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Linux: Use faccessat2 to implement faccessat (bug 18683)

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This provides correct AT_EACCESS handling and also takes
Linux security modules into account.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
2020-08-07 22:06:59 +02:00
parent 268ed383b5
commit 3d3ab573a5
2 changed files with 19 additions and 3 deletions
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14
sysdeps/unix/sysv/linux/faccessat.c
View File

@ -30,6 +30,13 @@
int int
faccessat (int fd, const char *file, int mode, int flag) faccessat (int fd, const char *file, int mode, int flag)
{ {
int ret = INLINE_SYSCALL_CALL (faccessat2, fd, file, mode, flag);
#if __ASSUME_FACCESSAT2
return ret;
#else
if (ret == 0 || errno != ENOSYS)
return ret;
if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS)) if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS))
return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
@ -41,9 +48,9 @@ faccessat (int fd, const char *file, int mode, int flag)
return -1; return -1;
mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */ mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */
#if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH # if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH
# error Oops, portability assumptions incorrect. # error Oops, portability assumptions incorrect.
#endif # endif
if (mode == F_OK) if (mode == F_OK)
return 0; /* The file exists. */ return 0; /* The file exists. */
@ -68,4 +75,5 @@ faccessat (int fd, const char *file, int mode, int flag)
return 0; return 0;
return INLINE_SYSCALL_ERROR_RETURN_VALUE (EACCES); return INLINE_SYSCALL_ERROR_RETURN_VALUE (EACCES);
#endif /* !__ASSUME_FACCESSAT2 */
} }

8
sysdeps/unix/sysv/linux/kernel-features.h
View File

@ -214,4 +214,12 @@
# define __ASSUME_WAITID_PID0_P_PGID # define __ASSUME_WAITID_PID0_P_PGID
#endif #endif
/* The faccessat2 system call was introduced across all architectures
in Linux 5.8. */
#if __LINUX_KERNEL_VERSION >= 0x050800
# define __ASSUME_FACCESSAT2 1
#else
# define __ASSUME_FACCESSAT2 0
#endif
#endif /* kernel-features.h */ #endif /* kernel-features.h */