ELF program properties will needed for detecting whether to enable optional architecture or ABI features for a new ELF process.
For now, there are no generic properties that we care about, so do nothing unless CONFIG_ARCH_USE_GNU_PROPERTY=y. Otherwise, the presence of properties using the PT_PROGRAM_PROPERTY phdrs entry (if any), and notify each property to the arch code. For now, the added code is not used. Signed-off-by: Dave Martin <[email protected]> --- fs/binfmt_elf.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++ fs/compat_binfmt_elf.c | 4 ++ include/linux/elf.h | 21 +++++++++ include/uapi/linux/elf.h | 4 ++ 4 files changed, 138 insertions(+) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index d4e11b2..52f4b96 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -39,12 +39,18 @@ #include <linux/sched/coredump.h> #include <linux/sched/task_stack.h> #include <linux/sched/cputime.h> +#include <linux/sizes.h> +#include <linux/types.h> #include <linux/cred.h> #include <linux/dax.h> #include <linux/uaccess.h> #include <asm/param.h> #include <asm/page.h> +#ifndef ELF_COMPAT +#define ELF_COMPAT 0 +#endif + #ifndef user_long_t #define user_long_t long #endif @@ -690,6 +696,93 @@ static unsigned long randomize_stack_top(unsigned long stack_top) #endif } +static int parse_elf_property(const void **prop, size_t *notesz, + struct arch_elf_state *arch) +{ + const struct gnu_property *pr = *prop; + size_t sz = *notesz; + int ret; + size_t step; + + BUG_ON(sz < sizeof(*pr)); + + if (sizeof(*pr) > sz) + return -EIO; + + if (pr->pr_datasz > sz - sizeof(*pr)) + return -EIO; + + step = round_up(sizeof(*pr) + pr->pr_datasz, elf_gnu_property_align); + if (step > sz) + return -EIO; + + ret = arch_parse_elf_property(pr->pr_type, *prop + sizeof(*pr), + pr->pr_datasz, ELF_COMPAT, arch); + if (ret) + return ret; + + *prop += step; + *notesz -= step; + return 0; +} + +#define NOTE_DATA_SZ SZ_1K +#define GNU_PROPERTY_TYPE_0_NAME "GNU" +#define NOTE_NAME_SZ (sizeof(GNU_PROPERTY_TYPE_0_NAME)) + +static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr, + struct arch_elf_state *arch) +{ + ssize_t n; + loff_t pos = phdr->p_offset; + union { + struct elf_note nhdr; + char data[NOTE_DATA_SZ]; + } note; + size_t off, notesz; + const void *prop; + int ret; + + if (!IS_ENABLED(ARCH_USE_GNU_PROPERTY)) + return 0; + + BUG_ON(phdr->p_type != PT_GNU_PROPERTY); + + /* If the properties are crazy large, that's too bad (for now): */ + if (phdr->p_filesz > sizeof(note)) + return -ENOEXEC; + n = kernel_read(f, ¬e, phdr->p_filesz, &pos); + + BUILD_BUG_ON(sizeof(note) < sizeof(note.nhdr) + NOTE_NAME_SZ); + if (n < 0 || n < sizeof(note.nhdr) + NOTE_NAME_SZ) + return -EIO; + + if (note.nhdr.n_type != NT_GNU_PROPERTY_TYPE_0 || + note.nhdr.n_namesz != NOTE_NAME_SZ || + strncmp(note.data + sizeof(note.nhdr), + GNU_PROPERTY_TYPE_0_NAME, n - sizeof(note.nhdr))) + return -EIO; + + off = round_up(sizeof(note.nhdr) + NOTE_NAME_SZ, + elf_gnu_property_align); + if (off > n) + return -EIO; + + prop = (const struct gnu_property *)(note.data + off); + notesz = n - off; + if (note.nhdr.n_descsz > notesz) + return -EIO; + + while (notesz) { + BUG_ON(((char *)prop - note.data) % elf_gnu_property_align); + ret = parse_elf_property(&prop, ¬esz, arch); + if (ret) + return ret; + } + + return 0; +} + static int load_elf_binary(struct linux_binprm *bprm) { struct file *interpreter = NULL; /* to shut gcc up */ @@ -697,6 +790,7 @@ static int load_elf_binary(struct linux_binprm *bprm) int load_addr_set = 0; unsigned long error; struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL; + struct elf_phdr *elf_property_phdata = NULL; unsigned long elf_bss, elf_brk; int bss_prot = 0; int retval, i; @@ -744,6 +838,11 @@ static int load_elf_binary(struct linux_binprm *bprm) char *elf_interpreter; loff_t pos; + if (elf_ppnt->p_type == PT_GNU_PROPERTY) { + elf_property_phdata = elf_ppnt; + continue; + } + if (elf_ppnt->p_type != PT_INTERP) continue; @@ -839,9 +938,14 @@ out_free_interp: goto out_free_dentry; /* Pass PT_LOPROC..PT_HIPROC headers to arch code */ + elf_property_phdata = NULL; elf_ppnt = interp_elf_phdata; for (i = 0; i < loc->interp_elf_ex.e_phnum; i++, elf_ppnt++) switch (elf_ppnt->p_type) { + case PT_GNU_PROPERTY: + elf_property_phdata = elf_ppnt; + break; + case PT_LOPROC ... PT_HIPROC: retval = arch_elf_pt_proc(&loc->interp_elf_ex, elf_ppnt, interpreter, @@ -852,6 +956,11 @@ out_free_interp: } } + retval = parse_elf_properties(interpreter ?: bprm->file, + elf_property_phdata, &arch_state); + if (retval) + goto out_free_dentry; + /* * Allow arch code to reject the ELF at this point, whilst it's * still possible to return an error to the code that invoked diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c index b7f9ffa..f9ee476 100644 --- a/fs/compat_binfmt_elf.c +++ b/fs/compat_binfmt_elf.c @@ -17,6 +17,8 @@ #include <linux/elfcore-compat.h> #include <linux/time.h> +#define ELF_COMPAT 1 + /* * Rename the basic ELF layout types to refer to the 32-bit class of files. */ @@ -28,11 +30,13 @@ #undef elf_shdr #undef elf_note #undef elf_addr_t +#undef elf_gnu_property_align #define elfhdr elf32_hdr #define elf_phdr elf32_phdr #define elf_shdr elf32_shdr #define elf_note elf32_note #define elf_addr_t Elf32_Addr +#define elf_gnu_property_align elf32_gnu_property_align /* * Some data types as stored in coredump. diff --git a/include/linux/elf.h b/include/linux/elf.h index e3649b3..886ffec 100644 --- a/include/linux/elf.h +++ b/include/linux/elf.h @@ -2,6 +2,7 @@ #ifndef _LINUX_ELF_H #define _LINUX_ELF_H +#include <linux/types.h> #include <asm/elf.h> #include <uapi/linux/elf.h> @@ -21,6 +22,9 @@ SET_PERSONALITY(ex) #endif +#define elf32_gnu_property_align 4 +#define elf64_gnu_property_align 8 + #if ELF_CLASS == ELFCLASS32 extern Elf32_Dyn _DYNAMIC []; @@ -31,6 +35,7 @@ extern Elf32_Dyn _DYNAMIC []; #define elf_addr_t Elf32_Off #define Elf_Half Elf32_Half #define Elf_Word Elf32_Word +#define elf_gnu_property_align elf32_gnu_property_align #else @@ -42,6 +47,7 @@ extern Elf64_Dyn _DYNAMIC []; #define elf_addr_t Elf64_Off #define Elf_Half Elf64_Half #define Elf_Word Elf64_Word +#define elf_gnu_property_align elf64_gnu_property_align #endif @@ -56,4 +62,19 @@ static inline int elf_coredump_extra_notes_write(struct coredump_params *cprm) { extern int elf_coredump_extra_notes_size(void); extern int elf_coredump_extra_notes_write(struct coredump_params *cprm); #endif + +struct arch_elf_state; + +#ifndef CONFIG_ARCH_USE_GNU_PROPERTY +static inline int arch_parse_elf_property(u32 type, const void *data, + size_t datasz, bool compat, + struct arch_elf_state *arch) +{ + return 0; +} +#else +extern int arch_parse_elf_property(u32 type, const void *data, size_t datasz, + bool compat, struct arch_elf_state *arch); +#endif + #endif /* _LINUX_ELF_H */ diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index a3eaad9..f03e3cf 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -368,6 +368,7 @@ typedef struct elf64_shdr { * Notes used in ET_CORE. Architectures export some of the arch register sets * using the corresponding note types via the PTRACE_GETREGSET and * PTRACE_SETREGSET requests. + * The note name for all these is "LINUX". */ #define NT_PRSTATUS 1 #define NT_PRFPREG 2 @@ -430,6 +431,9 @@ typedef struct elf64_shdr { #define NT_MIPS_FP_MODE 0x801 /* MIPS floating-point mode */ #define NT_MIPS_MSA 0x802 /* MIPS SIMD registers */ +/* Note types with note name "GNU" */ +#define NT_GNU_PROPERTY_TYPE_0 5 + /* Note header in a PT_NOTE section */ typedef struct elf32_note { Elf32_Word n_namesz; /* Name size */ -- 2.1.4
