - if ((prot & PROT_WRITE) == 0) - { - /* Dag nab it. */ - if (mprotect ((caddr_t) ((Elf32_Addr) zero - & ~(pagesize - 1)), - pagesize, - prot|PROT_WRITE) < 0) - lose (errno, "cannot change memory protections"); - } - memset (zero, 0, zeropage - zero); - if ((prot & PROT_WRITE) == 0) - mprotect ((caddr_t) ((Elf32_Addr) zero - & ~(pagesize - 1)), - pagesize, prot); + /* Dag nab it. */ + if (mprotect ((caddr_t) (zero & ~(pagesize - 1)), + pagesize, c->prot|PROT_WRITE) < 0) + lose (errno, "cannot change memory protections"); } + memset ((void *) zero, 0, zeropage - zero); + if ((c->prot & PROT_WRITE) == 0) + mprotect ((caddr_t) (zero & ~(pagesize - 1)), + pagesize, c->prot); + } - if (zeroend > zeropage) - /* Map the remaining zero pages in from the zero fill FD. */ - mapat = mmap (zeropage, zeroend - zeropage, prot, - MAP_ANON|MAP_PRIVATE|MAP_FIXED|MAP_INHERIT, - _dl_zerofd, 0); + if (zeroend > zeropage) + { + /* Map the remaining zero pages in from the zero fill FD. */ + caddr_t mapat; + mapat = mmap ((caddr_t) zeropage, zeroend - zeropage, c->prot, + MAP_ANON|MAP_PRIVATE|MAP_FIXED|MAP_INHERIT, + _dl_zerofd, 0); + if (mapat == (caddr_t) -1) + lose (errno, "cannot map zero pages"); } } - } - if (l->l_ld == 0) - { - if (type == ET_DYN) - LOSE ("object file has no dynamic section"); + ++c; } - else - (Elf32_Addr) l->l_ld += l->l_addr; + } - if (l->l_phdr == 0) - l->l_phdr = (void *) ((const Elf32_Ehdr *) l->l_addr)->e_phoff; - (Elf32_Addr) l->l_phdr += l->l_addr; + if (l->l_ld == 0) + { + if (type == ET_DYN) + LOSE ("object file has no dynamic section"); + } + else + (Elf32_Addr) l->l_ld += l->l_addr; - l->l_entry += l->l_addr; - } + if (l->l_phdr == 0) + l->l_phdr = (void *) ((const Elf32_Ehdr *) l->l_addr)->e_phoff; + (Elf32_Addr) l->l_phdr += l->l_addr; elf_get_dynamic_info (l->l_ld, l->l_info); if (l->l_info[DT_HASH]) |