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fs/binfmt_elf.c: extract PROT_* calculations 

There are two places where mapping protections are calculated: one for
executable, another one for interpreter -- take them out.

ELF read and execute permissions are interchanged with Linux PROT_READ
and PROT_EXEC, microoptimizations are welcome!

Link: http://lkml.kernel.org/r/20190417213413.GB26474@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan 2019-05-14 15:43:51 -07:00 committed by Linus Torvalds
parent 852643165a
commit d8e7cb39ac
1 changed files with 16 additions and 14 deletions
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30
fs/binfmt_elf.c
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@ -524,6 +524,19 @@ static inline int arch_check_elf(struct elfhdr *ehdr, bool has_interp,
#endif /* !CONFIG_ARCH_BINFMT_ELF_STATE */
static inline int make_prot(u32 p_flags)
{
int prot = 0;
if (p_flags & PF_R)
prot |= PROT_READ;
if (p_flags & PF_W)
prot |= PROT_WRITE;
if (p_flags & PF_X)
prot |= PROT_EXEC;
return prot;
}
/* This is much more generalized than the library routine read function,
so we keep this separate. Technically the library read function
is only provided so that we can read a.out libraries that have
@ -563,16 +576,10 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) {
if (eppnt->p_type == PT_LOAD) {
int elf_type = MAP_PRIVATE | MAP_DENYWRITE;
int elf_prot = 0;
int elf_prot = make_prot(eppnt->p_flags);
unsigned long vaddr = 0;
unsigned long k, map_addr;
if (eppnt->p_flags & PF_R)
elf_prot = PROT_READ;
if (eppnt->p_flags & PF_W)
elf_prot |= PROT_WRITE;
if (eppnt->p_flags & PF_X)
elf_prot |= PROT_EXEC;
vaddr = eppnt->p_vaddr;
if (interp_elf_ex->e_type == ET_EXEC || load_addr_set)
elf_type |= MAP_FIXED_NOREPLACE;
@ -891,7 +898,7 @@ out_free_interp:
the correct location in memory. */
for(i = 0, elf_ppnt = elf_phdata;
i < loc->elf_ex.e_phnum; i++, elf_ppnt++) {
int elf_prot = 0, elf_flags, elf_fixed = MAP_FIXED_NOREPLACE;
int elf_prot, elf_flags, elf_fixed = MAP_FIXED_NOREPLACE;
unsigned long k, vaddr;
unsigned long total_size = 0;
@ -932,12 +939,7 @@ out_free_interp:
elf_fixed = MAP_FIXED;
}
if (elf_ppnt->p_flags & PF_R)
elf_prot |= PROT_READ;
if (elf_ppnt->p_flags & PF_W)
elf_prot |= PROT_WRITE;
if (elf_ppnt->p_flags & PF_X)
elf_prot |= PROT_EXEC;
elf_prot = make_prot(elf_ppnt->p_flags);
elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE;